Henry's Home: May 2018

Monday, May 21, 2018

Moss

What is a Moss

Moss is a type of non-vascular plant, classified in the division Bryophyta in the kingdom Plantae. Moss, while typically associated with dark, damp environments, has actually adapted to occupy many drier, sunny regions. There are over 12,000 species of moss recognized, which span 8 classes and 23 different genera.

Examples of Moss

Bryopsida

The Bryopsida, the largest class of mosses, contains most of the recognized species. A typical species can be seen above. In this image the gametophyte form is seen, as the sporophytes have not developed. Moss in the class Bryopsida can be found all over the world and grows on nearly any available surface, from concrete to bare fields, given the right conditions. In all, there are over 11,500 species of moss in the class. Before genetic and anatomical evidence suggested the division of more classes, all species of moss were found within this class.

Andreaeobryopsida

The moss found in the class Andreaeobryopsida represents only a couple species. These moss species are endemic to only a few parts of Alaska and Western Canada. These moss plants have developed a unique tolerance to the climate in this region. This, plus differences in their genetics and the development of their spore capsules, led scientists to remove them from the Bryopsida and into their own unique class. Many of the other types of mosses have been divided into their own classes, eight in total. However, the large majority are still classified as Bryopsida.

Types of Moss

While there are not necessarily different types of moss, there are currently 8 recognized classes, which are distinguished by their genetics, anatomy, and physiology. Importantly, scientists look at their reproduction habits and structures to help identify and categorize the various moss groups. The eight different classes are listed below:

Takakiopsida

Sphagnopsida

Andreaeopsida

Andreaeobryopsida

Oedipodiopsida

Polytrichopsida

Tetraphidopsida

Bryopsida

As an example, the Sphagnopsida class holds the genus Sphagnum, which has important industrial uses. This moss, known for creating thick sheets of moss over large areas, can be commercially harvested as peat. The moss can be identified by the way it grows, which is in large flat sheets. Further, Sphagnum moss species have a unique way of spreading their spores. Instead of mildly cracking open the case surrounding the spores and letting them fall out, the moss in this class use a more explosive strategy. By compressing air in the chamber, pressure builds. The cells of the sporophyte continue this process until the operculum holding the spores back ruptures. This shoots the spores into the air, like a “party-popper” or overfilled balloon. This greatly increases the area the spores can reach and is unique to the class.

Life Cycle of Mosses

Like all plants, moss species show an alternation of generations, in which two different classes of individuals carry out separate parts of the reproductive process. In a system like this, one organism, the sporophyte, is a diploid organism which creates haploid spores through the process of meiosis. In the picture below, the tall stems with small structures at the top are the sporophyte.

However, after the sporophyte generation has released the spores, it dies off. The spores find a place to settle, and develop into a haploid organism, the gametophyte. This is the dominant structure of moss, what you typically see if the moss is not reproducing. This can be seen in the image at the base of the sporophyte, much shorter and seemingly a different species. The gametophyte is responsible for producing gametes, which are capable of fusing together. Look at the image below, of moss reproduction.

In the top left of the image, fertilization is occurring. Sperm and eggs, gametes, are produced in special organs of the gametophyte. The sperm are released into the environment, and travel to the archegonial head, which houses the egg. Once the sperm fertilizes the egg, the zygote is formed. The zygote will develop into the sporophyte, which actually grows out of the gametophyte. The sporophyte, again a diploid organism after the fusion of two haploid gametes, is responsible for undergoing meiosis, and starting the process over again.

Further, many moss species have the ability to reproduce asexually using bundles of cells called gemmae. These cells, produced on the gametophyte, fall off when exposed to running water. This allows them to be carried to a new location, where an entire new plant can be established. If you have ever seen moss growing below a drip of water, this is likely the route in which it got there. Sexual reproduction takes a lot of energy, and is generally good for diversifying the genetic pool. Asexual reproduction is much faster, and can happen every time it rains.

Within this life cycle, some moss species have the same sex represented on one gametophyte, while others have different gametophytes for different sexes. This is another way in which moss species can be distinguished and identified against each other.

Commercial Uses of Moss

The main commercial use of moss is as peat, a renewable fuel source. As the moss grows, it pushes down old moss and creates dense mats of biofuel. The peat can be burnt in a fire or stove, as it has been for centuries in many different countries. Peat moss can also be used as a fertilizer and growing medium for various commercially important plants and mushrooms. Even Scottish whiskey famously uses peat fires to smoke the malt, giving the whiskey a distinct flavor.

Moss is also becoming a more important and widespread landscaping plant. Several cultures, like the Japanese, have used moss for centuries as a way to decorate an outdoor space. Like a grass turf lawn, it is comfortable, pleasingly green, and easy to maintain. In more extreme uses, it can even be used as a base for a green roof, a new conservation technique aimed at reducing the urban heat effect.

In the past, moss has even had uses in the medical and consumer fields. Moss, when dried, is extremely absorbent. Even more absorbent than cotton. This lead to the use of moss in bandages for wounded soldiers. Some even claimed that the moss had antibacterial properties, which helped wounds heal. Further, moss has been used as a diaper alternative product in several countries. Moss, which is completely biodegradable, is said to outperform many plastic and cotton products used today.

Quiz

1. If moss can reproduce asexually, what is the benefit of reproducing sexually?
A. It uses less energy
B. It takes less time
C. It recombines and diversifies the gene’s an organism can use

Answer to Question #1

2. You identify a new form of plant. It is small, with tiny leaves that resemble moss. You take a closer look at the stem under the microscope. There are small bundles of vascular tissue, clearly distinguished from the rest. You determine that this new species is:
A. A moss
B. Not a moss
C. Impossible to tell

Answer to Question #2

3. A small insect, the springtail, is attracted to moss, and may be responsible for pollinating the moss plants. If an insecticide is developed which targets theses insects, how could the energy industry be affected?
A. It cannot be affected by an insect
B. The moss making peat could die, affecting energy consumers
C. The moss would reproduce more, making energy cheaper

Answer to Question #3

References

Hartwell, L. H., Hood, L., Goldberg, M. L., Reynolds, A. E., & Silver, L. M. (2011). Genetics: From Genes to Genomes. Boston: McGraw Hill.

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

Rubinstein, C. V., Gerrienne, P., de la Puente, G., Astini, R. A., & Steemans, P. (2010). Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana). New Phytologist, 188(2).

Moss

Liverworts

Liverworts Definition

Liverworts, like the species seen above, represent a branch of non-vascular plants, most of which are terrestrial. The name “liverworts” is derived from the belief in ancient times that the diseases of the liver could be cured with these plants. Liverworts are part of the kingdom Plantae, in the division Marchantiophyta. While the plants are small, and often overlooked, liverworts can be found globally, wherever plants can grow.

Liverwort Life Cycle

Liverworts, like most plants, display an alternation of generations between a haploid organism and a diploid organism. The general outline of this type of lifecycle can be seen below.

In alternation of generations, a single species displays multiple forms. There is the sporophyte, which is capable of producing haploid spores. These spores cannot fuse together like gametes, and instead they grow into a new organism, the gametophyte. The gametophyte is still haploid, but grows into a multicellular organism. The gametophyte can produce gametes, which are similar to spores except they will not grow into a new organism directly. Instead, gametes undergo fusion or fertilization, and form a new cell, the zygote.

The zygote, now a diploid organism, grows to be multicellular. It develops special organs capable of meiosis, a type of cell division which reduces the amount of DNA. Through this process, the spores produced are haploid, again. This means that they carry only 1 copy of DNA. They are released into the environment, and the process can start over. Sporophytes and gametophytes typically look and form differently, although this is not always the case. In the case of liverworts, the sporophyte and gametophyte versions are very different. Look at the image below.

In liverworts, the gametophyte is the dominant life cycle. This means that liverworts are typically haploid organisms. In the image above, you will see two gametophytes. Liverworts are also dioicous, meaning they have haploid gametophytes with separate sexes. The male plants produce an antheridial head, capable of producing sperm. The female archegonial head produces an egg. The sperm are dispersed from the male gametophytes, and are carried by wind or water to the egg found on another plant.

When the sperm fertilizes the egg, an embryo is formed. This is the sporophyte, and in liverworts it will not get very big. The liverwort sporophyte develops into the microscopic seta. The seta, or mature sporophyte, is completely dependent on the gametophyte for food and survival, and lives within the archegonium its entire life. The seta is responsible for conducting meiosis, and creating the haploid spores. The spores will be released into the environment, and will grow into adult gametophytes. The image shows the development of the first rhizoids on the spore, which will become a rudimentary root system for the grown gametophyte.

In most other terrestrial plants, the opposite of the liverworts is true. Typically, the sporophyte class is the much more represented species. In ferns and all higher vascular plants, the sporophyte is the one we see, while the gametophyte has been heavily reduced. A flower, for example, houses the entire gametophyte in most flowering plants. A single pollen grain is actually the male gametophyte, and produces sperm. The seed which is formed is the zygote, and will produce the sporophyte. Spores are produced, but instead of being released to form large gametophytes, they are retained within the plant to form small gametophytes. These gametophyte individuals then produce gametes, and the process repeats. Liverworts do the opposite of this process.

In compared with human biology, the liverwort lifecycle and alternation of generations can seem very different. However, humans also produce sperm and egg cells, which are haploid. Really, the only difference lies in when and how fertilization takes place. In humans and most other sexually reproducing animals, meiosis leads to single cells which undergo fertilization and create a new organism. In the alternation of generations, there is simply another step after meiosis. In this step, the haploid cell undergoes mitosis, growing into a multicellular organism. This structure or organism then produces the gametes, which can fuse together to create a zygote.

However, this is not the only way liverworts can reproduce. Take a look at the image above again. You will notice that the gametophytes both have small cups, called gemma cups. These cups contain small clusters of cells known as gemmae. When rain or water spashes into the cup, the gemmae are dispersed from the plant, and are capable of growing into full gametophytes in the right conditions. While liverworts have the ability to reproduce through the above mentioned process of alternation of generations, this much simpler process of asexual reproduction probably accounts for a large percentage of the plant’s reproduction and dispersal.

Evolutionary History of Liverworts

Like all terrestrial plants, vascular and non-vascular, liverworts appear to have their beginnings in the Ordovician period, the second of six Paleozoic Era periods. Nearly 485 million years ago, the Cambrian period came to a close, as the Ordovician opened. At this time, shallow seas covered much of a landmass known as Gondwana, a continent composed of modern Africa, South America, India, and Antarctica. The shallow sea supposedly allowed the development of the first non-vascular plants, including descendants of liverwort.

The emergence of the embryophytes, or land plants, greatly changed the atmosphere of the early world. The atmosphere was composed heavily of carbon dioxide, and contained little oxygen. As plants like ancient liverworts began to emerge, they consumed the carbon dioxide and released oxygen. This drastic changing of global chemistry would later lead to climate change and massive extinction events. Unlike liverwort, vascular plants had a distinct advantage in transporting and holding water. However, in the 485 million years since the emergence of land plants, both types have colonized nearly every terrestrial space. Liverworts and other non-vascular plants can be found in deserts, and in cold northern latitudes as well.

Liverworts, once thought to be firmly related to the ferns, have more recently been given their own subdivision. The ferns show an opposing alternation of generations. Unlike liverworts, they show a dominate sporophyte. It is now thought that ferns are more closely related to gymnosperms (conifers) and flowering plants. Liverworts, therefore, represent an ancient and mostly unchanged division of some of the first terrestrial organisms to ever come out of the water. The argument of whether to include the liverworts within the Bryophyte (moss) grouping is an ongoing debate, but recent classifications have kept them in their own division.

Quiz

1. Which of the following structures produces gametes within liverworts?
A. Spore
B. Gametophyte
C. Sporophyte

Answer to Question #1

2. Why are the liverworts considered closely related to moss?
A. They aren’t closely related
B. They are both plants
C. They are both non-vascular and exhibit an alternation of generations

Answer to Question #2

3. Which of the following most accurately describes the liverwort life cycle?
A. Alternation of Generations with Sporophyte dominance
B. Sexual reproduction alone
C. Asexual reproduction and Sexual reproduction through alternating generations, featuring a dominant gametophyte

Answer to Question #3

References

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2014). Campbell Biology, Tenth Edition (Vol. 1). Boston: Pearson Learning Solutions.

Rubinstein, C. V., Gerrienne, P., de la Puente, G., Astini, R. A., & Steemans, P. (2010). Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana). New Phytologist, 188(2).

Liverworts

Vascular Tissue

Vascular Tissue Definition

Vascular tissue is an arrangement of multiple cell types in vascular plants which allows for the transport of water, minerals, and products of photosynthesis to be transported throughout the plant. Non-vascular plants, such as some algae and moss, do not have vascular tissue and therefore cannot easily transport water and nutrients. Vascular plants use their vascular tissue to transport water and nutrients to great heights, able to feed the tops of trees hundreds of feet high.

Types of Vascular Tissue

Xylem

Xylem is a specialized type of vascular tissue created in vascular plants to transport water and nutrients from the roots of a plant to the tips of the leaves. Every cell in the plant needs water and minerals to survive, and complete necessary reactions. The xylem is created from hollow, dead cells. Water is absorbed into the roots, which creates a positive pressure on the water inside the column. As water evaporates out of the leaves, the process of transpiration pulls water into the leaves. In this way, the xylem serves as a straw, allowing water to carry minerals upwards through the plant.

Phloem

At the same time, the plant is producing sugars via photosynthesis, which must be transported downwards, to the stem and root cells. Another vascular tissue, the phloem, accounts for this process. Unlike the xylem, this vascular tissue is made up of living cells. The so-called sieve cells are connected via a thin membrane called the sieve plate. Through this channel of phloem cells sugar is transported throughout the plant. Unlike water, sugar is thick and sappy. The phloem requires inputs of water from the xylem and specialized proteins to help quickly pass the sugars through the plant.

Structure of Vascular Tissue

In different species of plants, vascular tissue is arranged differently. Typically, the cells are long, narrow, and tubular. The vascular tissue is also often arranged into bundles within the stem or leaf. Below is a comparison of the vascular tissue found in monocot and dicot plants.

As you can see, the vascular bundles in dicots are much larger and more consistently arranged. Monocot species, on the other hand, spread the xylem and phloem of the vascular tissue around throughout the stem. These two methods reflect the structure of the plants themselves. Monocots tend to be plants like grasses, which have veins and leaves which run in parallel. In dicots, such as many flowering trees and fruiting plants, the leaves and veins in the leaves branch off in various patterns. This organization favors a vascular tissue which is more organized, and can branch as the plant grows.

In woody dicots, the vascular tissue is even more organized, with a vascular cambium layer producing xylem on the inside and phloem on the outside. These layers are produced seasonally, which give woody plants their characteristic “rings”. By adding to the vascular tissue every season, these plants can handle an increase in growth and become very large. Some monocots such as palms have adopted a secondary growth technique while maintaining a scattered arrangement of vascular tissue.

Functions of Vascular Tissue

Vascular tissue functions mainly in maintaining the water balance and sugar balance of a plant. Not only does the plant’s cells need water to complete basic biological functions, they also need the minerals and nutrients found in the soil to complete their work. Most plants have small pores in the leaves called stoma, which allow water to evaporate and gases to exchange. To get more water and nutrients into the cells of leaves, these small pores open.

As the water evaporates, the forces of adhesion and cohesion pull the water up the tubes of the xylem. As water is absorbed through the roots, this also creates a pressure from the bottom to force the water upward. The tubes of the xylem are narrow to support this action, but there are many of them bundled together. The xylem portion of the vascular tissue can be seen below, on the left.

As the water moves up and into the leaves, some of it is needed to dissolve the sugars created by photosynthesis and carry them back down the plant. Remember that photosynthesis creates glucose, which the plant will use as energy. The plant combines glucose molecules to create sucrose, a temporary storage sugar. The root cells, and other cells in the stems and leaves, do not create their own glucose and rely on the plant to provide them energy. The phloem cells work to transport this created energy all throughout the plant from source cells, like leaves, to sink cells, such as those in the roots. The vascular tissue is also responsible for controlling the flow of nutrients when the plant is creating flowers and fruits, which drastically affects the process.

Farmers have learned to manipulate the vascular system of plants in various ways to modify their crops in various ways. For instance, by damaging the vascular tissue below a fruit on a branch, the sugars will be translocated to the fruit. While the roots may suffer, the fruit will become much larger as a result. This is called girdling, and is one of many techniques used to alter the flow of nutrients within a plant by modifying the vascular tissue.

Quiz

1. Which of the following is NOT a vascular tissue?
A. Xylem
B. Phloem
C. Meristem

Answer to Question #1

2. Why is phloem made of living cells, while xylem is made of dead cells?
A. No reason
B. Phloem is involved in active transport, Xylem is not
C. Phloem is a newer tissue, Xylem has simply died

Answer to Question #2

3. Why can vascular plants be much taller than non-vascular plants?
A. They can transfer nutrients higher
B. They need less water
C. They need less sunlight

Answer to Question #3

References

Hartwell, L. H., Hood, L., Goldberg, M. L., Reynolds, A. E., & Silver, L. M. (2011). Genetics: From Genes to Genomes. Boston: McGraw Hill.

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

Nelson, D. L., & Cox, M. M. (2008). Principles of Biochemistry. New York: W.H. Freeman and Company.

Vascular Tissue

Vascular Tissue Definition

Types of Vascular Tissue

Xylem

Phloem

Structure of Vascular Tissue

Functions of Vascular Tissue

Quiz

1. Which of the following is NOT a vascular tissue?
A. Xylem
B. Phloem
C. Meristem

Answer to Question #1

2. Why is phloem made of living cells, while xylem is made of dead cells?
A. No reason
B. Phloem is involved in active transport, Xylem is not
C. Phloem is a newer tissue, Xylem has simply died

Answer to Question #2

3. Why can vascular plants be much taller than non-vascular plants?
A. They can transfer nutrients higher
B. They need less water
C. They need less sunlight

Answer to Question #3

References

Hartwell, L. H., Hood, L., Goldberg, M. L., Reynolds, A. E., & Silver, L. M. (2011). Genetics: From Genes to Genomes. Boston: McGraw Hill.

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

Nelson, D. L., & Cox, M. M. (2008). Principles of Biochemistry. New York: W.H. Freeman and Company.

Vascular Tissue

Fauna

Fauna Definition

Fauna is a term which refers to all of the animal life within a specified region, time period, or both. The “flora and fauna” of a certain place is a descriptor of all the life in a region, including both the plant-like organisms and the animal-like organisms. However, while this was once used as a scientific term, advances in science and our understanding of the relationships between organisms has forced science to adopt the more descriptive systems of taxonomy and cladistics to describe the relationships between organisms.

History of Fauna

Fauna was first used as a biological term by naturalist Carl Linnaeus, as a term which described the animals of a region, as opposed to the plants. Plant life was dubbed flora. Thus, the flora and fauna of a region or time describe all of the life within. Linnaeus seems to have borrowed the term from Greek and Roman mythology.

In Greek mythology, the god Pan is the goat-legged offspring of a more powerful god and a wood nymph. This leads him to become the representative god of the wild. Roman mythology adopted this persona in the gods Faunus and Fauna, which gave rise to a number of man-creatures which populated the mythology. Linnaeus adopted the word for his formal work on the animals of Sweden Fauna Suecica, in 1745. Roughly translated, this means the “wildlife of Sweden”.

Following his lead, naturalists began to use the terms flora and fauna to identify the various living organisms in a taxonomic hierarchy. Flora included everything in the kingdom Plantae, while fauna included the kingdom Animalia. The definition of fauna has expanded and changed over the years. For instance, when genotyping became a reality and it was understood that there are actually 3 domains of life, the Archaea, Bacteria, and the Eukarya.

With this change came the formal phasing out of the word fauna, scientifically. While the word flora had maintained its definition as “any organism within the kingdom Plantae”, fauna had changed drastically. Fauna, as used currently, typically describes any organisms in the domains Archaea and Bacteria, plus the kingdom Animalia. This is not a monophyletic grouping, and as such does not accurately describe anything for scientists trying to organize the forms of life in a place or time. Further, flora and fauna tend to exclude the kingdom Fungi, which was once recognized as a plant but is now recognized as its own kingdom.

Examples of Fauna

Fauna of the Great Plains, 2018

If you were to conduct a survey, today, of all the fauna in the Great Plains of the United States, you would find a great many species. You would find many species of birds, from pheasants to eagles. You would find mammals, from the tiny field mouse to the mighty bison. Most other groups, from the reptiles to the worms, would also be represented. You would surely find an abundance of insects. On the microscopic level, the soil and waters are teeming with fauna. Even waters too acidic or hot for the normal fauna can host thermophilic or acidophilic bacteria and other organisms, evolved to deal with the harsh conditions. In essence, if you take the entirety of life on the Great Plains today, subtract all the plants, you have a representation of the fauna. This is obviously a large and intangible collection of many different inter-related species.

Fauna of the Great Plains, 100 Million Years Ago

If we could take ourselves back in time, the fauna of the Great Plains would look much different. Although we would remain in the same place, the environment would be very different. At that time, glaciers had melted to a low, and a vast inland sea had spread across the continental United States. The Great Plains was almost entirely covered by a vast inland sea, as seen in the image below.

In this inland sea would have existed a variety of monsters, from the first modern sharks, to giant marine reptiles like Ichthyosaur and Plesiosaur. Modern bony fishes were evolving, as well as a variety of other marine organism. In this vast sea, you could have found everything from early starfish, to horseshoe crabs, to all sorts of evolving arthropods. Other fauna of the historical Great Plains would include the microscopic diatoms and zooplankton and algae, which would have been the base of the food-chain at the time. As the glaciers reformed, the land was colonized by the terrestrial organisms we know today. You can see how the fauna of a region can easily change over time.

Gut Fauna

A popular term these days is “gut fauna”, or in other words, the creatures living inside of your digestive tract. Humans, like almost all other animals, have a complex symbiotic relationship with the organism harbored within them. While there are barriers in place to keep these organisms from infecting the body, they are essential to digesting many types of food. Technically speaking, the fauna in the gut is referred to as the microbiome, because it is its own unique ecosystem. There are many species of bacteria and eukaryotes which take part in digestion, and each fills a unique niche in the ecosystem. While scientists have yet to fully understand the microbiome of the digestive system, there are many diets and probiotics on the market which claim to positively affect the fauna of the microbiome. These claims have yet to be confirmed by mainstream science.

Quiz

1. Which of the following would NOT be considered fauna?
A. Palm tree
B. Crocodile
C. Jellyfish

Answer to Question #1

2. Why is the term “flora and fauna” no longer used in science?
A. It is still used by many scientists
B. There are more accurate terms for describing relationships between species
C. The terms are accurate, they simply fell out of fashion

Answer to Question #2

3. If someone were to refer to “The Fauna of Europe”, with no other context, which of the following would most accurately represent that statement?
A. A the living animals in Europe
B. All members of the kingdom Animalia, within Europe, throughout history
C. Any organism NOT in the kingdom Plantae, found within the bounds of modern day Europe, through time

Answer to Question #3

References

Brusca, R. C., & Brusca, G. J. (2003). Invertebrates. Sunderland, MA: Sinauer Associates, Inc.

Darwin, C., & Wallace, A. (1980). On the Tendency of Species to Form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection. In P. H. Barrett (Ed.), The Collected Papers of Charles Darwin (Vol. 2, pp. 3-18). Chicago: The University of Chicago Press.

Helfman, G. S., Collette, B. B., Facey, D. E., & Bowen, B. W. (2009). The Diversity of Fishes: Biology, Evolution, and Ecology. Oxford: Wiley-Blackwell.

Fauna

Threatened Species

Threatened Species Definition

A threatened species is any species which is vulnerable, endangered, or critically endangered. The International Union for Conservation of Nature, or IUCN, is commonly referenced as a leading organization in determining if a species can be considered a threatened species or not. The IUCN also defines the category nearly-threatened species, for any animals which are likely to become threatened species within the foreseeable future. The IUCN designation of threatened species can be seen below.

Other organizations may define a threatened species slightly differently. For instance, the United States Endangered Species Act defines a threatened species as any species which is likely to become endangered within the foreseeable future. However, most international organizations and conservation societies tend to use the definition of the IUCN. The difference is only subtle, and either way, a threatened species is one which is likely to go extinct if nothing is done to protect it.

Criteria for a Threatened Species

Population Size Decline

While the criteria for each organization differs, the following are general criteria developed by the IUCN and other organizations to determine if a species can be labeled a threatened species. One of the most important markers of a threatened species is the population size, and its overall direction. A small, decreasing population is much more likely to be threatened than a small, increasing population. Scientists typically measure a population using mark-recapture studies. In these studies, a portion of the population is captured and marked somehow. They are then released. After time has passed, another portion is captured. Based on the percentage of the recapture which have marks, the scientists can estimate the total population. Thus, they can see if a population is very small by capturing the same individuals repeatedly.

Further, the population must be observed over several generations, ideally, to have enough data to truly see decline in a population. Sometimes, there are not enough animals left for 3 generations, and these species would be a critically endangered threatened species. In larger populations it is helpful to observe multiple generations to be sure that the population is not simply adjusting to a predator and prey dynamic, or other natural cycle which. Some natural cycles can severely affect population numbers, but the general trend in the population can still be increasing. Data which effectively shows that this is not true, and that the population is declining generation-over-generation will be more effective in showing that species truly is threatened.

Number of Mature Individuals

Along those lines, scientist must also measure and separate the number of sexually active adults in the population. A sea-turtle, for instance, can lay hundreds of eggs each season. It would be inaccurate, however, to consider all of those offspring as contributing to the next generation. The fact for sea-turtles, and many other animals, is that many offspring will not make it to sexual maturity. In calculating a threatened species, it is more important to focus on the individuals which have already reached maturity and are actively reproducing.

Due to the limitations of a small genetic pool, the number of reproducing individuals must be relatively high for any population to have a good chance at long term survival. Anything less than 10,000 mature, reproducing adults is usually considered a threatened species, when the other criteria are also met. This is usually based on genetic models. Small populations are typically subject to conditions like genetic drift and population bottlenects, which can easily drive them to extinction in only a few generations. When a threatened species has less than 250 known mature individuals, it is typically considered critically endangered. Further, if a declining trend is seen in the reproducing adults, this can also be grounds for labeling a threatened species.

Geographic Range

Almost as important as the number of individuals is the geographic range of a threatened species. A species with a cosmopolitan distribution (found globally) is unlikely to be in danger of going extinct. However, if the reproducing adults in that range are actually separated and cannot reproduce, the possibility of extinction increases. This phenomenon is known as fragmentation. It can be natural, such as an impassable mountain range, or man-made, like a highway. Either way, if a species cannot cross the barrier, the populations on each side are effectively on their own.

In terms of designating a threatened species, fragmentation decreases the chances of two adults being able to cross the barrier and divide. Effectively, it creates two smaller populations, each with a lower number of breeding adults. The smaller population size increases the chance of extinction in each group, which raises the total chance of extinction for the species. Thus, fragmentation is an important consideration for threatened species. Generally, animals found in only 1 small area are considered critically endangered. The total size of the area depends on the animal, and the typical range it needs to survive.

As with population size, scientist quantify future and current risks to geographic range. A threatened species may also be designated in future actions to their habitat put part or all of their population in danger. Deforestation and ocean acidity are two events which are greatly affecting many species right now. The drastic effects will alter their ranges and ultimately their population sizes. Many animals are being added to the threaten species list because of large-scale events like this which affect their range.

Statistical Analysis

To put together a view of the “big-picture”, scientist often use computer modeling and simulations to estimate the risk presented to a species. In general, if the chance of the species going extinct over the next 100 years is greater than 10%, the label threatened species can be used. When that threshold begins to reach 50% or greater in the next 10 years, the threatened species is considered critically endangered. The vaquita, a small porpoise which lives in the Gulf of California, is considered a critically endangered threatened species. There are fewer than 30 individuals left, they are restricted to one location, and they have been declining steadily for decades. This is the kind of devastation that gets and animal to the critically endangered list.

Threatened Species Examples

Black-footed Ferret

The black-footed ferret (Mustela nigripes) is a threatened species on the verge of extinction. While it is though that the ferret once had an extended range, poising of their prey (prairie dogs) and the plague killed off their populaitons. Further, as the plains became more populated, many prairie dog town were destroyed, killing off their food-source. By the 1960’s, the black-footed ferret was extremely rare and limited to a few populations in Wyoming. By 1987, it was considered extinct in the wild.

A massive campaign was undertaken to breed captive black-footed ferrets and reintroduce them to the wild. Since then, the ferrets have been reintroduced to several location, with varying success. There are now 4 populations of self-sustaining wild ferrets, which greatly increased their chances of getting off the endangered species list. With sustained effort and protections, the ferrets could see a day when they are completely removed from the threatened species list, although that is a far way off.

Tawny Nurse Shark

Found off the coast of Australia and Indonesia, the tawny nurse shark (Nebrius ferrugineus) is a threatened species considered vulnerable by the IUCN. This threatened species has mostly declined, like many sharks, due to fishing practices and harvesting them for their fins. Gill nets and other forms of fishing which are non-selective often catch the sharks and kill them in the process. The sharks are also hunted for their fins, which are part of shark-fin soup, an Asian delicacy which is supposed to have mysterious powers. This is nonsense, of course, and the harvesting of sharks for their fins has decimated many species. The tawny nurse shark, which reproduces at a low rate and fails to distribute far from where they are born, takes a lot of time to recover. For this reason it is considered a threatened species, which will need protections in order to succeed in the future.

Other Species

These two species hardly represent all the species on the threaten species list. The IUCN keeps a global list, but every country and even locality may keep their own list or assesment protocol. Further, while these two were vertebrate species, vertebrates represent only a fraction of all threatened species. Below is a graph which breaks down the approximate proportions of species currently on the IUCN Red List.

As you can see, amphibians and other vertebrates do make up a large portion of this list. Also represented are plants, molluscs, and insects. There are even some fungi on the IUCN list (not pictured). There are several reasons for the disparity in the number of species represented from each group. First of all, vertebrates are by far the most studied group, even though their numbers pale in comparison to invertebrates. Secondly, amphibians are currently experiencing the drastic changing effects of climate change and deforestation, which is destroying their habitats and food sources. For this reason, we see a lot of amphibians as threatened species. Plants, molluscs, insects, and other groups with few threatened species are not necessarily doing well, scientist just don’t have enough information to label them as a threatened species.

Quiz

1. True or False? The threatened species list includes EVERY threatened species known to man.
A. True
B. False

Answer to Question #1

2. Which of the following is true?
A. A threatened species and an endangered species are exactly the same
B. A threatened species can be vulnerable, endangered, or critically endangered, according to the IUCN
C. A threatened species is NOT endangered

Answer to Question #2

3. You are a conservation scientist. You find a species which is restricted to a small geographic location. You gather data on the population and find that it is small and in serious decline. You submit your data to the IUCN and they classify the species as vulnerable. Is the species now protected?
A. No
B. Yes
C. Maybe

Answer to Question #3

References

Blumstein, D. T., & Fernandez-Juricic, E. (2010).A Primer of Conservation Behavior. Sunderland: Sinauer Associates, Inc. Publishers.

Feldhamer, G. A., Drickamer, L. C., Vessey, S. H., Merritt, J. F., & Krajewski, C. (2007). Mammology: Adaptation, Diversity, Ecology (3rd ed.). Baltimore: The Johns Hopkins University Press.

Internation Union for Conservation of Nature. (2000, February 9). IUCN Red List Categories and Criteria. Retrieved 5 14, 2018, from IUCNRedList.org: http://www.iucnredlist.org/technical-documents/red-list-documents

Sarkar, S. (2005). Biodiversity and Environmental Philosophy: an introduction. New York: Cambridge University Press.

Threatened Species

Gibberellin

Gibberellin Definition

Gibberellin is type of plant and fungal hormone. While its role in fungal development is not as clearly understood, it has been extensively studied in plants. Gibberellin is one of 5 major groups of plant hormones, the others being auxins, cytokinins, ethylene and abscisic acid.

Gibberellin was originally purified and identified by Japanese scientists studying a fungal rice disease in the 1930’s. By the end of the decade, they had extracted gibberellin from the fungus attacking the rice crops. Upon applying the extracted gibberellin solution to healthy crops, they noticed it had the same effect. Further tests in the United Stated in the 1940’s and 50’s revealed many more functions of gibberellin. Gibberellin has the ability to overcome dormancy in seeds, extend the length of cells and encourage division, and even has hormonal and signaling roles in the fruiting and senescence processes.

Gibberellin Function

Seed Germination

A dormant seed is dry, and thus little to no metabolic activity can occur. This allows a seed to remain dormant for an extended period of time. Most seeds, upon surviving the winter, are exposed to rain in the spring. This water saturates the seed, and allows metabolic processes to resume. Gibberellin is an essential hormone in this process.

As the embryo begins growing, it needs access to more energy. The embryo releases gibberellin molecules, which make their way to the aleurone layer, which surrounds the endosperm. The endosperm is a large mass of cells which stores starch, fats, and proteins for the developing embryo. The aleurone layer, upon receiving the signal from the gibberellin molecules, begins producing enzymes to digest the endosperm and provide nutrients to the growing embryo.

The gibberellin molecules act on several pathways, most of which increase DNA transcription for certain genes which produce the required enzymes. The aleurone layer releases amylase enzymes, which will convert the starch molecules into glucose. Glucose is the main energy source for the growing embryo, and it has not yet sprouted, so it cannot produce glucose through photosynthesis. Gibberellin molecules also stimulate the production and release of proteases, designed to break apart proteins into amino acids, and lipases, which break apart lipid molecules like fats and oils. Together, these enzymes digest the endosperm and allow the embryo to grow rapidly.

Stem Elongation and Other Functions

Once a plant has sprouted past the surface of the soil, the endosperm is long gone. The plant must now rely on photosynthesis for food. However, the role of gibberellin does not stop at the seed. Gibberellin is responsible for many aspects of plant development. Further, plants produce many forms of gibberellin molecules, which act on different parts of the plant. In the image below, you can see the effects of a specific gibberellin applied to a plant.

In number 1, no gibberellin was applied. Plants 2 and 3 both had gibberellins applied, with plant 3 receiving the highest dose. Gibberellin here encourages the plants to increase their internode length, or the length between their leaves. In many plants, the regulation of gibberellin is an important natural process which regulates their height due to this process. At the cellular level, gibberellin is influencing the balance of proteins. In doing so, it encourages cell growth and elongation in the stems and between nodes.

In some species of plant, gibberellin is involved in many more processes. These include flowering, fruiting, and senescence, or the natural death of leaves and other plant parts. Interestingly, many genes which regulate and adjust gibberellin levels are influenced by the temperature. Thus, when the temperature changes during seasonal change, the plants react to this as gibberellin levels change. This starts off many processes such as flowering and fruiting.

Gibberellin molecules are involved with and interact with other plant hormones. The auxin level, for example is directly related to the gibberellin level, and the two complement each other. Ethylene, on the other hand, tends to degrade gibberellin levels. Plants use these hormones, which respond to different inputs, to balance and react to inputs from the environment. These inputs signal various environmental conditions, which the plant is keen to take advantage of.

Gibberellin Structure

Gibberellin molecules of different types are synthesized in many different parts of the plant. Currently, there are over 100 uniquely identifiable gibberellin molecules. These molecules are synthesized in many cells of the plant, but tend to be concentrated in the roots. This is different from auxin, which tends to concentrate at the apex.

Gibberellin is a diterpenoid, which is a familiar and highly represented molecule in biochemistry. It forms the basis of molecules like Vitamin A and Vitamin E. Seen below is Gibberellin A1, which was the first identified gibberellin.

Other gibberellins have the same basic structure, but have various side groups attached. These groups affect where and how the gibberellin acts, which is how gibberellin can have so many diverse and unique functions in different tissues.

Uses of Gibberellin Commercially

Commercially, gibberellin is obtained from fungi, not plants. Plants produce very little gibberellin and are equally as hard to grow compared to fungi. The gibberellin fungi produce is active on plants, and can cause them to germinate from seeds or increase internode length. While still not commercially profitable in all plants, gibberellin treatments are used on a variety of human foods.

Seedless grapes, for example, have a hard time becoming very large without the use of gibberellin treatments. The molecules of gibberellin are typically sprayed onto the vines, where they increase the amount of water and sugar stored in each fruit. This is great for vineyards and grape-growers, who can significantly increase their harvest.

Interestingly, another use of gibberellin is removing it from plants. Semi-dwarf rice, a species which grows quickly and efficiently, was developed by selecting for strains in which the genetic codes for producing gibberellin molecules were wiped out. This effectively made the plants gibberellin deficient, and significantly reduced their height. While this may seem like a bad thing, the rice actually grows much quicker and produces the same amount of rice. Still other uses of gibberellin include using it on cucumber flowers, where it promotes all-male flowers. This allows farmers to obtain the pollen of a desirable cultivar, for use in hybridization with other varieties. An underdeveloped but interesting application of gibberellin is in eliminating the cold requirement for flowers. Typically, a cold spell is required to promote gibberellin production in the plant. By spraying the hormone on directly, this process is avoided and ornamentals will flower directly.

Quiz

1. A farmer is growing two tomato plants. One he allows to grow naturally, only watering it regularly. The other plant he supplements with gibberellin. Which of the following is NOT a possible outcome?
A. The gibberellin plant will be taller
B. The leaves of gibberellin plant will be much larger than the regular plant
C. The gibberellin plant may die

Answer to Question #1

2. A scientist is testing gibberellin on some seeds. One batch of seeds is left as the control, with no treatment. The other batch is sprayed with a concentrated gibberellin treatment. What is the expected outcome?
A. The control seeds will sprout less, and slower
B. Both groups will sprout, but the gibberellin seeds will be bigger plants
C. Neither group will sprout, but for different reasons

Answer to Question #2

3. When you “nip the bud” of a plant, or tear off the axial bud, auxin production in the top of the plant stops and the auxin levels drop. This also lowers the gibberellin level. What benefit does this give the injured plant?
A. Growth stops, allowing for repair
B. No benefits
C. This increases internode growth

Answer to Question #3

References

Bruice, P. Y. (2011). Organic Chemistry (6th ed.). Boston: Prentice Hall.

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

Nelson, D. L., & Cox, M. M. (2008). Principles of Biochemistry. New York: W.H. Freeman and Company.

Gibberellin

Sunday, May 20, 2018

Cultivar

Cultivar Definition

A cultivar is a subspecies classification describing plants varieties which are produced through artificial selection. Cultivar, the word, comes from a combination of cultivated variety. Different forms of the same species are considered varieties. When these varieties are then artificially selected by humans for particular traits, they become a cultivar.

Cultivar is a term recognized internationally, and more formally defined as certain plants which can be distinguished from others by any characteristic. In reproducing a cultivar either sexually or asexually, these characteristics always remain “true”. This mean that the characteristics are controlled by a homozygous gene for that cultivar. In this case, the plant can self-fertilize, which will produce plants that are also homozygous for particular traits. The alternative is that the line is maintained through vegetative propagation, also known as cloning.

Either way, an established line with defined characteristics becomes a cultivar. A cultivar is narrower than a species or a group, and represents one of the narrowest focuses, genetically speaking. Many cultivars, because they are so closely related, can produce hybrids with other cultivars of the same species. This allows an almost never ending variety of cultivars to be produced from only a few starting cultivars. In the United States “cultivar” is more or less synonymous with “variety”.

Cultivar Development

Cultivars have been developed for thousands of years, since humans first started artificially selecting plants. The first true cultivars were the first well-established lines of crop plants. These included rice, corn, beans, wheat, and other vegetables. These cultivars survived for millennia and formed the basis of modern civilizations. As such, a well-established, true-breeding cultivar always has a higher value than an unknown seed.

To this end, many organizations have been established throughout the world to certify various lines as being a true cultivar. Further, governments and academia have pulled together to fund and develop many more cultivars. Many modern cultivar vegetables have been produced in the last century through selective breeding and advances in plant propagation. Many modern cultivar vegetables and fruits have a history of both historical artificial selection and newer, more scientific advances to the many cultivars of the species. Below is an image of wild cabbage.

Wild cabbage is found in costal and southwestern Europe, while its cultivars are found globally. Wild cabbage has been cultivated for thousands of years, since the times of Ancient Greece. There, it was grown in gardens in several varieties, which mainly differed in the shape of the leaves. Each cultivar was then put through thousands of years of artificial selection. The end of this process left dozens of cultivars, each less like the original plant. Here is a shortened list of just some of the wild cabbage cultivars:

Broccoli

Cauliflower

Kohlrabi

Brussel Sprouts

Broccolini

Kale

Red Cabbage

Savoy Cabbage

But that’s not the end! While these used to be individual cultivars, these are now known as groups, another subspecies identifier. The actual cultivars of wild cabbage now have even more distinct names, such as King Cole cabbage. These lines were created from a single cultivar which had desirable characteristics. Future progeny of these plants were selected to start the new lines which “bred true”, in that they would consistently produce these features.

This, along with modern advancements such as genetic modification, have developed an entire new generation of cultivar plants. Some of these have modifications which improve the plant’s resistance to drought, disease, or insects. Other cultivar varieties grow a particular type of flower, or have enlarged leaves or roots. A cultivar can be maintained through a line of seeds, but this is not easy. Any cross-pollination or mutation within the seeds can allow other genetics to arise, which will change the properties of the plant. A cultivar that is maintained in a line through the seeds must be segregated to prevent cross-pollination. The plants must have an ability to self-fertilize to complete this process. Many flowers, vegetables, grains, and other such crops are maintained in this way.

Other plants, such as fruit trees, grape vines, and other woody ornamental plants are easier to propagate through cloning. In this process, a small piece of the plant is harvested and established in a growing media. Over time, the small bundle of cells differentiates into a fully formed plant, and can be transplanted outside. This also allows the formation of a cultivar which is not homozygous for a certain trait. Using this method, a difficult to breed and grow species can be maintained as a cultivar. Otherwise, entire groves of fruit trees would have to be grown indoors to keep them from becoming pollinated. This is simply not realistic, as trees grow very slowly and need an enormous amount of space and energy.

While many of the above cultivar plants may seem similar to each other, it may strike you to know that potatoes and tomatoes belong to the same genus of plants! These cultivated varieties produce entirely different products, from the same historical plant. It is amazing what artificial selection can accomplish in such a short timeframe.

Cultivar Nomenclature

It is important to note that true cultivars, today, are specific “brand names” of larger groups. For instance Bing cherries, or Rocky Ford Cantaloupe. These are specific varieties of the cherry and cantaloupe which have defining characteristics. Each cultivar has been established and can be consistently reproduced. The progeny always have the same characteristics.

Whether you think of Gala apples or Savoy cabbage, each of these is a cultivar of a larger group, which is a subset of a species. The nomenclature of such a complicated relationship can get complicated. However, below is a simple formula to help understand if you are talking about the species, group, or cultivar. The full scientific name of each cultivar should be in this format.

Scientific name (Group name) ‘Cultivar name’

A good example is King Cole cabbage. In this case, cabbage is a group within the species Brassica oleraceae. Therefore, the entire name of King Cole cabbage should look like this:

Brassica oleraceae (Capitata) ‘King Cole’

The part in italics represent the genus and species. Remember that this is the same species that produces broccoli, kale, and cauliflower. Capitata, which is always shown in parenthesis, is the group name. Capitata is the group for all cabbage cultivars, which includes a wide variety. Finally, each cultivar is distinguished by a unique epithet, in this case “King Cole”. This is often the name of the scientist responsible or the family behind the funding.

Quiz

1. Which of the following cultivar varieties are most related? (Multiple Select)
A. Brassica oleracea (Capitata) ‘Green’
B. Brassica oleracea (Botrytis) ‘Romanesco’
C. Malus pumila ‘Gala’

Answer to Question #1

2. Which of the following statements is FALSE?
A. A cultivar is an artificially created stable line of a particular species
B. A species can contain multiple cultivars
C. Each cultivar is its own species

Answer to Question #2

3. A farmer finds a new plant on his property. He decides to harvest and eat it. Is this a new cultivar?
A. No
B. Yes
C. Maybe…

Answer to Question #3

References

Hartwell, L. H., Hood, L., Goldberg, M. L., Reynolds, A. E., & Silver, L. M. (2011). Genetics: From Genes to Genomes. Boston: McGraw Hill.

McMahon, M. J., Kofranek, A. M., & Rubatzky, V. E. (2011). Plant Science: Growth, Development, and Utilization of Cultivated Plants (5th ed.). Boston: Prentince Hall.

University of Illinois Extension. (2018, May 8). Cabbage. Retrieved from Watch Your Garden Grow: https://extension.illinois.edu/veggies/cabbage.cfm

Cultivar

Thursday, May 17, 2018

Endemism

Endemism Definition

Endemism is the condition of being endemic, or restricted in geographical distribution to an area or region. The area or region can vary in size, and is defined or identified in different ways. Endemism is an ecological classification in that it describes the range or distribution of a species, or group of species. For instance, entire families of different species of birds are endemic to the island of Madagascar. The term endemism can applied to many things, including diseases and natural phenomenon. Endemism in these cases refers to the “normal” or standard level of some measured observation within a specific geographic region or area.

Endemism is not to be confused with indigenous, a term which refers to the origins of a species. Indigenous refers to where a group originated. A species can be both endemic and indigenous to an area. However, some species thrive and exceed the bounds of their original indigenous location. This means that the species is no longer endemic, but is still indigenous to the original area. Once a species has reached a wide-spread, global distribution it is said to be cosmopolitan. Animals like whales, once indigenous to a specific mainland in the form of their 4-legged ancestors, are now cosmopolitan in distribution.

Endemic Species

An endemic species is a species which is restricted geographically to a particular area. Endemism in a species can arise through a species going extinct in other regions. This is called paleoendemism. Alternatively, new species are always endemic to the region in which they first appear. This is called neoendemism. Both forms of endemism are discussed in more detail under the heading “Types of Endemism”, below.

Endemic species, regardless of how they came to be restricted to a particular area, experience the same threats to their existence. The smaller the region, the more dire the threat toward the survival of the species. Any action that reduces the size of the land, or divides it in any way can significantly affect the normal patterns of the endemic species. While endemism and being endangered or threatened are different things, being endemic to a small area is often a warning sign that a species may become threatened or endangered.

This is not always the case, as many globally distributed species are also considered threatened or endangered. In recent years, many sharks have joined the list. While they are distributed throughout many of the ocean’s waters, the harvesting of shark fins for soup has decimated their populations globally. Endemism sometimes protects species from being exploited globally, simply because of the fact that the species only exists in a small area. This can even make the species easier to protect, because the land can be placed under a conservation easement to restrict the construction and human impact on the land.

Endemic Disease

Scientists studying epidemiology, or disease outbreaks, have a similar definition of endemism. An endemic disease is a disease seen at consistent levels in specific location. For instance, endemic relapsing fever is a disease seen in Europe and in North America. The disease is not seen in any sort of observable amounts in other parts of the world. Other diseases, which are new to an area or are spiking in their prevalence, are known as epidemic diseases.

There are many endemic diseases, and their endemism has roots in the species and vectors which promote these diseases. In the case of relapsing fever, a vector carries the bacterium of the Borrelia species. There are several vectors which can carry these bacteria, mostly including ticks and lice. The species of ticks and lice which carry these bacteria are endemic to the Northern Hemisphere. Borrelia bacteria are also responsible for Lyme disease, a disease endemic to the Northern Hemisphere. A map of Lyme disease is shown below, and corresponds to the endemism seen in tick and lice species.

While Lyme disease and relapsing fever are endemic to these areas, they are not endemic to say, Australia. If there were even a few cases of Lyme disease in Australia, the disease would be considered epidemic, because the normal level of Lyme disease in Australia is zero.

Types of Endemism

Paleoendemism

There are two basic ways for a species to show endemism to a certain region. Basically, the difference between the two is whether the species is newly emerging, or historic and declining. Paleoendemism describes the later. In this form of endemism, a species which was once widespread has been reduced to a much smaller range. This is the case for many large predators today.

Before humans, large predators were widely distributed across the globe. As human society became more organized, large predators were driven away from society, and out of their historic ranges. Those which have not gone extinct are now restricted to limited ranges. Conservation efforts for these animal focus on protecting the current range and expanding it to encompass the historic range. This is hard however, as humans often oppose the re-introduction of large predators. Without protections from hunters, the species will easily be pushed back to their endemic range.

Neoendemism

On the opposite hand, new species are branching off the evolutionary tree every day. These species are both endemic and indigenous to the location in which they first appeared. They are restricted to a geographical location simply because that is where they started. This is known as neoendemism. There are many species, found on islands, which show this form of endemism.

Islands provide an interesting and isolated grounds for the development of new species. While the species on the island are now endemic, their ancestors were likely not. Take the Galapagos finches, as an example. The Galapagos archipelago contains many islands. Many thousands of years ago, a single finch species arrived on the islands. At first, it spread across the island as one species. However, evolution has now separated the birds so much that they represent different species. The differences in the vegetation on the islands divided the ancestor into many smaller species, which show endemism to the island they are found on.

Quiz

1. The Greenback Cutthroat Trout is a fish which is indigenous to many waters in Colorado. After heavy over-fishing, the species is now endemic to only a small handful of streams in Colorado. Which of the following statements says the same thing as the above sentences?
A. These trout are native to many waters, but have been reduced to only a handful
B. These trout both come from and reside in Colorado
C. Overfishing has not decreased the range of these trout

Answer to Question #1

2. Endemism is often mistaken with being endangered. How are the two terms different?
A. They are essentially the same.
B. Endemism simply describes the distribution, while endangered describes the threats to a population
C. Endemic species often become endangered

Answer to Question #2

3. Which of the following is NOT an endemic disease?
A. The common flu
B. Zika virus, found in Minnesota
C. Malaria, in Africa

Answer to Question #3

References

Blumstein, D. T., & Fernandez-Juricic, E. (2010). A Primer of Conservation Behavior. Sunderland: Sinauer Associates, Inc. Publishers.

Heymann, MD, D. L. (Ed.). (2015). Control of Communicable Diseases Manual. Washington: American Public Health Association.

Rogers, PhD, K. (2015). Colorado Outdoors – Piecing together the past (Cutthroat Trout). Retrieved from Colorado Parks and Wildlife: http://cpw.state.co.us/Documents/Research/Aquatic/CutthroatTrout/Rogers2012CoOutdoors.pdf

Endemism