Module 9 Blog Post

Chinese Water Deer

The Chinese water deer has a teddy bear face fluffy ears and huge fangs. When we think of artiodactyls, we probably think they'll have horns or antlers, not fangs like a big cat. 

The teeth look to long to be any help in assisting with digestion, and the water deer is a ruminant, which means it has a four chambered stomach. The Chinese water deer's diet is herbivorous, however, a part of the ruminal physiology of the Chinese water deer is not well developed and they are not able to properly digest a diet of highly fibrous plant material.

Like most deer, the males of the species use these bony appendages to fight other males. These are solitary animals and the males will fight other males who come too close. I could not find if this was also a characteristic used in sexual selection, the territorial behavior only gets worse during mating season, so maybe that's something that should be studied in in the future. The males battle other males kind of like giraffes (that's how its described in the article at least, I tried to find a video of males fighting each other but I think I just found one where the male is trying to mate). They stand shoulder to shoulder and try to stab each other in the neck and back. Why are antlers more common tools for fighting in deer instead of fangs. The fangs are so cute :3

They have inguinal scent glands, which most other species of cervids do not posses. These glands are located in the area around their groin. The water deer lives in a place where tall grass and tall water plants grow. This is most likely an evolution that came about as advantageous for scent marking their territory, as they seem to be very territorial animals. Being solitary from members of their own species also probably helped facilitate this adaptation, they know that there are other deer in the area and the males know if they are intruding in another males territory.

Sources

ADW: Hydropotes inermis: INFORMATION (animaldiversity.org)

Bambi attacked by fanged buck - YouTube

Water Deer | NatureRules1 Wiki | Fandom

Why is Genetic Variation not Eroded Over Time?

 

Blog Post Module 8: Reflection 

There are several factors that keep genetic variation from eroding over time; some of which include non random mating, genetic drift, and gene flow.

Genetic drift: is a force of evolution that can cause random changes to a populations allele frequencies. 

Gene flow/Migration can affect a population in a few ways

    1) Migration can homogenize allele frequencies of multiple connected populations.

    2) Migration can create genetic diversity by introducing new alleles from one population to             another population.

Migration acts as a homogenizer but also introduces new genetic material to populations.

Crossing over and recombination: These events can increase genetic variation by allowing new allele combinations; from generation to generation, offspring have a greater chance of being genetically different from their parents.

Mutation causes a change in DNA sequencing, and in addition, creates new alleles to be passed on in a population

Depending on what kind of organism is being observed and what kind of non-random mating is exhibited, this force can create new genetic variation within a population. One type of non-random mating, inbreeding, decreases genetic variation. Another category of non-random mating, outbreeding, increases genetic variation. These opposite modes of non-random mating can be controlled by humans or occur randomly in nature.

This is an interesting article concerning populations recovering from bottleneck effects:

Bottlenecks and rescue effects in a fluctuating population of golden-mantled ground squirrels (Spermophilus lateralis) | SpringerLink

 File:Golden-mantled ground squirrel - Bow Lake.jpg - Wikipedia

They study involved researchers trying to find real life evidence of a rescue effect in a population of these ground squirrels. The researchers studied a population of the squirrels that had bottle neck effect that lasted about four years. The results of the genetic analyzation showed that while less than ten squirrels in the population remained, the effect of immigration kept the allele frequency from reaching a point of 100% heterozygosity (which usually happens in bottle necks. Also, the results of the study showed that there wasn't really a loss of fitness in the population. 

Genes seem to mix and change continuously in a way that they keep somewhat of an equilibrium.

This study implies that outbreeding/gene flow can increase genetic diversity. Out breeding is also something zoos do with their breeding animals, in order to keep the genetic material of the animals in captivity diverse.

sources

Outbreeding - an overview | ScienceDirect Topics

Bottlenecks and rescue effects in a fluctuating population of golden-mantled ground squirrels (Spermophilus lateralis) | SpringerLink

Module 7 Blog Post: Reflection

 

Reflection

    In my first blog post, I wrote about what my high school biology teacher told us about evolution; that its a change over time and that we change every day. I thought she was trying to say it in an inspirational way, not in the scientific way. Throughout this class, I learned what the actual definition of evolution is, how it occurs, and the mechanisms that facilitate it. Mechanisms such as selection, fitness, epigenetics, mutation, mutation rates, and Hardy-Weinberg assumptions. Definitions of these words were taught in other classes but we were not exactly taught how to show them visually and quantitatively like we do in the R exercises. One important concept I personally did not understand was how mutation rates can change and more importantly, how do they change. Now I know that DNA polymerase; which copies the DNA during replication, can become mutated which in turn can change mutation rates. That was one of the most interesting concepts. My view of evolution has changed in the way that, not only do we know the math that goes into these terms, but we are also learning how to read and create visual representations of these concepts. Evolution has a lot of depth to it, and there are so many interdisciplinary concepts that tie into the theory.

Taking genetics was a prerequisite to take this class, so I think all of us have a good background when going through the different mutation types, the Hardy-Weinberg assumptions and mathematically learning how to compute frequencies but we learning how to model it was not taught. I personally have trouble with the models on R exercises, mainly the cave molly and modeling different scenarios involving heritability of standard length and eye size.

I think learning more about the coevolution of pathogens and humans and how it occurs or evolutionary epidemiology would be interesting to learn more about. How and what about these concepts are modeled and what can we learn from it theoretically and realistically. 

Module 6

Chinchilla inbreeding

Most pet chinchillas in the United States are probably descended from 11 chinchillas that were brought into the country from Chile in 1923. They were most likely almost hunted to extinction for fur in the 1800s and 1900s. Today, there are probably only around 10,000 individuals left in the wild. With only 11 individuals to work with, pet chinchillas were most likely the result of severe inbreeding. A lot of pet chinchillas today suffer from malocclusion, which is considered a polygenic trait.

Of course captive chinchilla breeding is not natural and usually involves selectivity, non-random mating is not really possible to observe. Malocclusion is a misalignment of the teeth and because chinchillas are rodents, this is a life-threatening medical condition for them. With inbreeding, or facilitative assortative mating, breeders can breed chinchillas with the cute characteristics everyone loves; thick fur in a variety of colors, a cute squirrely tail, and a stocky body. Captive breeding with this method could also give fur collectors what they want without assisting in extinction of the wild chinchilla. 

Wild chinchillas are generally a yellowish gray color to help them blend in with their native habitat in the mountains. Through domestication and selective breeding, chinchillas now come in colors like white, black, blue-gray, violet, and pearl. Some colors are recessive, some are dominant, and some are expressed by dosage and incomplete dominance. Some of these colors most likely arose and were kept in circulation by some degree of inbreeding. 

Assortative mating resulting from inbreeding in the wild could be beneficial for the remaining population of chinchillas to select for the traits that were most beneficial for survival in their changing environment (maybe?).

Disassortative mating stemming from inbreeding could also be beneficial for the remaining chinchilla population for keeping unhealthy phenotypes in check, such as a different fur color that does not blend in or malocclusion (if it occurs in wild chinchillas (possibly?). 

Sources

Chinchilla Colors - Pet Ponder color genetics

Chinchillas.com Chinchilla Malocclusion

Fun Facts About Chinchillas | Live Science