C. Gatschet - BIOL 520

With the recent and ongoing revolution of DNA sequencing technology, more and more species are able to be identified down to the genetic level. However, cryptic species have begun to reveal themselves through this readily available genetic information. Researchers, Pfenninger and Schwenk from Germany discovered that cryptic species are found in equal proportions across all major branches of the animal kingdom. This leads to the conclusion that there could be a multitude more species than we previously thought. Just last year, for example, an article was published by researchers in India studying the genus Ahaetulla, a type of peninsular Indian vine snake. Yes, this is the judgemental shoelace snake. (Do not boop, or you will get the hurt juice). When the first species of kind of vine snake, described by Linnaeus, was discovered, all the vine snakes in that region were thought to be part of a single species. However, as time drew on, the discovery of three additional species were added ...

Pipefish, along with seahorses, are both species in which the female deposits her eggs into the male, who carries and incubates them during gestation. In this case, the males must invest much more time and energy into their task of carrying the eggs than the female does. In a system such as this, with the "normal" sex roles reversed, sexual selection is also reversed. Therefore, we still see sexual dimorphism between the male and female, but it is the female who displays more of the related secondary sex traits, is visually more flamboyant, and participates in the courting of the male.  However, despite the divergence from what we normally observe, this mating system still proves the sexual selection hypothesis. The sex of the species who invests the most in the offspring is usually the one who chooses their mate, while the sex of the species who invests least in the offspring is the one who normally does the courting. https://onlinelibrary.wiley.com/doi/10.1002/ece3.4459  ht...

The ocean is home to the most extraneous creatures that we know of on this planet. From brightly colored, poisonous lionfish in the coral reefs, to ancient, practically immortal jellyfish in the open ocean, to large fanged creepy fish surviving in the harshest depths of the ocean floor, life seems to get stranger the further from the surface you look. One such deep-sea creature is the bloody belly comb jelly, of the class ctenophores (the cone jellies). To combat the lack of light this far down, bioluminescence is present in almost all deep-sea creatures and is used as a mechanism for communication, to lure prey, to attract mates, and defend against predators. The majority of bioluminescent animals glow blue due to the fact that blue wavelength light travels the furthest in water, this is the same phenomenon responsible for our observation of the ocean's blue color. If you have looked at the image below, though, the translucent bloody belly comb jelly lights up a brilliant shade of...

The issue with this question, or rather perspective on the topic, is that it implies selection is the only force acting on a population. While selection can limit the variation in a population, especially a small one, other forces will also act on that same population to counteract the effects of selection and revamp variation. So to redefine variation in evolutionary terms, genetic variation is essentially the diversity of allele frequency at a certain gene locus. On a molecular level, this results from single nucleotide polymorphisms (SNPs) in the DNA to produce different variations of the same gene. The most major player in increasing genetic variation is the force of mutation. No matter how great the strength of selection is, mutations will always be present in a population, adding variance with their effects, and creating a new gene pool for selection to act on again and again. In the the Module 7 R exercise, we saw the effects of the molecular clock, ticking away and producing vi...

I assume it will be a common thread across everyone's blog posts this module, but the biggest obstacle I've been overcoming is working with R and learning how it works. I'm certainly glad to be gaining the basic concepts behind R, the mechanisms of coding are less foreign to me now than at the start of the semester. Secondly, I appreciate the discussion format of the class in that it truly challenges my critical thinking skills, forcing me to consider perspectives I might not have before and question my preconceptions of what evolution really is. On that topic, I first defined evolution as "the result of a combination of several mechanisms which eventually contribute to changes in the genomes of a species, the most well-known of these mechanisms being natural selection." While I wasn't exactly wrong, I definitely didn't capture the mere scope of what evolution entails. Along with selection, other forces such as mutation, genetic drift, migration, and non-r...

Photograph by Christian Heeb / Redux (The New Yorker) As we talked about in class, recessive deleterious alleles can become more frequent in populations with inbreeding, where fixing of alleles generally results in an increase in homozygosity within a population. In larger populations where inbreeding is less common, heterozygous individuals mask the function and consequences of deleterious recessive alleles. With inbreeding as a factor in a population however, the deleterious allele, originally recessive, is exposed due to homogenization and becomes more common in an the population; thus, variation is depleted through selection (Waller and Keller, 2020). A example of this from the 1990s occurred in a population of Florida panthers (aka cougars, pumas, etc.). With a period of habitat destruction, the population of panthers weaned to about only 20-30 individuals. The resulting limited number of breeding pairs available led to excessive inbreeding within the population. Consequently, g...