Teenage Mutant Ninja Frogs! The Long-term Effect of Radiation on Chernobyl Tree Frogs

By: Stephen Cobbs, John de Abreu, Clare Feeman, and Molly Turner (Stonehill College, BIO323: Evolution, Spring 2022)

On April 26, 1986, the world effectively changed in the blink of an eye. An accident during a technical test at the Chernobyl Nuclear Power Plant near the city of Slavutych, Ukraine, produced what would eventually be referred to as “the worst nuclear disaster in history”. The consensus on the immediate, short-term effect of the accident was undeniably poor, as all wildlife within the area suffered mass casualties. 36 years later however, and the consensus is rather murky. Scientists have recently visited the Chernobyl Exclusion Zone (CEZ) and were shocked to find that area today presents great biodiversity, playing host to a multitude of different species from a multitude of different clades. Why is that you may ask? Well, some scientists believe that the radioactive pollution from the nuclear fallout led to an increase in mutation rates within genes of the animals in Chernobyl, which partially offset the diversity which was initially lost. This raises the question if there is such a thing as too many mutations and is there a line at which mutation rates cross from beneficial to deleterious? The paper Unusual evolution of tree frog populations in the Chernobyl exclusion zone, by Clément Car and 11 others, works to classify those questions, specifically looking at populations of Eastern Tree Frogs (Hyla orientalis) both in and around the CEZ and using simulations for populations throughout Europe as a whole.

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Facultative Crypsis in Lizards

By: Patrick McLaughlin, Natasha Moniz, and Emma Tedeschi (Stonehill College, BIO323: Evolution, Spring 2022)

Crypsis, another term for camouflage, is a strategy that many organisms use to protect themselves from predators. Many organisms perform a process known as ‘environmental matching’, which is when an organism changes the color of their skin to match their habitat. Disruptive camouflage is a specialized type of camouflage that disrupts the organism’s outline by creating false edges, making it hard for the predator to find their prey. Studies have been conducted and results have been compiled into a scientific article called “Rapid Body Color Change Provides Lizards with Facultative Crypsis in the Eyes of their Avian Predators,” with research done by Kelly Lin Wuthrich, Amber Nagel, and Lindsey Swierk. This research has helped with understanding the ability of organisms to be able to rapidly change their body color and its effects on their survival. The experiments were conducted using receiver visual models, digital image analysis, and spectrophotometric tests. However, researchers have yet to reveal if rapid color change can alter the whole color of the body or patterns of an organism. When gathering research, many factors need to be taken into consideration, such as the predators’ visual systems, the rapidity of the color change, and the variety of microhabitats. Anolis lizards, or anoles, are known for their rapid color-changing abilities. Some species can change colors within minutes, going from light to dark and vice-versa. However, it has been discovered that going from dark to light seems to be more difficult for an organism than going from light to dark- it is more time-consuming. The researchers tested whether rapid body color change in water anoles (Anolis aquaticus) could provide benefits to the organism with proper camouflage between different microhabitats.

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How Color Morph Frequency Affects Predation Risk in an Aposematic Moth

By: Abby Campbell, Molly Cannon, and Marissa Freitas (Stonehill College, BIO323: Evolution, Spring 2022)

Safety in numbers: How Color Morph Frequency Affects Predation Risk in an Aposematic Moth is an article with the main purpose of understanding polymorphic warning signals in aposematic systems. This article was published by the American Naturalist in July 2021, written by Swanne P. Gordon, Emily Burdfield-Steel, Jimi Kirvesoja and Johanna Mappes. Aposematic is defined as a defense strategy that combines a primary warning signal (aposematic) with a secondary chemical defense. This study evaluated how bird behavior influenced the survival of three morphs of the aposematic wood tiger moth (Arctia plantaginis) that coexist in the same environment to a predator located from the same area. The three morphs of the moth were white, yellow, and red/ orange coloration. It calls attention to the need to understand predator foraging in natural environments with variable prey defenses to better examine how behavioral interactions between predator and prey affect evolutionary change.

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How does Radiation Accelerate Evolution?

By: Kristina McEvoy, Eli Penza-Clyve, Amaya Toribio, and Lindsey Walsh (Stonehill College, BIO323: Evolution, Spring 2022)

Have you ever wondered how wildlife has been affected by the 1986 Chernobyl nuclear power plant explosion? The disaster has been a subject of fascination to many, inspiring media such as the 2012 horror film Chernobyl Diaries and HBO’s 2019 television miniseries, Chernobyl. Although the incident occurred a little over 35 years ago, the accident has left lasting effects on the creatures that inhabit the Chernobyl area, particularly in the realm of genetic mutations.

Researchers at the University of Stirling, in collaboration with the Ukrainian Hydrometeorological Institute in Kyiv, sought to determine how radiation affected genetic diversity in a freshwater crustacean living in lakes at varying distances to the disaster. Daphnia pulex, also known as water fleas, live in the seven lakes examined in this study; five lakes were within the Chernobyl Exclusion Zone, or the radioactive area surrounding the explosion site, and two were located outside this boundary. Water fleas are known to accumulate mutations and suffer from a reduced ability to survive and reproduce when exposed to radiation. Scientists investigated the variation between the water fleas at each location by extracting DNA and sequencing ten microsatellite gene locations on chromosomes. Essentially, microsatellites are short segments of repeated DNA motifs in many places within one’s genome. The variation in the length of these microsatellites can serve as a measure of genetic diversity. The radiation from Chernobyl can lead to the development of genetic mutations, which can, in turn, increase genetic diversity. However, this relationship can change drastically when taking other evolutionary factors into account. Considering the radioactive conditions, there are two possible outcomes: either mutations cause genetic diversity to increase, or natural selection eliminates individuals that cannot survive the cellular damage associated with radiation, thus decreasing genetic diversity.

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Taste Receptors in Grass Carp

By: Cierra Terceiro-Ciavatta, Jessica Gormley, Alyssa Cimino, and Jessica Medeiros (Stonehill College, BIO323: Evolution, Spring 2021)

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Article: Yuan, X.-C., X.-F. Liang, W.-J. Cai, S. He, W.-J. Guo, and K.-S. Mai. 2020. Expansion of sweet taste receptor genes in grass carp (Ctenopharyngodon idellus) coincided with vegetarian adaptation. BMC Evolutionary Biology 20: 25. https://doi.org/10.1186/s12862-020-1590-1

MHC molecular evolution in chimpanzees

By: Sarah Boles, Carly Russell, Tia Zephir, and Gabby Scarcella (Stonehill College, BIO323: Evolution, Spring 2021)

Have you ever wondered how your immune system just knows and acts on a variety of diseases? Especially now during COVID-19, it seems our immune systems are really being put to the test. The actions of your immune system are due to the major histocompatibility complex (MHC). In  a recent article in BMC Evolutionary Biology, researchers from the University of Geneva and the Biomedical Primate Research Center wanted to see if MHC genes are conserved and evolving similarly in Western chimpanzees (Pan troglodytes verus) and humans. The MHC region, referred to as Patr in chimpanzees and HLA in humans, is a family of genes that plays a key role in a population’s adaptive immunity. MHC diversity could affect a population’s survival because these genes code for proteins that help combat viral infections and protect the organism from harmful pathogens. MHC genes are classified as class I genes or class II genes, which differ in structure and function. The class I genes are named A, B, and C, and target viral invaders, whereas class II genes, such as DPB1, DQB1, DQA1, and DRB1, target parasitic and bacterial invaders. The objective of this study was to determine if the genetic diversity at different Patr genes is significantly reduced in present day Western chimpanzees due to a past bottleneck effect, which is defined as the sudden decrease of a population from natural causes. The researchers also compared human and chimpanzee genetic diversity to determine if MHC molecular evolution mechanisms were conserved between the two species.

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Rabbit and Hare Body Size Evolution

By: Meredith Kime, Courtney Marcos, Sean O’Leary, and Nick Scolaro (Stonehill College, BIO323: Evolution, Spring 2021)

Eastern cottontail: © Gareth Rasberry, shared under the CC BY-SA 3.0 license
Ungulates: © XAttlexattle, shared under the CC BY-SA 4.0 license

The rabbit, commonly known as a visitor in backyards, has evolved in a way to maintain a relatively small body size. In the Evolution article, “Why aren’t rabbits and hares larger?”, researchers Susumu Tomiya and Lauren Miller from UC-Berkeley sought to determine why rabbits and hares retained a small body size. Rabbits and hares are in the order Lagomorpha, along pikas. Compared to its sister clade, which includes rodents, rabbit body size evolution has been limited. This study does not include rabbits domestically bred, only wild populations of rabbits. Rabbits are an ideal group to study because of their limited diversity and extensive range across all continents, except for Antarctica.

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Projecting introgression from domestic cats into European wildcats in the Swiss Jura

By: Michael Piotte, Sylvia Mlynarski, Keith Francis, and Emily Yip (Stonehill College, BIO323: Evolution, Spring 2021)

© Michael Gäbler, cropped from the original, shared under the CC BY 3.0 license

Does this look like a normal pet cat to you? If so, keep reading; the true answer may surprise you.

When organisms reproduce, they randomly give half of their genetic information to their offspring. When two organisms from closely related species mate, the same process occurs. However, there is a significant issue. If this interbreeding between closely related species continues, it can lead to one or both species dying out. They will inevitably breed into one species, assuming they produce fertile offspring. This process is called hybridization, which can sometimes increase biodiversity by introducing a new species to the environment. This can also decrease biodiversity through changing environmental conditions and/or competition through a process known as introgression. This occurs when DNA from one species eventually swamps the genome of another species through interbreeding. Scientists from Switzerland and the U.K.  projected how this process might be affecting domestic cats and wildcats in the Jura Mountains of Switzerland.

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To Be Colorful, or Not to Be… There is no in-between!

By: Felicia Cafua, Maddie Fancher, Sydney Ledoux, and Deirdre Boyer (Stonehill College, BIO323: Evolution, Spring 2021)

One of the most exciting parts of life is the diversity of colors that animals exhibit. When looking at the diversity of an animal’s color, many questions arise: Why are there so many different colors? Wouldn’t this attract more predators? How do these different colors arise? Birds are a fantastic example of the diversity of coloration; even in one bird species, there can be considerable variation between individuals. Parrots, in particular, show a great diversity of coloration and can have very intense plumage coloration. Plumage color is the color of the feathers covering the entire bird collectively. The exact reasoning for such a wide range of plumage colors is not well understood. Here we summarize a recent paper on plumage coloration in parrots that was published in the Journal of Evolutionary Biology by researchers from the Max Planck Institute for Ornithology.

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Phenotypic Changes Across a Geographic Gradient: The Case of Three Sympatric Dolphin Species

By: Kalyani Twyman, Stella Martinelli, Devin Kiley, and Joe Monteiro (Stonehill College, BIO323: Evolution, Spring 2020)

This study aimed to investigate the morphological differences, or the differences in the form and structure of an organism, in three closely related dolphin species within the context of geography. The three species that were investigated were Delphinus delphis,the short-beaked common dolphin, Stenella coeruleoalba, the striped dolphin, and Tursiops truncatus, the bottlenose dolphin. These dolphins all belong to the same dolphin subfamily, Delphininae, and are all widely distributed. They can be found in both the tropical and temperate waters of the Pacific, Atlantic, and Indian oceans and in most of the world’s seas, including the Mediterranean. This study investigated the morphological differences in the dolphin’s mandible, or its jaw, across three species and a geographic gradient. This geographic gradient was from the North Atlantic to the Mediterranean. These two bodies of water are very different: the North Atlantic has dense, cold water that is characterized by low salinity, and the Mediterranean has warm water that is characterized by high salinity and variability in both ocean productivity and seabed structure. Previous studies have looked at both genetic and morphological differences in the three species within this area and have found significant differences when comparing Atlantic to Mediterranean dolphins within their species. This study aims to test two main hypotheses: (1) the three dolphin species show significant differences in the structure of the mandible when comparing organisms from the Mediterranean versus the Atlantic, and (2) these morphological variations follow a similar pattern across the discrete geographic areas in the three species. The scientists hypothesized that the three species of dolphins have experienced the same pressures from the outside environment in each of the distinct geographic locations and have evolved similarly. 

Figure 1. Labeled diagram of the short-beaked common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba), & bottlenose dolphin (Tursiops truncatus), and a close-up view of the mandibular shape configurations used for comparison.
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