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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A Species Arises: Ancient Reef-Building Coral Duplicates Genome in Response to Changing Environmental Conditions

By: Wafae El-Arar, Brandon Haffner, Grace Pickering, and Andrew Williams (Stonehill College, BIO323: Evolution, Spring 2020)

Due to rising sea water temperatures, a life-sustaining ecosystem in our oceans is under threat. Coral reefs are dying at a daunting rate, and climate change threatens many species that rely on the reefs. The coral species that are the architects of the reefs, such as Astreopora, or star coral, and Acropora, or stony coral, are some of many under threat. Researchers Yafei Mao and Noriyuki Satoh have been studying these species in order to determine their evolutionary history, and how more information on their evolutionary history can help to better understand coral reef biodiversity and support conservation efforts.  

Acropora donei, by K. Osborne <https://commons.wikimedia.org/wiki/File:Acropora_donei,_Masig.jpg>
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What’s All the Buzz About?

By: Kelsey DaSilva, Lauren Quintiliani, Cara Reynolds, and Mia Romano (Stonehill College, BIO323: Evolution, Spring 2020)

Welcome to the blog “What’s All the Buzz About,” serving you your daily buzz so prepare to be(e) amazed. This article examined honey bee queens of the species scientifically known as Apis mellifera. The common name for the species is western honey bee, and it is the most common honey bee species in the world. These bees are social insects, which means they exhibit a high level of societal organization. This is seen in their overlapping generations within a colony of adults, division of labor, and in the way broods, or groups of bees, work together. These characteristics make honey bees a model organism for studying social evolution. The article aimed to explore differences in observed egg size and the cause of egg size variation. Plasticity plays a large role here and is defined as the ability of an organism to be flexible and to change in various aspects based on factors in their environment. Plasticity occurs in organisms for evolutionary beneficial reasons. Understanding plasticity and variability in genes, specifically seen in the egg size of honey bees, is important because it serves as a model to understand life on earth, it can increase fitness, generate novelty, and facilitate evolution. This article helps to further understand evolution in a social context and provides a practical application of plasticity.

Western honey bee (Apis mellifera), by A. Trepte <https://commons.wikimedia.org/wiki/File:Apis_mellifera_Western_honey_bee.jpg>
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A Small Snail with Big Influence

By: Claire Shamber, Lauren O’Regan, Julia Nuzzo, and Julia Tawil (Stonehill College, BIO323: Evolution, Spring 2020)

Periwinkle is not just a color; it is also an organism! Flat periwinkles are small sea snails that live throughout the northern shores of the Atlantic Ocean. Researchers have been interested in periwinkles because of their large dispersal across different shores and their potential to provide information about the intertidal zone. The intertidal zone is the area where the ocean meets the shoreline between low and high tides. This environment is subject to ecological speciation, meaning that the varying conditions of the intertidal zone can create differences between species. Speciation is the process of a single species splitting into two separate distinct species. Periwinkles offer a good look into how we determine whether two populations should be considered as their own species.

Littorina obtusata, by H. Zell <https://commons.wikimedia.org/wiki/File:Littorina_obtusata_01.jpg>
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The Wonderful Venus Flytrap: Marginal Spikes Form a “Horrid Prison” for Moderate-Sized Insect

By: Daniel Bender, Thomas Dickey, Laryssa Kalbfus, and Emily Langmeyer (Stonehill College, BIO323: Evolution, Spring 2019)

The American Naturalist article, Testing Darwin’s Hypothesis about the Wonderful Venus Flytrap: Marginal Spikes Form a “Horrid Prison” for Moderate-Sized Insect Prey, by Davis et al. (2019) is a set of field observations and lab experiments in support of the hypothesis that marginal spikes increase the success rate of prey capture for medium-sized insects in carnivorous plants. Marginal spikes are the spikes along the edge of a Venus flytrap. As a Venus flytrap closes on its prey, these spikes create an enclosed cage-like structure securing it in place. Darwin theorized that very small insects can slip through the spaces between spikes for escape and very large insects are able to overpower the plant’s snap trap and break free, but moderate-sized insects will be trapped in a “horrid prison” should they find themselves captured. Davis et al. were able to test their hypothesis by measuring prey capture efficiency on plants with marginal spikes and with the marginal spikes removed for different sized crickets. They were able to collect these necessary data sets by performing field data collection of wild plants, a controlled laboratory experiment, and a semi-natural experiment.

Venus flytrap
The trap of a Venus flytrap, showing trigger hairs and marginal spikes. Photo by Noah Elhardt.

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Turtle Neck Evolution

By: Taylor Auletto, Nick Botelho, Jeremy Breen, and Rebecca Johnson (Stonehill College, BIO323: Evolution, Spring 2019)

The neck is a seriously underappreciated part of the body of most organisms. Think about it: what if you didn’t have a neck? Or, what if you were incapable of moving your neck? Weird, huh? The proper development and functioning of a neck are essential to survival for many species. This is especially true for turtles. Turtles have the unique ability to retract their neck into their shell when necessary; without this ability, they would be highly susceptible to predators and other such dangers. As such, researchers Christine Böhmer and Ingmar Werneburg wanted to investigate the way the cervical vertebral (CV) column appears across multiple extinct and living turtle taxa for the first time. The cervical vertebral column is essentially composed of segments of the skeleton that make up the neck. Turtles have 8 (referred to as CV1-CV8) of these segments. What’s more, these segments have been conserved through evolution for millions of years. What we already know, though, is that there are specializations in the CV column that are different (i.e., specialized) in different groups of turtles, depending on the method by which they retract their necks. These differences are known to be due to differences in how Hox genes have been modified through evolution. Hox genes are genes that are involved in the body plan of all organisms. Böhmer and Werneburg state that their work ultimately aims to understand how evolution has worked to create the differences in CV columns that we can see today.

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Telomere Length and Life Spans in Starlings

By: Maggie Diehl, Michaela Duffy, and Bryanna Norden (Stonehill College, BIO323: Evolution, Spring 2019)

When we hear the word “aging”, the first images that pop into our minds are usually those of wrinkled skin and gray hair. Although these are common visual characteristics of aging in humans (and other animals), we often fail to recognize the biological processes behind these physical features. Just as our bodies grow old and lose efficiency, our cells lose their ability to grow and divide properly. The process of the gradual deterioration of function of cells is also known as senescence, which is currently a popular topic in evolutionary biology. For many years, scientists have proposed theories to explain the inevitable struggle of aging. Likewise, they have pondered whether conditions during early development play a role in the longevity of one’s life. To examine this possibility, researchers in previous studies have used telomere length as a predictor of survival. Simply put, telomeres are noncoding DNA regions on the ends of eukaryotic chromosomes. They serve as protectors, preventing unwanted deterioration or fusion with surrounding chromosomes. Additionally, they maintain chromosome stability and serve as “mitotic clocks”, shortening (in length) with each round of cell division. When telomeres shorten to almost nothing, coding DNA is exposed and damaged, resulting in cells failing to function properly. The rate at which these vital “chromosome caps” shorten may be accelerated by various environmental stressors in early life, leading to a faster accumulation of senescent cells (which cannot replicate) and an overall shorter lifespan.

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