Sizing up Salmon

By Grace Veenstra

This article covers the 2020 study by Ulaski, Finkle and Westley on the direction and magnitude of natural selection of body size among age-classes of seaward-migrating sockeye salmon.

“Bigger Isn’t Always Better”

The idea that “bigger is better” is a prevalent one in biology. Body size has a significant impact on fitness, the ability of organisms to survive and reproduce, across all branches of life. In wolves, a larger body size gives them greater success in grappling and subduing large prey like moose or elk (MacNulty et al., 2009). In dall sheep, a larger body size gives males a reproductive advantage when they compete for the right to mate, and since adult sheep may lose up to 16% of their body mass during winter, those with a higher body mass are more likely to survive (U.S. National Park Service, 2020). However, “bigger” is not always a “better” lifestyle method for some animals, and can be actively harmful to their chances of survival.

Insects and arthropods are limited in their body size because they breathe by soaking in oxygen like a sponge. If they are too large, they cannot absorb sufficient oxygen and die of hypoxia. It was only during the Paleozoic, when oxygen concentrations reached as high as 35% during the ​​Carboniferous period, that insects were capable of gigantism, with some dragonflies as large as seagulls (Harrison et al., 2010). Furthermore, it is costly to support a large body mass: the larger the body, the greater the energy requirements and the more food is required to sustain the animal. There are also factors of predation, where a larger body size may reduce agility, increase detection by predators, or increase costs to reproduction (Blanckenhorn, 2000). In essence, how natural selection acts on size is complex. Understanding how size correlates with survival is important, particularly when we are examining the salmon populations of Alaska.

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From Microplastics to Microorganisms


Over the last decade, plastic has become a more and more concerning source of pollution. In 2013 alone, almost 300 million pounds of plastic were produced worldwide (Lu et al 2017)Microplastics are defined as any plastic particle smaller than 5mm in diameter. Microplastics have been well documented as health concerns for marine life as more plastic accumulates in the ocean than any other place on earth. Additionally, microplastics have been found in a variety of household products including toothpaste and cosmetic products. We are just beginning to understand the extent microplastics have infiltrated our environment as well as our bodies, let alone the health risks they pose. One area of study deserving attention is the effect these plastics have on the microbiome of an organism. A microbiome is all of the bacteria, fungi, and viruses that live within or on a specific organism. Some of these microorganisms provide essential services to their host and maintaining a healthy microbiome has been tied to overall organismal health. Past studies have linked altered microbiomes to everything from obesity (Ridura et al 2013) to asthma (Stein et al 2016) Continue reading “From Microplastics to Microorganisms”

The Selflessness of Bacteria is Making Our Drugs Less Effective


In the 1940s Sir Alexander Fleming released the antibiotic Penicillin to the public transforming modern medicine forever. The emergence of antibiotics has had a profound impact on our lives, helping to increase our average life span from 56 to nearly 80 years (Ventola 2015). Antibiotics are an effective tool in fighting infection and have greatly reduced surgical complications. However, the flurry of excitement around these wonder drugs quickly went away. It was realized that the very microbes these drugs were supposed to be fighting were actually making them stronger and eventually became resistant to them. Continue reading “The Selflessness of Bacteria is Making Our Drugs Less Effective”

The Human Salivary Microbiome: Where the environment trumps genetics


Genetics and the environment; how do these interact? Do they always interact, or do genetics sometimes overrule characteristics learned from our environment? The question of nature, generally thought of to be our genetic make-up, versus nurture, the environments we’re exposed to in our developmental years,  has been the topic of debate by scientists and philosophers for centuries. Yet, the definitive answer still frustratingly eludes us. Some things, like the number of limbs we’re born with, are entirely decided by genetic factors. Other things, like many of our behaviors, rely on an interaction between genetics and developmental environment. Continue reading “The Human Salivary Microbiome: Where the environment trumps genetics”