Image Credit: Connor Long, CC BY-NC-SA 3.0, Image Cropped
Of poisons and parasites—the defensive role of tetrodotoxin against infections in newts (2018) Johnson et al., Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.12816
Many organisms in nature produce powerful (and sometimes deadly) toxic substances, often taken as evidence that prey evolved chemical defenses against predators. Interestingly, these chemical defenses are deadly not only to predators, but also to parasites. This complementary defense, in addition to the ubiquity of parasites themselves, indicate that parasites may have had a hand in the evolution of host toxicity.
One particularly potent toxin found in the animal kingdom is tetrodotoxin (TTX). It can cause paralysis, difficulty with breathing, and even death in some cases. Newts in the genus Taricha are notorious for having high concentrations of TTX in their skin and eggs, and this has long been thought to have evolved as a defense against predators. In particular, Taricha newts and garter snakes (Thamnopholis spp.) are a classic example of arms-race dynamics (see Did You Know). Despite this relationship, newt toxicity and snake resistance to the toxin don’t always match up perfectly in nature, suggesting that other factors may influence newt toxicitiy. The goal of today’s study was to study parasitic infection and compare it to variation in toxicity among two newt species, the rough-skinned newt (T. granulosa) and the California newt (T. torosa).
Image Credit: Danyell Odhiambo/ICRAF, CC BY-NC-SA 2.0
Local Adaptation to Biotic Interactions: A Meta-analysis across Latitudes (2020) Hargreaves et al., The American Naturalist, https://doi.org/10.1086/707323
Local adaptation is a process whereby individuals native to a given area are better-suited to live in that environment than foreign individuals, and those local individuals will out-compete foreign individuals. This adaptation to local conditions can range from a predator that is better at finding and catching prey, to a plant that is more efficient than another at taking nutrients from the soil, or to a host that has evolved defenses against a local parasite. Despite a wealth of literature and science that has been dedicated to the study of local adaptation, it is not clear what it is about the environment that commonly drives it.
Early studies of local adaptation measured abiotic (non-living) factors like temperature and the amount of light, but this ignores the fact that all environments include biotic factors like other species and any interactions with them. A small amount of studies have shown that biotic interactions (i.e. interactions with other species) can drive local adaptation, but there isn’t a consensus on how common of a pattern that is. Today’s authors used a meta-analysis of previous studies to test how these biotic interactions affect local adaptation. Read more
Image Credit: Francesco Veronesi, CC BY-SA 2.0, Image Cropped
Macroevolutionary convergence connects morphological form to ecological function in birds (2020) Pigot et al, Nature Ecology & Evolution, https://doi.org/10.1038/s41559-019-1070-4
There are an astounding amount of different forms that the animals on our planet take. Likewise, there are a multitude of diverse functions that animals serve in the environment, such as that of a herbivore, a predator, or scavenger. In some cases it’s a clear link between the form of a given animal and its function in the environment, like that of the beak of a hummingbird that allows it to feed on nectar and their role as a pollinator. But whether or not there is a reliable way to predict the function of an animal based off of its form is has been the subject of considerable controversy.
Deciding on how many morphological traits to use to predict ecological function is a difficult prospect. One could argue that it’s impossible to pick a finite number of traits, as there are infinite possible niches that organisms can fill so there’s no way that a set of traits could fill those infinite possible niches. Mapping animal form to function has major implications for quantifying and and conserving biodiversity, and the authors of today’s paper wanted to to determine just how many traits are needed to do that.
Image Credit: Aravindhanp, CC BY-SA 3.0, Image Cropped
City life alters the gut microbiome and stable isotope profiling of the eastern water dragon (Intellagama lesueuriii) (2019) Littleford-Colquhoun, Weyrich, Kent & Frere, Molecular Ecology, https://doi.org/10.1111/mec.15240
It’s a pretty fair call to assume that if you build a city on a species’ habitat, it might be a little miffed. Yet as human settlements expand worldwide, many species are showing that they’re able to make rapid changes to their biology to adapt to living around humans.
This includes their diet, of course. As diets shift, many other aspects of a species’ biology follows, including the microbes that live in a species’ gut. And gut microbes influence a huge range of factors, including immunology, development, and general health. The response of a gut microbe community (the gut microbiome) to a new diet can in turn affect an animal’s ability to adapt to that environment.
Mandt’s Black Guillemont (Image Credit: Óskar Elías Sigurðsson, CC-BY 2.0, Image Cropped)
Phenotypic plasticity or evolutionary change? An examination of the phenological response of an arctic seabird to climate change (2019) Sauve et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13406
If you’re here on Ecology for the Masses, then you know that climate change is not only real but is causing all kinds of problems for organisms the world over. One of the things that climate change is doing is altering seasonality, the time of year in which a given season will take place. For example, where I live in the US, it is normally cold at this time of year, but as I write this it is 60F/16C, much warmer than it should be despite it almost being winter. These changes can affect when organisms start their seasonal breeding, but how these breeding events change is not always the same.
Some changes are due to evolution, or the change in a population’s gene frequencies over time. As mutations and selection take place, a given population may have some traits or behaviors selected for over others. Another way that these changes can happen is via plasticity, which is a change induced by the environment, but without changing the gene frequencies (See Did You Know? for more information). The authors of today’s paper wanted to know if the change in breeding dates of a colony of seabirds (Mandt’s black guillemont, Cepphus grylle mandtii) was due to evolution or plasticity.
Image Credit: Friends, 1995
Yes, I watched Friends as a kid. Yes, I know it’s a comedy show. Yes, I loved it. Yes, I know it had serious problems in it’s depiction of a few minorities. Yes, I know Phoebe is a ball of whimsy and Ross is a condescending jerk. But I run a podcast called Cinematica Animalia and I’m an avid science communicator, so I want to talk about this scene, and what it potentially teaches us about how to talk about science.