Tag Archives: prey

Protection from Two Enemies with One Defense

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

The Crux

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).

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Outdoor Cats are a Problem

Outdoor cats are a contentious issue for cat-owners, cat-lovers, and those that are concerned about the environment. Like it or not, Fluffy is doing a LOT of damage (Image credit: Cat Outside in Sweden-148884.jpg by Jonatan Svensson Glad, CC BY-SA 4.0, Image Cropped).

I hate to be the bearer of bad news, but domestic cats are bad for the environment. Sure, we as a species have adopted and incorporated them into our society (I live with two, myself), but that doesn’t mean we aren’t responsible for them and their actions.

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The Multiple Enemies of Prey Species

Image Credit: Mike Baird, CC BY 2.0, Image Cropped

The importance of functional responses among competing predators for avian nesting success (2019) Ellis et. al, Functional Ecology, https://doi.org/10.1111/1365-2435.13460

The Crux

In our ever-changing world, natural populations of different species are experiencing changes in both size and range. Part of the difficulty in predicting or responding to these changes is that ecological systems are made up of complex webs of species interactions, all of which have the potential to affect how populations respond to these changes. One of the most important interaction that occurs between species is predation.

Predators can affect the way prey species look, behave, and even where they live (see the Did You Know section). Different predator species can have varying effects on their prey, and as such it is important to consider these differences whenever wildlife managers make policy decisions on how to manage and control endangered populations. The authors of today’s paper were interested in uncovering how different predator species affected prey, using the snowy plover (Charadrius nivosus).

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Speed Kills. Or Does It?

In an eat or be eaten world, the survival of the fittest can come down to who the most physically able is. Today’s paper investigated the athletic ability of sidewinder rattlesnakes relative to their kangaroo rat prey. (Image Credit: TigerhawkvokCC BY-SA 3.0, Image Cropped).

Determinants of predation success: How to survive an attack from a rattlesnake (2019) Whitford et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13318

The Crux

In nature, many animals are part of the predator-prey cycle. One animal is subject to being eaten by the other, and must escape in order to avoid this fate. Despite what you may have seen on a variety of amazing nature documentaries, most predator-prey interactions don’t involve some flashy takedown and subsequent meal for the predator. Predators usually fail far more often than they succeed, with one of the most successful animals on the planet (the killer whale) only succeeding HALF of the time.

These interactions between predators and their prey depend on two things: the predator’s physical attack ability/performance and the prey’s escape ability. Basically, who is more athletic? There are many different ways that predators try and take down their prey, but the authors of today’s paper wanted to know what the key aspects of the predator-prey interaction are, and which of them is most important for each participant.
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Do As I Do

Predators like these Great tits (Parus major) eat a wide variety of insects, but some of those insects are so unpleasant to eat that birds tend to avoid them. How does this trait evolve in prey animals when its maintenance and origin depend on the predators learning by eating them? (Image Credit: Shirley ClarkeCC BY-SA 3.0).

Social information use about novel aposematic prey is not influenced by a predator’s previous experience with toxins (2019) Hämäläinen et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13395

The Crux

Many animals in nature have evolved a defense strategy known as aposematism, meaning that they display warning colors or patterns that tells predators that they are not worth eating due to their toxicity. Predators can learn to avoid aposematic prey by either sampling different prey animals and learning for themselves, or they can watch other predators eat different prey species and, depending on the reaction of that predator, learn what may or may not be good to eat.

The paradox of the evolution of this aposematic trait is that toxic prey species are not only highly visible and easily noticed by predators, but they must be attacked in order for predators to learn that they shouldn’t eat them, meaning that these prey species may not even survive long enough for them to enjoy the benefits of predator avoidance. The question then becomes are aposematic prey able to persist in nature because predator learn to avoid them? The authors of today’s paper wanted to investigate how predators that have learned to avoid toxic prey will watch and learn from other predators eating new, possibly toxic prey.  Read more

Fading Into the Background

Mostly limited to ocean animals, transparency is thought to help escape predators by blending the animal in with its environment, but is this what actually happens? (Image Credit: birdphotos.com, CC BY 3.0, Image Cropped)

Transparency reduces predator detection in mimetic clearwing butterflies (2019) Arias et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13315

The Crux

Predators are one of the strongest forces of selection in the natural world, and as a result it can be quite costly to stand out and be more easily noticed. This means that in order to survive, animals must adapt to avoid predators. Besides running away from what is trying to eat you, your best bet is to evolve body coloration that helps you avoid being seen by a predator.

Animals that rely on blending in will match the color or even the texture of their backgrounds, but when prey species live in areas where they cannot easily blend in (like plankton in the water column) they often evolve to be transparent. Unlike their marine counterparts, transparency is normally rare in terrestrial animals. The clearwing butterfly is one notable exception to this rule, and the authors of today’s paper wanted to test whether or not these clear wings actually reduce predation.
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To Blend in or Stand Out?

Body coloration of an animal can be useful for not only attracting prey, but also avoiding being eaten. One important question is whether or not this coloration can simultaneously serve both purposes? (Image Credit: Chen-Pan LiaoCC BY-SA 3.0, Image Cropped).

Multifunctionality of an arthropod predator’s body coloration (2019) Liao et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13326

The Crux

One topic that has interested ecologists for decades is that of animal body coloration, and what function that coloration can serve for the animal. Despite this fascination and the work that has been done to study this aspect of animal biology, the actual mechanisms driving the evolution and maintenance of body color are not well understood. Many different aspects of an organism’s life can shape and affect body color, such as avoiding predators, attracting mates, and whatever resources an organism has available to create specific colors. In addition, many of these aspects often compete with one another, such that a color that is good for attracting mates may also make you more easily-spotted by a predator.

Spiders provide an excellent system in which to study the evolutionary significance of body colors, as previous work has shown that body color affects mate attraction, predator avoidance, and prey attraction. The authors of today’s study wanted to know if these complex color patterns could serve more than one function in the spider’s life.
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How to Ecology Your Dragon

Image Credit: DreamWorks Dragons, 2012

In our second week on the dragons of Dreamworks’ How to Train Your Dragon trilogy, we have a flamin’ good time discovering why those dragons are WAY too wacky, exactly how much intraspecies predation goes on in Berk and why you should really make up your mind about domestication.

03:49 – Vikings in Cinema
10:57 – Ecology of the Dragons
29:17 – Toothless vs. the Furious Five

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Scared to Death

Fear itself of a predator is enough to reduce populations of a snowshoe hare, show Macleod at al.

Fear itself of a predator is enough to reduce populations of a snowshoe hare, show Macleod at al. (Image Credit: Dave Doe, CC BY 2.0, Image Cropped)

Fear and lethality in snowshoe hares: the deadly effects of non-consumptive predation risk (2018) MacLeod et al., Oikos 127(3)

The Crux

When we think of a predator-prey relationship, many colorful examples of charismatic animals come to mind: the lion and the wildebeest, the orca and the seal, the owl and the mouse. We think of these organisms locked in an endless battle, with one needing to catch and eat, the other to escape and live. While these are definitely interesting and important aspects of the predator-prey relationship, prey species need to worry about more than just being eaten. These “non-consumptive effects” play into what is called the Ecology of Fear.

This study was an attempt to show that the perceived risk of predation itself was enough to reduce survival in prey species. Unlike previous studies on this question, MacLeod et al. were the first to conclusively show this effect in mammals.

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