How does natural selection affects seasonal polyphenism in animals?

In this Wikipedia article there is a following statement:

Since these animals in widely separated groups have evolved separately, the similarity of coloration is due to convergent evolution, on the presumption that natural selection favours a particular coloration in a particular environment.

By looking at e.g. snowshoe rabbits, how can it be that natural selection "favors" a particular coloration during winter and summer? Is not the environment causes coloration without any "benefit" for these animals? How can it be proved, that these animals change their coloration because it is useful for them?

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    $\begingroup$ Thanks, the article focuses on social aspects only, but I will read it anyway. I'm more interested in ecological impact on coloration, though. And yes, I'm looking for the articles providing evidence. I.e. I want to see natural selection in action. $\endgroup$ – user35970 Aug 21 '17 at 23:46
  • $\begingroup$ I think that the textbook case of Peppered moths is a good example of how an environment can influence coloration and of evolution in action. It is not seasonal change but the principle is similar. en.wikipedia.org/wiki/Peppered_moth_evolution $\endgroup$ – have fun Mar 20 '18 at 14:50

[H]ow can it be that natural selection "favors" a particular coloration during winter and summer?

Camouflage for example. In regions, where it snows some animals would take advantage to have a fur colour that match the substrate in which they live and they may therefore be selected for having a white fur in winter and a non-white fur in summer.

Consider for example Lepus lepus in summer

enter image description here

vs in winter

enter image description here

How can it be proved, that these animals change their coloration because it is useful for them?

There are a whole lot of possible experimental design.

Considering seasonal coat colour in response to predation, a simple and obvious approach would be to experimentally dye the individuals and see how their survival varies depending on the colour they have been dyed.

Sometimes, you may have a sister clade that is non-plastic which it might be of interest to test against (depending on the exact question at play).

I'm more interested in ecological impact on coloration [..] I'm looking for the articles providing evidence

Cases of local adaptation (such as Hoesktra 2006 for example) or other evidence of natural selection on coat colour such as differential selection among lineages are probably way more common. But if you are specifically interested in seasonal variation then, here are a few papers I could find with a quick google scholar search showing selection on seasonal variation for fur colour.

  • $\begingroup$ Thank you for the quick response. I'd agree coloration is due camouflage, but it is hard for me to believe in that without evidence. Also, in summer they are more visible, but they are also visible in winter, though little more less. As to the testing method you proposed, I think it would be a good way to test natural selection in action. By the way, could this coloration happen without natural selection? $\endgroup$ – user35970 Aug 21 '17 at 23:04
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    $\begingroup$ @user35970 I think the issue is not about whether you can see the animal in its summer camo in the summer, especially in pictures of that animal (presumably selected by the photographer when you can see the animal..). The issue is that if it wore its winter coat in summer, it would stand out white against a non-white background; if it wore its summer coat in winter, it would stand out against a white background. It's certainly fine to have some skepticism, but being harder to see seems like it carries a pretty obvious benefit for any species, prey or predator. $\endgroup$ – Bryan Krause Aug 22 '17 at 2:33
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    $\begingroup$ @user35970 Sounds like you are being extremely opinion-based. You are selecting a specific trait (fur colour seasonal variation) and ask for evidence that it is adaptive, you read the paper and (whether or not your have much knowledge in data analysis but it does not sounds like you do reading your comments) you conclude that the paper is not good enough. There are tens of thousands of evidence out there (see for example the Hoekstra paper; I'm about to publish one more myself), it is not so hard to give an evidence that a trait is beneficial over another one. $\endgroup$ – Remi.b Aug 22 '17 at 14:51
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    $\begingroup$ Also, calling selection a creative force sounds like you you would take advantage of having a look at an intro course to evolutionary biology such as Understanding Evolution by UC Berkeley for example $\endgroup$ – Remi.b Aug 22 '17 at 14:51
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    $\begingroup$ @user35970: Differences in survival rates don't have to be large to have an effect, when they act over many thousands of generations. A practical way to test this would be to e.g. find a closely-related species (or even the same species) that lives in an area with little or no winter snow cover, and observe whether the same color changes occur, and their timing. Or (if you have sufficient time and funding, move color-changing species to a different location, and observe whether the change becomes less common over time. $\endgroup$ – jamesqf Dec 20 '17 at 3:51

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