Madam, can you do some erotic art?

Have you seen these two emoticons recently?

Color Bird Art｜Sina Weibo: @猛禽bot

These two emojis come from Weibo blogger @猛禽bot. They were reposted crazily and became “cyber patina” in a few days, which naturally shows the nature of human beings…

However, what I want to discuss is not humans, but birds in the real world - after all, some birds do deserve the title of "colorful birds".

As terrestrial vertebrates with the most developed color vision, birds are closely related to "color" (in both senses). Bright colors are an important criterion for many birds to choose a mate. If the male zebra finch, which is often used in biological experiments, is given a red leg ring, he will be very popular with female birds under ultraviolet light, but if he is given a green leg ring, he will be left out.

Darwin noticed more than a hundred years ago that female birds use bright colors as a criterion for choosing their ideal mates. However, as the theory of evolution has developed, we have discovered a new problem: among birds that love colors, there seems to be a "no color" ban, and it is quite common. A comparative study of 47 genera of Thraupidae showed that males evolved from bright colors to gray five times more often than they evolved from gray to bright colors!

A brightly coloured tanager, Tangara seledon | Lars Falkdalen Lindahl / Wikimedia Commons

01

You can't be as lustful as you want.

Why did birds give up color? The first thing to suspect is the simplest (and least interesting) reason: random genetic mutation. Mutations may make beautiful colors impossible to express, such as the white peacocks commonly seen in zoos, which are the result of mutations of blue peacocks.

The second is the change in female "aesthetics". The standards of female animals for "beautiful men" may be meaningful ("beautiful" features represent strong males or excellent genes), or they may be completely meaningless (such as the preference of moonfish for males with extended tails). However, once females with a certain "aesthetics" become the majority, it will trigger the evolution of females frantically chasing "beautiful men" just like chasing fashion.

This is because if you like "ugly men" (in the eyes of most females), your sons will also be "ugly", thus reducing your offspring. "Aesthetics" is always influenced by the tastes of the public. This is the "runaway selection" theory proposed by Sir Ronald Aylmer Fisher, one of the great men in evolutionary biology after Darwin. If females like gray males, then it is inevitable that males will become gray.

Scarlet Tanager Piranga olivacea | MaxPixel

Third, being beautiful can be hindered by various environmental factors. The beautiful colors of some birds are produced by consuming pigments such as carotene. In an environment lacking these nutrients, they will naturally become dull. Karen Marchetti's study of Phylloscopus warblers found that male birds living in an environment with poor lighting are more likely to have brightly colored feathers to increase their conspicuousness. On the contrary, in an environment with good lighting, male birds do not need to dress up in a flashy way.

Some birds get their bright colors from pigments in their food | Ricardo Jorge Lopes et al. / Current biology (2006)

02

Losing your life for sex?

Finally, beauty is expensive, and it can even cost one’s life. In fact, Darwin said long ago that the beautiful feathers of peacocks disgusted him. Because the natural selection he proposed could not explain the meaning of its existence. No matter how you look at it, the huge and bulky peacock’s feathers will only hinder survival rather than help it.

Evolutionary scientist John A. Endler studied another animal famous for its color, the Poecilia wingei. This small fish is a relative of the ubiquitous ornamental guppy. The males have beautiful red and blue spots on their bodies to attract females, but their colorful appearance also attracts predators. So, not surprisingly, the Poecilia wingei is more colorful in the upper reaches of the river where there are fewer carnivorous fish, and more low-key in the lower reaches where there are more carnivorous fish.

The brightly coloured patterns of the Wen's Puppy | Dgrummon / Wikimedia Commons

Denson Kelly McLain and others compared 132 species of birds introduced to islands (such as Hawaii and New Zealand) and found that birds with different male and female colors (males may be very "colorful" to attract females) are much more likely to become extinct on the islands than birds with the same male and female colors (males may be as gray as females). "Color" may have brought them disaster. Beautiful feathers may cost a lot of nutrients, or may attract the attention of predators.

03

Color is not good for the future

Scientists have also considered another possibility: male birds that are very "colorful" are almost certainly also "colorful" in another sense - the meaning of beautiful colors is to attract females, so the degree of male beauty indirectly reflects the potential benefits of attracting females. Among those species with extremely beautiful males (such as peacocks), a few of the most beautiful males occupy most mating opportunities, and the competition for talent shows is even more severe than in the entertainment industry. As a result, most females are inseminated by a few of the most "colorful" males, resulting in an extreme lack of genetic diversity in their paternal lineage. This leads to inbreeding or the loss of valuable genotypes.

Species with exceptionally beautiful males often have exceptionally exaggerated polygamy | Pixabay

A survey of another animal that is not good-looking but very "colorful" in another sense proves that this worrying situation is indeed possible. A study of the allozyme genes of the northern elephant seal (Mirounga angustirostris) found no mutations, which means that their genes are surprisingly consistent. On the one hand, this is because they were once hunted to the brink of extinction by humans, and nearly 100,000 northern elephant seals are the descendants of a few. On the other hand, it is because elephant seals have the most exaggerated marriage system among mammals, and the highest-ranking male elephant seals can have hundreds of "wives and concubines."

Evolution has no gods to direct it, so it has no foresight. In the short term, "sex" may make the male bird have many children and grandchildren, but it will sow the seeds of extinction in the future. As the saying goes, "sex is emptiness."

References

[1] Wiens, John J. "Widespread loss of sexually selected traits: how the peacock lost its spots." Trends in ecology & evolution 16.9 (2001): 517-523.

[2] McLain, Denson Kelly, Michael P. Moulton, and James G. Sanderson. "Sexual selection and extinction: the fate of plumage-dimorphic and plumage-monomorphic birds introduced onto islands." Evolutionary Ecology Research 1.5 (1999): 549-565.

Author: Little Wombat

Editor: pee pee shrimp

This article comes from the Species Calendar, welcome to forward

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