China News Service, Beijing, September 17 (Reporter Sun Zifa) Tail feathers are an important part of a bird's flight system. Its shape is influenced by natural selection (aerodynamics) and sexual selection that attracts the opposite sex.

How does sexual selection affect bird tail feather evolution?

Has always attracted the attention of academic circles.

  Scientists have recently discovered and named the new genus "Yuān chú" (Yuān chú), a new genus of the anti-avian pennidae 120 million years ago in the Early Cretaceous. "Zhuangzi·Autumn Water": "There are birds in the south, and their name is Grenald Chicks"), research reveals the impact of the dynamic interaction between sexual selection and natural selection on the early evolution of birds.

An orthotype specimen of the early Cretaceous anti-bird Ya-tailed Grenada fossil.

Photo courtesy of Wang Min

 Two special tail feather shapes converge for the first time

  This research on the evolution of bird tail feathers was led by Researcher Wang Min and Academician Zhou Zhonghe of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and jointly completed by the Field Museum of Natural History, Nanjing University, Linyi University, Tianyu Museum of Natural History, etc. The result paper was published online in the international professional academic journal "Contemporary Biology" on the night of September 16, Beijing time.

  Wang Min, a young scientist who has just won the Scientific Exploration Award, is the first author and corresponding author of the paper. He introduced that anti-birds are the first group to undergo global radiation differentiation in the evolution of birds. (All modern birds evolved from it) constitute sister groups.

The continuous discovery of fossils makes it possible to trace the ecological-morphological diversity changes of this sister group during the nearly 65 million years of co-evolution.

  The Ya-tailed Gnome fossil is produced in the Jiufotang Formation of the Lower Cretaceous in Liaoning. It belongs to a class of Mesozoic anti-birds with needle-shaped tails. Its tail feathers are fan-shaped by four pairs of flaky feathers, with a prominent pair of tail feathers in the middle. Lengthened, even more than 1.3 times the body length, the rachis on it is unusually wide, and the short tail feathers on both sides form a species that has never been seen in dinosaurs or Mesozoic birds, but is similar to some modern birds such as sunbirds. Very similar pin tail structure.

This study found that the Ya-tailed Grenade has combined the two special tail feathers of "pinnacle-dominated feathers with end feathering" and complete pinnacles together for the first time.

Or the effect of the "obstacle principle"

  Many male birds have colorful and complicated tail feathers, which are obviously not good for flying, but they are good for attracting the opposite sex. Darwin proposed the concept of "sexual selection" accordingly.

Wang Min pointed out that when the length of the feather exceeds the maximum width of the fan formed by the tail feathers, the excess feathers will reduce the efficiency of flight. Such feathers are often the result of sexual selection.

  He said that compared to the "pinnacle-dominant feathers with end-feathering", the full pinnacles of the long tail feathers on the Ya-tailed Grenada are obviously more detrimental to the survival of the individual in terms of growth and daily maintenance. Such a decorative feature, which is more unfavorable from the perspective of natural selection, in most cases reflects the relatively better competitiveness of the holder (obtaining food, building nests, raising offspring, etc.). This sexual selection mechanism is Called the "obstacle principle", the structure of the tail feathers of the Ya-tailed Grenada is likely to be the result of the "obstacle principle".

The morphology, pigment body, and hind limb feathers of Ya-tailed Grenade.

Photo courtesy of Wang Min

 Interaction affects bird evolution together

  Wang Min said that unlike anti-birds, the Mesozoic modern birds all had fan-shaped tail feathers, but they rarely had decorative tail feather structures.

The research team counted all the anti-birds and current bird types found, and found that long tail feathers that are subject to sexual selection are more common in anti-birds, and proposed that the tail feathers are completely different in the two sister groups. It is the result of the different ecological habits of the two:

  Anti-birds are dominated by arboreals, and need to bypass the shelter of shrubs through exaggerated tail feathers in order to attract the opposite sex; early modern bird-types inhabit open lakes, and complex tail feathers are easily found by predators, so they adapt The aerodynamic fan-shaped tail feathers are more widely distributed under the action of natural selection. These modern bird types may attract the opposite sex through singing, nesting or other methods.

  "The constantly discovered fossils further show that the interaction of sexual selection, natural selection, and ecological opportunities together has an impact on the evolution of birds." Wang Min said.

(over)