The negative link between flightworthiness and fight-worthiness in birds has been found by new research. Birds could either fly or arm themselves, but not both. The new research suggests that both sexual and natural selection were involved in the development of wings and spurs. This insight helps us understand how the world came to be.
Beetles, deer, and crabs all do it. Birds do not. It's kind of puzzling, says the lead author of the new paper. Dancing, singing, fancy feathers and fighting are all ways of getting a mate, and often go together.
To understand why, Menezes and his co-author searched for two things: a reliable estimate of how many species of birds carry weapons, and a way of measuring how well different species fly.
Although the vast majority of birds are free of weapons, a small percentage pack weapons in the form of spurs on their legs. The hand-wing index, or HWI, is an enormous dataset that evaluates more than 10,000 species of birds and lets researchers compare how efficiently different birds are at taking wing.
The best fliers tend to lack spurs, and the most heavily armed fighters tend to struggle in the air, according to Menezes.
The researchers ran a number of simulations and models to show how much the evolutionary cost could be. Weapons, like dancing and the ability to sing, can help attract a mate and so can an advantage in sexual selection, but the spurs make flying a more energy intensive activity. It is difficult to pin down exactly how spurs affected the course of evolution, but it seems likely that spurs decreased an individual's ability to fly fast, far and takeoff easily. spurs might make birds more likely to get eaten or require more food to meet their daily energy requirements, while their unspurred counterparts can get away, eat less and live to breed another day.
This helps explain why birds have an amazing range of plumage, song and dance, while almost completely lacking in weaponry.
More information: Flight hampers the evolution of weapons in birds, Ecology Letters (2022). DOI: 10.1111/ele.13964 Journal information: Ecology Letters Citation: Fight or flight? How birds are helping to reveal the mysteries of evolution (2022, February 24) retrieved 24 February 2022 from https://phys.org/news/2022-02-flight-birds-reveal-mysteries-evolution.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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