Global warming causes rapid morphological changes in birds. The speed of these changes varies according to the species. Small birds are the best adapted to climate change, at least apparently. Passively: Climate change is destroying species migratory birds and although it seems to benefit the large, the small, and the established.
As the birds get smaller, Wings get longer as the world warmsand smaller-bodied species are changing faster. These are the main findings of a University of Michigan-led study published a few days ago in the journal Proceedings of the National Academy of Sciences.
The study combines data from two previously published papers that measured changes in body size and wing length in 86,131 bird samples over four decades in North and South America.
One of the studies focusing on the migratory birds Died after colliding with buildings in Chicago; the other analyzed resident birds Caught on Amazon.
Although the two datasets do not overlap in terms of both species composition and geography, and the data were collected independently using different methods, In both studies, the birds showed widespread and similar reductions in body size.with simultaneous increases in wing length.
Scientists have now gone one step further. A new analysis of data collected from these two studies has revealed an even more surprising pattern: in both. body size of smaller bird species decreased proportionally faster and wing length increased proportionally faster.
Danger of Extinction
Researchers believe that smaller birds may be adapting faster to climate change. “The relationships between body size and rates of change are remarkably consistent. However, the biological mechanism underlying the observed link between body size and rates of morphological change requires further investigation,” said ornithologist Benjamin Winger, co-author of the latest report.
Both the Chicago and Amazonia studies attributed the reduction in the species’ body size to: rising temperatures in the last 40 yearssuggests that body size may be “an important determinant of species responses to climate change.”
However, the available data did not allow to test whether the observed size changes represent rapid evolutionary changes. Natural selection.
“If natural selection plays a role in the patterns we observe, our results suggest that smaller bird species may be evolving faster because they experience stronger selection, are more susceptible to selection, or both,” said Principal Brian Weeks.
“In one way or another, body size appears to be an important mediator of bird responses to contemporary climate change‘, he pointed.
There is another open question: If larger birds are responding more slowly to global change, what is the outlook for the coming decades as temperatures continue to rise?
“Our results show that a large body size can exacerbate the risk of extinction“In contrast, faster morphological change in small taxa reflects a faster adaptive response to changing conditions.”
random gene mutations
New study analyzed data 129 bird species: 52 migratory breeding in North America and 77 resident in South America. The smallest bird among the Chicago species was the golden-crested wren (satrap of Regulus) had an average size of 5.47 grams and the largest was the common quíscalo (quiscalus quiscula) with 107.90 grams.
Among the Amazon species, swallow sapphire (thalurania furcata) the smallest with 4.08 grams, the largest with Amazon motmo (little mother) with 131.00 grams.
Biologists hypothesize that the generation length of a species, defined as the average age of offspring-producing individuals, is an important indicator of its ability to adapt to rapid environmental change.
For this reason, Shorter-lived organisms that reproduce on relatively short timescales, such as mice, evolve faster than organisms with longer generations, such as elephants.because mice have more frequent opportunities to exploit random genetic mutations that occur during breeding.
“Body size can be a valuable indicator of adaptive capacity and the extent to which modern evolution can reduce the risk of extinction among species.‘, the authors wrote.
Climate change is causing more changes in birds. For example, migrate earlier in spring as the world warms.
Most lagging migrants now leave a week later than before, so the length of the autumn migration season has lengthened significantly.
The researchers suggest that increases in wing length help compensate for the reduced body size and increase flight efficiency, allowing migration to be sustained.
Reference report: https://phys.org/news/2023-05-smallest-species-shifting-fastest-bird.html
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