The story of the peppered moths is a textbook evolutionary tale. As coal smoke darkened tree bark near England's cities during the Industrial Revolution, white-bodied peppered moths became conspicuous targets for predators and their numbers quickly dwindled. Meanwhile, black-bodied moths, which had been rare, thrived and became dominant in their newly darkened environment.
The peppered moths became a classic example of how environmental change drives species evolution. But in recent years, scientists have begun thinking about the inverse process. Might there be a feedback loop in which species evolution drives ecological change? Now, a new study by researchers at the University of Rhode Island shows some of the best evidence yet for that very phenomenon.
In research published in the Proceedings of the National Academy of Sciences, the researchers show that an evolutionary change in the length of lizards' legs can have a significant impact on vegetation growth and spider populations on small islands in the Bahamas. This is one of the first times, the researchers say, that such dramatic evolution-to-environment effects have been documented in a natural setting.
[...] Armed with specialized lizard wrangling gear—poles with tiny lassos made of dental floss at the end—the team captured hundreds of brown anoles. They then measured the leg length of each lizard, keeping the ones whose limbs were either especially long or especially short and returning the rest to the wild. Once they had distinct populations of short- and long-limbed lizards, they set each population free on islands that previously had no lizards living on them.
Since the experimental islands were mostly covered by smaller diameter vegetation, the researchers expected that the short-legged lizards would be better adapted to that environment, that is, more maneuverable and better able to catch prey in the trees and brush. The question the researchers wanted to answer was whether the ecological effects of those highly effective hunters could be detected.
After eight months, the researchers checked back on the islands to look for ecological differences between islands stocked with the short- and long-legged groups. The differences, it turned out, were substantial. On islands with shorter-legged lizards, populations of web spiders—a key prey item for brown anoles—were reduced by 41% compared to islands with lanky lizards. There were significant differences in plant growth as well. Because the short-legged lizards were better at preying on insect herbivores, plants flourished. On islands with short-legged lizards, buttonwood trees had twice as much shoot growth compared to trees on islands with long-legged lizards, the researchers found.
The results, Kolbe says, help to bring the interaction between ecology and evolution full circle.
Journal Reference:
Kolbe, Jason J. et al, Experimentally simulating the evolution-to-ecology connection: Divergent predator morphologies alter natural food webs, PNAS (2023). DOI: 10.1073/pnas.2221691120
(Score: 2, Interesting) by krishnoid on Friday June 09, @07:58PM (5 children)
"Hey, we're back! Let's look for *any* differences in plants or animals on this island. Shouldn't be hard to identify since we all have eidetic memories about what everything used to look like."
I suppose that's possible, considering they were all descendants of whoever did the cargo manifest on Noah's ark.
(Score: 0) by Anonymous Coward on Friday June 09, @09:03PM (4 children)
Yes, I'm sure the scientists were using their memory to record the data. Dumbass.
But fair point, the interaction between species in the environment is more complex than the most complex neural network, so identifying one single thing as being caused by one other single thing is bound to be speculation or just plain coincidence.
(Score: 2) by JoeMerchant on Friday June 09, @09:32PM (3 children)
>identifying one single thing as being caused by one other single thing is bound to be speculation or just plain coincidence.
Certainly replication would strengthen their argument, but it's not hard to take a survey of the population/state of the primary species on a small island and compare to before to after introduction of a species.
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 2) by krishnoid on Saturday June 10, @02:56AM (2 children)
I really don't know how you count spiders in a jungle. Also, I guess they were specifically targeting buttonwood trees and counting the new growth on them before and after? It just seems so difficult to observe (for humans, anyway) compared to large-scale environmental modifiers [youtu.be] like beavers or physically large land/amphibious animals.
(Score: 1, Interesting) by Anonymous Coward on Saturday June 10, @11:45AM
> I really don't know how you count spiders in a jungle.
Someone figured it out, only took a minute of googling to find this:
https://www.researchgate.net/figure/Spider-density-in-tropical-forests-Estimated-number-of-total-and-adult-spiders-in-a_tbl1_24042655 [researchgate.net]
(Score: 3, Informative) by JoeMerchant on Saturday June 10, @11:48AM
I would imagine they counted spiders a lot like I almost counted brittle stars for bio surveys in the Florida Keys: mark off a grid of one meter squares and then flip over all the rocks they live under and count & measure them for size. After you have counted a sufficient number of squares you can use statistics to characterize the uniformity of distribution in the habitat you are measuring and be reasonably certain of how that projects across similar habitat which you can then characterize with a smaller number of samples.
For spiders or other insects in the jungle they probably use traps instead of flipping over rocks but with similar sampling statistics.
To what degree you trust statisticians is more of a personal choice, but the science publishing community is more or less "all in" with their methods.
Україна досі не є частиною Росії Слава Україні🌻 https://www.pravda.com.ua/eng/news/2023/06/24/7408365/
(Score: 5, Informative) by requerdanos on Friday June 09, @10:59PM
There are reasonable [discovery.org] voices [wikipedia.org] that dismiss the peppered moth "textbook" studies as somewhere between "bunkum" and "hoax."