A study led by researchers at the American Museum of Natural History presents the oldest known example in the fossil record of an evolutionary arms race.
Described in the journal Current Biology, the study provides the first demonstrable record of an evolutionary arms race in the Cambrian.
An evolutionary arms race is a process where predators and prey continuously adapt and evolve in response to each other.
This dynamic is often described as an arms race because one species’ improved abilities lead to the other species improving its abilities in response.
This suggests that a microevolutionary arms race was in place, with L. fasciculata finding a way to fortify its shell against predation and the predator, in turn, investing in the ability to puncture its prey despite its ever-bulkier armor.
The oldest known instance of an evolutionary arms race in the fossil record is presented in a study conducted by scientists at the American Museum of Natural History. A small, shelled animal that was distantly related to brachiopods and an unidentified marine animal that could pierce its shell engaged in predator-prey interactions 517 million years ago in the ocean that covers modern-day South Australia.
According to a report published in the journal Current Biology, the study offers the first concrete evidence of a Cambrian evolutionary arms race.
Given the sharp rise in the variety and quantity of biomineralizing organisms during this period, predator-prey relationships are frequently cited as a key factor in the Cambrian explosion. Russell Bicknell, a postdoctoral researcher in the Museum’s Division of Paleontology and the study’s lead author, stated that there has been little empirical evidence to support the idea that prey directly responded to predation and vice versa.
When predators and prey constantly adjust and change in response to one another, it’s known as an evolutionary arms race. This relationship is frequently referred to as an arms race since the enhanced capabilities of one species cause the other species to enhance its own capabilities in response.
A sizable sample of fossilized shells belonging to the early Cambrian tommotiid species Lapworthella fasciculata from South Australia was examined by Bicknell and associates from the Universities of New England and Macquarie University in Australia.
Over 200 of these minuscule specimens, which range in size from slightly bigger than a grain of sand to just smaller than an apple seed, have holes that were probably punched by a predator that is likely to be a soft-bodied mollusk or worm.
After comparing these specimens to their geologic ages, the researchers discovered that the number of perforated shells quickly increased in tandem with the thickness of the shell wall. This implies the existence of a microevolutionary arms race, with L. By strengthening its shell against predators, fasciculata invest in the capacity to pierce its prey despite its increasingly robust armor.
According to Bicknell, “this historically significant evolutionary record reveals, for the first time, that predation was essential to the growth of early animal ecosystems and demonstrates the rapid speed at which such phenotypic modifications arose during the Cambrian Explosion event.”.
