The ice age may have caused the extinction of dinosaurs and the woolly mammoths may have disappeared because of declining sources of food, but extinction doesn’t always have to be due to environmental triggers, as scientists at the University of California, and the University of Chicago recently found.
While exploring the genetic data of several species over 200 million years of fossil records, the researchers found that the extinction rates were phylogenetically conserved.
Basing the study on extinction rates of marine bivalves, the researchers proved that disappearance of certain species correlated among their closest genetic relatives. Hence, certain genetic traits make organisms more susceptible to extinction. Of course, this doesn’t exclude the possibility that these specific traits can be liable to certain environmental factors.
As one commentator pointed out, this study being restricted to marine bivalves could be exclusive to this particular class of organisms. Also, it does not completely exclude the possibility that environmental factors may have caused the changes as well. The authors point out that Cretaceous–Tertiary extinction event that caused the mass extinction of several animals and plants within a short period of time seemed to have caused little effect on the long-term extinction of these bivalve families.
Despite the evidence provided by such statistical studies, it’s hard to determine the comprehensive group of factors that would contribute to an organism’s extinction. It could simply be that another organism was able to adapt to certain environmental changes better than the species in question, and hence passed down the “survival mutation.”
The lead author Kaustuv Roy says that this study would have an impact on modern day attempt to save specific species from extinction. According to him the focus should be on saving a particular genus or family as opposed to the species level.
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