September 4th, 2016
(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: firstname.lastname@example.org
We found the same two mitochondrial genes (cob and nad5) under selection in lineages that independently invaded the land. This was a strong hint that similar selective forces left their footprint in the mitochondrial genome; both genes encode enzymes deeply involved in the energy production pathway, which is in line with our assumption that adaptation to the land environment required changes to cope with the increased energy demands.
Mitochondrial proteins are vital to organisms, and as such are highly conserved in their structure and functions between diverse organisms across the Tree of Life. That means that it is relatively easy to compare the amino acid sequences from snails against, for example, those from bats, dolphins, humans and rats. , we noticed that selection signatures were also found in vertebrates in similar amino acid positions in the proteins encoded by these genes.
Thus, we realized a similar pattern may have occurred in snails in order to adapt to changing energy demands in the transition to a new habitat as in vertebrates. The same proteins and sometimes even the same amino acid positions have apparently been under selection in whales as they moved from land to water, in bats moving from land to air, and in rodents going from living on the surface to subterranean habitats.
It seems that under drastically changing conditions, animals from very different groups came out with similar adaptations to their molecular machinery, probably because these changes are pivotal in answering the increased energy demands of their new habitats.