Scenario one seems implausible from a phylogenetic perspective, as it requires a very large number of parallel evolutions of the distinctive doubled cell morphology within the diplomonad-enteromonad clade.
We hypothesize that the selective environment imposed by the LCR's unique bathymetry and hydrology has shaped the evolution of these distinctive phenotypes multiple times and across phylogenetically disparate fish families.
The extreme cold of the European Ice Ages is considered at least partly responsible for the evolution of some of the distinctive Neanderthal anatomy, although other factors (functional demands, effects of chance in small populations) were probably also important.
Now that we understand who synapsids are and where they fall on the tree of life relative to other groups such as reptiles, let us turn to the topic of synapsid diversity and its implications for the evolution of many of the distinctive characters of mammals.
Genetic accommodation (see above) could have then refined the existing variation in shrimp foraging ability to favor the evolution and elaboration of the distinctive carnivore phenotype.
Instead, during several ice ages, rising glaciers over the past eons cut off Western Europe from the rest of the continent, and this isolation likely contributed to the evolution of Neanderthals' distinctive features from the more primitive Homo erectus.
Although in the monocots these two groups are highly diverse and have a strongly canalized floral morphology, there is no information on the role of positive selection in the evolution of their distinctive flower morphologies.
ON HIS CLAPPING Miles explained the evolution of his distinctive manner of clapping, which often involves his being hunched over as he smacks his palms together with his fingers spread wide.
The oldest synapsid fossils are about 315 million years old, and the synapsid fossil record provides insight into the changes these animals underwent between their origin and the evolution of mammals (about 205 million years ago), as well the evolution of many distinctive mammalian features like our three tiny middle ear bones.
This implies that an ancient subset of PARCELs was irreversibly fixed in Mollicutes (Additional file 4B), concurrent with the evolution of its distinctive codon usage.
