Sentence examples for has evolved twice from inspiring English sources
With the evidence we have, either story is possible: maybe the nervous system has evolved twice, or maybe it was reduced in sponges.
On the other hand, if FoxP2 does function in echolocation, then the signature at exon 17 might be more suggestive that echolocation has evolved twice in bats.
It is currently established that nectarivory has evolved twice independently within phyllostomids [ 3, 4], and despite a superficial phenotypic convergence (both lineages do present the mandibular elongation), there are many anatomical differences, particularly in tongue morphology [ 4].
Rather, it is plausible that the specialized PJA has evolved twice independently in the Percomorpha history, in a common ancestor of the Labridae (clade A) and that of the Cichlidae, Pomacentridae, and Embiotocidae (clade B).
Although the partial phylogeny suggests just one origin and one loss of the basic defence trait, it also suggests that pronounced defence through highly aggressive soldiers has evolved twice, once in the case of P. obesinymphae and once in the case of P. spyrothecae (points B and C on Figure 3).
"The need now is to figure out, could animals have evolved twice?" Dr. Maloof said.
Given this, homeothermy must have evolved twice.
Alternatively, feathers could have evolved twice during the course of evolution.
This conclusion is also corroborated by the shared strepsirhine toothcomb, an unusual trait that is unlikely to have evolved twice.
Advanced eusocial behaviour appears to have evolved twice in the group, giving rise to controversy, now largely settled, as to the phylogenetic origins of the four tribes; it had been supposed that eusocial behaviour had evolved only once, requiring the Apini to be close to the Meliponini, which they do not resemble.
The protocone, another example, may have evolved twice during the Mesozoic resulting in tribosphenic molars in both northern-continent tribosphenidans and southern-continent ausktribosphenidans [37].
