Friday, February 24, 2017

Eared and Western Grebes


Eared Grebes and Western Grebes look quite different. Ornithologists place them in different genera. Their similarly plumaged young, however, argue for their close evolutionary relationship. It was Ernst Haeckel (1834-1919), German zoologist and philosopher, who hypothesized “ontogeny recapitulates phylogeny.” In other words,  species’ biologic development parallels their evolutionary history. This dictum proved to be influential but is no longer widely held.

Grebes are among the oldest kinds of birds. They arose in Antarctica or southern South America. Half the 22 species of the world are found in the American tropics. Grebes do not appear to be closely related to other bird families. Their similarity to loons appears to lack genetic evidence. DNA studies suggest that they belong to the evolutionary lineage that also led to storks, shearwaters, pelicans, and penguins (del Hoyo et al 2017).

These photos were taken years ago at Sand Lake National Wildlife Refuge in northeastern South Dakota.

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