Evolution

The importance of variation

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Science  30 Sep 2016:
Vol. 353, Issue 6307, pp. 1510
DOI: 10.1126/science.353.6307.1510-a

Magellanic penguins in Punto Tombo, Argentina

PHOTO: DON FAULKNER/FLICKR

The environment exerts powerful selective forces on species, shaping their morphology. Despite this, individuals within a species can be quite variable, suggesting that selection may not always operate in expected ways. Koehn et al. measured selection in Magellanic penguins at Punta Tombo, Argentina, over nearly 30 years. Though this extreme environment would seem to impose powerful selective forces, they found evidence of selection at a suite of traits in only 7 of those years. When selection was detected, primarily for body size, it favored larger individuals. Such inconsistency in the strength and shape of selection over time likely maintains important variation within the population overall and suggests that there is no clear best-adapted morphology in this dynamic habitat.

Auk 10.1642/AUK-16-50.1 (2016).

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