Eurytemora is a genus of copepods in the family Temoridae.

Directional selection is one type of natural selection where individuals with characteristics at one end of a continuum are favored, hence increasingly shifting the overall mean of that trait within the population. For example, in the copepod Eurytemora affinis, the populations that had invaded freshwater environments experienced directional selection for improved osmoregulatory ability, such that individuals were able to cope better with lowered levels of salinity and therefore survive and reproduce more successfully.

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