A group of Chinese researchers provided some new views on the origin of giraffe height which has been the subject of heated debates for centuries among many biologists and common people, as showed by an article recently published by Newpubli.
First, the researchers proposed that the striking height of the giraffe possibly resulted from and is maintained by interaction of sexual and non-sexual selection constraints. This is different from previous views which all emphasized the effect of a single factor, e.g., browsing competition or sexual competition, on the striking trait. They further suggested that, after the animal stature has reached to a considerable height (e.g., three to four meters), non-sexual selection constraints began to inhibit further heightening of the stature, while the sexual selection constraint further heightened the stature to a striking degree (i.e., five to six meters). The interaction of sexual and non-sexual selection constraints can also explain why giraffe height possibly changed little for most of the geological history, but substantially in a relatively short geological period.
Second, the researchers explained, in genetics and physiology, why female giraffes are also very tall as a by-product of sexual selection, and why absence of some gender differences is insufficient to disprove the effect of sexual selection on giraffe height.
Third, the researchers presented some genomic sequence data which suggested that the origin of the giraffe height likely involved many small phenotypic and genetic variations, although great phenotypic and genetic variations could not be excluded.
These novel views have answered more questions than previous hypotheses on the origin of giraffe height, and may shed new insight into natural selection and biological evolution.
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