"The fact that it occurred so rapidly is rare indeed, and is a direct function of the strength of selection," he said via email. "In other words, it happened so quickly because tuskless females had a MUCH higher probability of surviving the war, and thus a MUCH greater potential for passing their genes on to the next generation."
Photo credit to Keyur Nandaniya
"Tusklessness does occur naturally -- and only in females -- even in the absence of poaching, but usually only in a small minority of elephants. In Gorongosa in the 1970s, 18.5% of female elephants didn't have tusks, while three decades later 51% did."
"Females have 2 X chromosomes. In tuskless females, one of those chromosomes is 'normal' and the other contains the deleted information," Long explained.
"When a tuskless female conceives a male offspring, that male has a 50/50 shot of receiving the affected X-chromosome from its mother. If it receives the 'normal' chromosome then it will survive and be born with the necessary genetic information to produce tusks."
However, if the male elephant fetus receives the chromosome with the genetic variant, it dies in the womb because the variant that produces tusklessness females is lethal to males, Long said.
Our appreciation to CNN for the photos and article. Thanks to Larry for sharing his incredible research
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