Sperm Evolution Becomes Supercharged Only When They Swim Inside Females [View all]

[JoeOtterbein]

SciTechDaily

By STOCKHOLM UNIVERSITY JUNE 21, 2021

Sperm size varies dramatically among different animal species. But why is sperm size so variable when they share the same job — to fertilize eggs? In a new article published in Nature Ecology and Evolution, researchers from Stockholm University show that animal sperm evolution becomes supercharged only when sperm swim inside females.

Sperm are the most variable cell type known, ranging in size from 0.002 millimeters in a freshwater rotifer to nearly 6 centimeters in a fruit fly. Explaining why sperm are so variable has been a major focus in evolutionary biology over the last 100 years because sperm, no matter from what organism, always have the same function: to fertilize eggs.

“Researchers usually try to explain sperm diversity by focusing on how sperm compete to fertilize eggs or how females choose which sperm fertilize their eggs,” says Ariel Kahrl, a researcher in the Department of Zoology at Stockholm University.

“But it turns out that there is a missing piece of the puzzle — the location where sperm and eggs meet can also influence sperm size.”

snip

more at link

Brilliant study that still seems kinda obliviously "Duh" in an odd way for me!