Abstract
Sperm, the male most fundamental reproductive feature allowing egg fertilization, evolves under sexual selection. Two components of sperm are mainly under selection, their number and their morphology (including the associated quality). Here we study the evolution of sperm morphology in the genus Daphnia. Based on microscopic observations of sperm morphologies mapped on a Daphnia phylogeny, we found that increase in sperm length evolved at least twice in Daphnia, once in the Daphnia sensus lato clade and once in the Ctenodaphnia clade. Furthermore, Daphnia s.l. lost the ability of cell compaction by losing extracellular encapsulation and exposing large filaments. We discuss the potential reasons for such convergent evolution in sperm morphology.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
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