1 Citation 284 Views 52 Downloads
Male genitalia evolve rapidly, probably as a result of sexual selection.
Whether this pattern extends to the internal infrastructure that
influences genital movements remains unknown. Cetaceans (whales and
dolphins) offer a unique opportunity to test this hypothesis: since
evolving from land-dwelling ancestors, they lost external hind limbs and
evolved a highly reduced pelvis which seems to serve no other function
except to anchor muscles that maneuver the penis. Here we create a novel
morphometric pipeline to analyze the size and shape evolution of pelvic
bones from 130 individuals (29 species) in the context of inferred mating
system. We present two main findings: 1) males from species with
relatively intense sexual selection (inferred by relative testes size)
have evolved relatively large penises and pelvic bones compared to their
body size, and 2) pelvic bone shape diverges more quickly in species pairs
that have diverged in inferred mating system. Neither pattern was observed
in the anterior-most pair of vertebral ribs, which served as a negative
control. This study provides evidence that sexual selection can affect
internal anatomy that controls male genitalia. These important functions
may explain why cetacean pelvic bones have not been lost through
evolutionary time.
284 views reported since publication in 2014.