BLOOMINGTON, Ind. -- Believed critical for determining which individuals can -- or cannot -- successfully reproduce with each other, genitalia not only figure prominently in the origin of new species, but are also typically the first type of trait to change as new species form.
Today, new international research led by Indiana University shows that as populations and species diversify, the exact shape and fit of genitalia steals the show over size.
In data gathered from populations isolated for less than 50 years, to species separated for millions of years, researchers studying scarab beetles have shown that both male and female genitalia have evolved extremely rapidly and have done so along parallel timetables. But most surprisingly, this codivergence occurred much faster in, or was even restricted to, genital shape rather than size.
"Parallel evolutionary divergence in male and female genitalia was something scientists long suspected or assumed, but we've had little or no data to support this assumption," said lead author Armin Moczek, an associate professor in the IU Bloomington College of Arts and Sciences' Department of Biology. "But to see that this parallel divergence is so much faster for genital shape than size is a big surprise."
Too much focus in past research on sizes, rather than shapes of genitalia -- which is much harder to measure in arthropods -- may have misled past research in judging how genitalic evolution may enable diverging populations to evolve into separate species unable to hybridize.
Just as interesting is the remarkably short time frame -- as short as populations being separated by 50 years -- that would support the notion that it may be surprisingly easy for the genitalia of males and females to evolve concomitantly, and for males and females of different populations to diverge from each other to a degree approximating what is normally seen only between species separated for more
|Contact: Steve Chaplin|