Evolution of Genders From Hermaphroditic Ancestors Mapped

[Whitney]

http://www.sciencedaily.com/releases/20 ... 171328.htm

ScienceDaily (Nov. 27, 2008) â€" Research from the University of Pittsburgh published in the Nov. 20 edition of the journal Heredity could finally provide evidence of the first stages of the evolution of separate sexes, a theory that holds that males and females developed from hermaphroditic ancestors. These early stages are not completely understood because the majority of animal species developed into the arguably less titillating separate-sex state too long ago for scientists to observe the transition.

However, Tia-Lynn Ashman, a plant evolutionary ecologist in the Department of Biological Sciences in Pitt's School of Arts and Sciences, documented early separate-sex evolution in a wild strawberry species still transitioning from hermaphroditism. These findings also apply to animals (via the unified theory) and provide the first evidence in support of the theory that the establishment of separate sexes stemmed from a genetic mutation in hermaphroditic genes that led to male and female sex chromosomes. With the ability to breed but spared the inbred defects of hermaphrodites, the separate sexes flourished.

“This is an important test of the theory of the early stages of sex chromosome evolution and part of the process of understanding the way we are today,” Ashman said. She added that the study also shows that plants can lend insight into animal and human evolution. “We have the opportunity to observe the evolution of sex chromosomes in plants because that development is more recent. We wouldn't see this in animals because the sex chromosomes developed so long ago. Instead, we can study a species that is in that early stage now and apply it to animals based on the unified theory that animal and plant biology often overlaps.”

Ashman reported in the journal Science in 2004 that animals and flowering plants employ similar reproductive strategies to increase reproductive success and genetic diversity. These methods include large numbers of sperm cells in males, mate competition and attraction through fighting or natural ornamentation, aversion to inbreeding, and the male inclination to sire as many offspring as possible.

For the current study, Ashman and Pitt postdoctoral research associate Rachel Spigler worked with a wild strawberry species in which the evolution of separate sexes is not complete, so hermaphrodites exist among male and female plants. Sex chromosomes in these plants have two loci-or positions of genes on a chromosome-one that controls sterility and fertility in males and the other in females. Offspring that inherit both fertility versions are hemaphrodites capable of self-breeding. Plants that possess one fertility and one sterility version become either male or female. Those with both sterility versions are completely sterile, cannot reproduce, and, thus, die out.

The single-sex plants breed not only with one another but also with hermaphroditic plants and pass on the mutation, which can result in single-sex offspring. (Sterile plants also can result, but plants with genes that favor the production of fertile offspring will be more successful.) When inbreeding depression in hermaphrodites is also considered, Ashman said, a gradual decline in the number of hermaphroditic plants is to be expected. Consequently, fewer chromosomes with both fertility versions of the loci will be passed on and the frequency of single-sex individuals will increase.

[curiosityandthecat]

So, in the beginning there was.. Adamandeve?  

[Wechtlein Uns]

and god created them in his own image... tsk tsk.

[Asmodean]

Adamandeve... Now THAT is a cool name for a specie

[Caucmusulman]

the hermaphroditic strawberries, yeah, god is a perv

[crocofish]

My dogs like to eat wild strawberries in the back yard.  I wonder if they are eating hermaphroditic strawberries.

[gwyn428]

The closest anthropomorphic god to this "creation" would be Ardhanarishwara, the Lord who is Half-Woman.

Seriously, this is very interesting!

[DennisK]

My dogs like to eat wild strawberries in the back yard.  I wonder if they are eating hermaphroditic strawberries.

Holy crap!  I think there's a chance I might be an hermaphrodite.

[VanReal]

I had to look up the unified theory about plant and animal biology overlapping.  Never heard of that before and was confused at the comparison of the wild strawberry and the animal.  Hmmm, can they not study this on those animal species that can "switch" gender to continue breeding?  It's less confusing to those of us that were excused from biology class for not being able to focus, hehe.  Very interesting, never really thought about the gender issue in evolving, just kind of follow the thinking of a bunch of morphing like those little sponge tablets you drop in the tub and "viola" instant little friends to play with.

[karadan]

roflol

and god created them in his own image... tsk tsk.

So, God has an inny and an outy? I wonder if both sets of plumbing work :p