Friday, September 5, 2014

Parent-offspring conflict, placentas, fish!

Continuing the trend from last week of a phylogenetic comparative study published in Nature with a colorful tree graph and a little picture of an animal next to it, I suggest That we read:


The evolution of the placenta from a non-placental ancestor causes a shift of maternal investment from pre -to post-fertilization, creating a venue for parent-offspring conflicts during pregnancy 1 , 2 , 3 , 4 . Theory predicts That The Rise Of These conflicts Should drive a shift from a reliance on pre-copulatory female mate choice to polyandry in Conjunction with post-zygotic mechanisms of sexual selection 2 . This hypothesis has not yet been empirically tested. Here we apply comparative methods to test a key prediction of this hypothesis, Which Is that the evolution of placentation is Associated with Reduced pre-copulatory female mate choice. We exploit a unique quality of the fish family Poeciliidae livebearing: placentas have repeatedly evolved or been lost, creating Diversity Among pray be closely related lineages in the Presence or Absence of placentation 5 , 6 . We Show That post-zygotic maternal provisioning by means of a placenta is Associated with the Absence of bright coloration, courtship behavior and exaggerated ornamental display traits in males. Further More, we found That background of placental species have smaller bodies and longer genitalia, Which Facilitate sneak or coercive mating and, hence, circumvents female choice. Moreover, We demonstrate That post-zygotic maternal provisioning correlates with superfetation, a female reproductive adaptation That May resulted in polyandry through the formation of temporally overlapping, mixed-paternity litters. Our results suggest That The Emergence of prenatal Conflict During The evolution of the placenta correlates with a suite of phenotypic and behavioral male traits That is Associated with a Reduced reliance on pre-copulatory female mate choice.


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