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Publications filtered by: Coevolution

Experimental coevolution of male and female genital morphology
Simmons L. W. & Garcia-Gonzalez, F. 2011 Experimental coevolution of male and female genital morphology Nature Communications, 2:374
Male genitalia typically exhibit patterns of rapid and divergent evolution, and there is now considerable evidence that sexual selection is an important driver of these patterns of phenotypic variation. Female genitalia have been less well studied, and are generally thought to be relatively invariant. Here we use experimental evolution to show that sexual selection drives the correlated evolution of female and male genital morphology in the scarabaeine dung beetle Onthophagus taurus. Moreover, we use quantitative genetic analyses to provide a rare insight into the genetic architecture underlying morphological variation in female genital morphology, and uncover evidence of the genetic covariation with male genital morphology that is expected to arise under persistent sexual selection.
Seen one seen them all? More to genitalia than meets the eye
Simmons, L. W. & Garcia-Gonzalez, F. 2011 Seen one seen them all? More to genitalia than meets the eye The Conversation
Shorter sperm confer higher competitive fertilization success
Garcia-Gonzalez, F. & Simmons, L. W. 2007 Shorter sperm confer higher competitive fertilization success Evolution, 61: 816-824

Spermatozoa exhibit taxonomically widespread patterns of divergent morphological evolution. However, the adaptive significance of variation in sperm morphology remains unclear. In this study we examine the role of natural variation in sperm length on fertilization success in the dung beetle Onthophagus taurus. We conducted sperm competition trials between males that differed in the length of their sperm and determined the paternity of resulting offspring using amplified fragment length polymorphism (AFLP) markers. We also quantified variation in the size and shape of the female’s sperm storage organ to determine whether female morphology influenced the competitiveness of different sperm morphologies. We found that fertilization success was biased toward males with relatively shorter sperm, but that selection on sperm length was dependent on female tract morphology; selection was directional for reduced sperm length across most of the spermathecal size range, but stabilizing in females with the smallest spermathecae. Our data provide empirical support for the theory that sperm competition should favor the evolution of numerous tiny sperm. Moreover, because sperm length is both heritable and genetically correlated with condition, our results are consistent with a process by which females can accrue genetic benefits for their offspring from the incitement of sperm competition and/or cryptic female choice, as proposed by the “sexy sperm” and “good sperm” models for the evolution of polyandry.