CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S3
Sexual selection and genital evolution in mammals
Paula Stockley
Mammalian Behaviour & Evolution Group, Faculty of Veterinary
Science, University of Liverpool, Leahurst Campus, CH64 7TE, UK.
Animal genitalia evolve rapidly and divergently, with the result that
closely related species often have conspicuously different genital
anatomy. Following the pioneering work of William G. Eberhard,
there is now growing evidence that sexual selection may be largely
responsible for this diversity. In the current presentation I will review
evidence that the genital anatomy of male mammals is subject to
sexual selection, with emphasis on understanding diversity in the
relative size of particularly variable traits such as penile spines and
the baculum or os penis. After providing a broad overview of
comparative trends in genital diversity among primates and other
taxa, I will focus on a case study of post-copulatory sexual selection
in wild house mice (Mus musculus domesticus) that provides new
evidence for an association between male genital anatomy and
reproductive success in a mammal. Overall, the evidence presented
indicates that sexual selection is likely to be a significant factor
explaining certain aspects of genital evolution in mammals. However,
as for other taxa, distinguishing between alternative models of
genital evolution by sexual selection may prove a significant
challenge.
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Morphological and phylogenetic implications of female genitalia
in micronetine spiders (Araneae, Linyphiidae)
Lihong Tu 1,2 and Gustavo Hormiga 2
1
College of Life Sciences, Capital Normal University, Beijing100037,
P. R. China
2
Department of Biological Sciences, The George Washington
University, Washington, DC 20052, USA
The genital morphology of spiders provides a rich source of
phylogenetic data and can help our understanding of many issues in
evolutionary biology and phylogenic reconstruction. Male palpal
morphology has played a critical role in phylogenetic studies, often
dominating character data matrices. In contrast, very limited
information is available on the morphological details of the female
genitalia (the epigynum). The present paper focuses on the female
genitalia of micronetine spiders, a group of linyphiids with a very
complex epigyna. We have studied the external and internal
morphology of the epigynum of representatives of more than 30
micronetine genera. A growing body of evidence suggests that the
so called ducts used to transmit sperm (copulatory and fertilization
ducts) are furrows derived from integument folds. We try to use this
model to explain variations in different linyphiid groups. A set of
comparative morphological characters is presented here. We discuss
the phylogenetic implications of these new findings and whether
there is coevolution between male and female genitalia.