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Misconceptions of sexual selection and species recognition in extinct animals



From: Ben Creisler
bcreisler@gmail.com

A new item of interest:

Letter

Kevin Padian & John R. Horner (2013)
Misconceptions of sexual selection and species recognition: a response
to Knell et al. and to Mendelson and Shaw.
Trends in Ecology & Evolution (advance online publication)
http://dx.doi.org/10.1016/j.tree.2013.01.011
http://www.sciencedirect.com/science/article/pii/S0169534713000281

Highlights
► Sexual selection requires sexual dimorphism; this was integral to
Darwin's original definition.
► Claims of sexual selection in extinct animals often rely on vague or
untested assertions.
► There is at present no documented case of sexual dimorphism or
sexual selection among dinosaurs and their relatives.
► A test of sexual dimorphism requires an independent understanding of
the chronological age of the specimens in question; this has never
been accomplished in an extinct animal.



==
The papers referred to are


Robert J. Knell, Darren Naish, Joseph L. Tomkins & David W.E. Hone (2013)
Sexual selection in prehistoric animals: detection and implications.
Trends in Ecology & Evolution 28(1): 38–47
http://dx.doi.org/10.1016/j.tree.2012.07.015
http://www.sciencedirect.com/science/article/pii/S0169534712001875

pdf for free at:
http://darrennaish.files.wordpress.com/2013/01/knell-et-al-2012-sexual-selection-in-fossil-animals.pdf


Many fossil animals bear traits such as crests or horns that probably
functioned as sexually selected signals or weapons. Interpretations of
these structures as functioning in mate choice or intrasexual contests
are often controversial, with interpretations based on biomechanics or
physiology being favoured by many. Although testing hypotheses based
on sexual selection can be difficult, especially given that there is
no single, reliable means of recognising sexual selection, we argue
that it is not impossible; indeed, there are now several cases where
sexual selection is strongly supported. In other cases, a careful
study of features such as sexual dimorphism, ontogeny, and allometry,
coupled with testing of alternative hypotheses, will be necessary to
distinguish between possible explanations for exaggerated features.

[first posted in prepublication form in September:

http://dml.cmnh.org/2012Sep/msg00023.html


==

I have not read the Padian and Horner piece yet but I assume they are
referring to the following paper, available for free:

Mendelson, T. C. and Shaw, K. L. 2012. The (mis)concept of species
recognition. Trends in Ecology and Evolution 27: 421-427.

http://www.nbb.cornell.edu/PDF/Mendelson%20and%20Shaw%202012.pdf