© 2004 British
Blackwell Publishing, Ltd.
Does testis size track expected mating success in
yellow dung flies?
W. U. BLANCKENHORN*, B. HELLRIEGEL*, D. J. HOSKEN*, P. JANN*,
R. ALTWEGG and P. I. WARD*
*Zoologisches Museum and Zoologisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich,
1. We quantitatively compare the fitness function linking male mating success in the
field to body size and the allometric relationship linking testis length (estimating sperm
production) to body size, both empirically derived, for the yellow dung fly Scathophaga
stercoraria (Diptera: Scathophagidae).
2. We find that both relationships are similarly non-linear (quadratic) and increasing.
The most parsimonious interpretation of this congruence is that the evolution of testis