Testes size (square mm; Testes.area) in 8
populations of common yellow dung flies
(Scathophaga stercoraria) with different mating
systems (Mating.system).
Arguments
source
Hosken, D.J. and P.I. Ward. 2001. Experimental evidence
for testis size evolution via sperm competition.
Ecology Letters 4: 10-13.