Discriminating Males Alter Sperm Production between Species

Prezygotic reproductive isolation and its importance in speciation is traditionally approached from the viewpoint of those events that occur before mating. However, recent interest in sperm competition theory has shown that prezygotic isolation can be affected by mechanisms that occur after mating b...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2004-11, Vol.101 (45), p.15970-15973
Main Authors: Aspbury, Andrea S., Gabor, Caitlin R., Wake, David B.
Format: Article
Language:English
Subjects:
Animal reproduction
Animals
Biological Evolution
Biological Sciences
Bisexuality
Capital costs
Competition
Evolution
Female
Female animals
Fish
Freshwater
Male
Male animals
Males
Mating behavior
Poecilia - genetics
Poecilia - physiology
Poecilia formosa
Poecilia latipinna
Production costs
Reproduction
Reproductive isolation
Sexual Behavior, Animal
Species Specificity
Spermatogenesis - genetics
Spermatogenesis - physiology
Spermatozoa
Sympatry
T tests
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Summary:Prezygotic reproductive isolation and its importance in speciation is traditionally approached from the viewpoint of those events that occur before mating. However, recent interest in sperm competition theory has shown that prezygotic isolation can be affected by mechanisms that occur after mating but before fertilization. One neglected aspect of these studies is how the cost of sperm production might play a role in species isolation. We examined differential sperm production in a species whose males are sexually parasitized by a unisexual gynogenetic species. Gynogens are clonal females that require sperm from males of closely related bisexual species to initiate embryogenesis. We tested for differential sperm production by male sailfin mollies (Poecilia latipinna) when they were in the presence of either a heterospecific, gynogenetic female (Poecilia formosa, Amazon molly) or a conspecific female. We found that previously demonstrated male mate choice for conspecific over heterospecific females also is revealed in sperm production. Males from both an allopatric and a sympatric population produce more sperm when in the presence of a conspecific female than when in the presence of a heterospecific female. We suggest that differential sperm production also could play a role in prezygotic reproductive isolation in bisexual species complexes that occur in sympatry.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0405653101