Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish.
Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites (Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites (Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent-but complementary-effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations.
Plath
Martin
M
Department of Ecology and Evolution, J.W. Goethe University of Frankfurt, Siesmayerstrasse 70a, 60054, Frankfurt am Main, Germany. mplath@bio.uni-frankfurt.de
Riesch
Rüdiger
R
Oranth
Alexandra
A
Dzienko
Justina
J
Karau
Nora
N
Schiessl
Angela
A
Stadler
Stefan
S
Wigh
Adriana
A
Zimmer
Claudia
C
Arias-Rodriguez
Lenin
L
Schlupp
Ingo
I
Tobler
Michael
M
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D049628:Body Size; D002755:Choice Behavior; D017753:Ecosystem; D005260:Female; D005399:Fishes / Q000502:physiology*; D008297:Male; D052586:Mating Preference, Animal / Q000502:physiology*; D011036:Poecilia / Q000033:anatomy & histology / Q000502:physiology; D012098:Reproduction / Q000502:physiology*; D012641:Selection, Genetic / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology*; D012934:Social Isolation