Selection analysis on the rapid evolution of a secondary sexual trait.
Evolutionary analyses of population translocations (experimental or accidental) have been important in demonstrating speed of evolution because they subject organisms to abrupt environmental changes that create an episode of selection. However, the strength of selection in such studies is rarely measured, limiting our understanding of the evolutionary process. This contrasts with long-term, mark-recapture studies of unmanipulated populations that measure selection directly, yet rarely reveal evolutionary change. Here, we present a study of experimental evolution of male colour in Trinidadian guppies where we tracked both evolutionary change and individual-based measures of selection. Guppies were translocated from a predator-rich to a low-predation environment within the same stream system. We used a combination of common garden experiments and monthly sampling of individuals to measure the phenotypic and genetic divergence of male coloration between ancestral and derived fish. Results show rapid evolutionary increases in orange coloration in both populations (1 year or three generations), replicating the results of previous studies. Unlike previous studies, we linked this evolution to an individual-based analysis of selection. By quantifying individual reproductive success and survival, we show, for the first time, that males with more orange and black pigment have higher reproductive success, but males with more black pigment also have higher risk of mortality. The net effect of selection is thus an advantage of orange but not black coloration, as reflected in the evolutionary response. This highlights the importance of considering all components of fitness when understanding the evolution of sexually selected traits in the wild.
Department of Biology, University of California, Riverside, CA, USA Center of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland swanne.gordon@jyu.fi.
Swanne P
SP
Gordon
Department of Biology, University of California, Riverside, CA, USA.
David
D
Reznick
Department of Biology, University of California, Riverside, CA, USA.
Jeff D
JD
Arendt
Department of Biology, University of California, Riverside, CA, USA.
Allen
A
Roughton
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
Michelle N
MN
Ontiveros Hernandez
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Paul
P
Bentzen
Center of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland Institute of Ecology and Environmental Sciences-Paris (iEES), CNRS UMR 7618, Paris, France.
Andrés
A
López-Sepulcre
D000818:Animals; D005075:Biological Evolution; D003116:Color; D056084:Genetic Fitness; D008136:Longevity; D008297:Male; D052586:Mating Preference, Animal; D010641:Phenotype; D011036:Poecilia / Q000235:genetics / Q000502:physiology*; D012641:Selection, Genetic
common garden experiments; fitness; mark–recapture; rapid evolution; sexual selection