The geographic mosaic of arms race coevolution is closely matched to prey population structure

Evolution Letters

Amber N. Stokes¹  Chris R. Feldman²  Edmund D. Brodie III³  Edmund D. Brodie Jr.⁴  Michael T. J. Hague⁵ 

[1] Department of Biology California State University Bakersfield California 93311;Department of Biology University of Nevada Reno Nevada 89557;Department of Biology University of Virginia Charlottesville Virginia 22904;Department of Biology Utah State University Logan Utah 84322;Division of Biological Sciences University of Montana Missoula Montana 59812;

关键词: Arms race;    coevolution;    geographic mosaic theory;    NaV1.4;    tetrodotoxin;   

DOI  :  10.1002/evl3.184

来源: DOAJ

【 摘 要 】

Abstract Reciprocal adaptation is the hallmark of arms race coevolution. Local coadaptation between natural enemies should generate a geographic mosaic pattern where both species have roughly matched abilities across their shared range. However, mosaic variation in ecologically relevant traits can also arise from processes unrelated to reciprocal selection, such as population structure or local environmental conditions. We tested whether these alternative processes can account for trait variation in the geographic mosaic of arms race coevolution between resistant garter snakes (Thamnophis sirtalis) and toxic newts (Taricha granulosa). We found that predator resistance and prey toxin levels are functionally matched in co‐occurring populations, suggesting that mosaic variation in the armaments of both species results from the local pressures of reciprocal selection. By the same token, phenotypic and genetic variation in snake resistance deviates from neutral expectations of population genetic differentiation, showing a clear signature of adaptation to local toxin levels in newts. Contrastingly, newt toxin levels are best predicted by genetic differentiation among newt populations, and to a lesser extent, by the local environment and snake resistance. Exaggerated armaments suggest that coevolution occurs in certain hotspots, but prey population structure seems to be of particular influence on local phenotypic variation in both species throughout the geographic mosaic. Our results imply that processes other than reciprocal selection, like historical biogeography and environmental pressures, represent an important source of variation in the geographic mosaic of coevolution. Such a pattern supports the role of “trait remixing” in the geographic mosaic theory, the process by which non‐adaptive forces dictate spatial variation in the interactions among species.

【 授权许可】

Unknown