Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies.
Range expansions can result in founder effects, increasing genetic differentiation between expanding populations and reducing genetic diversity along the expansion front. However, few studies have addressed these effects in long-distance migratory species, for which high dispersal ability might counter the effects of genetic drift. Monarchs (Danaus plexippus) are best known for undertaking a long-distance annual migration in North America, but have also dispersed around the world to form populations that do not migrate or travel only short distances. Here, we used microsatellite markers to assess genetic differentiation among 18 monarch populations and to determine worldwide colonization routes. Our results indicate that North American monarch populations connected by land show limited differentiation, probably because of the monarch's ability to migrate long distances. Conversely, we found high genetic differentiation between populations separated by large bodies of water. Moreover, we show evidence for serial founder effects across the Pacific, suggesting stepwise dispersal from a North American origin. These findings demonstrate that genetic drift played a major role in shaping allele frequencies and created genetic differentiation among newly formed populations. Thus, range expansion can give rise to genetic differentiation and declines in genetic diversity, even in highly mobile species.
Department of Biology, Emory University, Atlanta, GA 30322, USA aapierc@emory.edu.
Amanda A
AA
Pierce
School of Biological Sciences, The University of Queensland, Brisbane 4072, Australia.
Myron P
MP
Zalucki
Department of Biology, Emory University, Atlanta, GA 30322, USA.
Marie
M
Bangura
Department of Biology, Emory University, Atlanta, GA 30322, USA.
Milan
M
Udawatta
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
Marcus R
MR
Kronforst
Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.
Sonia
S
Altizer
Área de Ecología, Universidad de Córdoba, Córdoba 14071, Spain.
Juan Fernández
JF
Haeger
Department of Biology, Emory University, Atlanta, GA 30322, USA.
Jacobus C
JC
de Roode
D063147:Animal Distribution; D025041:Animal Migration; D000818:Animals; D002080:Butterflies / Q000235:genetics* / Q000502:physiology; D018703:Founder Effect; D014644:Genetic Variation; D018895:Microsatellite Repeats
Columbus hypothesis; cline; dispersal; ecological genetics; gene surfing; landscape genetics