Sequential Sympatric Speciation Across Trophic Levels
Andrew A. Forbes,1*
Thomas H.Q. Powell,1
Lukasz L. Stelinski,2
James J. Smith,3
Jeffrey L. Feder1
A major cause for biodiversity may be biodiversity itself. As
new species form, they may create new niches for others to exploit,
potentially catalyzing a chain reaction of speciation events
across trophic levels. We tested for such sequential radiation
in the
Rhagoletis pomonella (Diptera: Tephritidae) complex,
a model for sympatric speciation via host plant shifting. We
report that the parasitic wasp
Diachasma alloeum (Hymenoptera:
Braconidae) has formed new incipient species as a result of
specializing on diversifying fly hosts, including the recently
derived apple-infesting race of
R. pomonella. Furthermore, we
show that traits that differentially adapt
R. pomonella flies
to their host plants have also quickly evolved and serve as
ecological barriers to reproduction, isolating the wasps. Speciation
therefore cascades as the effects of new niche construction
move across trophic levels.
2 Department of Entomology and Nematology, University of Florida Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
3 Department of Entomology and Lyman Briggs College, Michigan State University, East Lansing, MI 48824, USA.
* Present address: Department of Entomology, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA.
Present address: Wissenschaftskolleg zu Berlin Institute for Advanced Study, Wallotstrasse 19, D14193 Berlin, Germany.
To whom correspondence should be addressed. E-mail: aaforbes{at}ucdavis.edu
