Evaluating the Dynamics of Coevolution Among Geographically Structured Populations

Abstract

The geographic mosaic theory of coevolution suggests that reciprocal evolution involves three processes that operate among populations: selection mosaics, coevolutionary hotspots, and trait remixing. These processes, in turn, produce three patterns: population differences in traits favored by an interaction, a combination of trait matches and mismatches among populations, and few species-level coevolved traits (i.e., coevolved traits that have spread to all populations). Here I show how studies of the interactions between the pollinating floral parasite Greya politella and its host plants provide evidence for most of the components of this view of the coevolutionary process, including indications of the ecological conditions that can prevent coevolutionary change. These studies are suggesting that the dynamics of coevolution in these interactions are interpretable only when analyzed over broad geographic scales.

On the elusiveness of enemy-free space: spatial, temporal, and host-plant-related variation in parasitoid attack rates on three gallmakers of goldenrods

“…The variation shown in the literature (Table 1) supports the view that temporal and spatial variation in EFS is likely to be common if not universal. As a result, ecologists should think about enemy-free space as part of the emerging paradigm of ecological and evolutionary forces as a temporal and geographic mosaic (Thompson 1994(Thompson , 1997Schiers and De Bruyn 2002;Forde et al 2004).…”

“…In addition, EFS will be most effective in facilitating host shifts if it is spatially widespread, at least relative to the scale of dispersal by the herbivores. For several reasons, the selective effect of enemy-free space may resemble a geographic and/or temporal mosaic (Thompson 1994(Thompson , 1997 rather than a simple parasitoid-escape advantage. After all, attack by parasitoids and predators on a given herbivore is often highly variable in space and time (e.g., Feeny et al 1985;Mira and Bernays 2002;Stireman and Singer 2002;Singer and Stireman 2003;Kumpulainen et al 2004;Singer et al 2004), and if nothing else EFS cannot exist at sites or times where attack is negligible on either host (e.g., Mira and Bernays 2002).…”

A review of brood-site pollination mutualism: plants providing breeding sites for their pollinators

“…the presence or absence of copollinators and predators of pollinators, can affect the outcome of these interactions (Pellmyr 1989(Pellmyr , 1992; Thompson and Pellmyr 1992;Herre 1996;West et al 1996;Thompson 1997;Holland and Fleming 1999). In fig-fig-wasp and yucca-yucca-moth interactions, the ovule parasites are the only pollinators for the host plant, and the pollinators can survive only on the single host species.…”

Plant polyploidy and host expansion in an insect herbivore

“…The geographically complex interactions between the pollinating, flower-feeding prodoxid moth Greya politella and its closely related host plants in Saxifragaceae provide a useful model system for studying the role of polyploidization in structuring species interactions and coevolution (e.g., Thompson 1997Thompson , 1999Thompson et al 1997;. Throughout much of its geographic range, G. politella feeds exclusively on the genus Lithophragma (Saxifragaceae).…”