Resource Competition and Coevolution in Sticklebacks

Abstract

Threespine stickleback in young postglacial lakes provide a compelling example of coevolution between species that compete for resources. Coexisting pairs of stickleback species are highly divergent in habitat, diet, and body size and shape, whereas stickleback occurring alone in lakes are intermediate. We used experiments in ponds to test mechanisms of divergence between coexisting species. The results support the hypothesis of coevolution by resource competition between stickleback, but we found evidence that interactions with natural enemies also contribute to divergence. Natural selection arising from these interactions selects against intermediate phenotypes, included hybrids, and thus has contributed to the origin and persistence of stickleback species.

Diversification and coevolution in brood pollination mutualisms: Windows into the role of biotic interactions in generating biological diversity

“…Even so, a number of studies have argued that hybridization between closely related sympatric figs mediated by shared pollinating fig wasps may be common (Jackson et al, 2008; Renoult et al, 2009; Cornille et al, 2011; Wang et al, 2016). The role of allopatry in speciation within pollination brood mutualisms is consistent with examples of potential coevolutionary speciation from other interactions (Parchman and Benkman, 2002; Hoso et al, 2010; Smith and Benkman, 2007; Schluter, 2010), in which geographic isolation was always implicated in diversification (Hembry et al, 2014). Continued examination of the role of geography and biotic selection in brood pollination mutualisms is crucial for understanding the mechanisms of speciation.…”

Four Central Points About Coevolution

“…Hence, clues to coevolution through character displacement can often be found by studying multiple populations of potentially competing species. Initial evidence for competition comes from observations indicating that the traits of species differ more in regions where they co-occur than in regions in which only one of the species occurs, or the traits differ geographically in predictable ways depending on which combinations of species co-occur (Schluter 2000;Losos 2009;Schluter 2010). Those differences may involve divergence in traits (e.g., body size), the habitats used by the competing species, or the times of year that the species use a particular habitat, and they may also involve multiple forms of selection other than competition (Pfennig and Pfennig 2009).…”

Rapid buildup of sympatric species diversity in Alpine whitefish

“…Many postglacial fish species emerged from adaptive radiation, a process wherein a suite of species rapidly evolves from a common ancestor through adaptation to different ecological niches (Gavrilets & Losos, ). Postglacial fish species pairs (e.g., stickleback, Schluter, ; North American whitefish, Bernatchez, ) have served as model systems in adaptive radiation research to study its key elements: ecological opportunity, divergent natural selection, resource competition, and ecological speciation, whereby reproductive isolation (RI) evolves as a consequence of divergent natural or ecologically mediated divergent sexual selection (Schluter, ). However, the buildup of high sympatric species richness (>2 species) through adaptive radiation, though diagnostic of classic cases of adaptive radiation (Grant & Grant, ; Losos, ; Seehausen, ), has rarely been studied in postglacial radiations.…”