Sympatric Speciation: Models and Empirical Evidence

Abstract

Sympatric speciation, the evolution of reproductive isolation without geographic barriers, remains highly contentious. As a result of new empirical examples and theory, it is now generally accepted that sympatric speciation has occurred in at least a few instances, and is theoretically plausible. Instead, debate has shifted to whether sympatric speciation is common, and whether models’ assumptions are generally met in nature. The relative frequency of sympatric speciation will be difficult to resolve, because biogeographic changes have obscured geographical patterns underlying many past speciation events. In contrast, progress is being made on evaluating the empirical validity of key theoretical conditions for sympatric speciation. Disruptive selection and direct selection on mating traits, which should facilitate sympatric speciation, are biologically well supported. Conversely, costs to assortative mating are also widely documented, but inhibit speciation. Evaluating the joint incidence of these key factors may illuminate why sympatric speciation appears to be relatively uncommon.

High-Dimensional Fitness Landscapes and Speciation

“…In particular, as Maynard Smith told me once, a significant part of his motivation for writing his classical 1966 paper on sympatric speciation was to annoy Mayr, whose 1963 book was very critical of this mode of speciation. Although sympatric speciation still remains a controversial topic (Coyne and Orr 2004;Dieckmann et al 2004;Gavrilets 2004), most researchers tend to agree with Mayr's intuition, as conditions for sympatric speciation appear to be very restrictive (Bolnick and Fitzpatrick 2007;Coyne and Orr 2004;Gavrilets 2004Gavrilets , 2005Waxman and Gavrilets 2005).…”

“…In particular, as Maynard Smith told me once, a significant part of his motivation for writing his classical 1966 paper on sympatric speciation was to annoy Mayr, whose 1963 book was very critical of this mode of speciation. Although sympatric speciation still remains a controversial topic (Coyne and Orr 2004;Dieckmann et al 2004;Gavrilets 2004), most researchers tend to agree with Mayr's intuition, as conditions for sympatric speciation appear to be very restrictive (Bolnick and Fitzpatrick 2007;Coyne and Orr 2004;Gavrilets 2004Gavrilets , 2005Waxman and Gavrilets 2005).Ironically, in spite of his expressed disregard for theoretical work, Mayr himself was apparently strongly influenced by Wright's ideas on the importance of random drift for evolution in rugged fitness landscapes. In the theory of founder effect speciation, which he proposed in 1942 (and was elaborated later by Carson 1968;Carson and Templeton 1984;Kaneshiro 1980;Mayr 1954;Templeton 1980; see also Provine 1989 for a history of this theory), a few individuals found a new population which rapidly grows in size.…”

Genomics of habitat choice and adaptive evolution in a deep-sea fish

“…The allele frequencies of juveniles differed significantly from the adults captured at the same depth ( Table 4). Disruptive selection has been proposed as an important driver of ecological speciation when coupled with assortative mating [21][22][23] . However, as illustrated in Fig.…”

Surgeons and suture zones: Hybridization among four surgeonfish species in the Indo-Pacific with variable evolutionary outcomes

“…Much of the debate on the formation of species has focused on allopatry (Dobzansky, 1937;Mayr, 1942) versus sympatry (Bolnick and Fitzpatrick, 2007;Bird et al, 2012). The allopatric model has been favored for decades and stresses geographic isolation with negligible gene flow.…”