Sexual selection and speciation in field crickets

Abstract

Recent theoretical work has shown that sexual selection may cause speciation under a much wider range of conditions than previously supposed. There are, however, no empirical studies capable of simultaneously evaluating several key predictions that contrast this with other speciation models. We present data on male pulse rates and female phonotactic responses to pulse rates for the field cricket Gryllus texensis; pulse rate is the key feature distinguishing G. texensis from its cryptic sister species G. rubens. We show (i) genetic variation in male song and in female preference for song, (ii) a genetic correlation between the male trait and the female preference, and (iii) no character displacement in male song, female song recognition, female species-level song discrimination, or female song preference. Combined with previous work demonstrating a lack of hybrid inviability, these results suggest that divergent sexual selection may have caused speciation between these taxa.

Sexual selection drives speciation in an Amazonian frog

“…Coyne & Orr 1989Seehausen et al 1997;Masta & Maddison 2002), and some have also demonstrated female preferences for local male signals (e.g. Seehausen et al 1997;Gray & Cade 2000). Divergence in male signals has proceeded faster than expected by genetic drift in Habronattus jumping spiders (Masta & Maddison 2002), but in this case, females do not prefer local male signals (Hebets & Maddison 2005).…”

“…Several studies provide tantalizing evidence that sexual selection may cause speciation in the wild (Coyne & Orr 1989Barraclough et al 1995;Seehausen et al 1997;Gray & Cade 2000;Masta & Maddison 2002), yet support for this hypothesis remains incomplete. To demonstrate conclusively that sexual selection drives speciation, several criteria must be met: male signals must differ significantly among populations or recent sister species; females must prefer local male signals to foreign ones; divergence in male signals must result from selection and not genetic drift; and finally, divergent signals and preferences must be correlated with restricted gene flow at nuclear loci to show that populations are diverging towards distinct species (i.e.…”

“…Many of these traits are involved in mate recognition and result in assortative mating within and among species (Boake 2000;Panhuis et al 2001;Coyne & Orr 2004). Therefore, it has been proposed that sexual selection can facilitate divergence of mate recognition systems among populations and thus, incidentally, lead to speciation (Fisher 1930;West-Eberhard 1979;Lande 1981;Andersson 1994;Gray & Cade 2000;Boughman 2001;Panhuis et al 2001;Masta & Maddison 2002). In fact, some researchers suggest that sexual selection is the primary driver of speciation (Carson 2003).…”

Natural and sexual selection against hybrid flycatchers

“…Vamosi & Schluter 1999;Gray & Cade 2000;Bridle et al 2006), but the relative importance of sexual selection for postzygotic isolation is rarely investigated, due to it being a rather complicated undertaking. The most informative approach for estimating effects of hybridization is to measure the relative difference in fitness between hybrid and parental species under natural conditions.…”

Difference in Plumage Color Used in Species Recognition between Incipient Species Is Linked to a Single Amino Acid Substitution in the Melanocortin‐1 Receptor

“…In many organisms, reproductive isolation often starts with individuals from distinct populations failing to recognize each other as potential mates (i.e., species recognition; Baker and Baker 1990;Gray and Cade 2000;Shaw and Parsons 2002;Patten et al 2004;Seehausen et al 2008). Such discrimination between incipient species is typically mediated by divergent mating signals, including visual (Baker 1991;Seehausen et al 2008), acoustic (Irwin et al 2001;Grant 2002a, 2002b), and olfactory (Mullen et al 2007) signals.…”