Table 2.

Studies of the effects of sexual selection or sexual conflict on species richness.

group	sexual selection measure studied	speciation effect	claim	authority
birds (passerines)	sexual dichromatism	increased species richness	sexual selection drives speciation	Barraclough et al. (1995, 1998)
	sexual dichromatism	no effect		Price (1998) (part of same data set as above)
birds	mating system	increased species richness	sexual selection drives speciation	Mitra et al. (1996)
birds	ornamented versus non-ornamented	increased species richness	sexual selection drives speciation	Møller & Cuervo (1998)
birds	sexual dichromatism	increased species richness	sexual selection drives speciation	Owens et al. (1999)
	sexual dimorphism	no effect
	mating system	no effect
birds	sexual size dimorphism	no effect	increased speciation due to sexual conflict may be countered by increased extinction	Morrow et al. (2003a)
	sexual dichromatism	no effect
	testis size	no effect
insects: Coleoptera, Diptera, Ephemeroptera, Homoptera, Lepidoptera	monandry versus polyandry	increased species richness under polyandry	postcopulatory sexual conflict drives speciation	Arnqvist et al. (2000)
insects: Syrphidae (Diptera)	spermathecal width	increased species richness	postcopulatory sexual conflict drives speciation	Katzourakis et al. (2001)
	testis length	increased species richness
insects: Papuan butterflies	sexual size dimorphism	no effect	species richness may arise through allopatry	Gage et al. (2002)
	mating frequency	no effect
spiders	sexual size dimorphism	no effect	species richness may arise through allopatry	Gage et al. (2002)
mammals	sexual size dimorphism	no effect	species richness may arise through allopatry	Gage et al. (2002)
	testis size	no effect
fish: Goodeinae	sexual size dimorphism	no effect	species richness may arise primarily through allopatry and ecological divergence	Ritchie et al. (2005)