Divergence in the calling songs between sympatric and allopatric populations of the southern wood cricket Gryllus fultoni (Orthoptera: Gryllidae)

Abstract

In the eastern United States the wood cricket Gryllus fultoni (Orthoptera: Gryllidae) occurs in sympatry with G. vernalis in an area between eastern Kansas and west of the Appalachian Mountains. Calling songs were recorded from 13 sympatric and allopatric localities. Both field and laboratory recordings showed that chirp rate (CR) and pulse rate (PR) overlapped extensively between allopatric populations of G. fultoni and sympatric populations of G. vernalis; by contrast, there was little or no overlap in these variables between sympatric populations of these two species. Divergence in PR and CR between the two species was thus greater in areas of sympatry than in areas of allopatry. Our field and laboratory studies of G. fultoni calling songs thus demonstrate the pattern expected of character displacement and support the genetic assumptions of this hypothesis. Other possible explanations for the sympatric divergence such as ecological character displacement and clinal variation are discussed.

Premating Reproductive Barriers between Hybridising Cricket Species Differing in Their Degree of Polyandry

“…Prezygotic reproductive barriers have been described in many different taxa and crickets are no exception [12], [51], [54], [55]. The results from these studies and ours are broadly similar, but differ on several important points.…”

Character displacement of song and morphology in African tinkerbirds

“…Yet, despite evidence that song frequencies are negatively correlated with body size and beak size (8,9), character displacement in Darwin's finch songs has not been reported. Indeed, despite some evidence of call divergence in Hyla and Litoria tree frogs (10,11) and Gryllus crickets (12), as well as plumage divergence in Ficedula flycatchers (13), there remains no convincing example of character displacement in bird song, and none that control for geographic and environmental variation (14). Bird songs of related species are predicted to diverge in sympatry to reduce species recognition errors when hybrids have lower fitness (14).…”

Morphometric Variation and Population Relationships of Krüper's Nuthatch (Sitta krueperi) in Turkey

“…Characteristic inconsistency in R. turcicus populations can be assumed to be a discrepancy between the rates of divergence in morphology and song, rapid in the first and slow in the second. A similar conflict is very common in allopatric populations of the Ensiferan species (Jang andGerhardt 2006, Heller 2006, and references therein); however, it is rare in the Acrididae species (Heller 2006). The results of this study highlight the importance of the song characteristics in the definition and description of the Gomphocerinae species, which use the song as a premating isolation barrier.…”