Reproductive Behavior of Female Buntings: Isolating Mechanisms in a Hybridizing Pair of Species

Abstract

Abstract. -The plumage characteristics of male Indigo and Lazuli Buntings are distinct, but the two species can learn each other's songs. Populations comprising Indigo, Lazuli and hybrid individuals occur in the Great Plains of North America, and assortative mating has been inferred from morphometric data. We devised a laboratory assay for determining female preferences for visual and vocal characteristics of conspecific and heterospecific males and for mixtures of these characteristics, such as might be encountered in an overlap population. Females of both species gave more copulation-solicitation displays when exposed to conspecific plumage and vocalizations than when exposed to heterospecific plumage and vocalizations. Females gave intermediate and similar responses to the combinations of conspecific plumage with heterospecific vocalizations and heterospecific plumage with conspecific vocalizations. Thus, in the absence of other potentially important variables, female reproductive behavior is consistent with the hypothesis of assortative mating, based upon both vocal and visual traits of the males and caused by female choice in this semispecies pair.

Plumage and Song Differences Mediate Species Recognition Between Incipient Flycatcher Species of the Solomon Islands

“…With our phylogenetic analyses indicating rapid divergence of plumage color and song among island endemics, we then tested for the roles of divergent multimodal signals in species recognition with the expectation that the more variable plumage color should be more important than song structure. Our behavioral experiments indicate that male and female territory‐owners ignored the heterospecific golden whistler control and responded more strongly to homotypic than to heterotypic plumage and song types, indicating that individual birds use divergent plumage and song in conspecific/homotypic recognition (e.g., Baker and Baker 1990). Note, that the use of the heterospecific control attempts to distinguish between an aggressive response to an ecological and sexual competitor.…”

Variability of Female Responses to Conspecific vs. Heterospecific Male Mating Calls in Polygynous Deer: An Open Door to Hybridization?

“…There was also a non-significant trend ( p  = 0.091) for females to spend more total time in the conspecific proximity zone. Mating preferences for conspecifics over heterospecifics is well documented [17], [49]–[51], although there can be interspecific or intersexual variation in the directionality of such preferences within hybridizing species [20], [21], [52]. We hypothesized that the very different spectral properties of the sexual calls that characterize these two closely related deer species might contribute to species discrimination, and consequently expected that female red deer would strongly discriminate between the two species by showing a significant preference for conspecific calls.…”

A hybrid zone revisited: molecular and morphological analysis of the maintenance, movement, and evolution of a Great Plains avian (Cardinalidae: Pheucticus) hybrid zone

“…Anderson & Daugherty (1974) historically found a significant decrease in hybrid female clutch size compared to pure female clutch size, implying reduced female hybrid fitness and suggesting Haldane's Rule [1922, which expects the heterogametic sex (avian females) to exhibit reduced fitness before the homogametic sex] may be important within the zone of contact. In addition to Haldane's Rule, positive assortative mating was previously suggested to be occurring in the grosbeak hybrid zone (West 1962; Anderson & Daugherty 1974), and other passerine hybrid zones in the Great Plains (Sibley & West 1959; Baker & Baker 1990; Baker & Boylan 1999). In other studies of hybridizing avian species pairs, character displacement of male plumage traits has been shown to be sex linked in sympatric hybridizing bird populations (Sætre et al .…”