Vocal signals, isolation and hybridization in the vinaceous dove ( Streptopelia vinacea ) and the ring-necked dove ( S. capicola )

Aim Bats communicate by emitting social calls, and these often elicit reactions in conspecifics. Many such vocalizations are species-specific so that unambiguous signals can be transmitted and interpreted by conspecifics. In species-rich assemblages, evolutionary pressures might prompt interspecific diversification of call structure so that communication with heterospecifics is avoided. In species-poor island communities, where no risk of miscommunication occurs, stabilizing selection should prevail and preserve call structure and function. Call structure in island bats might be inherited from colonizers from the mainland and be maintained with little change in the absence of selection from heterospecifics. To test this hypothesis we studied Pipistrellus maderensis, an insular taxon occurring on the Madeira Archipelago, the Canary Islands and the Azores. It is closely related to one of the most widespread European pipistrelles, Pipistrellus kuhlii. Pipistrellus maderensis most probably evolved from a common ancestor shared with P. kuhlii, or from founders of that taxon that colonized the islands. We hypothesized that on Madeira Island, where no risk of ambiguous communication with heterospecifics exists, the structure and function of social calls should have been preserved by stabilizing selection. Echolocation calls, subject to different selection pressures, may instead show more pronounced differences between P. maderensis and P. kuhlii. Location Madeira Island (Portugal, Atlantic Ocean), central and southern Italy. Methods We recorded social and echolocation calls from allopatric populations of the two pipistrelles and explored interspecific differences in time and frequency characteristics. We also conducted playback experiments by broadcasting recordings of social calls from P. kuhlii and P. maderensis (taken respectively in peninsular Italy and on Madeira) and monitoring the bats’ responses. Results Social call structure showed a strong similarity between species, whereas echolocation calls were markedly different and exhibited a mean divergence of over 6 kHz in their frequency of maximum energy. On Madeira, P. maderensis significantly reduced flight activity when we broadcast P. kuhlii signals, as did P. kuhlii in Italy in response to P. maderensis calls. Main conclusions Reliable interpretation of social calls provides benefits to both the signaller and the receiver because signals help to optimize food exploitation at foraging sites. In the absence of closely related species that can emit similar calls, this advantage may have acted as a strong evolutionary pressure, stabilizing social call structure in P. maderensis in insular ecosystems with limited foraging resources

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“…, 2006), birds (Irwin et al. , 2001; de Kort et al. , 2002) and, more recently, nocturnal primates (Braune et al.…”

Section: Introductionmentioning

confidence: 99%

Social calls are subject to stabilizing selection in insular bats

Russo

Teixeira

Cistrone³

et al. 2009

Journal of Biogeography

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“…Although the idea that preferences for local song dialects could lead to reproductive isolation is relatively old (Marler & Tamura, 1962; Baker, 1975), consistent patterns of assortative mating based on intraspecific variation in birdsong structure are few (Slabbekoorn & Smith, 2002a). This may reflect the fact that, with the exception of some work on Streptopelia doves (de Kort, den Hartog & ten Cate, 2002a, b; de Kort & ten Cate, 2004), most studies have focused on oscine passerines; for example, white‐crowned sparrow Zonotrichia leucophrys (Baker, 1975); Darwin’s finches Geospiza spp. (Grant & Grant, 1996); song sparrow Melospiza melodia (Searcy et al , 1997); blue tit Parus caeruleus (Doutrelant et al ., 2000); greenish warbler Phylloscopus trochiloides (Irwin, 2000); and flycatchers Ficedula spp.…”

Section: Introductionmentioning

confidence: 99%

Song divergence at the edge of Amazonia: an empirical test of the peripatric speciation model

Seddon

Tobias

2007

Biological Journal of the Linnean Society

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The evolutionary divergence of mating signals provides a powerful basis for animal speciation. Divergence in sympatry strengthens reproductive isolation, and divergence in allopatry can reduce or eliminate gene flow between populations on secondary contact. In birds, the first of these processes has empirical support, but the second remains largely hypothetical. This is perhaps because most studies have focused on oscine passerines, whose song learning ability may reduce the influence of vocalizations in reproductive isolation. In suboscine passerines, the role of learning in song development is thought to be minimal, and the resultant signals are relatively fixed. To investigate the role of song in the early stages of peripatric speciation, we therefore studied a suboscine, the chestnut-tailed antbird Myrmeciza hemimelaena . We recorded male songs in a natural forest island (isolated for < 3000 years) at the southern fringe of Amazonia, and at two nearby sites in continuous forest. A previous study found the isolated population to be weakly differentiated genetically from the ancestral population suggesting that peripatric speciation was underway. In support of this, although we detected minor but significant differences in song structure between each site, the most divergent songs were those of island birds. On simulating secondary contact using playback, we found that pairs from the forest island responded more strongly to island (i.e. local) songs than to those from both nonisland sites, and vice versa. This pattern was not observed in pairs from one non-island site, which responded with equal strength to local songs and songs from the other non-island site. Island females were more likely to approach and sing after hearing local male songs, rather than songs from the non-island populations, and vice versa; nonisland females did not appear to discriminate between local songs and those from the other non-island site. These findings are consistent with the idea that vocal divergence arising in small populations at the edge of Amazonia may result in partial reproductive isolation when contact is resumed. They also suggest the possibility that song divergence in peripatry may, after much longer time-frames, act as a barrier to gene flow in suboscines, perhaps because of an inability to learn or recognize divergent songs on secondary contact.

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“…Capicola coos usually consist of three elements. Previous playback experiments have shown that both capicola and vinacea respond more strongly to their conspecific than to the heterospecific and hybrid coos (de Kort et al 2002b;den Hartog et al 2007). Hybrids, as a population, respond equally strongly to coo types from all three populations (den Hartog et al 2007).…”

Section: Methodsmentioning

confidence: 97%

Male territorial vocalizations and responses are decoupled in an avian hybrid zone

Hartog

Slabbekoorn

Cate

2008

Phil. Trans. R. Soc. B

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A core area of speciation research concerns the coevolution of species-specific signals and the selective sensitivity to such signals. Signals and responses to them should be tuned to each other, to be effective in intraspecific communication. Hybrid zones are ideal to study the presence of such 'behavioural coupling' and the mechanisms governing it, and this has rarely been done. Our study examines acoustic signals of males and their response to them in the context of territorial interactions in a natural hybrid zone between two dove species, Streptopelia vinacea and Streptopelia capicola. Male signals are important in hybrid zone dynamics as they are essential for territory establishment, which is crucial for successful reproduction. We tested whether the response of individual male hybrids is linked to how similar their own signal is to the playback signal. We did not find evidence for behavioural coupling. The combined evidence from the low level of response to hybrid and heterospecific signals outside the hybrid zone and a lack of coupling within the hybrid zone suggests that perceptual learning may explain our results. Learning to respond to locally abundant signals may be the best individual strategy and is likely to contribute to the maintenance of a hybrid zone.

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Vocal signals, isolation and hybridization in the vinaceous dove ( Streptopelia vinacea ) and the ring-necked dove ( S. capicola )

Cited by 34 publications

References 35 publications

Social calls are subject to stabilizing selection in insular bats

Social calls are subject to stabilizing selection in insular bats

Song divergence at the edge of Amazonia: an empirical test of the peripatric speciation model

Male territorial vocalizations and responses are decoupled in an avian hybrid zone

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