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

Divergence in sexual signals may drive reproductive isolation between lineages, but behavioural barriers can weaken in contact zones. Here, we investigate the role of song as a behavioural and genetic barrier in a contact zone between two subspecies of white-crowned sparrows (Zonotrichia leucophrys). We employed a reduced genomic data set to assess population structure and infer the history underlying divergence, gene flow and hybridization. We also measured divergence in song and tested behavioural responses to song using playback experiments within and outside the contact zone. We found that the subspecies form distinct genetic clusters, and demographic inference supported a model of secondary contact. Song phenotype, particularly length of the first note (a whistle), was a significant predictor of genetic subspecies identity and genetic distance along the hybrid zone, suggesting a close link between song and genetic divergence in this system. Individuals from both parental and admixed localities responded significantly more strongly to their own song than to the other subspecies song, supporting song as a behavioural barrier. Putative parental and admixed individuals were not significantly different in their strength of discrimination between own and other songs; however, individuals from admixed localities tended to discriminate less strongly, and this difference in discrimination strength was explained by song dissimilarity as well as genetic distance. Therefore, we find that song acts as a reproductive isolating mechanism that is potentially weakening in a contact zone between the subspecies. Our findings also support the hypothesis that intraspecific song variation can reduce gene flow between populations.

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“…den Hartog et al . ). However, these studies focus on the strength of behavioural response to a stimulus (e.g.…”

Section: Discussionmentioning

confidence: 97%

“…; Gee ; den Hartog et al . ), or there is asymmetric song recognition (Kershner & Bollinger ; Dingle et al . ; Ruegg et al .…”

Section: Introductionmentioning

confidence: 99%

Behavioural response to song and genetic divergence in two subspecies of white‐crowned sparrows (Zonotrichia leucophrys)

et al. 2017

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“…The equivalent tests on allopatric H. subflava were not possible due to logistical difficulties. Heterospecific responses are sometimes learnt in sympatry (e.g., Emlen et al 1975; Matyjasiak 2005; den Hartog et al 2008), providing a possible alternative explanation for muted responses in allopatry. We therefore assessed the role of learning by comparing (1) the response of naïve H. peruviana at Los Indios to H. subflava with (2) the response of naïve H. peruviana at CICRA to H. striata .…”

Section: Methodsmentioning

confidence: 99%

SIGNAL DESIGN AND PERCEPTION INHYPOCNEMISANTBIRDS: EVIDENCE FOR CONVERGENT EVOLUTION VIA SOCIAL SELECTION

2009

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Natural selection is known to produce convergent phenotypes through mimicry or ecological adaptation. It has also been proposed that social selection-i.e., selection exerted by social competition-may drive convergent evolution in signals mediating interspecific communication, yet this idea remains controversial. Here, we use color spectrophotometry, acoustic analyses, and playback experiments to assess the hypothesis of adaptive signal convergence in two competing nonsister taxa, Hypocnemis peruviana and H. subflava (Aves: Thamnophilidae). We show that the structure of territorial songs in males overlaps in sympatry, with some evidence of convergent character displacement. Conversely, nonterritorial vocal and visual signals in males are strikingly diagnostic, in line with 6.8% divergence in mtDNA sequences. The same pattern of variation applies to females. Finally, we show that songs in both sexes elicit strong territorial responses within and between species, whereas songs of a third, allopatric and more closely related species (H. striata) are structurally divergent and elicit weaker responses. Taken together, our results provide compelling evidence that social selection can act across species boundaries to drive convergent or parallel evolution in taxa competing for space and resources.

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“…Our survey of research on acoustic communication in this group reveals that there is a bias towards certain topics and species. Several papers addressed the topic of the mechanism of sound production (ten Cate and Ballintijn 1996;ten Cate 1997a, 1998;Beckers et al 2003a, b), neurobiology of vocalization (Terpstra et al 2005;Elemans et al 2008), and species identity coding, including studies on hybrid vocalization and the role of song divergence in speciation processes (Lade and Thorpe 1964;Tubaro and Mahler 1998;Beckers and ten Cate 2001;de Kort and ten Cate 2001;de Kort et al 2002a, b;den Hartog et al 2008). In addition, the relationship between song structure and its functions in territorial defence or mate attraction was studied in detail for certain model species (e.g.…”

Section: Introductionmentioning

confidence: 99%

Hey mister Tambourine Dove, sing a song for me: simple but individually specific songs of Turtur tympanistria from Cameroon

et al. 2019

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Background: The broadcast song of the Tambourine Dove (Turtur tympanistria) is a repetitive coo series produced in a very stereotyped way. The song is similar to those of the other species within the Turtur genus and likely reflects the adaptation to long distance signalling in tropical habitats. There is no study assessing individual variation of the Tambourine Dove song or for the possibility of identity coding through song features. Methods: We obtained recordings of 578 songs from 41 males within a population inhabiting montane forest in Cameroon between 2008 and 2018. Additionally, we analysed also recordings from automatic recorders working for a longer time during the year. Songs were analysed to get basic information about within-and between-individual spectro-temporal variation. Potential of identity coding and discriminant analyses were used to investigate if and how these songs may convey information about male identity. Results: The song of the Tambourine Dove is a very simple series of short, unmodulated whistles with low frequency and a narrow bandwidth. Measurements of single song features indicated either none or a weak potential for identity coding. The overall variation in song frequency characteristics was very low. However, the number of notes forming a song (and consequently the duration) had a similar variability both within-and between individuals. When using multiple song measurements discrimination analysis revealed a high potential for identity coding although it seems that the temporal pattern of the beginning of a song carries the most information about sender identity. The production of initial notes within a song has very precise, individually specific timing allowing for up to 96.7% correct recognitions of songs. Comparison of recordings from the same points but separated in time by over a month indicates that song parameters are individually stable over longer period. Conclusions: Despite having highly stereotyped and simple songs, Tambourine Dove males produce individually specific signals which have a great potential for recognition by rivals or mates. All Turtur doves have similar yet unique songs that are different to the songs of other pigeon species. This genus seems to be a perfect model for studying the trade-off between coding for species identity and individual identity in a non-learning bird species. The described method of individual recognition allows for nonintrusive population monitoring.

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

Cited by 17 publications

References 71 publications

Behavioural response to song and genetic divergence in two subspecies of white‐crowned sparrows (Zonotrichia leucophrys)

Behavioural response to song and genetic divergence in two subspecies of white‐crowned sparrows (Zonotrichia leucophrys)

SIGNAL DESIGN AND PERCEPTION INHYPOCNEMISANTBIRDS: EVIDENCE FOR CONVERGENT EVOLUTION VIA SOCIAL SELECTION

Hey mister Tambourine Dove, sing a song for me: simple but individually specific songs of Turtur tympanistria from Cameroon

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