Biology subjects

Kirschel, A. N. G.

Publications and source records attributed to Kirschel, A. N. G..

6 recordsLinked to original sources

bioRxiv2024

Introgression across narrow contact zones shapes the genomic landscape of phylogenetic variation in an African bird clade

Genomic analyses of hybrid zones provide excellent opportunities to investigate the consequences of introgression in nature. In combination with phylogenomics analyses, hybrid zone studies may illuminate the role of ancient and contemporary gene flow in shaping variation of phylogenetic signals across the genome, but this avenue has not been explored yet. We combined phylogenomic and geographic cline analyses in a Pogoniulus tinkerbird clade to determine whether contemporary introgression through hybrid zones contributes to gene-tree heterogeneity across the species ranges. We found diverse phylogenetic signals across the genome with the most common topologies supporting monophyly among taxa connected by secondary contact zones. Remarkably, these systematic conflicts were also recovered when selecting only individuals from each taxons core range. Using analyses of derived allele sharing and "recombination aware" phylogenomics, we found that introgression shapes gene-tree heterogeneity, and the species tree most likely supports monophyletic red-fronted tinkerbirds, as recovered in previous reconstructions based on mitochondrial DNA. Furthermore, by fitting geographic clines across two secondary contact zones, we found that introgression rates were lower in genomic regions supporting the putative species tree compared to those supporting the two taxa in contact as monophyletic. This demonstrates that introgression through narrow contact zones shapes gene-tree heterogeneity even in allopatric populations. Finally, we did not find evidence that mitochondria-interacting nuclear genes acted as barrier loci. Our results show that species can withstand important amounts of introgression while maintaining their phenotypic integrity and ecological separation, raising questions regarding the genomic architecture of adaptation and barriers to gene flow.

evolutionary biology↗

bioRxiv2020

Ambient noise from ocean surf drives frequency shifts in non-passerine bird song

Effective communication in birds is often hampered by background noise, with many recent studies focusing on the effect of anthropogenic noise on passerine bird song. Continuous low-frequency natural noise is predicted to drive changes in both frequency and temporal patterning of bird vocalizations, but the extent to which these effects may also affect birds that lack vocal learning is not yet fully understood. Here we use a gradient of exposure to natural low-frequency noise to assess whether it exerts selective pressure on vocalizations in a species whose songs are innate. We tested whether three species of Pogoniulus tinkerbirds adapt their song when exposed to a source of continuous low-frequency noise from ocean surf. We show that dominant frequency increases the closer birds are to the coast in all the three species, and in line with higher noise levels, indicating that ocean surf sound may apply a selective pressure on tinkerbird songs. As a consequence, tinkerbirds adapt their songs with an increase in frequency to avoid the masking effect due to overlapping frequencies with ambient noise, therefore improving long-range communication with intended receivers. Our study provides for the first time, compelling evidence that natural ambient noise affects vocalizations in birds whose songs are developed innately. We believe that our results can also be extrapolated in the context of anthropogenic noise pollution, hence providing a baseline for the study of the effects of low-frequency ambient noise on birds that lack vocal learning. Significance StatementBirdsong is constantly under selection as it mediates key interactions such as mate attraction, competition with same-sex individuals for reproduction and competition with heterospecifics for space-related resources. Any phenomenon that interferes with communication can therefore have a profound impact on individual fitness. Passerines are more likely to avoid the masking effect of background noise because of their higher vocal flexibility. Many non-passerine species lacking such flexibility might therefore be more vulnerable to the negative effects on their fitness of exposure to low-frequency background noise. Species incapable of adapting their signals to background noise are predicted to disappear from noisy areas. Despite this, we show that species that lack song learning may show an adaptive response to natural noise which may develop over evolutionary timescales.

evolutionary biology↗

bioRxiv2020

Breeding success of Eleonora's falcon (Falco eleonorae) in Cyprus revisited using survey techniques for cliff-nesting species

The global breeding population of Eleonoras falcon is distributed from the Canary Islands in the west, across the Mediterranean Sea, to Cyprus in the east. The remoteness of nesting colonies, which are predominantly located on sea cliffs and islets, renders breeding success estimation a challenging task, requiring a composite approach to assess each of the breeding stages. Early estimates of the breeding success of Eleonoras falcon suggested that Akrotiri colony in Cyprus had the lowest breeding success among all the colonies throughout the species breeding range, at a level seemingly unsustainable, suggesting the colony might have been in danger of gradual extinction. Here we use a diversity of survey methods using boat, ground and aerial surveys, with the incorporation of photography and photogrammetry, to reassess the breeding success and the effect of nest characteristics on the Eleonoras falcon breeding population in Cyprus. During a six-year study, we found that Cyprus hosts ~138 {+/-} 8 breeding pairs and that breeding success equals 1.54 {+/-} 0.85 fledglings per breeding pair, thus considerably higher than previous estimates. In addition, by analyzing temporal variation in breeding and nest characteristics, we found that early breeding and reuse of nests positively influence breeding success, but physical nest characteristics have a limited effect on colony productivity. The range of survey methods employed, as well as the array of photography techniques utilized, highly enhanced the efficiency and accuracy of this study, allowing us to overcome the challenge of inaccessibility of nesting cliffs.

ecology↗

bioRxiv2020

Tape lures swell bycatch on a Mediterranean island harbouring illegal bird trapping

Mediterranean islands are critical for migrating birds, providing shelter and sustenance for millions of individuals each year. Humans have long exploited bird migration through hunting and illegal trapping. On the island of Cyprus, trapping birds during their migratory peak is considered a local tradition, but has long been against the law. Illegal bird trapping is a lucrative business, however, with trappers using tape lures that broadcast species’ vocalizations because it is expected to increase numbers of target species. Yet, by how much the use of song playback increases capture rates remains underappreciated. In particular, it is not known whether song playback of target species affects bycatch rates. Here, we show with the use of playback experiments that song playback is highly effective in luring birds towards trapping sites. We found that playback increases six to eight times the number of individuals of target species captured, but also significantly increases bycatch. Our findings thus show that in contrast to popular belief that tape lures are a selective trapping method, they also lead to increased captures of non-target species, which can include species of conservation concern.View Full Text

zoology↗

bioRxiv2019

Females don't always sing in response to male song, but when they do, they sing to males with higher pitched songs

The long-held view that bird song is exclusively a male trait has been challenged recently by a number of studies and reviews highlighting the prevalence of female song. In spite of that, there remains a lack of knowledge on the function of female song, with most evidence thus far focusing on females performing duets with males in courtship displays, typically for joint territory defence or mate guarding purposes. Here we show in a tracheophone suboscine passerine Formicarius moniliger, a sexually monomorphic species in which both sexes sing, that females may participate in both intrasexual and intersexual territory defence. Females sing more in response to females than to males, suggesting they consider females more of a threat to their territory. Yet, females also demonstrate an unexpected pattern of singing back to playback of males singing higher frequency song than themselves. Unlike males, who respond indiscriminately to playback of any song performed by either sex, females appear to discern not only the sex, but perhaps also the size of the presumed intruder. There is a strong negative relationship between body mass and frequency, and females responding only to higher frequency male song suggests they will only engage in territory defence with males when they expect those males to be weaker than they are. While our results are consistent with expectations of a shared ancestral function of song in territory defence, they also suggest females may suffer greater costs in engaging in territorial disputes and thus limit their vocal contribution according to the perceived threat.

animal behavior and cognition↗

bioRxiv2019

Range-wide spatial mapping reveals convergent character displacement of bird song

A long-held view in evolutionary biology is that character displacement generates divergent phenotypes in closely related coexisting species to avoid the costs of hybridisation or ecological competition, whereas an alternative possibility is that signals of dominance or aggression may instead converge to facilitate coexistence among ecological competitors. Although this counter-intuitive process--termed convergent agonistic character displacement--is supported by recent theoretical and empirical studies, the extent to which it drives spatial patterns of trait evolution at continental scales remains unclear. By modeling variation in song structure of two ecologically similar species of Hypocnemis antbird across western Amazonia, we show that their territorial signals converge such that trait similarity peaks in the sympatric zone, where intense interspecific territoriality between these taxa has previously been demonstrated. We also use remote sensing data to show that signal convergence is not explained by environmental gradients and is thus unlikely to evolve by sensory drive (i.e. acoustic adaptation to the sound transmission properties of habitats). Our results suggest that agonistic character displacement driven by interspecific competition can generate spatial patterns opposite to those predicted by classic character displacement theory, and highlight the potential role of social selection in shaping geographical variation in signal phenotypes of ecological competitors.

evolutionary biology↗