Biology subjects

Sebastianelli, M.

Publications and source records attributed to Sebastianelli, M..

4 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

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↗

bioRxiv2018

Impending regeneration failure of the IUCN Vulnerable Borneo ironwood (Eusideroxylon zwageri)

The regeneration of many climax species in tropical forest critically depends on adequate seed dispersal and seedling establishment. Here we report the decreased abundance and increased spatial aggregation of younger trees of the Borneo ironwood (Eusideroxylon zwageri) in a protected forest in Sabah Malaysia. We observed a high level of seedling herbivory with strong density dependence, likely exacerbated by local aggregation and contributing to the progressively shrinking size-distribution. We also note the largely undocumented selective herbivory by sambar deer on E. zwageri seedlings. This study highlights the combined impact of altered megafauna community on a tree population through interlinked ecological processes and the need for targeted conservation intervention for this iconic tropical tree species.

ecology↗