Biology subjects

Claramunt, S.

Publications and source records attributed to Claramunt, S..

4 recordsLinked to original sources

bioRxiv2026

A time-calibrated phylogeny of hummingbirds supports stepwise diversification in the Andes

Hummingbirds (Trochilidae) represent the second largest avian family, with [~]356 species occupying diverse habitats across the Neotropical and Nearctic regions. Their extensive diversification includes notable adaptations to extreme environments, with nearly one-third of extant taxa belonging to the predominantly high-altitude Coquettes and Brilliants. Although recent work proposed a monophyletic Andean clade uniting these groups, consistent with rapid radiation during Andean orogeny, we find no support for this relationship. Using 2,949 nuclear loci sampled from 47 species spanning all nine major hummingbird clades, we recover a different evolutionary pattern: a stepwise sequence of diversification in which Brilliants are sister to a broader assemblage comprising Coquettes, the genus Patagona, Emeralds, Mountain Gems, and the recently diverged Bees. By assembling complete mitochondrial genomes, we additionally detect significant discordance between nuclear topologies and those derived from the mitogenome and Z chromosome. Analyses of gene-tree heterogeneity show that incomplete lineage sorting is pervasive across the phylogeny, with particularly strong impacts on branches associated with Andean diversification. Divergence-time estimation further indicates that the major Andean radiation--including Brilliants, Coquettes, Emeralds, Bees, and Mountain Gems--originated around [~]14 Ma, with the three younger clades diversifying [~]12 Ma, coinciding with both the mid-Miocene Andean uplift and the mid-Miocene Climate Transition that increased habitat heterogeneity and likely promoted rapid speciation. To support future phylogenomic efforts, we identify a reduced set of highly informative, independent protein-coding loci and present a near-complete species-level phylogeny constrained by our autosomal backbone. Our findings highlight the importance of integrating loci with distinct inheritance modes to detect and interpret phylogenetic incongruence in rapid radiations.

evolutionary biology↗

bioRxiv2025

Song complexity in suboscine birds: evolutionary drivers and ecological constraints

Acoustic signal complexity varies widely in the animal kingdom for reasons that remain unclear. In birds, it is widely proposed that vocal complexity evolves as an honest signal of individual quality driven by sexual selection. Other hypotheses related to social interactions include competition for ecological resources (social selection) and intra-group communication in group- living animals, both of which may favour signal complexity. However, these hypotheses are rarely explored at macroevolutionary scales, particularly in the context of constraints on sound production, transmission and detection, leading to ongoing uncertainty about the evolutionary origins of complex vocal signals. Using Bayesian phylogenetic models, we test whether different forms of social communication and ecological constraints predict the temporal and spectral complexity of songs in 1,288 species of suboscine passerine birds. We found that song complexity was reduced by sexual selection, along with other limiting factors including large body size and dense vegetation. Conversely, territoriality boosted the temporal complexity of songs. These findings challenge the common assumption that sexual selection is the main driver of increased signal complexity, and instead highlight the role of social selection as a key component of multiple inter-related drivers and constraints.

evolutionary biology↗

bioRxiv2025

Coalescent-based branch length estimation improves dating of species trees

Species trees need to be dated for many downstream applications. Typical molecular dating methods take a phylogenetic tree with branch lengths in substitution units as well as a set of calibrations as input and convert the branch lengths of the species tree to the unit of time while being consistent with the pre-specified calibrations. When dating species trees from multi-locus genome-scale datasets, the branch lengths and sometimes the topology of the species tree are estimated using concatenation. However, concatenation does not address gene tree heterogeneity across the genome. While Bayesian dating methods can address some forms of gene tree heterogeneity, such as incomplete lineage sorting, they are not scalable to large datasets. In this paper, we introduce a new scalable pipeline for dating species trees that addresses gene tree discordance for both topology and branch length estimation. The pipeline uses discordance-aware methods that account for incomplete lineage sorting for estimating the topology and branch lengths and maximum likelihood-based methods for the dating step. Our simulation study on datasets with gene tree discordance shows that this pipeline produces more accurate and less biased dates than pipelines that use concatenation or unpartitioned Bayesian methods. Furthermore, it is substantially more scalable and can handle datasets with thousands of species and genes. Our results on two biological datasets show that this new pipeline improves the inference of node ages and branch lengths for some nodes, in particular extant taxa, and improves the downstream diversification analysis.

evolutionary biology↗

bioRxiv2019

The latitudinal gradient in hand-wing-index: global patterns and predictors of wing morphology in birds

An organisms ability to disperse influences many fundamental processes in ecology. However, standardised estimates of dispersal ability are rarely available, and thus the patterns and drivers of broad-scale variation in dispersal ability remain unclear. Here we present a global dataset of avian hand-wing index (HWI), an estimate of wingtip pointedness widely adopted as a proxy for flight efficiency and dispersal in birds. We show that HWI is correlated with geography and ecology across 10,391 (>99 %) bird species, increasing at higher latitudes and in migratory and/or non-territorial species. After controlling for these effects, the strongest predictor of HWI is temperature variability (i.e. seasonality), with secondary effects of diet and habitat type. Our analyses (1) reveal a prominent latitudinal gradient in HWI shaped by ecological and environmental factors, and (2) provide a global index of avian dispersal ability for wider use in community ecology, macroecology, and macroevolution.\n\nStatement of authorshipThe study was conceived by CS and JAT. Data collection was led by JAT, SC, and CS, with contributions from CS, MNC, NA, SEIJ, CV, HEAM, TPB, and SC. CS performed the analyses. CS and JAT wrote the manuscript and all authors revised the text.

evolutionary biology↗