bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/424770

Change in sexual signaling traits outruns morphological divergence in a recent avian radiation across an ecological gradient

Friis, G.·Mila, B.
View original source ↗Export metadata ↓

Abstract

The relative roles of natural and sexual selection in promoting evolutionary lineage divergence remains controversial and difficult to assess in natural systems. Local adaptation through natural selection is known to play a central role in adaptive radiations, yet secondary sexual traits can vary widely among species in recent radiations, suggesting that sexual selection may also be important in the early stages of speciation. Here we compare rates of divergence in ecologically relevant traits (morphology) and sexually selected signaling traits (coloration) relative to neutral structure in genome-wide molecular markers, and examine patterns of variation in sexual dichromatism to understand the roles of natural and sexual selection in the diversification of the songbird genus Junco (Aves: Passerellidae). Juncos include divergent lineages in Central America and several dark-eyed junco (J. hyemalis) lineages that diversified recently as the group recolonized North America following the last glacial maximum (c.a. 18,000 years ago). We found an accelerated rate of divergence in sexually selected characters relative to ecologically relevant traits. Moreover, a synthetic index of sexual dichromatism comparable across lineages revealed a positive relationship between the degree of color divergence and the strength of sexual selection, especially when controlling for neutral genetic distance. We also found a positive correlation between dichromatism and latitude, which coincides with the latitudinal pattern of decreasing lineage age but also with a steep ecological gradient. Finally, we detected an association between outlier loci potentially under selection and both sexual dichromatism and latitude of breeding range. These results suggest that the joint effects of sexual and ecological selection have played a role in the junco radiation and can be important in the early stages of lineage formation.

Source connections

Explore related subjects

evolutionary biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Friis, G., Mila, B.. 2018-09-23. Change in sexual signaling traits outruns morphological divergence in a recent avian radiation across an ecological gradient. https://doi.org/10.1101/424770

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Efficient growth factor production stabilizes cooperation in a cellular public goods game

Eukaryotic cells secrete growth factors that facilitate the proliferation and survival of neighboring cells in a coordinated manner essential for tissue development, repair, and homeostasis. However, mutant cells that fail to produce these factors may exploit the benefits provided by neighboring producers, thereby gaining a proliferative advantage that could lead to the extinction of the producer clone. Evolutionary theory predicts that preventing this "tragedy of the commons" requires a fixed spatial structure or other mechanisms that enable cells to interact preferentially with copies of themselves. Contrary to this expectation, we found that, in competition experiments, cells producing the diffusible growth factor interleukin-3 (IL3) resist invasion by non-producing mutant cells even in well-mixed populations, and that non-producers are driven to extinction instead. Using evolutionary game theory, we show that this outcome arises when the cost-to-benefit ratio of growth factor production falls below a critical threshold. We derive this tipping point analytically across the full parameter space of benefit function shape and group size and confirm that IL3 production in our experimental system satisfies this condition with a production cost less than 0.1% of the benefit conferred. These results demonstrate that efficient public good production alone can resolve the tragedy of the commons in populations of cells, and potentially in other biological systems.

evolutionary biology↗
bioRxiv2026

Repeated Transitions in Migratory Behavior Across a Songbird Radiation Are Not Driven by Selection on Shared Variation in Candidate Genes

Understanding the mechanisms facilitating the repeated evolution of traits is a core question in evolutionary biology. While repeated evolution has been observed across many systems, behavioral phenotypes have been less well studied than morphological traits. Migration is a behavioral adaptation to seasonality that has evolved independently in many animals, and repeated gains and losses of migratory behavior have been especially prevalent throughout the diversification of birds. While migratory traits are heritable in many taxa and candidate genes underlying intraspecific variation in migratory behavior have been identified, whether similar genetic changes are responsible for the repeated evolution of migration remains poorly understood. We used a phylogenomic approach to investigate the relationship between variation in candidate genes and migratory propensity across nearly all species in the parulid warbler radiation (n = 101), a group of songbirds in which migratory behavior has been lost and gained multiple times. Comparisons of candidate gene tree topologies to the parulid warbler species tree revealed cases of discordance, though these were explained by differences in the number of phylogenetically informative sites among genes rather than by elevated genetic similarity among species sharing migratory strategies. Testing models of coding sequence evolution identified sites with elevated dN/dS in five candidate genes, suggestive of positive selection; however, variation at these sites showed no clear association with migratory strategy, nor did we detect recurrent selection across lineages where transitions in migratory behavior most likely occurred. Together, these results contradict the hypothesis that selection on shared variation (ancestral polymorphisms or introgressed alleles) facilitated the repeated evolution of migration in this clade.

evolutionary biology↗
bioRxiv2026

Polygenic evolution towards a morning chronotype in modern humans

Chronotype is a behavioural phenotype, and its phenotypic trend is considered to change at higher latitudes. In the current study, we performed a polygenic assessment of chronotype trend using associated single nucleotide polymorphisms identified by a genome wide-association study. We found that the phenotypic trend towards morningness increased drastically during the migration of anatomically modern humans above 20 degrees north. Furthermore, two types of latitudinal selection of morningness alleles contributed to establishing the trend towards the morning chronotype at higher latitudes. We propose that the trend towards morningness is stronger in present-day modern humans living above 20 degrees north than in Neanderthals.

evolutionary biology↗