Biology subjects

Natale, R.

Publications and source records attributed to Natale, R..

4 recordsLinked to original sources

bioRxiv2023

Correlated evolution of beak and braincase morphology is present only in select bird clades

1Complex morphological structures, such as skulls or limbs, are often composed of multiple morphological components (e.g. bones, sets of bones) that may evolve in a covaried manner with one another. Previous research has reached differing conclusions on the number of semi-independent units, or modules, that exist in the evolution of structures and on the strength of the covariation, or integration, between these hypothesized modules. We focus on the avian skull as an example of a complex morphological structure for which highly variable conclusions have been reached in the numerous studies analyzing support for a range of simple to complex modularity hypotheses. We hypothesized that past discrepancies may stem from both the differing densities of data used to analyze support for modularity hypotheses and the differing taxonomic levels of study. To test these hypotheses, we applied a comparative method to 3D geometric morphometric data collected from the skulls of a diverse order of birds (the Charadriiformes) to test support for 11 distinct hypotheses of modular skull evolution. Across all Charadriiformes, our analyses suggested that charadriiform skull evolution has been characterized by the semi-independent, but still correlated, evolution of the beak from the rest of the skull. When we adjusted the density of our morphometric data, this result held, but the strength of the signal varied substantially. Additionally, when we analyzed subgroups within the order in isolation, we found support for distinct hypotheses between subgroups. Taken together, these results suggest that differences in the methodology of past work (i.e. statistical method and data density) as well as clade-specific dynamics may be the reasons past studies have reached varying conclusions.

evolutionary biology↗

bioRxiv2023

Genetic drift vs natural selection affecting the evolution of spectral and functional traits of two key macrophytes: Phragmites australis and Nuphar lutea

Both genetic and phenotypic intraspecific diversity play a crucial role in the ecological and evolutionary dynamics of organisms. Several studies have compared phenotypic divergence (Pst) and differentiation of neutral loci (Fst) to infer the relative roles of genetic drift and natural selection in population differentiation (Pst - Fst comparison). For the first time, we assessed and compared the genetic variation and differentiation at the leaf trait level in two key macrophytes, Phragmites australis and Nuphar lutea. To this aim, we quantified and described the genetic structure and phenotypic diversity of both species in five lake systems in north-central Italy. We then investigated the relative roles of genetic drift and natural selection on leaf trait differentiation (Pst - Fst), assuming that Fst reflects divergence caused only by genetic drift while Pst also incorporates the effects of selective dynamics on the phenotype. In terms of genetic structure, the results for P. australis were in line with those observed for other Italian and European conspecific populations. Conversely, N. lutea showed a more complex genetic structure than expected at the site level, likely due to the combined effect of genetic isolation and its mixed mating system. Both species exhibited high variability in leaf functional traits within and among sites, highlighting a high degree of phenotypic plasticity. Pst - Fst comparisons showed a general tendency towards directional selection in P. australis and a more complex pattern in N. lutea. Indeed, the drivers of phenotypic differentiation in N. lutea showed a variable mix of stabilizing and directional selection or neutral divergence at most sites. The prevalence of vegetative over generative reproduction leads P. australis populations to be dominated by a few clones that are well adapted to local conditions, including phenotypes that respond plastically to the environment. In contrast, in N. lutea the interaction of a mixed mating system and geographical isolation among distant sites tends to reduce the effect of outbreeding depression and provides the genetic basis for adaptive capacity. The first joint analysis of the genetic structure of these two key macrophytes allowed a better understanding of the relative roles of genetic drift and natural selection in the diversification of phenotypic traits within habitats dominated by P. australis and N. lutea.

ecology↗

bioRxiv2022

Choice of 3D morphometric method leads to diverging interpretations of form--function relationships in the carnivoran calcaneus

AO_SCPLOWBSTRACTC_SCPLOWThree dimensional morphometric methods are a powerful tool for comparative analysis of shape. However, morphological shape is often represented using landmarks selected by the user to describe features of perceived importance, and this may lead to over confident prediction of form-function relationships in subsequent analyses. We used Generalized Procrustes Analysis (GPA) of 13 homologous 3D landmarks and spherical harmonics (SPHARM) analysis, a homology-free method that describes the entire shape of a closed surface, to quantify the shape of the calcaneus, a landmark poor structure that is important in hind-limb mechanics, for 111 carnivoran species spanning 12 of 13 terrestrial families. Both approaches document qualitatively similar patterns of shape variation, including a dominant continuum from short/stout to long/narrow calcanea. However, while phylogenetic generalized linear models indicate that locomotor mode best explains shape from the GPA, the same analyses find that shape described by SPHARM is best predicted by foot posture and body mass without a role for locomotor mode, though effect sizes for all are small. User choices regarding morphometric methods can dramatically impact macroevolutionary interpretations of shape change in a single structure, an outcome that is likely exacerbated when readily landmarkable features are few.

evolutionary biology↗

bioRxiv2021

Comprehensive taxon sampling and vetted fossils help clarify the time tree of shorebirds (Aves, Charadriiformes)

Shorebirds (Charadriiformes) are a globally distributed clade of modern birds and, due to their ecological and morphological disparity, a frequent subject of comparative studies. While molecular phylogenies have been instrumental to resolving the suprafamilial backbone of the charadriiform tree, several higher-level relationships, including the monophyly of plovers (Charadriidae) and the phylogenetic positions of several monotypic families, have remained unclear. The timescale of shorebird evolution also remains uncertain as a result of extensive disagreements among the published divergence dating studies, stemming largely from different choices of fossil calibrations. Here, we present the most comprehensive non-supertree phylogeny of shorebirds to date, based on a total-evidence dataset comprising 336 ingroup taxa (89% of all extant species), 24 loci (15 mitochondrial and 9 nuclear), and 69 morphological characters. Using this phylogeny, we clarify the charadriiform evolutionary timeline by conducting a node-dating analysis based on a subset of 8 loci tested to be clock-like and 16 carefully selected, updated, and vetted fossil calibrations. Our concatenated, species-tree, and total-evidence analyses consistently support plover monophyly and are generally congruent with the topologies of previous studies, suggesting that the higher-level relationships among shorebirds are largely settled. However, several localized conflicts highlight areas of persistent uncertainty within the gulls (Laridae), true auks (Alcinae), and sandpipers (Scolopacidae). At shallower levels, our phylogenies reveal instances of genus-level nonmonophyly that suggest changes to currently accepted taxonomies. Our node-dating analyses consistently support a mid-Paleocene origin for the Charadriiformes and an early diversification for most major subclades. However, age estimates for more recent divergences vary between different relaxed clock models, and we demonstrate that this variation can affect phylogeny-based macroevolutionary studies. Our findings demonstrate the impact of fossil calibration choice on the resulting divergence time estimates, and the sensitivity of diversification rate analyses to the modeling assumptions made in time tree inference.

evolutionary biology↗