Biology subjects

Felice, R. N.

Publications and source records attributed to Felice, R. N..

8 recordsLinked to original sources

bioRxiv2025

Correlated evolution of the neck, head and forelimb across the theropod-bird transition

Powered flight has required birds to undergo numerous dramatic and coordinated evolutionary responses across the entire body, yet studies are limited to a small number of traits and often exclude a critical component of the vertebrate skeleton - the vertebrae. The neck is a critical region of the avian spine as it operates in tandem with the head as a surrogate forelimb across a diverse array of behaviours. However, the drivers of cervical vertebral evolution remain poorly understood. Here, we model shifts in adaptive optima and evolutionary rates of the neck, forelimb and head of extinct dinosaurs and extant birds to test if these modules co-evolved. We observe a co-occurrence of adaptive optima shifts for neck and forelimb proportion at the base of Avialae - to vertebrae adapted for stability and a forelimb better adapted for flight. These patterns are due to shifts in neck and forelimb allometry and suggest that heterochrony is an important factor in avian neck and forelimb evolution. Further, we find lower rates of both neck and forelimb evolution in birds compared to their non-avian theropod ancestors. The coordinated evolutionary response of the neck and forelimb is a derived feature of Avialae that initially evolved to stabilise in-flight vision. This axio-appendicular co-evolution has contributed to avian macroevolutionary dynamics by facilitating the evolution of a novel locomotory mode without sacrificing the grasping capability needed to directly interact with a huge diversity of environments.

evolutionary biology↗

bioRxiv2025

Rapid canalisation of mandible structure in Tetrapoda

Evolution of the mandibular structure has played a key role in the taxonomic diversification and niche exploration of tetrapods, from the initial water-to-land transition to the origin and radiation of mammals. While jaw evolution through these key transition points have long attracted attention, no studies of jaw evolution to date capture the breadth of tetrapod diversity and evolutionary history. Here, we reconstruct the compositional evolution of the tetrapod mandible with a comprehensive dataset of 36 traits scored in 3047 species. This sampling spans the earliest eotetrapodiforms to extant amphibians, mammals, and reptiles and birds, capturing immense ecological, developmental, and taxonomic diversity among a near-even split of extant and fossil tetrapods. We find that lower jaw morphology rapidly canalises at the base of each major clade, including, Eotetrapodiformes, Amniota, Synapsida, Sauropsida, and Amphibia, as well as subclades within those groups, and that, as a result, jaw compositional variation is highly phylogenetically structured. We estimate an average of over 100 shifts in three key traits: number of elements (dermal and endochondral bones), number of tooth-bearing elements, and total teeth per hemimandible, with symmetrical rates of gains and losses estimated for the number of elements, and correlated evolution between these three characters. Although novel elements arise occasionally, disparity in jaw composition overwhelmingly decreases as clades canalise rapidly, successively, and pervasively through tetrapod evolutionary history.

evolutionary biology↗

bioRxiv2025

Brain size dependent speciation and extinction rates in birds and the cognitive buffer hypothesis

Both brain and body size vary greatly across birds, with both traits hypothesized to play a key role in diversification patterns across the group. Larger brains facilitate the evolution of greater behavioural plasticity, which could facilitate diversification in two ways, either by driving increased speciation (behavioural drive) or by making lineages more resilient to extinction (cognitive buffer). Here, we model brain size dependent diversification dynamics from published endocranial volume data for a sample of 2291 extant and fossil bird taxa, jointly modelling speciation rate, extinction rate and fossilisation rate separately for perching birds and other groups. We find that increasing relative brain size primarily increases diversification rate through decreasing extinction rate, supporting the cognitive buffer hypothesis and suggesting that larger brains in birds promote diversification by making species more resilient to extinction. Although speciation and extinction are dependent on relative brain size in both perching birds and other groups, this dependence is non-linear. In perching birds, the highest diversification rates are found over a narrow range of relative brain sizes, in contrast to other bird groups which show lower diversification rates over a broader range of relative brain sizes. SignificanceThe potential for speciation and extinction are thought to be shaped by key phenotypic traits. In birds, brain size is one important trait hypothesized to have an impact on diversification. Testing this hypothesis requires the evolution of brain size, speciation rate, and extinction rate to be jointly modelled across the bird phylogeny. The inclusion of information on past diversity has been shown to be important in inferring diversification patterns, and so we include not only data from a broad sample of living birds but also information from the fossil record. Our study reveals patterns of brain size dependent diversification in birds which are consistent with the cognitive buffer hypothesis, with higher relative brain sizes being associated with lower extinction rates.

evolutionary biology↗

bioRxiv2024

The role of many-to-one mapping of vertebral form to function in Psittaciform tripedal locomotion

Parrots highlight the functional diversity of the avian neck by contributing to a range of behaviors, including arboreal locomotion. The parrot neck is used alongside the beak and hindlimb to allow them to successfully navigate arboreal habitats via tripedal locomotion. Whether specific morphological characteristics of the neck enable this behavior are currently unknown. By combining geometric morphometrics with phylogenetic comparative methods we investigate the factors correlate with shape variation in the cervical vertebrae of parrots. We find that phylogeny, allometry, integration, diet and tripedal locomotion all have a significant influence on the morphology of psittaciform cervical vertebrae. However, the influence of diet and tripedal locomotion is weak, with a high degree of morphospace overlap existing between dietary and neck use groups. Additionally, we find no evidence of convergence in parrot neck morphology due to the incidence of tripedal locomotion or dietary specialization. We thus conclude that changes to the neuromuscular control of the neck, not morphological adaptations, are primarily responsible for tripedal locomotion in parrots. We argue that many-to-one mapping of form to function allows parrots with similar neck morphologies to participate in a range of behaviors, and this may be a common feature amongst all birds.

evolutionary biology↗

bioRxiv2023

Neither Williston nor Dollo: mandibular complexity from stem tetrapods to modern amphibians

Directional trends in evolution have long captured the attention of biologists, and are particularly interesting when they reflect fundamental developmental processes that underlie morphological change. Here, we apply deep time data and a phylogenetic comparative framework to assess two fundamental "laws" - Willistons law of phenotypic simplification and Dollos law of irreversibility - in the tetrapod mandible, a structure that has sustained the same primary function of feeding for nearly 400 million years. In spite of this conserved function, the tetrapod mandible has undergone numerous morphological and compositional changes during and since the initial water-to-land transition around 390Ma. To quantify these shifts, we reconstructed the compositional ev olution of the mandible with 31 traits scored in 568 species from early tetrapods through to modern amphibians, thereby capturing immense developmental and ecological diversity as well as an excellent fossil record. Mandibular complexity and jaw disparity are highest at the base of the tetrapod tree and generally decrease through time, with stasis dominating over the last ~160M years. Nonetheless, we find a lack of support for Willistons and Dollos laws, with loss and gain of jaw components equally likely throughout the course of early tetrapod and amphibian evolution. Combined, our results demonstrate that evolutionary patterns of mandibular complexity are more nuanced than either Willistons or Dollos laws allow. Thus, laws of simplification are too crude to capture the evolutionary processes underlying the evolution of even a functionally conserved structure through deep time. SummaryThe lower jaw is a key innovation in vertebrate evolution with a unifying primary function: feeding. In spite of this conserved function, the jaw is extremely diverse in shape and composition. In limbed vertebrates (tetrapods), the jaw evolves from a complex structure comprising multiple elements and high numbers of teeth towards a simpler structure comprising few elements and generally fewer teeth. Superficially, this pattern suggests support for both Willistons and Dollos laws of phenotypic simplification and irreversibility, respectively. However, we find a lack of support for either law in the jaw of the earliest tetrapods and amphibians, adding to growing literature refuting overly simplified "laws" governing organismal evolution.

evolutionary biology↗

bioRxiv2023

Carrion converging: Skull shape is predicted by feeding ecology in vultures

The link between skull shape and dietary ecology in birds at macroevolutionary scales has recently been called into question by analyses of 3D shape that reveal that cranial anatomy is mainly influenced by other factors such as allometry. It is still unknown whether this form-function disconnect also exists at smaller evolutionary scales, for example within specialized ecological guilds. Vultures are a diverse guild of 23 extant species in two families (Accipitridae and Cathartidae) that exhibit phenotypic convergence as a result of highly-specialized feeding ecology. Vultures are the only known obligate scavengers among vertebrates and are usually grouped together under this single dietary category, but within this specialized diet there are three distinct, species-specific feeding strategies termed ripper, gulper, and scrapper. We use three-dimensional geometric morphometrics to quantify the relative contributions of feeding ecology, allometry, and phylogeny on vulture skull shape, along with several non-vulture raptors of similar size, range and ecology. Families show clear separation in shape, but phylogenetic signal is comparatively weak (Kmult = 0.33). Taking into account the influence of phylogeny, skull shape is not significantly correlated with either skull size or feeding type, but there are examples of strong, significant convergence and parallel shape evolution across feeding groups. Furthermore, skull shape performs strongly in predicting feeding ecology in a phylogenetic discriminant function analysis. These findings highlight the importance of detailed assessment of feeding behavior in studies of ecomorphology, rather than broader dietary categories alone, and reveal that ecology can be readily inferred from form given appropriate information.

evolutionary biology↗

bioRxiv2023

Ecological and life history drivers of avian skull evolution

One of the most famous examples of adaptive radiation is that of the Galapagos finches, where skull morphology, particularly the beak, varies with feeding ecology. Yet increasingly studies are questioning the strength of this correlation between feeding ecology and morphology in relation to the entire neornithine radiation, suggesting that other factors also significantly affect skull evolution. Here, we broaden this debate to assess the influence of a range of ecological and life history factors, specifically habitat density, migration, and developmental mode, in shaping avian skull evolution. Using 3D geometric morphometric data to robustly quantify skull shape for 354 extant species spanning avian diversity, we fitted flexible phylogenetic regressions and estimated evolutionary rates for each of these factors across the full dataset. The results support a highly significant relationship between skull shape and both habitat density and migration, but not developmental mode. We further found heterogenous rates of evolution between different character states within habitat density, migration, and developmental mode, with rapid skull evolution in species which occupy dense habitats, are migratory, or are precocial. These patterns demonstrate that diverse factors impact the tempo and mode of avian phenotypic evolution, and that skull evolution in birds is not simply a reflection of feeding ecology. Impact summaryAlmost 200 years ago, Darwin found that the beaks of Galapagos finches were different shapes in birds with different diets. Nowadays, it is well established that phylogeny, allometry, and ecology can also be key factors in shaping skulls. Yet, the influence of specific aspects of ecology, as well as life history, on morphological evolution remain poorly constrained. Here, we examined whether three novel factors also influence the shape of bird skulls and rates of evolution: habitat density, migration, or developmental mode. To do so, we combine high resolution 3D quantification of skull shape with dense taxonomic sampling across living birds. Our analyses revealed that skull shape varies in birds based on the density of vegetation in their habitats and on the extent to which they migrate. However, how independent birds are when they are born does not appear to influence overall skull shape. Despite these differences in how much they influence the shape of the skull, habitat density, migration and life history all influence the rate at which bird skulls evolve. Birds evolved fastest if they live in densely vegetated habitats, migrate long distances, or are precocial. These results add to the growing body of evidence that skull evolution in birds is impacted by a diverse range of factors, and suggests that habitat density, migration and life history should be considered in future analyses on drivers of phenotypic evolution.

evolutionary biology↗

bioRxiv2021

Quantifying asymmetry in non-symmetrical morphologies, with an example from Cetacea

1. Three-dimensional measurements of morphology are key to gaining an understanding of a species biology and to answering subsequent questions regarding the processes of ecology (or palaeoecology), function, and evolution. However, the collection of morphometric data is often focused on methods designed to produce data on bilaterally symmetric morphologies which may mischaracterise asymmetric structures. 2. Using 3D landmark and curve data on 3D surface meshes of specimens, we present a method for first quantifying the level of asymmetry in a specimen and second, accurately capturing the morphology of asymmetric specimens for further geometric analyses. 3. We provide an example of the process from initial landmark placement, including details on how to place landmarks to quantify the level of asymmetry, and then on how to use this information to accurately capture the morphology of asymmetric morphologies or structures. We use toothed whales (odontocetes) as a case study and include examples of the consequences of mirroring landmarks and curves, a method commonly used in bilaterally symmetrical specimens, on asymmetric specimens. 4. We conclude by presenting a step-by-step method to collecting 3D landmark data on asymmetric specimens. Additionally, we provide code for placing landmarks and curves on asymmetric specimens in a manner designed to both save time and ultimately accurately quantify morphology. This method can be used as a first crucial step in morphometric analyses of any biological specimens by assessing levels of asymmetry and then if required, accurately quantifying this asymmetry. The latter not only saves the researcher time, but also accurately represents the morphology of asymmetric structures.

ecology↗