20 research outputs found
RPANDA: an R package for macroevolutionary analyses on phylogenetic trees
A number of approaches for studying macroevolution using phylogenetic trees have been developed in the last few years. Here, we present RPANDA, an R package that implements model‐free and model‐based phylogenetic comparative methods for macroevolutionary analyses. The model‐free approaches implemented in RPANDA are recently developed approaches stemming from graph theory that allow summarizing the information contained in phylogenetic trees, computing distances between trees, and clustering them accordingly. They also allow identifying distinct branching patterns within single trees. RPANDA also implements likelihood‐based models for fitting various diversification models to phylogenetic trees. It includes birth–death models with i) constant, ii) time‐dependent and iii) environmental‐dependent speciation and extinction rates. It also includes models with equilibrium diversity derived from the coalescent process, as well as a likelihood‐based inference framework to fit the individual‐based model of Speciation by Genetic Differentiation, which is an extension of Hubbell's neutral theory of biodiversity. RPANDA can be used to (i) characterize trees by plotting their spectral density profiles (ii) compare trees and cluster them according to their similarities, (iii) identify and plot distinct branching patterns within trees, (iv) compare the fit of alternative diversification models to phylogenetic trees, (v) estimate rates of speciation and extinction, (vi) estimate and plot how these rates have varied with time and environmental variables and (vii) deduce and plot estimates of species richness through geological time. RPANDA provides investigators with a set of tools for exploring patterns in phylogenetic trees and fitting various models to these trees, thereby contributing to the ongoing development of phylogenetics in the life sciences
Amazonia is the primary source of Neotropical biodiversity.
The American tropics (the Neotropics) are the most species-rich realm on Earth, and for centuries, scientists have attempted to understand the origins and evolution of their biodiversity. It is now clear that different regions and taxonomic groups have responded differently to geological and climatic changes. However, we still lack a basic understanding of how Neotropical biodiversity was assembled over evolutionary timescales. Here we infer the timing and origin of the living biota in all major Neotropical regions by performing a cross-taxonomic biogeographic analysis based on 4,450 species from six major clades across the tree of life (angiosperms, birds, ferns, frogs, mammals, and squamates), and integrate >1.3 million species occurrences with large-scale phylogenies. We report an unprecedented level of biotic interchange among all Neotropical regions, totaling 4,525 dispersal events. About half of these events involved transitions between major environmental types, with a predominant directionality from forested to open biomes. For all taxonomic groups surveyed here, Amazonia is the primary source of Neotropical diversity, providing >2,800 lineages to other regions. Most of these dispersal events were to Mesoamerica (∼1,500 lineages), followed by dispersals into open regions of northern South America and the Cerrado and Chaco biomes. Biotic interchange has taken place for >60 million years and generally increased toward the present. The total amount of time lineages spend in a region appears to be the strongest predictor of migration events. These results demonstrate the complex origin of tropical ecosystems and the key role of biotic interchange for the assembly of regional biotas
Toward a Self-Updating Platform for Estimating Rates of Speciation and Migration, Ages, and Relationships of Taxa.
Rapidly growing biological data-including molecular sequences and fossils-hold an unprecedented potential to reveal how evolutionary processes generate and maintain biodiversity. However, researchers often have to develop their own idiosyncratic workflows to integrate and analyze these data for reconstructing time-calibrated phylogenies. In addition, divergence times estimated under different methods and assumptions, and based on data of various quality and reliability, should not be combined without proper correction. Here we introduce a modular framework termed SUPERSMART (Self-Updating Platform for Estimating Rates of Speciation and Migration, Ages, and Relationships of Taxa), and provide a proof of concept for dealing with the moving targets of evolutionary and biogeographical research. This framework assembles comprehensive data sets of molecular and fossil data for any taxa and infers dated phylogenies using robust species tree methods, also allowing for the inclusion of genomic data produced through next-generation sequencing techniques. We exemplify the application of our method by presenting phylogenetic and dating analyses for the mammal order Primates and for the plant family Arecaceae (palms). We believe that this framework will provide a valuable tool for a wide range of hypothesis-driven research questions in systematics, biogeography, and evolution. SUPERSMART will also accelerate the inference of a "Dated Tree of Life" where all node ages are directly comparable. [Bayesian phylogenetics; data mining; divide-and-conquer methods; GenBank; multilocus multispecies coalescent; next-generation sequencing; palms; primates; tree calibration.]
Dispersal is a major driver of the latitudinal diversity gradient of Carnivora
AimUnderstanding the relative contribution of diversification rates (speciation and extinction) and dispersal in the formation of the latitudinal diversity gradient - the decrease in species richness with increasing latitude - is a main goal of biogeography. The mammalian order Carnivora, which comprises 286 species, displays the traditional latitudinal diversity gradient seen in almost all mammalian orders. Yet the processes driving high species richness in the tropics may be fundamentally different in this group from that in other mammalian groups. Indeed, a recent study suggested that in Carnivora, unlike in all other major mammalian orders, net diversification rates are not higher in the tropics than in temperate regions. Our goal was thus to understand the reasons why there are more species of Carnivora in the tropics.
LocationWorld-wide.
MethodsWe reconstructed the biogeographical history of Carnivora using a time-calibrated phylogeny of the clade comprising all terrestrial species and dispersal-extinction-cladogenesis models. We also analysed a fossil dataset of carnivoran genera to examine how the latitudinal distribution of Carnivora varied through time.
ResultsOur biogeographical analyses suggest that Carnivora originated in the East Palaearctic (i.e. Central Asia, China) in the early Palaeogene. Multiple independent lineages dispersed to low latitudes following three main paths: toward Africa, toward India/Southeast Asia and toward South America via the Bering Strait. These dispersal events were probably associated with local extinctions at high latitudes. Fossil data corroborate a high-latitude origin of the group, followed by late dispersal events toward lower latitudes in the Neogene.
Main conclusionsUnlike most other mammalian orders, which originated and diversified at low latitudes and dispersed out of the tropics', Carnivora originated at high latitudes, and subsequently dispersed southward. Our study provides an example of combining phylogenetic and fossil data to understand the generation and maintenance of global-scale geographical variations in species richness
Teasing Apart Mountain Uplift, Climate Change and Biotic Drivers of Species Diversification
International audienceIdentifying the causes of species diversification and extinction remains a major challenge. Such biodiversity dynamics can be influenced by two major classes of factors: (i) biotic (intrinsic to the species, such as biological traits or species interactions), as in the Red Queen scenario; and (ii) abiotic (extrinsic to the species, such as climatic and geological events), as in the Court Jester scenario. Both classes are likely at play in most montane systems, where the interaction between mountain building and climate change may generate species diversity in a variety of ways; for example, via increased environmental heterogeneity, the generation of local habitats, the immigration of species or the formation of island-like ecological opportunities. Teasing apart the relative contributions of abiotic and biotic processes is challenging, because both may occur simultaneously and interact with each other, and a statistical framework that enables the separation of their relative contributions is still lacking. Here, we review the origin and evolution of biodiversity within a unified phylogenetic framework that explicitly disentangles the influences of mountain orogeny, climate change and ecological interactions. Relying on recently developed birth-death models, we build a model-testing approach that compares various diversification scenarios. Our approach includes a series of biologically realistic models to estimate speciation and extinction rates using a phylogeny, while assessing the relationship between diversification in the focal clade with an environmental variable, with growing species diversity within the focal clade or with the diversity of interacting clades. We illustrate the usefulness of this approach on two clades of Andean hummingbirds. We find that hummingbird speciation is positively correlated with temperature throughout their history. In contrast, speciation is negatively correlated with paleo-elevation, indicating that hummingbirds diversified faster in the early stages of the Andean orogeny. The analytical framework and empirical examples presented here demonstrate the power of combining phylogenetic and Earth-science models to untangle the complex interplay of geology, climate and ecology in generating biodiversity
Testing the Role of the Red Queen and Court Jester as Drivers of the Macroevolution of Apollo Butterflies.
In macroevolution, the Red Queen (RQ) model posits that biodiversity dynamics depend mainly on species-intrinsic biotic factors such as interactions among species or life-history traits, while the Court Jester (CJ) model states that extrinsic environmental abiotic factors have a stronger role. Until recently, a lack of relevant methodological approaches has prevented the unraveling of contributions from these 2 types of factors to the evolutionary history of a lineage. Herein, we take advantage of the rapid development of new macroevolution models that tie diversification rates to changes in paleoenvironmental (extrinsic) and/or biotic (intrinsic) factors. We inferred a robust and fully-sampled species-level phylogeny, as well as divergence times and ancestral geographic ranges, and related these to the radiation of Apollo butterflies (Parnassiinae) using both extant (molecular) and extinct (fossil/morphological) evidence. We tested whether their diversification dynamics are better explained by an RQ or CJ hypothesis, by assessing whether speciation and extinction were mediated by diversity-dependence (niche filling) and clade-dependent host-plant association (RQ) or by large-scale continuous changes in extrinsic factors such as climate or geology (CJ). For the RQ hypothesis, we found significant differences in speciation rates associated with different host-plants but detected no sign of diversity-dependence. For CJ, the role of Himalayan-Tibetan building was substantial for biogeography but not a driver of high speciation, while positive dependence between warm climate and speciation/extinction was supported by continuously varying maximum-likelihood models. We find that rather than a single factor, the joint effect of multiple factors (biogeography, species traits, environmental drivers, and mass extinction) is responsible for current diversity patterns and that the same factor might act differently across clades, emphasizing the notion of opportunity. This study confirms the importance of the confluence of several factors rather than single explanations in modeling diversification within lineages
The role of the Neotropics as a source of world tetrapod biodiversity
Aim: The Neotropics currently host outstanding levels of species richness, with one-third of the global tetrapod species. The underlying causes of these extraordinary levels of biodiversity are a topic debated in evolutionary ecology, but the main processes at work remain elusive. Location: Neotropics. Time period: Cenozoic and Mesozoic. Major taxa studied: Tetrapods. Methods: Using global phylogenies for amphibians, birds, lepidosaurs and mammals, biogeographical and time-variable (trait-dependent and trait-independent) diversification models, we examined changes in speciation and extinction rates through time in the Neotropics in relationship to other areas of the world, and estimated the time of Neotropical colonizations. Results: We found that from the origin of lepidosaurs and mammals until the Pliocene (the Miocene for birds), diversification rates within the Neotropics were lower than rates in other regions (i.e., turnover was high). Afterwards, extinction decreased relative to speciation, and Neotropical diversification outpaced diversification in other regions. Dispersal out of the Neotropics also increased after the Pliocene (the Miocene for birds), exceeding into-the-Neotropics migrations. For amphibians, diversification rates in the Neotropics have been higher than in other areas through time, and dispersal out of the Neotropics decreased in the Cenozoic. Main conclusions: The common view that the Neotropics are an ancient source of world species diversity, with high in situ speciation, dispersal to other areas and low extinction, might be true only for amphibians. For mammals, birds and lepidosaurs, the Neotropics acted as a diversity sink from their origin until the Miocene–Pliocene (i.e., diversification rates were lower and turnover higher than in other areas). Only afterwards did the region turn into a diversity source. Our study highlights that models accounting for rates of diversification that vary through time could improve our capacity to assess evolutionary dynamics over long time-scales
A global phylogeny of butterflies reveals their evolutionary history, ancestral hosts and biogeographic origins
Butterflies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfly larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfly species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterflies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfly tribes require reclassification. Divergence time analyses imply an origin ~100 million years ago for butterflies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterflies are likely to have first fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterflies crossed Beringia and diversified in the Palaeotropics. Our results also reveal that most butterfly species are specialists that feed on only one larval host plant family. However, generalist butterflies that consume two or more plant families usually feed on closely related plants. © 2023, The Author(s)