Nonequilibrium dynamics and non-neutral processes, such as trait-dependent dispersal, are often missing from quantitative island biogeography models despite their potential explanatory value. One of the most influential nonequilibrium models is the taxon cycle, but it has been difficult to test its validity as a general biogeographical framework. Here, we test predictions of the taxon cycle model using six expected phylogenetic patterns and a time-calibrated phylogeny of Indo-Pacific Odontomachus (Hymenoptera: Formicidae: Ponerinae), one of the ant genera that E.O. Wilson used when first proposing the hypothesis. We used model-based inference and a newly developed trait-dependent dispersal model to jointly estimate ancestral biogeography, ecology (habitat preferences for forest interiors, vs. "marginal" habitats, such as savannahs, shorelines, disturbed areas) and the linkage between ecology and dispersal rates. We found strong evidence that habitat shifts from forest interior to open and disturbed habitats increased macroevolutionary dispersal rate. In addition, lineages occupying open and disturbed habitats can give rise to both island endemics re-occupying only forest interiors and taxa that re-expand geographical ranges. The phylogenetic predictions outlined in this study can be used in future work to evaluate the relative weights of neutral (e.g., geographical distance and area) and non-neutral (e.g., trait-dependent dispersal) processes in historical biogeography and community ecology.
Regional species diversity is explained ultimately by speciation, extinction and dispersal. Here, we estimate dispersal and speciation rates of Neotropical butterflies to propose an explanation for the distribution and diversity of extant species. We focused on the tribe Brassolini (owl butterflies and allies), a Neotropical group that comprises 17 genera and 108 species, most of them endemic to rainforest biomes. We inferred a robust species tree using the multispecies coalescent framework and a dataset including molecular and morphological characters. This formed the basis for three changes in Brassolini classification: (1) Naropina syn. nov. is subsumed within Brassolina; (2) Aponarope syn. nov. is subsumed within Narope; and (3) Selenophanes orgetorix comb. nov. is reassigned from Catoblepia to Selenophanes. By applying biogeographical stochastic mapping, we found contrasting species diversification and dispersal dynamics across rainforest biomes, which might be explained, in part, by the geological and environmental history of each bioregion. Our results revealed a mosaic of biome-specific evolutionary histories within the Neotropics, where butterfly species have diversified rapidly (cradles: Mesoamerica), have accumulated gradually (museums: Atlantic Forest) or have diversified and accumulated alternately (Amazonia). Our study contributes evidence from a major butterfly lineage that the Neotropics are a museum and a cradle of species diversity.
26PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3074v1 | CC BY 4.0 Open Access | rec: 6 Jul 2017, publ: 6 Jul 2017 Abstract: The outstanding biodiversity found in the American tropics (the Neotropics) has attracted the 45 attention of naturalists for centuries. Despite major advances in the generation of biodiversity data, many 46 questions remain to be answered. In this review, we first summarize some of the knowns and unknowns 47 about Neotropical biodiversity, and discuss how human impact may have drastically affected some of the 48 patterns observed today. We then link biodiversity to landscape, and outline major advances in 49 biogeographical research. In particular, we argue that it is crucial to test the effect of landscape and 50 climatic evolution to biotic diversification and distribution in order to achieve a comprehensive 51 understanding of current patterns. In this context, it is also important to consider extant and extinct taxa, 52 as well as to use probabilistic and parametric methods that explicitly include landscape evolution models.
The latitudinal diversity gradient (LDG) is arguably one of the most striking patterns in nature. The global increase in species richness toward the tropics across continents and taxonomic groups stimulated the formulation of many hypotheses to explain the underlying mechanisms of this pattern. We evaluated several of these hypotheses to explain spatial diversity patterns in the butterfly family, Nymphalidae, by assessing the contributions of speciation, extinction, and dispersal to the LDG, and also the extent to which these processes differ among regions at the same latitude. We generated a new, time-calibrated phylogeny of Nymphalidae based on 10 gene fragments and containing ca. 2,800 species (∼45% of extant diversity). Neither speciation nor extinction rate variations consistently explain the LDG among regions because temporal diversification dynamics differ greatly across longitude. For example, we found that Neotropical nymphalid diversity results from low extinction rates, not high speciation rates, and that biotic interchanges with other regions were rare. Southeast Asia was also characterized by a low speciation rate but, unlike the Neotropics, was the main source of dispersal events through time. Our results suggest that global climate change throughout the Cenozoic, particularly during the Eocene-Oligocene transition, combined with the conserved ancestral tropical niches, played a major role in generating the modern LDG of butterflies.
Species delimitation is at the core of biological sciences. During the last decade, molecular‐based approaches have advanced the field by providing additional sources of evidence to classical, morphology‐based taxonomy. However, taxonomy has not yet fully embraced molecular species delimitation beyond threshold‐based, single‐gene approaches, and taxonomic knowledge is not commonly integrated into multilocus species delimitation models. Here we aim to bridge empirical data (taxonomic and genetic) with recently developed coalescent‐based species delimitation approaches. We use the multispecies coalescent model as implemented in two Bayesian methods (dissect/stacey and bp&p) to infer species hypotheses. In both cases, we account for phylogenetic uncertainty (by not using any guide tree) and taxonomic uncertainty (by measuring the impact of using a priori taxonomic assignments to specimens). We focus on an entire Neotropical tribe of butterflies, the Haeterini (Nymphalidae: Satyrinae). We contrast divergent taxonomic opinion – splitting, lumping and misclassifying species – in the light of different phenotypic classifications proposed to date. Our results provide a solid background for the recognition of 22 species. The synergistic approach presented here overcomes limitations in both traditional taxonomy (e.g. by recognizing cryptic species) and molecular‐based methods (e.g. by recognizing structured populations, and not raising them to species). Our framework provides a step forward towards standardization and increasing reproducibility of species delimitations.
Natural history museums are unique spaces for interdisciplinary research and for educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they provide a place-based window to focus on integration of science and discovery, as well as a locus for community engagement. At the same time, like a synthesis radio telescope, when joined together through emerging digital resources, the global community of museums (the ‘Global Museum’) is more than the sum of its parts, allowing insights and answers to diverse biological, environmental, and societal questions at the global scale, across eons of time, and spanning vast diversity across the Tree of Life. We argue that, whereas natural history collections and museums began with a focus on describing the diversity and peculiarities of species on Earth, they are now increasingly leveraged in new ways that significantly expand their impact and relevance. These new directions include the possibility to ask new, often interdisciplinary questions in basic and applied science; inform biomimetic design; and even provide solutions to climate change, global health and food security challenges. As institutions, they are incubators for cutting-edge research in biology and simultaneously protect core infrastructure for present and future societal needs. In this perspective, we discuss challenges to the realization of the full potential of natural history collections and museums to serve society. After reviewing collections and types of museums, including local and global efforts, we discuss the value of specimens and the importance of observations. We then focus on mapping and modelling of museum data (including place-based approaches and discovery), and explore the main projects, platforms and databases enabling this. We also explore ways in which improved infrastructure will allow higher quality science and increased opportunities for interdisciplinary research and communication, as well as new uses of collections. Finally, we aim to improve relevant protocols for the long-term storage of specimens and tissues, ensuring proper connection with tomorrow’s technologies and hence further increasing the relevance of natural history museums.
Regional species diversity is ultimately explained by speciation, extinction, and dispersal. Here we estimate dispersal and speciation rates in Neotropical rainforest biomes to propose an explanation for the distribution and diversity of extant butterfly species. We focus on the tribe Brassolini (owl butterflies and allies): a Neotropical group that comprises 17 genera and 108 species, most of them endemic to rainforest biomes. We infer a total-evidence species tree using the multispecies coalescent framework. By applying biogeographical stochastic mapping, we infer ancestral ranges and estimate rates of dispersal and cladogenesis at the scale of millions of years. We suggest that speciation in Mesoamerica and the northwestern flank of the Andes have only increased within the past 2 million years. In contrast, speciation in the Brazilian Atlantic Forest has been constant throughout the past 10 million years. The disparate species diversification dynamics may be partly explained by the geological and environmental history of each bioregion. Importantly, the dispersal rates into the Atlantic Forest and Mesoamerica plus NW Andes increased simultaneously in the middle-Miocene, suggesting that lineages from such regions have had comparable times for speciation despite their decoupled diversification dynamics. Diversification of extant Amazonian lineages, on the other hand, has episodically increased since the late Miocene, including a rise in speciation rate during the Pleistocene. Altogether, our results reveal a mosaic of biome-specific evolutionary histories within the Neotropics, where species have diversified rapidly (cradles: e.g., Mesoamerica), have accumulated gradually (museums: e.g., Atlantic Forest), or have alternately diversified and accumulated (e.g., Amazonia).
This paper discusses the systematic position of the rare and endangered satyrine butterfly Caenoptychia boulleti Le Cerf, the only included species in Caenoptychia (type species), based on adult morphology and molecular data. The results showed that Caenoptychia Le Cerf belongs to the Euptychia Hübner clade, and the genus is synonymized with Euptychia, new synonymy. Euptychia boulleti (Le Cerf) is a new combination. The male genitalia of E. boulleti showed at least one important synapomorphy with the other species of Euptychia, which is the presence of a posterior projection of the tegumen above the uncus. Molecular data reinforces the position of Caenoptychia within the genus Euptychia.
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