Chiropterans Are a Hotspot for Horizontal Transfer of DNA Transposons in Mammalia.

Horizontal transfer of transposable elements (TEs) is an important mechanism contributing to genetic diversity and innovation. Bats (order Chiroptera) have repeatedly been shown to experience horizontal transfer of TEs at what appears to be a high rate compared with other mammals. We investigated the occurrence of horizontally transferred (HT) DNA transposons involving bats. We found over 200 putative HT elements within bats; 16 transposons were shared across distantly related mammalian clades, and 2 other elements were shared with a fish and two lizard species. Our results indicate that bats are a hotspot for horizontal transfer of DNA transposons. These events broadly coincide with the diversification of several bat clades, supporting the hypothesis that DNA transposon invasions have contributed to genetic diversification of bats.

Morphology and niche evolution influence hummingbird speciation rates.

How traits affect speciation is a long-standing question in evolution. We investigate whether speciation rates are affected by the traits themselves or by the rates of their evolution, in hummingbirds, a clade with great variation in speciation rates, morphology and ecological niches. Further, we test two opposing hypotheses, postulating that speciation rates are promoted by trait conservatism or, alternatively, by trait divergence. To address these questions, we analyse morphological (body mass and bill length) and niche traits (temperature and precipitation position and breadth, and mid-elevation), using a variety of methods to estimate speciation rates and correlate them with traits and their evolutionary rates. When it comes to the traits, we find faster speciation in smaller hummingbirds with shorter bills, living at higher elevations and experiencing greater temperature ranges. As for the trait evolutionary rates, we find that speciation increases with rates of divergence in the niche traits, but not in the morphological traits. Together, these results reveal the interplay of mechanisms through which different traits and their evolutionary rates (conservatism or divergence) influence the origination of hummingbird diversity.

Parthenogenesis is self-destructive for scaled reptiles.

Parthenogenesis is rare in nature. With 39 described true parthenogens, scaled reptiles (Squamata) are the only vertebrates that evolved this reproductive strategy. Parthenogenesis is ecologically advantageous in the short term, but the young age and rarity of parthenogenetic species indicate it is less advantageous in the long term. This suggests parthenogenesis is self-destructive: it arises often but is lost due to increased extinction rates, high rates of reversal or both. However, this role of parthenogenesis as a self-destructive trait remains unknown. We used a phylogeny of Squamata (5388 species), tree metrics, null simulations and macroevolutionary scenarios of trait diversification to address the factors that best explain the rarity of parthenogenetic species. We show that parthenogenesis can be considered as self-destructive, with high extinction rates mainly responsible for its rarity in nature. Since these parthenogenetic species occur, this trait should be ecologically relevant in the short term.

Updated distribution maps for neotropical bats in the superfamily Noctilionoidea.

The IUCN provides a spatial database for many species, including terrestrial mammals. This database includes shapefiles with taxonomic information and the extent of occurrence for each species, and has been used in hundreds of studies in ecology, biogeography and conservation. Here we provide updated distribution maps that comprise the extent of occurrence of the neotropical bat species in the superfamily Noctilionoidea (Mammalia: Chiroptera) after a thorough research of new records published between January 2008 and March 2018. The main motivation for this update was the inclusion of spatial and climatic variables in explaining the ecological and taxonomic diversity of noctilionoid bats. The core of the superfamily (246 species distributed in five families out of 250 species) occurs in the Neotropics and shows ecological diversity unparalleled among mammals. This clade also shows the only evolutionary shift towards higher speciation rates within the order Chiroptera. Updating the range maps for these bats resulted in the modification of maps of 94 species, and the creation of new maps for 37 species missing from the IUCN database. From the 94 modified maps, 55 species increased their latitudinal range and 38 increased their longitudinal range. These modifications did not change the overall extent of occurrence of the clade. Altogether, modified and new maps represent 53% of Noctilionoidea. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.

Eating down the food chain: generalism is not an evolutionary dead end for herbivores.

The role of trophic specialisation in taxonomic diversification remains unclear. Plant specialists diversify faster than omnivores and animalivores, but at shorter macroevolutionary scales this pattern sometimes reverses. Here, we estimate the effect of diet diversification on speciation rates in noctilionoid bats, controlling for tree shape, rate heterogeneity and macroevolutionary regimes. We hypothesise that niche subdivision among herbivores positively relates to speciation rates, differing between macroevolutionary regimes. We found the rate at which new herbivorous lineages originate decreases as rates of diet evolution increase. Herbivores experience higher speciation rates, but generalist herbivores and predominantly herbivorous omnivores speciate faster than specialised herbivores, omnivores and animalivores. Generalised herbivory is not a dead end. We show that analysing ecological traits and diversification requires accounting for macroevolutionary regimes and within- and between-clade variation in evolutionary rates. Our approach overcomes the high false-positive rates of other methods and illuminates the roles of herbivory and specialisation in speciation.

Associations between sex-organ deployment and morph bias in related heterostylous taxa with different stylar polymorphisms.

PREMISE OF THE STUDY: Populations of heterostylous species are characterized by two or three floral morphs with reciprocal positioning of stigmas and anthers. Theoretical models predict equal morph frequencies (isoplethy) when disassortative mating is prevalent in populations, but biased morph ratios may occur when variation in the expression of heterostyly causes deviations from intermorph mating. METHODS: We explore the role of sex-organ deployment in governing morph ratios in two closely related genera of Boraginaceae, exhibiting striking variation in floral traits associated with the heterostylous syndrome. We sampled 66 populations of six species of Glandora and 39 populations of three species of Lithodora across their distributional range in the Mediterranean. In each population we estimated morph ratios and measured several floral traits. We used phylogenetically corrected and noncorrected regressions to test the hypothesis that differences in sex-organ reciprocity and herkogamy are associated with deviations from isoplethy. KEY RESULTS: Biased morph ratios occurred in 24% of populations, particularly in Lithodora. Populations biased for the long-styled morph (L-morph) were more frequent than the short-styled morph (S-morph). Distylous species were less likely to exhibit biased ratios than species with stigma-height dimorphism. In Lithodora fruticosa, a species lacking reciprocity, decreased herkogamy in the S-morph was associated with increasing L-morph bias, perhaps resulting from self-interference. CONCLUSION: Striking variation in the expression of heterostyly in Glandora and Lithodora is associated with biased morph ratios, which probably result from pollinator-mediated mating asymmetries within populations.

Bats (Chiroptera: Noctilionoidea) Challenge a Recent Origin of Extant Neotropical Diversity.

The mechanisms underlying the high extant biodiversity in the Neotropics have been controversial since the 19th century. Support for the influence of period-specific changes on diversification often rests on detecting more speciation events during a particular period. The timing of speciation events may reflect the influence of incomplete taxon sampling, protracted speciation, and null processes of lineage accumulation. Here we assess the influence of these factors on the timing of speciation with new multilocus data for New World noctilionoid bats (Chiroptera: Noctilionoidea). Biogeographic analyses revealed the importance of the Neotropics in noctilionoid diversification, and the critical role of dispersal. We detected no shift in speciation rate associated with the Quaternary or pre-Quaternary periods, and instead found an increase in speciation linked to the evolution of the subfamily Stenodermatinae (∼18 Ma). Simulations modeling constant speciation and extinction rates for the phylogeny systematically showed more speciation events in the Quaternary. Since recording more divergence events in the Quaternary can result from lineage accumulation, the age of extant sister species cannot be interpreted as supporting higher speciation rates during this period. Instead, analyzing the factors that influence speciation requires modeling lineage-specific traits and environmental, spatial, and ecological drivers of speciation.

Bayesian hierarchical models suggest oldest known plant-visiting bat was omnivorous.

The earliest record of plant visiting in bats dates to the Middle Miocene of La Venta, the world's most diverse tropical palaeocommunity. Palynephyllum antimaster is known from molars that indicate nectarivory. Skull length, an important indicator of key traits such as body size, bite force and trophic specialization, remains unknown. We developed Bayesian models to infer skull length based on dental measurements. These models account for variation within and between species, variation between clades, and phylogenetic error structure. Models relating skull length to trophic level for nectarivorous bats were then used to infer the diet of the fossil. The skull length estimate for Palynephyllum places it among the larger lonchophylline bats. The inferred diet suggests Palynephyllum fed on nectar and insects, similar to its living relatives. Omnivory has persisted since the mid-Miocene. This is the first study to corroborate with fossil data that highly specialized nectarivory in bats requires an omnivorous transition.

When did plants become important to leaf-nosed bats? Diversification of feeding habits in the family Phyllostomidae.

A great proportion of bats of the New World family Phyllostomidae feed on fruit, nectar and pollen, and many of them present adaptations to feed also on insects and small vertebrates. So far, attempts to examine the diversification of feeding specialization in this group, and particularly the evolution of nectarivory and frugivory, have provided contradictory results. Here we propose a molecular phylogenetic hypothesis for phyllostomids. On the basis of a matrix of feeding habits that takes into account geographical and seasonal variation, we tested different hypotheses of the evolution of feeding specializations in the group. We find strong support for the evolutionary model of a direct dietary diversification from insectivory. The estimates of divergence times of phyllostomid bats and the reconstruction of ancestral states with a Bayesian approach support the parallel evolution of frugivory in five lineages and of nectarivory in three lineages during the Miocene. On the basis of these findings, and recent dietary studies, we propose that during the evolution of phyllostomids switches to new feeding mechanisms to access to abundant and/or underexploited resources provided selective advantages that favoured the appearance of ecological innovations independently in different lineages of the family. We did not find evidences to support or reject the hypothesis that the insectivorous most recent common ancestor of all phyllostomids was also phytophagous.