Unveiling underestimated species diversity within the Central American Coralsnake, a medically important complex of venomous taxa.

Coralsnakes of the genus Micrurus are a diverse group of venomous snakes ranging from the southern United States to southern South America. Much uncertainty remains over the genus diversity, and understanding Micrurus systematics is of medical importance. In particular, the widespread Micrurus nigrocinctus spans from Mexico throughout Central America and into Colombia, with a number of described subspecies. This study provides new insights into the phylogenetic relationships within M. nigrocinctus by examining sequence data from a broad sampling of specimens from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama. The recovered phylogenetic relationships suggest that M. nigrocinctus is a species complex originating in the Pliocene and composed of at least three distinct species-level lineages. In addition, recovery of highly divergent clades supports the elevation of some currently recognized subspecies to the full species rank while others may require synonymization.

Atypical life cycle does not lead to inbreeding or selfing in parasites despite clonemate accumulation in intermediate hosts.

Many parasites utilize asexual and sexual reproduction and multiple hosts to complete their life cycles. How these taxa avoid inbreeding is an essential question for understanding parasite evolution and ecology. Aquatic trematodes that require multiple host species may benefit from diverse genetic parasite assemblages accumulating within second intermediate hosts prior to sexual reproduction in definitive hosts. However, Cotylurus species are able to utilize the same snail species as first and second intermediate hosts, potentially resulting in the accumulation of genetically identical clones (clonemates) prior to sexual reproduction. In this study, we developed and analysed novel microsatellite loci to determine if clones are accumulating within snail hosts prior to ingestion by bird hosts and the effects this could have on parasite inbreeding. Contrary to previous studies of aquatic trematodes, significantly large numbers of clonemates were present within snails, but full-sibs were not. Genetic structure was present over a relatively small geographical scale despite the use of vagile definitive hosts. Phylogenetic analysis identified the Cotylurus sp. clones as belonging to a single species. Despite the presence of clones within snails, mating between clones/selfing was not common and heterozygosity is maintained within individuals. Potential issues with clones mating may be mitigated by the presence of snails with numerous clones, the consumption of many snails by bird hosts and parasite clone recognition/avoidance. Use of the same host species for multiple life stages may have advantages when parasites are able to avoid inbreeding and the required hosts are common.

Do New World pitvipers "scale-down" at high elevations? Macroecological patterns of scale characters and body size.

Bergmann's rule describes the macroecological pattern of increasing body size in response to higher latitudes and elevations. This pattern is extensively documented in endothermic vertebrates, within and among species; however, studies involving ectotherms are less common and suggest no consistent pattern for amphibians and reptiles. Moreover, adaptive traits, such as epidermal features like scales, have not been widely examined in conjunction with Bergmann's rule, even though these traits affect physiological processes, such as thermoregulation, which are hypothesized as underlying mechanisms for the pattern. Here, we investigate how scale characters correlate with elevation among 122 New World pitviper species, representing 15 genera. We found a contra-Bergmann's pattern, where body size is smaller at higher elevations. This pattern was mainly driven by the presence of small-bodied clades at high elevations and large-bodied clades at low elevations, emphasizing the importance of taxonomic scope in studying macroecological patterns. Within a subset of speciose clades, we found that only Crotalus demonstrated a significant negative relationship between body size and elevation, perhaps because of its wide elevational range. In addition, we found a positive correlation between scale counts and body size but no independent effect of elevation on scale numbers. Our study increases our knowledge of Bergmann's rule in reptiles by specifically examining characters of squamation and suggests a need to reexamine macroecological patterns for this group.

A revised molecular phylogeny reveals polyphyly in Schistura (Teleostei: Cypriniformes: Nemacheilidae).

There is a general consensus that the genus Schistura (Nemacheilidae), currently with 241 species, is not monophyletic. However, weak morphological synapomorphies and a lack of genetic data for most species of Schistura and their presumptive relatives have prevented meaningful diagnoses of species groups within this genus. To aid in deciphering evolutionary relationships, sequence data from two mitochondrial genes (cytochrome b and D-loop) were implemented in phylogenetic analyses for species of Schistura and other nemacheilids for which data from earlier studies and recently collected material were available. This analysis of 67 nemacheilid species, including 28 species of Schistura, provides the most comprehensive phylogeny of Nemacheilidae to date. In the phylogenetic tree for the combined data set, species of Schistura clustered in three clades. One clade contained 14 species of Schistura and Sectoria heterognathos and was sister to Homatula. A second clade of 11 species of Schistura was in a larger clade with Turcinoemacheilus kosswigi and Nemacheilus corica. The third clade contained three species, all from the Mae Khlong basin of Thailand. Taxonomic implications of these results are discussed; however, a more taxon-rich dataset and nuclear sequence data are needed before making taxonomic changes.

Hiding in the lianas of the tree of life: Molecular phylogenetics and species delimitation reveal considerable cryptic diversity of New World Vine Snakes.

The Brown Vine Snake, Oxybelis aeneus, is considered a single species despite the fact its distribution covers an estimated 10% of the Earth's land surface, inhabiting a variety of ecosystems throughout North, Central, and South America and is distributed across numerous biogeographic barriers. Here we assemble a multilocus molecular dataset (i.e. cyt b, ND4, cmos, PRLR) derived from Middle American populations to examine for the first time the evolutionary history of Oxybelis and test for evidence of cryptic lineages using Bayesian and maximum likelihood criteria. Our divergence time estimates suggest that Oxybelis diverged from its sister genus, Leptophis, approximately 20.5 million years ago (Ma) during the lower-Miocene. Additionally, our phylogenetic and species delimitation results suggest O. aeneus is likely a complex of species showing relatively deep species-level divergences initiated during the Pliocene. Finally, ancestral area reconstructions suggest a Central American origin and subsequent expansion into North and South America.

Multilocus phylogeny of the Asian Lance-headed pitvipers (Squamata, Viperidae, Protobothrops).

Despite the public health significance and potential applications to medical research, the evolutionary history of the Asian Lance-headed pitvipers (genus Protobothrops) remains inadequately studied. Previous research generally focused on a few selected species with no comprehensive molecular study of Protobothrops. Here, we conduct the first study to infer the phylogenetic relationships of all currently recognized species in this genus based on four mitochondrial DNA fragments and four nuclear genes. Bayesian Inference and Maximum Likelihood analyses show that within Protobothrops there are four strongly supported clades forming distinct subgroups. The first subgroup, which is sister to the other three, consists of three species, P. himalayanus, P. kaulbacki, and P. sieversorum. The second subgroup contains only P. mangshanensis. The final two subgroups, which are sister groups, include the other four and six Protobothrops species. Although our findings provide additional information on the phylogenetic relationships of the genus Protobothrops, the placement of P. dabieshanensis and P. elegans remains problematic. In addition, our molecular results indicate that P. trungkhanhensis, currently considered endemic to Vietnam, should be added to the species known from China. Our ancestral area estimation indicated that Protobothrops likely originated in southwestern China. This study improves our understanding of the evolutionary relationships among species of Asian Lance-headed pitvipers, providing a greater framework for future studies.

It's a predator-eat-parasite world: how characteristics of predator, parasite and environment affect consumption.

Understanding the effects of predation on disease dynamics is increasingly important in light of the role ecological communities can play in host-parasite interactions. Surprisingly, however, few studies have characterized direct predation of parasites. Here we used an experimental approach to show that consumption of free-living parasite stages is highly context dependent, with significant influences of parasite size, predator size and foraging mode, as well as environmental condition. Among the four species of larval trematodes and two types of predators (fish and larval damselflies) studied here, parasites with larger infective stages (size >1,000 µm) were most vulnerable to predation by fish, while small-bodied fish and damselflies (size <10 mm) consumed the most infectious stages. Small parasite species (size approx. 500 µm) were less frequently consumed by both fish and larval damselflies. However, these results depended strongly on light availability; trials conducted in the dark led to significantly fewer parasites consumed overall, especially those with a size of <1,000 µm, emphasizing the importance of circadian shedding times of parasite free-living stages for predation risk. Intriguingly, active predation functioned to help limit fishes' infection by directly penetrating parasite species. Our results are consistent with established theory developed for predation on zooplankton that emphasizes the roles of body size, visibility and predation modes and further suggest that consumer-resource theory may provide a predictive framework for when predators should significantly influence parasite transmission. These results contribute to our understanding of transmission in natural systems, the role of predator-parasite links in food webs and the evolution of parasite morphology and behavior.

A relict lineage and new species of green palm-pitviper (Squamata, Viperidae, Bothriechis) from the Chortís Highlands of Mesoamerica.

A new species of palm-pitviper of the genus Bothriechis is described from Refugio de Vida Silvestre Texíguat in northern Honduras. The new species differs from congeners by having 19 dorsal scale rows at midbody, a bright green dorsal coloration in adults, the prelacunal scale fused to the second supralabial, and in representing a northern lineage that is sister to Bothriechis lateralis, which is distributed in Costa Rica and western Panama and is isolated from the new taxon by the Nicaraguan Depression. This represents the 15th endemic species occurring in Refugio de Vida Silvestre Texíguat, one of the richest herpetofaunal sites in Honduras, itself being the country with the highest degree of herpetofaunal endemism in Central America. We name this new species in honor of a Honduran conservationist slain in fighting against illegal logging, highlighting the sacrifices of rural activists in battling these issues and the critical importance of conservation in these areas.

ResumenUna nueva especie de tamagás verde del género Bothriechis se describe del Refugio de Vida Silvestre Texíguat en el norte de Honduras. La nueva especie difiere de sus congéneres por tener filas de 19 escamas dorsales en la mitad del cuerpo, una brillante coloración verde en la porción dorsal del cuerpo en adultos, la escama prelacunal fusionada con la segunda supralabial, y en representación del linaje del norte que es clado hermano de Bothriechis lateralis, la cual se distribuye en Costa Rica y el Occidente de Panamá y está aislada del nuevo taxón por la Depresión de Nicaragua. Representa la decimoquinta especie endémica encontrada en el Refugio de Vida Silvestre Texíguat, uno de los lugares más ricos de herpetofauna en Honduras, el país con el más alto grado de endemismo de la herpetofauna en Centroamérica. Nombramos esta nueva especie en honor a un conservacionista Hondureño asesinado en contienda contra la tala ilegal, destacando los sacrificios de los activistas rurales luchando frente a estos problemas y la importancia crítica de la conservación en estas áreas.

Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians.

While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. Here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (Ribeiroia ondatrae) infection in a focal amphibian host (Pseudacris regilla). In short-term predation bioassays involving mollusks, zooplankton, fish, larval insects, or newts, four of seven tested species removed 62-93% of infectious stages. In transmission experiments, damselfly nymphs (predators) and newt larvae (alternative hosts) reduced infection in P. regilla tadpoles by -50%, whereas mosquitofish (potential predators and alternative hosts) did not significantly influence transmission. Additional bioassays indicated that predators consumed parasites even in the presence of alternative prey. In natural wetlands, newts had similar infection intensities as P. regilla, suggesting that they commonly function as alternative hosts despite their unpalatability to downstream hosts, whereas mosquitofish had substantially lower infection intensities and are unlikely to function as hosts. These results underscore the importance of studying host-parasite interactions in complex communities and of broadly linking research on predation, biodiversity loss, and infectious diseases.