Folding Stability of Pax9 Intronic G-Quadruplex Correlates with Relative Molar Size in Eutherians.

Eutherian dentition has been the focus of a great deal of studies in the areas of evolution, development, and genomics. The development of molar teeth is regulated by an antero-to-posterior cascade mechanism of activators and inhibitors molecules, where the relative sizes of the second (M2) and third (M3) molars are dependent of the inhibitory influence of the first molar (M1). Higher activator/inhibitor ratios will result in higher M2/M1 or M3/M1. Pax9 has been shown to play a key role in tooth development. We have previously shown that a G-quadruplex in the first intron of Pax9 can modulate the splicing efficiency. Using a sliding window approach with we analyzed the association of the folding energy (Mfe) of the Pax9 first intron with the relative molar sizes in 42 mammalian species, representing 9 orders. The Mfe of two regions located in the first intron of Pax9 were shown to be significantly associated with the M2/M1 and M3/M1 areas and mesiodistal lengths. The first region is located at the intron beginning and can fold into a stable G4 structure, whereas the second is downstream the G4 and 265 bp from intron start. Across species, the first intron of Pax9 varied in G-quadruplex structural stability. The correlations were further increased when the Mfe of the two sequences were added. Our results indicate that this region has a role in the evolution of the mammalian dental pattern by influencing the relative size of the molars.

Little genetic structure in a Bornean endemic small mammal across a steep ecological gradient.

Janzen's influential "mountain passes are higher in the tropics" hypothesis predicts restricted gene flow and genetic isolation among populations spanning elevational gradients in the tropics. Few studies have tested this prediction, and studies that focus on population genetic structure in Southeast Asia are particularly underrepresented in the literature. Here, we test the hypothesis that mountain treeshrews (Tupaia montana) exhibit limited dispersal across their broad elevational range which spans ~2,300 m on two peaks in Kinabalu National Park (KNP) in Borneo: Mt Tambuyukon (MT) and Mt Kinabalu (MK). We sampled 83 individuals across elevations on both peaks and performed population genomics analyses on mitogenomes and single nucleotide polymorphisms from 4,106 ultraconserved element loci. We detected weak genetic structure and infer gene flow both across elevations and between peaks. We found higher genetic differentiation on MT than MK despite its lower elevation and associated environmental variation. This implies that, contrary to our hypothesis, genetic structure in this system is not primarily shaped by elevation. We propose that this pattern may instead be the result of historical processes and limited upslope gene flow on MT. Importantly, our results serve as a foundational estimate of genetic diversity and population structure from which to track potential future effects of climate change on mountain treeshrews in KNP, an important conservation stronghold for the mountain treeshrew and other montane species.

Genome sequence and population declines in the critically endangered greater bamboo lemur (Prolemur simus) and implications for conservation.

BACKGROUND: The greater bamboo lemur (Prolemur simus) is a member of the Family Lemuridae that is unique in their dependency on bamboo as a primary food source. This Critically Endangered species lives in small forest patches in eastern Madagascar, occupying a fraction of its historical range. Here we sequence the genome of the greater bamboo lemur for the first time, and provide genome resources for future studies of this species that can be applied across its distribution. RESULTS: Following whole genome sequencing of five individuals we identified over 152,000 polymorphic single nucleotide variants (SNVs), and evaluated geographic structuring across nearly 19 k SNVs. We characterized a stronger signal associated with a north-south divide than across elevations for our limited samples. We also evaluated the demographic history of this species, and infer a dramatic population crash. This species had the largest effective population size (estimated between ~ 900,000 to one million individuals) between approximately 60,000-90,000 years before present (ybp), during a time in which global climate change affected terrestrial mammals worldwide. We also note the single sample from the northern portion of the extant range had the largest effective population size around 35,000 ybp. CONCLUSIONS: From our whole genome sequencing we recovered an average genomic heterozygosity of 0.0037%, comparable to other lemurs. Our demographic history reconstructions recovered a probable climate-related decline (60-90,000 ybp), followed by a second population decrease following human colonization, which has reduced the species to a census size of approximately 1000 individuals. The historical distribution was likely a vast portion of Madagascar, minimally estimated at 44,259 km2, while the contemporary distribution is only ~ 1700 km2. The decline in effective population size of 89-99.9% corresponded to a vast range retraction. Conservation management of this species is crucial to retain genetic diversity across the remaining isolated populations.

Behaviour and Ecology of Male Aye-Ayes (Daubentonia madagascariensis) in the Kianjavato Classified Forest, South-Eastern Madagascar.

Previous studies found that aye-ayes (Daubentonia madagascariensis) consume a variety of non-invertebrate resources, supporting the hypothesis that aye-ayes are too large-bodied to focus feeding efforts on insects. However, these conclusions were based on introduced populations, with little known about aye-aye behaviour and ecology in its natural habitat. This study investigates activity budgets, diet, and home range/territories of 2 male aye-ayes in the Kianjavato Classified Forest, a disturbed forest in south-eastern Madagascar, from October 2013 to October 2014. We used radiotelemetry and focal-animal sampling methods to collect behavioural data. We recorded GPS coordinates of the focal animal every 20 min, calculating the home range size for each individual. Results showed that male aye-ayes spent most of their time feeding and travelling. Their feeding time primarily focussed on larvae and adult insects from various substrates, and to a lesser extent Canarium spp. seeds. Home range sizes of the 2 males varied between individuals, overlapped greatly, and appeared to be related to the location of females. Our findings indicate that aye-aye behaviours are strongly indicative of insect-centric feeding ecology.

Novel opsin gene variation in large-bodied, diurnal lemurs.

Some primate populations include both trichromatic and dichromatic (red-green colour blind) individuals due to allelic variation at the X-linked opsin locus. This polymorphic trichromacy is well described in day-active New World monkeys. Less is known about colour vision in Malagasy lemurs, but, unlike New World monkeys, only some day-active lemurs are polymorphic, while others are dichromatic. The evolutionary pressures underlying these differences in lemurs are unknown, but aspects of species ecology, including variation in activity pattern, are hypothesized to play a role. Limited data on X-linked opsin variation in lemurs make such hypotheses difficult to evaluate. We provide the first detailed examination of X-linked opsin variation across a lemur clade (Indriidae). We sequenced the X-linked opsin in the most strictly diurnal and largest extant lemur, Indri indri, and nine species of smaller, generally diurnal indriids (Propithecus). Although nocturnal Avahi (sister taxon to Propithecus) lacks a polymorphism, at least eight species of diurnal indriids have two or more X-linked opsin alleles. Four rainforest-living taxa-I. indri and the three largest Propithecus species-have alleles not previously documented in lemurs. Moreover, we identified at least three opsin alleles in Indri with peak spectral sensitivities similar to some New World monkeys.

Phylogenomic Reconstruction of Sportive Lemurs (genus Lepilemur) Recovered from Mitogenomes with Inferences for Madagascar Biogeography.

The family Lepilemuridae includes 26 species of sportive lemurs, most of which were recently described. The cryptic morphological differences confounded taxonomy until recent molecular studies; however, some species' boundaries remain uncertain. To better understand the genus Lepilemur, we analyzed 35 complete mitochondrial genomes representing all recognized 26 sportive lemur taxa and estimated divergence dates. With our dataset we recovered 25 reciprocally monophyletic lineages, as well as an admixed clade containing Lepilemur mittermeieri and Lepilemur dorsalis. Using modern distribution data, an ancestral area reconstruction and an ecological vicariance analysis were performed to trace the history of diversification and to test biogeographic hypotheses. We estimated the initial split between the eastern and western Lepilemur clades to have occurred in the Miocene. Divergence of most species occurred from the Pliocene to the Pleistocene. The biogeographic patterns recovered in this study were better addressed with a combinatorial approach including climate, watersheds, and rivers. Generally, current climate and watershed hypotheses performed better for western and eastern clades, while speciation of northern clades was not adequately supported using the ecological factors incorporated in this study. Thus, multiple mechanisms likely contributed to the speciation and distribution patterns in Lepilemur.

Evolutionary history of endemic Sulawesi squirrels constructed from UCEs and mitogenomes sequenced from museum specimens.

BACKGROUND: The Indonesian island of Sulawesi has a complex geological history. It is composed of several landmasses that have arrived at a near modern configuration only in the past few million years. It is the largest island in the biodiversity hotspot of Wallacea-an area demarcated by the biogeographic breaks between Wallace's and Lydekker's lines. The mammal fauna of Sulawesi is transitional between Asian and Australian faunas. Sulawesi's three genera of squirrels, all endemic (subfamily Nannosciurinae: Hyosciurus, Rubrisciurus and Prosciurillus), are of Asian origin and have evolved a variety of phenotypes that allow a range of ecological niche specializations. Here we present a molecular phylogeny of this radiation using data from museum specimens. High throughput sequencing technology was used to generate whole mitochondrial genomes and a panel of nuclear ultraconserved elements providing a large genome-wide dataset for inferring phylogenetic relationships. RESULTS: Our analysis confirmed monophyly of the Sulawesi taxa with deep divergences between the three endemic genera, which predate the amalgamation of the current island of Sulawesi. This suggests lineages may have evolved in allopatry after crossing Wallace's line. Nuclear and mitochondrial analyses were largely congruent and well supported, except for the placement of Prosciurillus murinus. Mitochondrial analysis revealed paraphyly for Prosciurillus, with P. murinus between or outside of Hyosciurus and Rubrisciurus, separate from other species of Prosciurillus. A deep but monophyletic history for the four included species of Prosciurillus was recovered with the nuclear data. CONCLUSIONS: The divergence of the Sulawesi squirrels from their closest relatives dated to ~9.7-12.5 million years ago (MYA), pushing back the age estimate of this ancient adaptive radiation prior to the formation of the current conformation of Sulawesi. Generic level diversification took place around 9.7 MYA, opening the possibility that the genera represent allopatric lineages that evolved in isolation in an ancient proto-Sulawesian archipelago. We propose that incongruence between phylogenies based on nuclear and mitochondrial sequences may have resulted from biogeographic discordance, when two allopatric lineages come into secondary contact, with complete replacement of the mitochondria in one species.

Genome sequence, population history, and pelage genetics of the endangered African wild dog (Lycaon pictus).

BACKGROUND: The African wild dog (Lycaon pictus) is an endangered African canid threatened by severe habitat fragmentation, human-wildlife conflict, and infectious disease. A highly specialized carnivore, it is distinguished by its social structure, dental morphology, absence of dewclaws, and colorful pelage. RESULTS: We sequenced the genomes of two individuals from populations representing two distinct ecological histories (Laikipia County, Kenya and KwaZulu-Natal Province, South Africa). We reconstructed population demographic histories for the two individuals and scanned the genomes for evidence of selection. CONCLUSIONS: We show that the African wild dog has undergone at least two effective population size reductions in the last 1,000,000 years. We found evidence of Lycaon individual-specific regions of low diversity, suggestive of inbreeding or population-specific selection. Further research is needed to clarify whether these population reductions and low diversity regions are characteristic of the species as a whole. We documented positive selection on the Lycaon mitochondrial genome. Finally, we identified several candidate genes (ASIP, MITF, MLPH, PMEL) that may play a role in the characteristic Lycaon pelage.

Phylogeny, biogeography and systematic revision of plain long-nosed squirrels (genus Dremomys, Nannosciurinae).

The plain long-nosed squirrels, genus Dremomys, are high elevation species in East and Southeast Asia. Here we present a complete molecular phylogeny for the genus based on nuclear and mitochondrial DNA sequences. Concatenated mitochondrial and nuclear gene trees were constructed to determine the tree topology, and date the tree. All speciation events within the plain-long nosed squirrels (genus Dremomys) were ancient (dated to the Pliocene or Miocene), and averaged older than many speciation events in the related Sunda squirrels, genus Sundasciurus. Within the plain long-nosed squirrels, the most recent interspecific split occurred 2.9 million years ago, older than some splits within Sunda squirrels, which dated to the Pleistocene. Our results demonstrate that the plain long-nosed squirrels are not monophyletic. The single species with a distinct distribution, the Bornean mountain ground squirrel (Dremomys everetti), which is endemic to the high mountains of Borneo, is nested within the Sunda squirrels with high support. This species diverged from its sister taxa in the Sunda squirrels 6.62 million years ago, and other plain long-nosed squirrels over 11 million years ago. Our analyses of morphological traits in these related genera support the re-classification of the Bornean mountain ground squirrel, Dremomys everetti, to the genus Sundasciurus, which changes its name to Sundasciurus everetti. Past inclusion in the plain long-nosed squirrels (Dremomys) reflects convergent evolution between these high elevation species.

Epigenetic changes to gene pathways linked to male fertility in ex situ black-footed ferrets.

Environmental variation can influence the reproductive success of species managed under human care and in the wild, yet the mechanisms underlying this phenomenon remain largely mysterious. Molecular mechanisms such as epigenetic modifiers are important in mediating the timing and progression of reproduction in humans and model organisms, but few studies have linked epigenetic variation to reproductive fitness in wildlife. Here, we investigated epigenetic variation in black-footed ferrets (Mustela nigripes), an endangered North American mammal reliant on ex situ management for survival and persistence in the wild. Despite similar levels of genetic diversity in human-managed and wild-born populations, individuals in ex situ facilities exhibit reproductive problems, such as poor sperm quality. Differences across these settings suggest that an environmentally driven decline in reproductive capacity may be occurring in this species. We examined the role of DNA methylation, one well-studied epigenetic modifier, in this emergent condition. We leveraged blood, testes, and semen samples from male black-footed ferrets bred in ex situ facilities and found tissue-type specificity in DNA methylation across the genome, although 1360 Gene Ontology terms associated with male average litter size shared functions across tissues. We then constructed gene networks of differentially methylated genomic sites associated with three different reproductive phenotypes to explore the putative biological impact of variation in DNA methylation. Sperm gene networks associated with average litter size and sperm count were functionally enriched for candidate genes involved in reproduction, development, and its regulation through transcriptional repression. We propose that DNA methylation plays an important role in regulating these reproductive phenotypes, thereby impacting the fertility of male ex situ individuals. Our results provide information into how DNA methylation may function in the alteration of reproductive pathways and phenotypes in artificial environments. These findings provide early insights to conservation hurdles faced in the protection of this rare species.

Novel genomic resources contribute to the systematics of threatened arboreal deer mice of the genus Habromys Hooper & Musser, 1964 (Cricetidae, Neotominae) within a neotomine-peromyscine phylogeny.

The Crested-tailed deer mouse, Habromyslophurus, is one of seven arboreal species within the genus Habromys. Species of this genus are monotypic, relatively rare, and occur in low densities. Their geographical distribution is highly fragmented due to being restricted to montane cloud forest in Mesoamerica and they are of conservation concern. All Habromys species are endemic to Mexico, except H.lophurus, which is also distributed in Guatemala and El Salvador. In this study, we obtained and characterized the first mitogenome and several thousand nuclear ultraconserved elements (UCEs) of H.lophurus to determine its phylogenetic position within neotomine-peromyscine mice. Its mitogenome sequence (16,509 bp) is only the second complete mitogenome obtained for this poorly known genus. We also obtained the first nuclear genomic data for H.lophurus, including 3,654 UCE loci, as well as a partial mitogenome of H.simulatus (6,349 bp), and 2,186 UCE for the outgroup Holochilussciureus. Phylogenetic analyses that included our newly generated genomic data coupled with previously published data from other neotomine-peromyscine mice confirm the placement of H.lophurus, H.simulatus, and H.ixtlani within a highly supported clade. The Habromys clade was nested within a clade that also contains members of the genus Peromyscus and provides further support for the hypothesis of the paraphyly of Peromyscus. These genomic resources will contribute to future phylogenomic studies that aim to further elucidate the evolutionary history of this rare and critically endangered genus of rodents.

The history of Coast Salish "woolly dogs" revealed by ancient genomics and Indigenous Knowledge.

Ancestral Coast Salish societies in the Pacific Northwest kept long-haired "woolly dogs" that were bred and cared for over millennia. However, the dog wool-weaving tradition declined during the 19th century, and the population was lost. In this study, we analyzed genomic and isotopic data from a preserved woolly dog pelt from "Mutton," collected in 1859. Mutton is the only known example of an Indigenous North American dog with dominant precolonial ancestry postdating the onset of settler colonialism. We identified candidate genetic variants potentially linked with their distinct woolly phenotype. We integrated these data with interviews from Coast Salish Elders, Knowledge Keepers, and weavers about shared traditional knowledge and memories surrounding woolly dogs, their importance within Coast Salish societies, and how colonial policies led directly to their disappearance.

Challenging ecogeographical rules: Phenotypic variation in the Mountain Treeshrew (Tupaia montana) along tropical elevational gradients.

Bergmann's and Allen's rules were defined to describe macroecological patterns across latitudinal gradients. Bergmann observed a positive association between body size and latitude for endothermic species while Allen described shorter appendages as latitude increases. Almost two centuries later, there is still ongoing discussion about these patterns. Temperature, the common variable in these two rules, varies predictably across both latitude and elevation. Although these rules have been assessed extensively in mammals across latitude, particularly in regions with strong seasonality, studies on tropical montane mammals are scarce. We here test for these patterns and assess the variation of several other locomotory, diet-associated, body condition, and thermoregulatory traits across elevation in the Mountain Treeshrew (Tupaia montana) on tropical mountains in Borneo. Based on morphological measurements from both the field and scientific collections, we found a complex pattern: Bergmann's rule was not supported in our tropical mountain system, since skull length, body size, and weight decreased from the lowest elevations (<1000 m) to middle elevations (2000-2500 m), and then increased from middle elevations to highest elevations. Allen's rule was supported for relative tail length, which decreased with elevation, but not for ear and hindfoot length, with the former remaining constant and the latter increasing with elevation. This evidence together with changes in presumed diet-related traits (rostrum length, zygomatic breadth and upper tooth row length) along elevation suggest that selective pressures other than temperature, are playing a more important role shaping the morphological variation across the distribution of the Mountain Treeshrew. Diet, food acquisition, predation pressure, and/or intra- and inter-specific competition, are some of the potential factors driving the phenotypic variation of this study system. The lack of variation in body condition might suggest local adaptation of this species across its elevational range, perhaps due to generalist foraging strategies. Finally, a highly significant temporal effect was detected in several traits but not in others, representing the first phenotypic variation temporal trends described on treeshrews.

Nuclear and Mitochondrial Phylogenomics of the Sifakas Reveal Cryptic Variation in the Diademed Sifaka.

The most comprehensive phylogenomic reconstruction to date was generated on all nominal taxa within the lemur genus Propithecus. Over 200 wild-caught individuals were included in this study to evaluate the intra and interspecific relationships across this genus. Ultraconserved Elements (UCEs) resulted in well-supported phylogenomic trees. Complete mitochondrial genomes (CMGs) largely agreed with the UCEs, except where a mitochondrial introgression was detected between one clade of the diademed sifaka (Propithecus diadema) and the Milne-Edwards sifaka (P. edwardsi). Additionally, the crowned (P. coronatus) and Von der Decken's (P. deckeni) sifakas belonged to a single admixed lineage from UCEs. Further sampling across these two species is warranted to determine if our sampling represents a hybrid zone. P. diadema recovered two well-supported clades, which were dated and estimated as being ancient as the split between the Perrier's (P. perrierii) and silky (P. candidus) sifakas. The reconstructed demographic history of the two clades also varied over time. We then modeled the modern ecological niches of the two cryptic P. diadema clades and found that they were significantly diverged (p < 0.01). These ecological differences result in a very limited zone of geographic overlap for the P. diadema clades (<60 km2). Niche models also revealed that the Onive River acts as a potential barrier to dispersal between P. diadema and P. edwardsi. Further taxonomic work is required on P. diadema to determine if its taxonomic status should be revised. This first genomic evaluation of the genus resolved the relationships between the taxa and the recovered cryptic diversity within one species.

Endemism and diversity of small mammals along two neighboring Bornean mountains.

Mountains offer replicated units with large biotic and abiotic gradients in a reduced spatial scale. This transforms them into well-suited scenarios to evaluate biogeographic theories. Mountain biogeography is a hot topic of research and many theories have been proposed to describe the changes in biodiversity with elevation. Geometric constraints, which predict the highest diversity to occur in mid-elevations, have been a focal part of this discussion. Despite this, there is no general theory to explain these patterns, probably because of the interaction among different predictors with the local effects of historical factors. We characterize the diversity of small non-volant mammals across the elevational gradient on Mount (Mt.) Kinabalu (4,095 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We documented a decrease in species richness with elevation which deviates from expectations of the geometric constraints and suggests that spatial factors (e.g., larger diversity in larger areas) are important. The lowland small mammal community was replaced in higher elevations (from above ~1,900 m) with montane communities consisting mainly of high elevation Borneo endemics. The positive correlation we find between elevation and endemism is concordant with a hypothesis that predicts higher endemism with topographical isolation. This supports lineage history and geographic history could be important drivers of species diversity in this region.

A gene-tree test of the traditional taxonomy of American deer: the importance of voucher specimens, geographic data, and dense sampling.

The taxonomy of American deer has been established almost entirely on the basis of morphological data and without the use of explicit phylogenetic methods; hence, phylogenetic analyses including data for all of the currently recognized species, even if based on a single gene, might improve current understanding of their taxonomy. We tested the monophyly of the morphology-defined genera and species of New World deer (Odocoileini) with phylogenetic analyses of mitochondrial DNA sequences. This is the first such test conducted using extensive geographic and taxonomic sampling. Our results do not support the monophyly of Mazama, Odocoileus, Pudu, M. americana, M. nemorivaga, Od. hemionus, and Od. virginianus. Mazama contains species that belong to other genera. We found a novel sister-taxon relationship between "Mazama" pandora and a clade formed by Od. hemionus columbianus and Od. h. sitkensis, and transfer pandora to Odocoileus. The clade formed by Od. h. columbianus and Od. h. sitkensis may represent a valid species, whereas the remaining subspecies of Od. hemionus appear closer to Od. virginianus. Pudu (Pudu) puda was not found sister to Pudu (Pudella) mephistophiles. If confirmed, this result will prompt the recognition of the monotypic Pudella as a distinct genus. We provide evidence for the existence of an undescribed species now confused with Mazama americana, and identify other instances of cryptic, taxonomically unrecognized species-level diversity among populations here regarded as Mazama temama, "Mazama" nemorivaga, and Hippocamelus antisensis. Noteworthy records that substantially extend the known distributions of M. temama and "M." gouazoubira are provided, and we unveil a surprising ambiguity regarding the distribution of "M." nemorivaga, as it is described in the literature. The study of deer of the tribe Odocoileini has been hampered by the paucity of information regarding voucher specimens and the provenance of sequences deposited in GenBank. We pinpoint priorities for future systematic research on the tribe Odocoileini.

In-solution hybridization for mammalian mitogenome enrichment: pros, cons and challenges associated with multiplexing degraded DNA.

Here, we present a set of RNA-based probes for whole mitochondrial genome in-solution enrichment, targeting a diversity of mammalian mitogenomes. This probes set was designed from seven mammalian orders and tested to determine the utility for enriching degraded DNA. We generated 63 mitogenomes representing five orders and 22 genera of mammals that yielded varying coverage ranging from 0 to >5400X. Based on a threshold of 70% mitogenome recovery and at least 10× average coverage, 32 individuals or 51% of samples were considered successful. The estimated sequence divergence of samples from the probe sequences used to construct the array ranged up to nearly 20%. Sample type was more predictive of mitogenome recovery than sample age. The proportion of reads from each individual in multiplexed enrichments was highly skewed, with each pool having one sample that yielded a majority of the reads. Recovery across each mitochondrial gene varied with most samples exhibiting regions with gaps or ambiguous sites. We estimated the ability of the probes to capture mitogenomes from a diversity of mammalian taxa not included here by performing a clustering analysis of published sequences for 100 taxa representing most mammalian orders. Our study demonstrates that a general array can be cost and time effective when there is a need to screen a modest number of individuals from a variety of taxa. We also address the practical concerns for using such a tool, with regard to pooling samples, generating high quality mitogenomes and detail a pipeline to remove chimeric molecules.

Simultaneous identification of host, ectoparasite and pathogen DNA via in-solution capture.

Ectoparasites frequently vector pathogens from often unknown pathogen reservoirs to both human and animal populations. Simultaneous identification of the ectoparasite species, the wildlife host that provided their most recent blood meal(s), and their pathogen load would greatly facilitate the understanding of the complex transmission dynamics of vector-borne diseases. Currently, these identifications are principally performed using multiple polymerase chain reaction (PCR) assays. We developed an assay (EctoBaits) based on in-solution capture paired with high-throughput sequencing to simultaneously identify ectoparasites, host blood meals and pathogens. We validated our in-solution capture results using double-blind PCR assays, morphology and collection data. The EctoBaits assay effectively and efficiently identifies ectoparasites, blood meals, and pathogens in a single capture experiment, allowing for high-resolution taxonomic identification while preserving the DNA sample for future analyses.

Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of rodents.

Time calibration derived from the fossil record is essential for molecular phylogenetic and evolutionary studies. Fossil mice and rats, discovered in the Siwalik Group of Pakistan, have served as one of the best-known fossil calibration points in molecular phylogenic studies. Although these fossils have been widely used as the 12 Ma date for the Mus/Rattus split or a more basal split, conclusive paleontological evidence for the nodal assignments has been absent. This study analyzes newly recognized characters that demonstrate lineage separation in the fossil record of Siwalik murines and examines the most reasonable nodal placement of the diverging lineages in a molecular phylogenetic tree by ancestral state reconstruction. Our specimen-based approach strongly indicates that Siwalik murines of the Karnimata clade are fossil members of the Arvicanthini-Otomyini-Millardini clade, which excludes Rattus and its relatives. Combining the new interpretation with the widely accepted hypothesis that the Progonomys clade includes Mus, the lineage separation event in the Siwalik fossil record represents the Mus/Arvicanthis split. Our test analysis on Bayesian age estimates shows that this new calibration point provides more accurate estimates of murine divergence than previous applications. Thus, we define this fossil calibration point and refine two other fossil-based points for molecular dating.

The Taxonomic Status of Mazama bricenii and the Significance of the Táchira Depression for Mammalian Endemism in the Cordillera de Mérida, Venezuela.

We studied the taxonomy and biogeography of Mazama bricenii, a brocket deer classified as Vulnerable by the IUCN, drawing on qualitative and quantitative morphology and sequences of the mitochondrial cytochrome-b gene. We used Ecological Niche Modeling (ENM) to evaluate the hypothesis that M. bricenii of the Venezuelan Cordillera de Mérida (CM) might have become isolated from populations of its putative sister species, Mazama rufina, in the Colombian Cordillera Oriental (CO). This hypothesis assumes that warm, dry climatic conditions in the Táchira Depression were unsuitable for the species. Our analyses did not reveal morphological differences between specimens geographically attributable to M. bricenii and M. rufina, and phylogenetic analyses of molecular data recovered M. bricenii nested within the diversity of M. rufina. These results indicate that M. bricenii should be regarded as a junior synonym of M. rufina. ENM analyses revealed the existence of suitable climatic conditions for M. rufina in the Táchira Depression during the last glacial maximum and even at present, suggesting that gene flow between populations in the CO and CM may have occurred until at least the beginning of the current interglacial period and may continue today. Because this pattern might characterize other mammals currently considered endemic to the CM, we examined which of these species match two criteria that we propose herein to estimate if they can be regarded as endemic to the CM with confidence: (1) that morphological or molecular evidence exists indicating that the putative endemic taxon is distinctive from congeneric populations in the CO; and (2) that the putative endemic taxon is restricted to either cloud forest or páramo, or both. Only Aepeomys reigi, Cryptotis meridensis, and Nasuella meridensis matched both criteria; hence, additional research is necessary to assess the true taxonomic status and distribution of the remaining species thought to be CM endemics.