Molly M. McDonough

Microbiome analysis among bats describes influences of host phylogeny, life history, physiology and geography

Metagenomic methods provide an experimental approach to inform the relationships between hosts and their microbial inhabitants. Previous studies have provided the conceptual realization that microbiomes are dynamic among hosts and the intimacy of relation between micro‐ and macroorganisms. Here, we present an intestinal microflora community analysis for members of the order Chiroptera and investigate the relative influence of variables in shaping observed microbiome relationships. The variables ranged from those considered to have ancient and long‐term influences (host phylogeny and life history) to the relatively transient variable of host reproductive condition. In addition, collection locality data, representing the geographic variable, were included in analyses. Results indicate a complex influence of variables in shaping sample relationships in which signal for host phylogeny is recovered at broad taxonomic levels (family), whereas intrafamilial analyses disclosed various degrees of resolution for the remaining variables. Although cumulative probabilities of assignment indicated both reproductive condition and geography influenced relationships, comparison of ecological measures among groups revealed statistical differences between most variable classifications. For example, ranked ecological diversity was associated with host phylogeny (deeper coalescences among families were associated with more microfloral diversity), dietary strategy (herbivory generally retained higher diversity than carnivory) and reproductive condition (reproductively active females displayed more diverse microflora than nonreproductive conditions). Overall, the results of this study describe a complex process shaping microflora communities of wildlife species as well as provide avenues for future research that will further inform the nature of symbiosis between microflora communities and hosts.

Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya.

Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large-wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife declines on other animals in a community, we examined the effects of three common forms of large-wildlife loss (removal without replacement [using fences], removal followed by replacement with domestic stock, and removal accompanied by crop agricultural use) on small-mammal abundance, diversity, and community composition, in landscapes that varied in several abiotic attributes (rainfall, soil fertility, land-use intensity) in central Kenya. We found that small-mammal communities were indeed heavily impacted by all forms of large-wildlife decline, showing, on average: (1) higher densities, (2) lower species richness per site, and (3) different species assemblages in sites from which large wildlife were removed. However, the nature and magnitude of these effects were strongly context dependent. Rainfall, type of land-use change, and the interaction of these two factors were key predictors of both the magnitude and type of responses of small mammals. The strongest effects, particularly abundance responses, tended to be observed in low-rainfall areas. Whereas isolated wildlife removal primarily led to increased small-mammal abundance, wildlife removal associated with secondary uses (agriculture, domestic stock) had much more variable effects on abundance and stronger impacts on diversity and composition. Collectively, these results (1) highlight the importance of context in determining the impacts of large-wildlife decline on small-mammal communities, (2) emphasize the challenges in extrapolating results from controlled experimental studies to predict the effects of wildlife declines that are accompanied by secondary land-uses, and (3) suggest that, because of the context-dependent nature of the responses to large-wildlife decline, large-wildlife status alone cannot be reliably used to predict small-mammal community changes.

New Species of Bonneted Bat, Genus Eumops (Chiroptera: Molossidae) from the Lowlands of Western Ecuador and Peru

We describe and formally name a species of bonneted bat (genus Eumops), which is a member of the E. glaucinus complex. Closely related species are E. glaucinus, E. ferox, and E. floridanus. The conceptual basis for the description of this species is the Genetic Species Concept with speciation by the Bateson-Dobzhanzky-Muller model. The new species is distinguished from all other species of bats by its unique karyotype (2N = 38, FN = 54), sequence of the mitochondrial cytochrome-b gene, and genetic markers revealed through analysis of Amplified Fragment Length Polymorphisms. The series from the type locality (Ecuador, Guayas) is comprised of seven specimens. Morphologically, the new species is smaller than E. floridanus and E. glaucinus, but is indistinguishable from E. ferox. The new species is significantly smaller in size than E. glaucinus in six out of eight measurements and is distinguishable from E. glaucinus based on length of maxillary toothrow and zygomatic breadth. The geographic range of E. wilsoni, as currently documented, is the dry forests of southwestern Ecuador and adjacent northwestern Peru. We propose the common name for this species be Wilsons bonneted bat.

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.

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.

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

BackgroundThe 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.ResultsOur 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.ConclusionsThe 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.

Multilocus phylogeography of a widespread savanna‐woodland adapted rodent reveals the influence of Pleistocene geomorphology and climate change in Africa's Zambezi region

Understanding historical influences of climate and physiographic barriers in shaping patterns of biodiversity remains limited for many regions of the world. For mammals of continental Africa, phylogeographic studies, particularly for West African lineages, implicate both geographic barriers and climate oscillations in shaping small mammal diversity. In contrast, studies for southern African species have revealed conflicting phylogenetic patterns for how mammalian lineages respond to both climate change and geologic events such as river formation, especially during the Pleistocene. However, these studies were often biased by limited geographic sampling or exclusively focused on large‐bodied taxa. We exploited the broad southern African distribution of a savanna–woodland‐adapted African rodent, Gerbilliscus leucogaster (bushveld gerbil) and generated mitochondrial, autosomal and sex chromosome data to quantify regional signatures of climatic and vicariant biogeographic phenomena. Results indicate the most recent common ancestor for all G. leucogaster lineages occurred during the early Pleistocene. We documented six divergent mitochondrial lineages that diverged ~0.270–0.100 mya, each of which was geographically isolated during periods characterized by alterations to the course of the Zambezi River and its tributaries as well as regional ‘megadroughts’. Results demonstrate the presence of a widespread lineage exhibiting demographic expansion ~0.065–0.035 mya, a time that coincides with savanna–woodland expansion across southern Africa. A multilocus autosomal perspective revealed the influence of the Kafue River as a current barrier to gene flow and regions of secondary contact among divergent mitochondrial lineages. Our results demonstrate the importance of both climatic fluctuations and physiographic vicariance in shaping the distribution of southern African biodiversity.

Molecular systematics of bonneted bats (Molossidae: Eumops) based on mitochondrial and nuclear DNA sequences

Abstract Previous understanding of the relationships among the species of bats in the genus Eumops has been primarily based on phenetic and cladistic analyses of morphological genetic similarity data. The objective of this study was to construct a phylogeny using DNA sequence data from 2 mitochondrial loci (cytochrome-b [Cytb] and nicotinamide adenine dinucleotide dehydrogenase subunit 1 [ND1]) and 1 nuclear locus (β-fibrinogen intron 7 [βFib]) for members of Eumops and outgroups from the family Molossidae. Data for each locus were analyzed separately using maximum-likelihood and Bayesian methods and combined for complete data analyses using Bayesian inference and Bayesian concordance analysis on a total of 2,715 base pairs. The monophyly of Eumops was significantly supported in all analyses and molecular dating estimated a most recent common ancestor of the genus at approximately 15.7 million years ago. Placement of E. hansae was problematic, with ND1 analyses supporting a sister relationship with E. patagonicus and E. nanus, whereas Cytb and βFib analyses placed this species as a basal lineage in the genus. Analysis of all genes recovered E. hansae as a poorly supported basal lineage with E. patagonicus and E. nanus as sister to the remaining species. These 3 major lineages of Eumops diverged during the mid-Miocene.

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

Abstract 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.

Performance of commonly requested destructive museum samples for mammalian genomic studies

High-throughput sequencing methods have facilitated obtaining large amounts of data from degraded DNA, thus resulting in a dramatic increase in destructive sampling requests to museums. Because the tissues taken from museum specimens as sources of DNA are destroyed during analysis, consideration of the costs and benefits of loss of valuable specimen material relative to knowledge gained is required for any project utilizing destructive sampling. Variation exists in the preservation of DNA in historical specimens due to specimen age and type of museum preparation, among other factors. Thus, it is important to assess DNA yield and quality from different sources of museum specimens when considering the needs of a particular molecular project. We compared DNA derived from several common sources of museum specimens including bone, claw, skin, and soft tissue adherent to skeletal preparations. To account for differences in preparation type and therefore specimen preservation, we tested the performance of samples representing 3 taxonomic groups: mephitids, rodents, and marsupials. We also compared yields from 2 commonly used DNA extraction techniques. DNA quality was assessed by comparing average fragment size, concentration, and copy number of template DNA (for mitochondrial and nuclear markers) in genomic DNA extracts, as well as mitochondrial genome sequence coverage resulting from shotgun sequencing. We show that DNA quality derived from historic museum samples differs depending on specimen and sample type; however, all samples yielded high mitochondrial copy number except the skin and nail from the tanned specimen. Overall, claw samples produced the greatest number of high-quality sequencing reads with the least amount of bacterial contamination. We also found that high DNA concentrations did not necessarily result in high percentages of on-target reads; in fact, the samples that yielded the highest DNA quantities also had the highest amount of exogenous bacterial DNA. Our results indicate that most historical tissue types can be suitable for next-generation sequencing approaches, therefore providing multiple options for natural history collection staff and researchers when considering destructive sampling requests.