Biology subjects

Perry, G. H.

Publications and source records attributed to Perry, G. H..

17 recordsLinked to original sources

bioRxiv2026

Evolutionary Histories and Environments Shape Ugandan and Global Oral Microbiomes

Industrialization has been identified as the single biggest factor driving global microbiome diversity. While many studies examining gut microbiomes attribute these shifts to dietary increases in fat and reductions in protein, oral microbiome responses to industrialization remains debated. The oral microbiome is more resilient due to long-standing coevolution with host tissues and biofilm stability. However, limited geographic and historical representation has constrained our understanding of how these transitions unfolded globally in the oral microbiomes. Here, we investigate oral microbiome variation in Batwa rainforest hunter-gatherers and neighboring Bakiga subsistence farmers from southwestern Uganda, comparing them with publicly available data from Tanzanian, Venezuelan, and industrialized populations from North America, Europe, and Australia. Using 16S rRNA gene sequencing, we characterized salivary microbiota and evaluated differences in local and global diversity, composition, and differential abundance. Ugandan populations contained significant compositional differences but similar levels of diversity, suggesting that shared environments and dietary overlap may shape microbial assemblages despite distinct cultural histories. Globally, strong continental and industrialization effects were observed in the oral microbiome, with all industrial populations clustering separately from people living in other locations. African populations also clustered separately from non-African groups. Oral microbiome diversity was highest in Ugandan individuals and lowest in industrialized populations, mirroring patterns previously observed in the gut microbiome. Together, these findings demonstrate that both geography and subsistence strategy structure global oral microbiome variation. They also clarify the position that oral microbial communities record biocultural transitions and highlight the need to better understand the industrial mechanisms that shape microbial diversity in the oral cavity.

evolutionary biology↗

bioRxiv2025

Museum genomics reveals temporal genetic stasis and global genetic diversity in Arabidopsis thaliana

Global patterns of population genetic variation through time offer a window into evolutionary processes that maintain diversity. Over time, lineages may expand or contract their distribution, causing turnover in population genetic composition. At individual loci, migration, drift, and selection (among other processes) may affect allele frequencies. Museum specimens of widely distributed species offer a unique window into the genetics of understudied populations and changes over time. Here, we sequenced genomes of 130 herbarium specimens and 91 new field collections of Arabidopsis thaliana and combined these with published genomes. We sought a broader view of genomic diversity across the species, and to test if population genomic composition is changing through time. We documented extensive and previously uncharacterized diversity in a range of populations in Africa, populations that are under threat from anthropogenic climate change. Through time, we did not find dramatic changes in genomic composition of populations. Instead, we found a pattern of genetic change every 100 years of the same magnitude seen when comparing Eurasian populations that are 185 km apart, potentially due to a combination of drift and changing selection. We found only mixed signals of polygenic adaptation at phenology and physiology QTL. We did find that genes conserved across eudicots show altered levels of directional allele frequency change, potentially due to variable purifying and background selection. Our study highlights how museum specimens can reveal new dimensions of population diversity and show how wild populations are evolving in recent history.

evolutionary biology↗

bioRxiv2024

Ancient tree-topologies and gene-flow processes among human lineages in Africa

The deep history of human evolution in Africa remains intensely debated, with increasingly complex models being proposed. To investigate this, we sequenced and analysed 73 novel high-quality whole genomes from 14 Central and Southern African populations with diverse cultural practices. Using extensive simulations and machine-learning Approximate Bayesian Computation (ABC), we jointly reconstructed their demographic history of divergences and migrations. We find extensive genome-wide diversity within and among populations, including substantial local genetic differentiation not fully explained by geography or cultural practices. These patterns highlight the importance of explicitly considering local genomic diversity when reconstructing human evolutionary history. We find that tree-like population histories with long periods of drift separated by short pulses of unidirectional gene-flow better explain the data than continuous gene-flow. Without invoking archaic admixture, our models accurately fit observed genomic variation and identify multiple episodes of gene-flow coinciding with major ecological and cultural changes in Sub-Saharan Africa.

genetics↗

bioRxiv2023

Genomic signatures of adaptation in native lizards exposed to human-introduced fire ants

Understanding the process of genetic adaptation in response to human-mediated ecological change will help elucidate the eco-evolutionary impacts of human activity. Red fire ants (Solenopsis invicta) spread across Southeastern USA since their accidental introduction via Port Mobile, Alabama in the 1930s, serving today as both novel venomous predator and novel toxic prey to native eastern fence lizards (Sceloporus undulatus). To identify potential signatures of genetic adaptation in lizards to invasive fire ants, we generated whole genome sequencing data from 420 native fence lizards sampled across three populations, two of which had not been invaded by fire ants (in Tennessee and Arkansas) and one which had been invaded for [~]70 years (Alabama). We detected signatures of positive selection exclusive to the exposed Alabama population for genetic variants overlapping genes related to the membrane attack complex of the complement immune system, growth factor pathways, and morphological development. Prior work identified a relationship between increased lizard survival of fire ant attack and longer hind limbs, which lizards use to remove ants from their bodies. Furthermore, we conducted a genome-wide association study with 381 Alabama lizards to identify 24 hind limb length-associated genetic loci. For two loci, positive-effect alleles occur in high frequency and overlap genomic regions that are highly differentiated from the populations naive to fire ants. Collectively, these findings represent plausible genetic adaptations in response to fire ant invasion, whereby morphological differentiation may increase survival against swarming ants and altered immune responses may allow the exploitation of a novel, toxic food resource. Significance statementHuman activity can force interactions between species from distinct ecological backgrounds. These interactions can consequently impose novel selective pressures on endemic populations via predation or disruption of ecological niches through community-wide effects. While some endemic taxa have been able to adapt biologically to these disruptions, we do not have a full understanding of the underlying genetic processes that may allow it. Here we identify genomic signatures of recent adaptation nearby genes involved in morphological and immunological processes in native fence lizards that are consistent with pressures imposed by the venomous, predatory fire ants introduced by humans. These signatures are largely absent from lizard populations that are naive to fire ants.

evolutionary biology↗

bioRxiv2021

An integrative skeletal and paleogenomic analysis of prehistoric stature variation suggests relatively reduced health for early European farmers

Human culture, biology, and health were shaped dramatically by the onset of agriculture ~12,000 years before present (BP). Subsistence shifts from hunting and gathering to agriculture are hypothesized to have resulted in increased individual fitness and population growth as evidenced by archaeological and population genomic data alongside a simultaneous decline in physiological health as inferred from paleopathological analyses and stature reconstructions of skeletal remains. A key component of the health decline inference is that relatively shorter statures observed for early farmers may (at least partly) reflect higher childhood disease burdens and poorer nutrition. However, while such stresses can indeed result in growth stunting, height is also highly heritable, and substantial inter-individual variation in the height genetic component within a population is typical. Moreover, extensive migration and gene flow were characteristics of multiple agricultural transitions worldwide. Here, we consider both osteological and ancient DNA data from the same prehistoric individuals to comprehensively study the trajectory of human stature variation as a proxy for health across a transition to agriculture. Specifically, we compared predicted genetic contributions to height from paleogenomic data and achieved adult osteological height estimated from long bone measurements on a per-individual basis for n=160 ancient Europeans from sites spanning the Upper Paleolithic to the Iron Age (~38,000-2,400 BP). We found that individuals from the Neolithic were shorter than expected (given their individual polygenic height scores) by an average of -4.47 cm relative to individuals from the Upper Paleolithic and Mesolithic (P=0.016). The average osteological vs. expected stature then increased relative to the Neolithic over the Copper (+2.67 cm, P=0.052), Bronze (+3.33 cm, P=0.032), and Iron Ages (+3.95 cm, P=0.094). These results were partly attenuated when we accounted for genome-wide genetic ancestry variation in our sample (which we note is partly duplicative with the individual polygenic score information). For example, in this secondary analysis Neolithic individuals were -3.48 cm shorter than expected on average relative to individuals from the Upper Paleolithic and Mesolithic (P=0.056). We also incorporated observations of paleopathological indicators of non-specific stress that can persist from childhood to adulthood in skeletal remains (linear enamel hypoplasia, cribra orbitalia, and porotic hyperostosis) into our model. Overall, our work highlights the potential of integrating disparate datasets to explore proxies of health in prehistory.

genomics↗

bioRxiv2020

Evolutionary and phylogenetic insights from a nuclear genome sequence of the extinct, giant subfossil koala lemur Megaladapis edwardsi

No endemic Madagascar animal with body mass >10 kg survived a relatively recent wave of extinction on the island. From morphological and isotopic analyses of skeletal subfossil remains we can reconstruct some of the biology and behavioral ecology of giant lemurs (primates; up to ~160 kg), elephant birds (up to ~860 kg), and other extraordinary Malagasy megafauna that survived well into the past millennium. Yet much about the evolutionary biology of these now extinct species remains unknown, along with persistent phylogenetic uncertainty in some cases. Thankfully, despite the challenges of DNA preservation in tropical and sub-tropical environments, technical advances have enabled the recovery of ancient DNA from some Malagasy subfossil specimens. Here we present a nuclear genome sequence (~2X coverage) for one of the largest extinct lemurs, the koala lemur Megaladapis edwardsi (~85kg). To support the testing of key phylogenetic and evolutionary hypotheses we also generated new high-coverage complete nuclear genomes for two extant lemur species, Eulemur rufifrons and Lepilemur mustelinus, and we aligned these sequences with previously published genomes for three other extant lemur species and 47 non-lemur vertebrates. Our phylogenetic results confirm that Megaladapis is most closely related to the extant Lemuridae (typified in our analysis by E. rufifrons) to the exclusion of L. mustelinus, which contradicts morphology-based phylogenies. Our evolutionary analyses identified significant convergent evolution between M. edwardsi and extant folivorous primates (colobine monkeys) and ungulate herbivores (horses) in genes encoding protein products that function in the biodegradation of plant toxins and nutrient absorption. These results suggest that koala lemurs were highly adapted to a leaf-based diet, which may also explain their convergent craniodental morphology with the small-bodied folivore Lepilemur.

genomics↗

bioRxiv2020

Modern, archaeological, and paleontological DNA analysis of a human-harvested marine gastropod (Strombus pugilis) from Caribbean Panama

Although protocols exist for the recovery of ancient DNA from land snail and marine bivalve shells, marine conch shells have yet to be studied from a paleogenomic perspective. We first present reference assemblies for both a 623.7 Mbp nuclear genome and a 15.4 kbp mitochondrial genome for Strombus pugilis, the West Indian fighting conch. We next detail a method to extract and sequence DNA from conch shells and apply it to conch from Bocas del Toro, Panama across three time periods: recently-eaten and discarded (n=3), Late Holocene (984-1258 BP) archaeological midden (n=5), and a mid-Holocene (5711-7187 BP) paleontological fossil coral reef (n=5). These results are compared to control DNA extracted from live-caught tissue and fresh shells (n=5). Using high-throughput sequencing, we were able to obtain S. pugilis nuclear sequence reads from shells across all age periods: up to 92.5 thousand filtered reads per sample in live-caught shell material, 4.57 thousand for modern discarded shells, 12.1 thousand reads for archaeological shells, and 114 reads in paleontological shells. We confirmed authenticity of the ancient DNA recovered from the archaeological and paleontological shells based on 5.7x higher average frequency of deamination-driven misincorporations and 15% shorter average read lengths compared to the modern shells. Reads also mapped to the S. pugilis mitochondrial genome for all but the paleontological shells, with consistent ratios of mitochondrial to nuclear mapped reads across sample types. Our methods can be applied to diverse archaeological sites to facilitate reconstructions of the long-term impacts of human behavior on mollusc evolutionary biology.

evolutionary biology↗

bioRxiv2020

Evolutionary genomic patterns of recent natural selection on loci associated with sexually differentiated human body size and shape phenotypes

Levels of sex differences for human body size and shape phenotypes are hypothesized to have adaptively reduced following the agricultural transition as part of an evolutionary response to relatively more equal divisions of labor and new technology adoption. In this study, we tested this hypothesis by studying genetic variants associated with five sexually differentiated human phenotypes: height, body mass, hip circumference, body fat percentage, and waist circumference. We first analyzed genome-wide association (GWAS) results for UK Biobank individuals ([~]197,000 females and [~]167,000 males) to identify a total of 119,023 single nucleotide polymorphisms (SNPs) significantly associated with at least one of the studied phenotypes in females, males, or both sexes (P<5x10-8). From these loci we then identified 3,016 SNPs (2.5%) with significant differences in the strength of association between the female- and male-specific GWAS results at a low false-discovery rate (FDR<0.001). Genes with known roles in sexual differentiation are significantly enriched for co-localization with one or more of these SNPs versus SNPs associated with the phenotypes generally but not with sex differences (2.93-fold enrichment; permutation test; P=0.0041). We also confirmed that the identified variants are disproportionately associated with greater phenotype effect sizes in the sex with the stronger association value. We then used the singleton density score statistic, which quantifies recent (within the last [~]3,000 years; post-agriculture adoption in Britain) changes in the frequencies of alleles underlying polygenic traits, to identify a signature of recent positive selection on alleles associated with greater body fat percentage in females (permutation test; P=0.0038; FDR=0.0380), directionally opposite to that predicted by the sex differentiation reduction hypothesis. Otherwise, we found no evidence of positive selection for sex difference-associated alleles for any other trait. Overall, our results challenge the longstanding hypothesis that sex differences adaptively decreased following subsistence transitions from hunting and gathering to agriculture. Author SummaryThere is uncertainty regarding the evolutionary history of human sex differences for quantitative body size and shape phenotypes. In this study we identified thousands of genetic loci that differentially impact body size and shape trait variation between females and males using a large sample of UK Biobank individuals. After confirming the biological plausibility of these loci, we used a population genomics approach to study the recent (over the past 3,000 years) evolutionary histories of these loci in this population. We observed significant increases in the frequencies of alleles associated with greater body fat percentage in females. This result is contradictory to longstanding hypotheses that sex differences have adaptively decreased following subsistence transitions from hunting and gathering to agriculture.

evolutionary biology↗

bioRxiv2020

A chromosome-level genome assembly for the Eastern Fence Lizard (Sceloporus undulatus), a reptile model for physiological and evolutionary ecology

High-quality genomic resources facilitate population-level and species-level comparisons to answer questions about behavioral ecology, morphological and physiological adaptations, as well as the evolution of genomic architecture. Squamate reptiles (lizards and snakes) are particularly diverse in characteristics that have intrigued evolutionary biologists, but high-quality genomic resources for squamates are relatively sparse. Lizards in the genus Sceloporus have a long history as important ecological, evolutionary, and physiological models, making them a valuable target for the development of genomic resources. We present a high-quality chromosome-level reference genome assembly, SceUnd1.0, (utilizing 10X Genomics Chromium, HiC, and PacBio data) and tissue/developmental stage transcriptomes for the Eastern Fence Lizard, Sceloporus undulatus. We performed synteny analysis with other available squamate chromosome-level assemblies to identify broad patterns of chromosome evolution including the fusion of micro- and macrochromosomes in S. undulatus. Using this new S. undulatus genome assembly we conducted reference-based assemblies for 34 other Sceloporus species to improve draft nuclear genomes assemblies from 1% coverage to 43% coverage on average. Across these species, typically >90% of reads mapped for species within 20 million years divergence from S. undulatus, this dropped to 75% reads mapped for species at 35 million years divergence. Finally we use RNAseq and whole genome resequencing data to compare the three assemblies as references, each representing an increased level of sequencing, cost and assembly efforts: Supernova Assembly with data from10X Genomics Chromium library; HiRise Assembly that added data from HiC library; and PBJelly Assembly that added data from PacBio sequencing. We found that the Supernova Assembly contained the full genome and was a suitable reference for RNAseq, but the chromosome-level scaffolds provided by the addition of the HiC data allowed the reference to be used for other whole genome analysis, including synteny and whole genome association mapping analyses. The addition of PacBio data provided negligible gains. Overall, these new genomic resources provide valuable tools for advanced molecular analysis of an organism that has become a model in physiology and evolutionary ecology.

genomics↗

bioRxiv2020

Factors influencing taxonomic unevenness in scientific research: A mixed-methods case study of non-human primate genomic sequence data generation

Scholars have often noted major disparities in the extent of scientific research conducted among taxonomic groups. Such trends may cascade if future scientists gravitate towards study species with more data and resources already available. As new technologies emerge, do research studies employing these technologies continue these disparities? Here, using non-human primates as a case study, we first identified disparities in recently-generated massively-parallel genomic sequencing data and we then conducted interviews with the scientists who produced these data to learn their motivations when selecting species for study. Specifically, we tested whether variables including publication history and conservation status were significantly correlated with publicly-available sequence data in the NCBI Sequence Read Archive. Of the 179.6 terabases (Tb) of sequence data in this database for 519 non-human primate species, 135 Tb (~75%) were from only five species: rhesus macaques, olive baboons, green monkeys, chimpanzees, and crab-eating macaques. The strongest individual predictors of the amount of genomic data were the total number of non-medical scholarly publications (linear regression; r2=0.37; P=6.15x10-12) and number of medical publications (r2=0.27; P=9.27x10-9). In a generalized linear model, the number of non-medical publications (P=0.00064) and closer phylogenetic distance to humans (P=0.024) were the most predictive of the amount of genomic sequence data. We interviewed 33 authors of genomic data-producing publications and analyzed their responses using a grounded theory approach. Consistent with our quantitative results, authors mentioned that their choices of species were motivated by sample accessibility, prior published work, and perceived relevance (especially health-related) to humans. Our mixed-methods approach helped us to identify and contextualize some of the driving factors behind species-uneven patterns of scientific research, which can now be considered by funding agencies, scientific societies, and research teams aiming to align their broader goals with future data generation efforts. SIGNIFICANCE STATEMENTOur study sheds lights on the species-uneven distribution of genomic sequence data generation across the order Primates. We used a combination of quantitative data analyses and qualitative interviews with authors of data-producing studies to identify factors that have driven the observed pattern of unevenness; these included the extent of prior research conducted on each species, the relevance to human medicine, phylogenetic distance to humans, and sample accessibility. While our study focused on factors influencing non-human primate genomic sequence data, similar questions can be asked about how the scientific community engages with research projects more broadly. Our goal is to bring attention to the diversity of factors that influence scientists as they plan their projects, so that this process can be considered in the future by research groups and funding agencies aiming to align their broader goals with future data generation efforts.

genomics↗

bioRxiv2020

Potential evolutionary body size reduction in a Malagasy primate (Propithecus verreauxi) in response to human size-selective hunting pressure

The Holocene arrival of humans on Madagascar precipitated major changes to the islands biodiversity. The now-extinct, endemic "subfossil" megafauna of Madagascar were likely hunted by the islands early human inhabitants. Perhaps in part due to preferential hunting of larger prey, no surviving species on Madagascar is larger than 10 kg. Outside of Madagascar, size-selective hunting pressure has resulted in the phyletic dwarfism of many still-living species across a diversity of phyla. On Madagascar, some subfossil bones of extant lemurs are considerably larger than those of the modern members of their species, but relatively large distances between the subfossil localities and modern samples that have been compared to date makes it impossible to reject the possibility that these size differences more simply reflect pre-existing ecogeographic variation. Here, we used high-resolution 3D scan data to conduct comparative morphological analyses of subfossil and modern skeletal remains of one of the larger extant lemurs, Verreauxs sifakas (Propithecus verreauxi) from subfossil and modern sites [~]10 km adjacent: Taolambiby (bones dated to 725-560 - 1075-955 cal. years before present) and Beza Mahafaly Special Reserve, respectively. We found that the average subfossil sifaka bone (n=12) is 9% and significantly larger than that of modern sifakas (n=31 individuals; permutation test; p=0.037). When restricting the analysis to the single element and side with the largest representation in the subfossil sample (n=4 right distal femora), the average subfossil bone is 10% larger (p=0.046). While we cannot yet conclude whether this size difference reflects evolutionary change or an archaeological aggregation/taphonomic process, if this is a case of phyletic dwarfism in response to human size-selective harvesting pressures then the estimated rate of evolutionary change is slightly higher than that previously calculated for other archaeological cases of this phenomenon.

evolutionary biology↗

bioRxiv2018

Natural selection contributed to immunological differences between human hunter-gatherers and agriculturalists

The shift from a hunter-gatherer (HG) to an agricultural (AG) mode of subsistence is believed to have been associated with profound changes in the burden and diversity of pathogens across human populations. Yet, the extent to which the advent of agriculture may have impacted the evolution of the human immune system remains unknown. Here we present a comparative study of variation in the transcriptional responses of peripheral blood mononuclear cells to bacterial and viral stimuli between Batwa rainforest hunter-gatherers and Bakiga agriculturalists from Uganda. We observed increased divergence between hunter-gatherers and agriculturalists in the transcriptional response to viruses compared to that for bacterial stimuli. We demonstrate that a significant fraction of these transcriptional differences are under genetic control, and we show that positive natural selection has helped to shape population differences in immune regulation. Across the set of genetic variants underlying inter-population immune response differences, however, the signatures of positive selection were disproportionately observed in the rainforest hunter-gatherers. This result is counter to expectations based on the popularized notion that shifts in pathogen exposure due to the advent of agriculture imposed radically heightened selective pressures in agriculturalist populations.

evolutionary biology↗

bioRxiv2018

Polygenic adaptation and convergent evolution across both growth and cardiac genetic pathways in African and Asian rainforest hunter-gatherers

Different human populations facing similar environmental challenges have sometimes evolved convergent biological adaptations, for example hypoxia resistance at high altitudes and depigmented skin in northern latitudes on separate continents. The pygmy phenotype (small adult body size), a characteristic of hunter-gatherer populations inhabiting both African and Asian tropical rainforests, is often highlighted as another case of convergent adaptation in humans. However, the degree to which phenotypic convergence in this polygenic trait is due to convergent vs. population-specific genetic changes is unknown. To address this question, we analyzed high-coverage sequence data from the protein-coding portion of the genomes (exomes) of two pairs of populations, Batwa rainforest hunter-gatherers and neighboring Bakiga agriculturalists from Uganda, and Andamanese rainforest hunter-gatherers (Jarawa and Onge) and Brahmin agriculturalists from India. We observed signatures of convergent positive selection between the Batwa and Andamanese rainforest hunter-gatherers across the set of genes with annotated growth factor binding functions (p < 0.001). Unexpectedly, for the rainforest groups we also observed convergent and population-specific signatures of positive selection in pathways related to cardiac development (e.g. cardiac muscle tissue development; p = 0.001). We hypothesize that the growth hormone sub-responsiveness likely underlying the pygmy phenotype may have led to compensatory changes in cardiac pathways, in which this hormone also plays an essential role. Importantly, in the agriculturalist populations we did not observe similar patterns of positive selection on sets of genes associated with either growth or cardiac development, indicating that our results most likely reflect a history of convergent adaptation to the similar ecology of rainforest hunter-gatherers rather than a more common or general evolutionary pattern for human populations.

genomics↗

bioRxiv2018

A novel environmental DNA (eDNA) sampling method for aye-ayes from their feeding traces

Non-invasive sampling is an important development in population genetic monitoring of wild animals. Particularly, the collection of environmental DNA (eDNA) which can be collected without needing to encounter the target animal, facilitates the genetic analysis of cryptic and threatened species. One method that has been applied to these types of sample is target capture and enrichment which overcomes the issue of high proportions of exogenous (non-host) DNA from these lower quality samples. We tested whether target capture of mitochondrial DNA from sampled feeding traces of wild aye-ayes would yield mitochondrial DNA sequences for population genetic monitoring. We sampled gnawed wood from feeding traces where aye-ayes excavate wood-boring insect larvae from trees. We designed RNA probes complementary to the aye-ayes mitochondrial genome and used these to isolate aye-aye DNA from other non-target DNA in these samples. We successfully retrieved six near-complete mitochondrial genomes from two sites within the aye-ayes geographic range that had not been sampled previously. This method can likely be applied to alternative foraged remains to sample species other than aye-ayes. Our method demonstrates the application to next-generation molecular techniques to species of conservation concern.

molecular biology↗

bioRxiv2017

Mitochondrial genomes of the regionally extinct Nittany Lion (Puma concolor from Pennsylvania)

Mountain lions (Puma concolor) were once endemic across the United States. The Northeastern population of mountain lions has been largely nonexistent since the early 1800s and was officially declared extinct in 2011. This regionally extinct mountain lion is Pennsylvania State Universitys official mascot, where it is referred to as the Nittany Lion. Our goal in this study was to use recent methodological advances in ancient DNA and massively parallel sequencing to reconstruct complete mitochondrial DNA (mtDNA) genomes of multiple Nittany Lions by sampling from preserved skins. This effort is part of a broader Nittany Lion Genome project intended to involve undergraduates in ancient DNA and bioinformatics research and to engage the broader Penn State community in discussions about conservation biology and extinction. Complete mtDNA genome sequences were obtained from five individuals. When compared to previously published sequences, Nittany Lions are not more similar to each other than to individuals from the Western U.S. and Florida. Supporting previous findings, North American mountain lions overall were more closely related to each other than to those from South America and had lower genetic diversity. This result emphasizes the importance of continued conservation in the Western U.S. and Florida to prevent further regional extinctions.

ecology↗

bioRxiv2017

The demographic history and mutational load of African hunter-gatherers and farmers

The distribution of deleterious genetic variation across human populations is a key issue in evolutionary biology and medical genetics. However, the impact of different modes of subsistence on recent changes in population size, patterns of gene flow, and deleterious mutational load remains unclear. Here, we report high-coverage exome sequencing data from various populations of rainforest hunter-gatherers and farmers from central Africa. We find that the recent demographic histories of hunter-gatherers and farmers differed considerably, with population collapses for hunter-gatherers and expansions for farmers, accompanied by increased gene flow. We show that purifying selection against deleterious alleles is of similar efficiency across African populations, in contrast with Europeans where we detect weaker purifying selection. Furthermore, the per-individual mutation load of rainforest hunter-gatherers is similar to that of farmers, under both additive and recessive models. Our results indicate that differences in the cultural practices and demographic regimes of African populations have not resulted in large differences in mutational burden, and highlight the beneficial role of gene flow in reshaping the distribution of deleterious genetic variation across human populations.

evolutionary biology↗

bioRxiv2016

Transposable element exaptation is the primary source of novelty in the primate gene regulatory landscape

Gene regulation plays a critical role in the evolution of phenotypic diversity. We investigated the evolution of liver promoters and enhancers in six primate species. We performed ChlP-seq for two histone modifications and RNA-seq to profile cis-regulatory element (CRE) activity and gene expression. The primate regulatory landscape is largely conserved across the lineage. Conserved CRE function is associated with sequence conservation, proximity to coding genes, cell type specificity of CRE function, and transcription factor binding. Newly evolved CREs are enriched in immune response and neurodevelopmental functions, while conserved CREs bind master regulators. Transposable elements (TEs) are the primary source of novelty in primate gene regulation. Newly evolved CREs are enriched in young TEs that affect gene expression. However, only 17% of conserved CREs overlap a TE, suggesting that target gene expression is under strong selection. Finally, we identified specific genomic features driving the functional recruitment of newly inserted TEs.

genomics↗