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result(s) for
"Alexander, Alana"
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Genomic data reveals potential for hybridization, introgression, and incomplete lineage sorting to confound phylogenetic relationships in an adaptive radiation of narrow-mouth frogs
by
Alexander, Alana M.
,
Travers, Scott L.
,
Su, Yong-Chao
in
Adaptive radiation
,
Amphibians
,
Animals
2017
The microhylid frog genus Kaloula is an adaptive radiation spanning the edge of the Asian mainland and multiple adjacent island archipelagos, with much of the clade’s diversity associated with an endemic Philippine radiation. Relationships among clades from the Philippines, however, remain unresolved. With ultraconserved element (UCE) and mitogenomic data, we identified highly supported differences in topology and areas of poor resolution, for each marker set. Using the UCE data, we then identified possible instances of contemporary hybridization, past introgression, and incomplete lineage sorting (ILS) within the Philippine Kaloula. Using a simulation approach, and an estimate of the Philippine Kaloula clade origin (12.7—21.0 mya), we demonstrate that an evolutionary history including inferred instances of hybridization, introgression, and ILS leads to phylogenetic reconstructions that show concordance with results from the observed mitogenome and UCE data. In the process of validating a complex evolutionary scenario in the Philippine Kaloula, we provide the first demonstration of the efficacy of UCE data for phylogenomic studies of anuran amphibians.
Journal Article
The Eurasian invasion: phylogenomic data reveal multiple Southeast Asian origins for Indian Dragon Lizards
by
Grismer, Jesse L.
,
Welton, Luke J.
,
Travers, Scott L.
in
Adaptation (Biology)
,
Agamid lizards
,
Analysis
2016
Background
The Indian Tectonic Plate split from Gondwanaland approximately 120 MYA and set the Indian subcontinent on a ~ 100 million year collision course with Eurasia. Many phylogenetic studies have demonstrated the Indian subcontinent brought with it an array of endemic faunas that evolved
in situ
during its journey, suggesting this isolated subcontinent served as a source of biodiversity subsequent to its collision with Eurasia. However, recent molecular studies suggest that Eurasia may have served as the faunal source for some of India’s biodiversity, colonizing the subcontinent through land bridges between India and Eurasia during the early to middle Eocene (~35–40 MYA). In this study we investigate whether the Draconinae subfamily of the lizard family Agamidae is of Eurasian or Indian origin, using a multi locus Sanger dataset and a novel dataset of 4536 ultraconserved nuclear element loci.
Results
Results from our phylogenetic and biogeographic analyses revealed support for two independent colonizations of India from Eurasian ancestors during the early to late Eocene prior to the subcontinent’s hard collision with Eurasia.
Conclusion
These results are consistent with other faunal groups and new geologic models that suggest ephemeral Eocene land bridges may have allowed for dispersal and exchange of floras and faunas between India and Eurasia during the Eocene.
Journal Article
Coat colour in marsupials: genetic variants at the ASIP locus determine grey and black fur of the brushtail possum
by
Hore, Timothy A.
,
Bond, Donna M.
,
Alexander, Alana
in
agouti signalling protein
,
ASIP
,
brushtail possum
2024
The possession of fur or hair is a defining characteristic of mammals and can occur in a variety of colours and patterns. While genetic determinants of coat colour are well described in eutherian ‘placental’ mammals, the other major mammalian infraclass, marsupials, is grossly understudied. The fur of the common brushtail possum ( Trichosurus vulpecula ), an iconic native mammal found throughout Australia and introduced into Aotearoa New Zealand, possesses two main colour morphs: grey and black. To identify genetic variants associated with coat colour, we performed a genome-wide association study (GWAS) with genotype by sequencing (GBS) data. Single nucleotide variants (SNVs) on chromosome 3, close to the agouti signalling protein ( ASIP ) gene that controls the temporal and spatial distribution of pigments in eutherian mammals, were identified. Fine-mapping identified a C>T variant at chr3:100483705 that results in a ASIP:p.Arg115Cys missense substitution, and animals homozygous for this variant have black fur. In addition to uncovering the first genetic determinant of coat colour in a natural marsupial population, comparative analysis of ASIP in divergent marsupial species identified the dasyurids as having accelerated evolution, reflecting their well described diversity of coat colour and pattern.
Journal Article
The admixed brushtail possum genome reveals invasion history in New Zealand and novel imprinted genes
2023
Combining genome assembly with population and functional genomics can provide valuable insights to development and evolution, as well as tools for species management. Here, we present a chromosome-level genome assembly of the common brushtail possum (
Trichosurus vulpecula
), a model marsupial threatened in parts of their native range in Australia, but also a major introduced pest in New Zealand. Functional genomics reveals post-natal activation of chemosensory and metabolic genes, reflecting unique adaptations to altricial birth and delayed weaning, a hallmark of marsupial development. Nuclear and mitochondrial analyses trace New Zealand possums to distinct Australian subspecies, which have subsequently hybridised. This admixture allowed phasing of parental alleles genome-wide, ultimately revealing at least four genes with imprinted, parent-specific expression not yet detected in other species (
MLH1
,
EPM2AIP1
,
UBP1
and
GPX7
). We find that reprogramming of possum germline imprints, and the wider epigenome, is similar to eutherian mammals except onset occurs after birth. Together, this work is useful for genetic-based control and conservation of possums, and contributes to understanding of the evolution of novel mammalian epigenetic traits.
The brushtail possum is a treasured Australian marsupial, but also a harmful pest introduced into New Zealand. Here, using functional genomics and a new chromosome-level genome assembly of New Zealand possums, Bond et al. quantify their genome admixture and identify unique parent-specific and weaning associated gene expression.
Journal Article
Landscape Genetics of Aedes mcintoshi (Diptera: Culicidae), an Important Vector of Rift Valley Fever Virus in Northeastern Kenya
2017
Rift Valley fever virus (RVFV) is a vector-borne, zoonotic disease that affects humans, wild ungulates, and domesticated livestock in Africa and the Arabian Peninsula. Rift Valley fever virus exhibits interepizootic and epizootic phases, the latter defined by widespread virus occurrence in domesticated livestock. Kenya appears to be particularly vulnerable to epizootics, with 11 outbreaks occurring between 1951 and 2007. The mosquito species Aedes mcintoshi (subgenus Neomelaniconion) is an important primary vector for RVFV in Kenya. Here, we investigate associations between genetic diversity and differentiation of one regional subclade of Ae. mcintoshi in Northeastern Kenya with environmental variables, using a multivariate statistical approach. Using CO1 (cytochrome oxidase subunit 1) sequence data deposited in GenBank, we found no evidence of isolation by distance contributing to genetic differentiation across the study area. However, we did find significant CO1 subpopulation structure and associations with recent mean precipitation values. In addition, variation in genetic diversity across our seven sample sites was associated with both precipitation and percentage clay in the soil. The large number of haplotypes found in this data set indicates that a great deal of diversity remains unsampled in this region. Additional sampling across a larger geographic area, combined with next-generation sequencing approaches that better characterize the genome, would provide a more robust assessment of genetic diversity and differentiation. Further understanding of the genetic structure of Ae. mcintoshi could provide useful information regarding the potential for RVFV to spread across East African landscapes.
Journal Article
Ultraconserved element (UCE) probe set design: Base genome and initial design parameters critical for optimization
2019
Targeted capture and enrichment approaches have proven effective for phylogenetic study. Ultraconserved elements (UCEs) in particular have exhibited great utility for phylogenomic analyses, with the software package phyluce being among the most utilized pipelines for UCE phylogenomics, including probe design. Despite the success of UCEs, it is becoming increasing apparent that diverse lineages require probe sets tailored to focal taxa in order to improve locus recovery. However, factors affecting probe design and methods for optimizing probe sets to focal taxa remain underexplored. Here, we use newly available beetle (Coleoptera) genomic resources to investigate factors affecting UCE probe set design using phyluce. In particular, we explore the effects of stringency during initial design steps, as well as base genome choice on resulting probe sets and locus recovery. We found that both base genome choice and initial bait design stringency parameters greatly alter the number of resultant probes included in final probe sets and strongly affect the number of loci detected and recovered during in silico testing of these probe sets. In addition, we identify attributes of base genomes that correlated with high performance in probe design. Ultimately, we provide a recommended workflow for using Phyluce to design an optimized UCE probe set that will work across a targeted lineage, and use our findings to develop a new, open‐source UCE probe set for beetles of the suborder Adephaga. Base genome and initial design parameters are found to greatly affect UCE probe set design. In order to design an optimized probe set with the largest number of probes with the longest lengths, base genome experiments should be conducted or the taxon with the smallest average genetic distance from all other taxa of interest should be selected to serve as the base genome. Probe design should then proceed with less stringent initial design parameters, targeting loci share between the base genome and as few as one other taxon.
Journal Article
Long Distance Runners in the Marine Realm: New Insights Into Genetic Diversity, Kin Relationships and Social Fidelity of Indian Ocean Male Sperm Whales
by
Sarano, Véronique
,
Alexander, Alana
,
Vitry, Hugues
in
Biodiversity
,
cultural species
,
Environmental Sciences
2022
Adult male sperm whales ( Physeter macrocephalus ) are long distance runners of the marine realm, feeding in high latitudes and mating in tropical and subtropical waters where stable social groups of females and immatures live. Several areas of uncertainty still limit our understanding of their social and breeding behavior, in particular concerning the potential existence of geographical and/or social fidelities. In this study, using underwater observation and sloughed-skin sampling, we looked for male social fidelity to a specific matrilineal sperm whale group near Mauritius. In addition, we captured a wider picture of kin relationships and genetic diversity of male sperm whales in the Indian Ocean thanks to biopsies of eight individuals taken in a feeding ground near the Kerguelen and Crozet Archipelagos (Southern Indian Ocean). Twenty-six adult male sperm whales were identified when socializing with adult females and immatures off Mauritius. Sloughed-skin samples were taken from thirteen of them for genetic analysis. Long-term underwater observation recorded several noteworthy social interactions between adult males and adult females and/or immatures. We identified seven possible male recaptures over different years (three by direct observation, and four at the gametic level), which supports a certain level of male social fidelity. Two probable first- and thirty second-degree kin relationships were highlighted between members of the social unit and adult males, confirming that some of the adult males observed in Mauritian waters are reproductive. Male social philopatry to their natal group can be excluded, as none of the males sampled shared the haplotype characteristic of the matrilineal social group. Mitochondrial DNA control region haplotype and nucleotide diversities calculated over the 21 total male sperm whales sampled were similar to values found by others in the Indian Ocean. Our study strongly supports the existence of some levels of male sperm whale social fidelity, not directed to their social group of birth, in the Indian Ocean. Males sampled in breeding and feeding grounds are linked by kin relationships. Our results support a model of male mediated gene flow occurring at the level of the whole Indian Ocean, likely interconnected with large-scale geographical fidelity to ocean basin, and a small-scale social fidelity to matrilineal social groups.
Journal Article
The complete mitogenome sequence of the agricultural pest, clover root weevil: the key to its own demise?
by
Tompkins, Daniel M.
,
Gemmell, Neil J.
,
Dearden, Peter K.
in
Complete mitochondrial sequence
,
Mitochondrial DNA
,
Pest control
2019
We report the complete mitogenome of Sitona obsoletus, an agricultural pest in New Zealand and some European countries. Like other Sitona mitogenomes, the 6 tRNA gene box is ordered RNSAEF, supporting the hypothesis that this signature is common to, and potentially diagnostic, of this genus. The Trojan Female Technique (TFT) is a genetic pest control strategy that exploits mitochondrial DNA alleles that affect male, but not female fertility and fitness. The complete mitogenome is an essential first step in exploring the utility of TFT for the control of S. obsoletus.
Journal Article
Narratives of Resilience: The Power of Creative Expression and Community Support During Familial Incarceration
2024
Existing literature stresses that the far-reaching effects of mass incarceration extend beyond prison walls, profoundly shaping familial experiences. Despite this, families remain consistently overlooked in criminal justice discourse, leading to heightened stress and diminished resilience. This thesis is a program review of a community-based program, referred to here as the Storytelling, Creativity, and Care (SCC) program, to protect the confidentiality of its participants and activities. The SCC program integrates neuroscience and narrative theory to explore how storytelling influences cultural perceptions, shapes lived experiences, and supports psychological and physiological healing. Additionally, this work investigates the socio-political narratives that perpetuate stigma and shame, further entrenching the carceral system’s impact on families. By tailoring interventions to the unique challenges faced by system-impacted families, this review emphasizes the essential role of community-based programs in breaking cycles of recidivism and intergenerational incarceration while amplifying the voices of families to drive healing and social justice.
Dissertation
Divergent sensory and immune gene evolution in sea turtles with contrasting demographic and life histories
by
Benson, Scott R.
,
Jarvis, Erich D.
,
Arantes, Larissa Souza
in
Adaptation
,
Animals
,
Anthropogenic factors
2023
Sea turtles represent an ancient lineage of marine vertebrates that evolved from terrestrial ancestors over 100 Mya. The genomic basis of the unique physiological and ecological traits enabling these species to thrive in diverse marine habitats remains largely unknown. Additionally, many populations have drastically declined due to anthropogenic activities over the past two centuries, and their recovery is a high global conservation priority. We generated and analyzed high-quality reference genomes for the leatherback (Dermochelys coriacea) and green (Chelonia mydas) turtles, representing the two extant sea turtle families. These genomes are highly syntenic and homologous, but localized regions of noncollinearity were associated with higher copy numbers of immune, zinc-finger, and olfactory receptor (OR) genes in green turtles, with ORs related to waterborne odorants greatly expanded in green turtles. Our findings suggest that divergent evolution of these key gene families may underlie immunological and sensory adaptations assisting navigation, occupancy of neritic versus pelagic environments, and diet specialization. Reduced collinearity was especially prevalent in microchromosomes, with greater gene content, heterozygosity, and genetic distances between species, supporting their critical role in vertebrate evolutionary adaptation. Finally, diversity and demographic histories starkly contrasted between species, indicating that leatherback turtles have had a low yet stable effective population size, exhibit extremely low diversity compared with other reptiles, and harbor a higher genetic load compared with green turtles, reinforcing concern over their persistence under future climate scenarios. These genomes provide invaluable resources for advancing our understanding of evolution and conservation best practices in an imperiled vertebrate lineage.
Journal Article