Browsing by Author "Platt, Roy N. (TTU)"
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Item Conflicting Evolutionary Histories of the Mitochondrial and Nuclear Genomes in New World Myotis Bats(2018) Platt, Roy N. (TTU); Faircloth, Brant C.; Sullivan, Kevin A.M. (TTU); Kieran, Troy J.; Glenn, Travis C.; Vandewege, Michael W. (TTU); Lee, Thomas E.; Baker, Robert J. (TTU); Stevens, Richard D. (TTU); Ray, David A. (TTU)The rapid diversification of Myotis bats into more than 100 species is one of the most extensive mammalian radiations available for study. Efforts to understand relationships within Myotis have primarily utilized mitochondrial markers and trees inferred from nuclear markers lacked resolution.Our current understanding of relationships within Myotis is therefore biased towards a set of phylogenetic markers that may not reflect the history of the nuclear genome. To resolve this, we sequenced the full mitochondrial genomes of 37 representative Myotis, primarily from the NewWorld, in conjunction with targeted sequencing of 3648 ultraconserved elements (UCEs). We inferred the phylogeny and explored the effects of concatenation and summary phylogenetic methods, as well as combinations of markers based on informativeness or levels of missing data, on our results. Of the 294 phylogenies generated from the nuclear UCE data, all are significantly different from phylogenies inferred using mitochondrial genomes. Even within the nuclear data, quartet frequencies indicate that around half of all UCE loci conflict with the estimated species tree. Several factors can drive such conflict, including incomplete lineage sorting, introgressive hybridization, or even phylogenetic error. Despite the degree of discordance between nuclear UCE loci and the mitochondrial genome and among UCE loci themselves, the most common nuclear topology is recovered in one quarter of all analyses with strong nodal support. Based on these results, we re-examine the evolutionary history of Myotis to better understand the phenomena driving their unique nuclear, mitochondrial, and biogeographic histories.Item Differential SINE evolution in vesper and non-vesper bats(2015) Ray, David A. (TTU); Pagan, Heidi J.T.; Platt, Roy N. (TTU); Kroll, Ashley R.; Schaack, Sarah; Stevens, Richard D. (TTU)Background: Short interspersed elements (SINEs) have a powerful influence on genome evolution and can be useful markers for phylogenetic inference and population genetic analyses. In this study, we examined survey sequence and whole genome data to determine the evolutionary dynamics of Ves SINEs in the genomes of 11 bats, nine from Vespertilionidae. Results: We identified 41 subfamilies of Ves and linked several to specific lineages. We also revealed substantial differences among lineages including the observation that Ves accumulation and Ves subfamily diversity is significantly higher in vesper as opposed to non-vesper bats. This is especially interesting when one considers the increased transposable element diversity of vesper bats in general. Conclusions: Our data suggest that survey sequencing and genome mining are valuable tools to investigate SINE evolution among related lineages and can provide substantial information about the ability of SINEs to proliferate in diverse genomes. This method would also be a useful first step in determining which subfamilies would be the best to target when developing SINEs as markers for phylogenetic and population genetic analyses.Item Evolution and diversity of transposable elements in vertebrate genomes(2017) Sotero-Caio, Cibele G. (TTU); Platt, Roy N. (TTU); Suh, Alexander; Ray, David A. (TTU)Transposable elements (TEs) are selfish genetic elements that mobilize in genomes via transposition or retrotransposition and often make up large fractions of vertebrate genomes. Here, were view the current understanding of vertebrate TE diversity and evolution in the context of recent advances in genome sequencing and assembly techniques. TEs make up 4-60% of assembled vertebrate genomes, and deeply branching lineages such as ray-finned fishes and amphibians generally exhibit a higher TE diversity than the more recent radiations of birds andmammals. Furthermore, the list of taxa with exceptional TE landscapes is growing. We emphasize that the current bottleneck in genome analyses lies in the proper annotation of TEs and provide examples where superficial analyses led tomisleading conclusions about genome evolution. Finally, recent advances inlong-read sequencing will soon permit access to TErich genomic regions that previously resisted assembly including the gigantic, TE-rich genomes of salamanders and lungfishes.Item Genome sequence of Phormia regina Meigen (Diptera: Calliphoridae): Implications for medical, veterinary and forensic research(2016) Andere, Anne A.; Platt, Roy N. (TTU); Ray, David A. (TTU); Picard, Christine J.Background: Blow flies (Diptera: Calliphoridae) are important medical, veterinary and forensic insects encompassing 8 % of the species diversity observed in the calyptrate insects. Few genomic resources exist to understand the diversity and evolution of this group. Results: We present the hybrid (short and long reads) draft assemblies of the male and female genomes of the common North American blow fly, Phormia regina (Diptera: Calliphoridae). The 550 and 534 Mb draft assemblies contained 8312 and 9490 predicted genes in the female and male genomes, respectively; including>93 % conserved eukaryotic genes. Putative X and Y chromosomes (21 and 14 Mb, respectively) were assembled and annotated. The P. regina genomes appear to contain few mobile genetic elements, an almost complete absence of SINEs, and most of the repetitive landscape consists of simple repetitive sequences. Candidate gene approaches were undertaken to annotate insecticide resistance, sex-determining, chemoreceptors, and antimicrobial peptides. Conclusions: This work yielded a robust, reliable reference calliphorid genome from a species located in the middle of a calliphorid phylogeny. By adding an additional blow fly genome, the ability to tease apart what might be true of general calliphorids vs. what is specific of two distinct lineages now exists. This resource will provide a strong foundation for future studies into the evolution, population structure, behavior, and physiology of all blow flies.Item Improved genome assembly of American alligator genome reveals conserved architecture of estrogen signaling(2017) Rice, Edward S.; Kohno, Satomi; St John, John; Pham, Son; Howard, Jonathan; Lareau, Liana F.; O'Connell, Brendan L.; Hickey, Glenn; Armstrong, Joel; Deran, Alden; Fiddes, Ian; Platt, Roy N. (TTU); Gresham, Cathy; McCarthy, Fiona; Kern, Colin; Haan, David; Phan, Tan; Schmidt, Carl; Sanford, Jeremy R.; Ray, David A. (TTU); Paten, Benedict; Guillette, Louis J.; Green, Richard E.The American alligator, Alligator mississippiensis, like all crocodilians, has temperature-dependent sex determination, in which the sex of an embryo is determined by the incubation temperature of the egg during a critical period of development. The lack of genetic differences between male and female alligators leaves open the question of how the genes responsible for sex determination and differentiation are regulated. Insight into this question comes from the fact that exposing an embryo incubated at male-producing temperature to estrogen causes it to develop ovaries. Because estrogen response elements are known to regulate genes over long distances, a contiguous genome assembly is crucial for predicting and understanding their impact. We present an improved assembly of the American alligator genome, scaffolded with in vitro proximity ligation (Chicago) data. We use this assembly to scaffold two other crocodilian genomes based on synteny. We perform RNA sequencing of tissues from American alligator embryos to find genes that are differentially expressed between embryos incubated at male- versus female-producing temperature. Finally, we use the improved contiguity of our assembly along with the current model of CTCF-mediated chromatin looping to predict regions of the genome likely to contain estrogen-responsive genes. We find that these regions are significantly enriched for genes with female-biased expression in developing gonads after the critical period during which sex is determined by incubation temperature. We thus conclude that estrogen signaling is a major driver of female-biased gene expression in the posterature sensitive period gonads.Item Multiple lineages of ancient CR1 retroposons shaped the early genome evolution of amniotes(2014) Suh, Alexander; Churakov, Gennady; Ramakodi, Meganathan P.; Platt, Roy N. (TTU); Jurka, Jerzy; Kojima, Kenji K.; Caballero, Juan; Smit, Arian F.; Vliet, Kent A.; Hoffmann, Federico G.; Brosius, Jurgen; Green, Richard E.; Braun, Edward L.; Ray, David A. (TTU); Schmitz, JurgenChicken repeat 1 (CR1) retroposons are long interspersed elements (LINEs) that are ubiquitous within amniote genomes and constitute the most abundant family of transposed elements in birds, crocodilians, turtles, and snakes. They are also present in mammalian genomes, where they reside as numerous relics of ancient retroposition events. Yet, despite their relevance for understanding amniote genome evolution, the diversity and evolution of CR1 elements has never been studied on an amniote-wide level. We reconstruct the temporal and quantitative activity of CR1 subfamilies via presence/absence analyses across crocodilian phylogeny and comparative analyses of 12 crocodilian genomes, revealing relative genomic stasis of retroposition during genome evolution of extant Crocodylia. Our large-scale phylogenetic analysis of amniote CR1 subfamilies suggests the presence of at least seven ancient CR1 lineages in the amniote ancestor; and amniote-wide analyses of CR1 successions and quantities reveal differential retention (presence of ancient relics or recent activity) of these CR1 lineages across amniote genome evolution. Interestingly, birds and lepidosaurs retained the fewest ancient CR1 lineages among amniotes and also exhibit smaller genome sizes. Our study is the first to analyze CR1 evolution in a genome-wide and amniote-wide context and the data strongly suggest that the ancestral amniote genome contained myriad CR1 elements from multiple ancient lineages, and remnants of these are still detectable in the relatively stable genomes of crocodilians and turtles. Early mammalian genome evolution was thus characterized by a drastic shift from CR1 prevalence to dominance and hyperactivity of L2 LINEs in monotremes and L1 LINEs in therians.Item Pinpointing the vesper bat transposon revolution using the Miniopterus natalensis genome(2016) Platt, Roy N. (TTU); Mangum, Sarah F. (TTU); Ray, David A. (TTU)Background: Around 40 million years ago DNA transposons began accumulating in an ancestor of bats in the family Vespertilionidae. Since that time, Class II transposons have been continuously reinvading and accumulating in vespertilionid genomes at a rate that is unprecedented in mammals. Miniopterus (Miniopteridae), a genus of long-fingered bats that was recently elevated from Vespertilionidae, is the sister taxon to the vespertilionids and is often used as an outgroup when studying transposable elements in vesper bats. Previous wet-lab techniques failed to identify Helitrons, TcMariners, or hAT transposons in Miniopterus. Limitations of those methods and ambiguous results regarding the distribution of piggyBac transposons left some questions as to the distribution of Class II elements in this group. The recent release of the Miniopterus natalensis genome allows for transposable element discovery with a higher degree of precision. Results: Here we analyze the transposable element content of M. natalensis to pinpoint with greater accuracy the taxonomic distribution of Class II transposable elements in bats. These efforts demonstrate that, compared to the vespertilionids, Class II TEs are highly mutated and comprise only a small portion of the M. natalensis genome. Despite the limited Class II content, M. natalensis possesses a limited number of lineage-specific, low copy number piggyBacs and shares several TcMariner families with vespertilionid bats. Multiple efforts to identify Helitrons, one of the major TE components of vesper bat genomes, using de novo repeat identification and structural based searches failed. Conclusions: These observations combined with previous results inform our understanding of the events leading to the unique Class II element acquisition that characterizes vespertilionids. While it appears that a small number of TcMariner and piggyBac elements were deposited in the ancestral Miniopterus + vespertilionid genome, these elements are not present in M. natalensis genome at high copy number. Instead, this work indicates that the vesper bats alone experienced the expansion of TEs ranging from Helitrons to piggyBacs to hATs.Item Targeted capture of phylogenetically informative ves SINE insertions in genus Myotis(2015) Platt, Roy N. (TTU); Zhang, Yuhua; Witherspoon, David J.; Xing, Jinchuan; Suh, Alexander; Keith, Megan S. (TTU); Jorde, Lynn B.; Stevens, Richard D. (TTU); Ray, David A. (TTU)Identification of retrotransposon insertions in nonmodel taxa can be technically challenging and costly. This has inhibited progress in understanding retrotransposon insertion dynamics outside of a fewwell-studied species. To address this problem,wehave extended a retrotransposon-based capture and sequence method (ME-Scan [mobile element scanning]) to identify insertions belonging to the Ves family of short interspersed elements (SINEs) across seven species of the bat genus Myotis. We identified between 120,000 and 143,000 SINE insertions in six taxa lacking a draft genomeby comparing to the M. lucifugus reference genome.Onaverage, eachVes insertion was sequenced to 129.6 × coverage. When mapped back to the M. lucifugus reference genome, all insertions were confidently assigned within a 10-bp window. Polymorphic Ves insertions were identified in each taxon based on their mapped locations. Using cross-species comparisons and the identified insertion positions, a presence-absence matrix was created for approximately 796,000 insertions. Dollo parsimony analysis of more than 85,000 phylogenetically informative insertions recovered strongly supported, monophyletic clades that correspond with the biogeography of each taxa. This phylogeny is similar to previously published mitochondrial phylogenies, with the exception of the placement of M. vivesi. These results support the utility of our variation on ME-Scan to identify polymorphic retrotransposon insertions in taxa without a reference genome and for large-scale retrotransposon-based phylogenetics.Item Whole mitochondrial genomes provide increased resolution and indicate paraphyly in deer mice(2017) Sullivan, Kevin A.M. (TTU); Platt, Roy N. (TTU); Bradley, Robert D. (TTU); Ray, David A. (TTU)Background Recent phylogenies of deer mice, genus Peromyscus, have relied heavily on mitochondrial markers. These markers provided resolution at and below the level of species groups, but relationships among species groups and Peromyscus affiliated genera have received little support. Here, we present the mitochondrial genomes of 14 rodents and infer the phylogeny of Peromyscus and related taxa. Results Our analyses support results from previous molecular phylogenies, but also yield support for several previously unsupported nodes throughout the Peromyscus tree. Our results also confirm several instances of paraphyly within the clade and suggest additional taxonomic work will be required to clarify some relationships. Conclusions Our findings greatly enhance our understanding of the evolution of Peromyscus providing support for previously unsupported relationships. However, the results also highlight the need to address paraphyly that may exist in this clade.