34 results on '"Welch, Mark E."'
Search Results
2. Contrasting Patterns of Movement across Life Stages in an Insular Iguana Population
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Moss, Jeanette B., Gerber, Glenn P., Goetz, Matthias, Haakonsson, Jane E., Harvey, Jessica C., Laaser, Tanja, and Welch, Mark E.
- Published
- 2020
3. Clinal Variation in Short Tandem Repeats Linked to Gene Expression in Sunflower (Helianthus annuus L.).
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Ranathunge, Chathurani and Welch, Mark E.
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BIOLOGICAL evolution , *MICROSATELLITE repeats , *COMMON sunflower , *GENE expression , *PHENOTYPES - Abstract
Short tandem repeat (STR) variation is rarely explored as a contributor to adaptive evolution. An intriguing mechanism involving STRs suggests that STRs function as "tuning knobs" of adaptation whereby stepwise changes in STR allele length have stepwise effects on phenotypes. Previously, we tested the predictions of the "tuning knob" model at the gene expression level by conducting an RNA-Seq experiment on natural populations of common sunflower (Helianthus annuus L.) transecting a well-defined cline from Kansas to Oklahoma. We identified 479 STRs with significant allele length effects on gene expression (eSTRs). In this study, we expanded the range to populations further north and south of the focal populations and used a targeted approach to study the relationship between STR allele length and gene expression in five selected eSTRs. Seeds from 96 individuals from six natural populations of sunflower from Nebraska and Texas were grown in a common garden. The individuals were genotyped at the five eSTRs, and gene expression was quantified with qRT-PCR. Linear regression models identified that eSTR length in comp26672 was significantly correlated with gene expression. Further, the length of comp26672 eSTR was significantly correlated with latitude across the range from Nebraska to Texas. The eSTR locus comp26672 was located in the CHUP1 gene, a gene associated with chloroplast movement in response to light intensity, which suggests a potential adaptive role for the eSTR locus. Collectively, our results from this targeted study show a consistent relationship between allele length and gene expression in some eSTRs across a broad geographical range in sunflower and suggest that some eSTRs may contribute to adaptive traits in common sunflower. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. The Origin of Ecological Divergence in Helianthus paradoxus (Asteraceae): Selection on Transgressive Characters in a Novel Hybrid Habitat
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Lexer, Christian, Welch, Mark E., Raymond, Olivier, and Rieseberg, Loren H.
- Published
- 2003
5. Patterns of Genetic Variation Suggest a Single, Ancient Origin for the Diploid Hybrid Species Helianthus paradoxus
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Welch, Mark E. and Rieseberg, Loren H.
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- 2002
6. Habitat Divergence between a Homoploid Hybrid Sunflower Species, Helianthus paradoxus (Asteraceae), and Its Progenitors
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Welch, Mark E. and Rieseberg, Loren H.
- Published
- 2002
7. First evidence for crossbreeding between invasive Iguana iguana and the native rock iguana (Genus Cyclura) on Little Cayman Island
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Moss, Jeanette B., Welch, Mark E., Burton, Frederic J., Vallee, Michael V., Houlcroft, Edward W., Laaser, Tanja, and Gerber, Glenn P.
- Published
- 2018
- Full Text
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8. Molecular variation and population structure in critically endangered Turks and Caicos Rock Iguanas: identifying intraspecific conservation units and revising subspecific taxonomy
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Welch, Mark E., Colosimo, Giuliano, Pasachnik, Stesha A., Malone, Catherine L., Hilton, Jace, Long, June, Getz, Angela H., Alberts, Allison C., and Gerber, Glenn P.
- Published
- 2017
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9. Re-Evaluating the Taxonomic Status of the Booby Cay Iguana, Cyclura carinata bartschi
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Bryan, Jason J., Gerber, Glenn P., Welch, Mark E., and Stephen, Catherine L.
- Published
- 2007
10. Inheritance of Chloroplast DNA Is Not Strictly Maternal in Silene vulgaris (Caryophyllaceae): Evidence from Experimental Crosses and Natural Populations
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McCauley, David E., Sundby, Allyson K., Bailey, Maia F., and Welch, Mark E.
- Published
- 2007
11. Patterns of microsatellite evolution inferred from the Helianthus annuus (Asteraceae) transcriptome
- Author
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PRAMOD, SREEPRIYA, PERKINS, ANDY D., and WELCH, MARK E.
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- 2014
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12. Phylogeography of the Endangered Lesser Antillean Iguana, Iguana Delicatissima: A Recent Diaspora in an Archipelago Known for Ancient Herpetological Endemism
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Martin, Jessica L., Knapp, Charles R., Gerber, Glenn P., Thorpe, Roger S., and Welch, Mark E.
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- 2015
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13. Forensic Genetic Analyses of Melanistic Iguanas Highlight the Need to Monitor the Iguanid Trade.
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Mitchell, Blaklie, Welch, Mark E., and van den Burg, Matthijs P.
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IGUANAS , *PRINCIPAL components analysis , *PET industry , *HAPLOTYPES , *SHORT tandem repeat analysis - Abstract
Simple Summary: The illegal pet trade remains an ongoing, substantial threat to wild populations, especially small insular populations, and can even lead to extinction. Fraudulent activity within the global reptile trade is known to occur, but its identification through forensic applications depends on knowledge of diversity within wild populations. In this study, we assessed the geographic origin of melanistic iguanas (Iguana iguana), which are only found in nations that have never authorized legal export of live animals. Analysis of genetic data from two pet iguanas in the USA flag these as originating from Saba or Montserrat, from which no export permits have ever been issued, confirming their illegal origin. Despite the international trade in I. iguana, in which tens- if not hundreds of thousands of specimens are traded each year, only a handful of individuals have been genetically assessed. Our work highlights the utility of applying forensic genetic techniques to this trade in order to track and discourage illegal activity. Lizards within the Iguana iguana species complex are among the most common reptilian pets, with the widest natural geographic range among iguanids. Deep phylogenetic divergence distinguishes multiple mitochondrial clades, and several taxonomic changes have recently been proposed. These small populations, typically island endemics, are threatened by numerous factors, including the international pet trade. Recent investigations reveal the absence of required CITES permits for lawful export of animals, providing evidence of ongoing illegal trade. Additional monitoring of trade in iguanas can be achieved through the application of forensic molecular techniques. In this study, two captive melanistic iguanas were genotyped for molecular markers for which geographic distributions of alleles have been established. Mitochondrial sequencing indicates that both animals carry a haplotype known to originate from the islands of Saba and Montserrat, populations taxonomically proposed to be Iguana melanoderma. Genotypes at 15 microsatellite loci are equally consistent with this origin, given the results of a principal component analysis. This first forensic genetic assessment within the extensive I. iguana pet trade highlights the presence of illegal activity. The need for additional forensic assessments of pet-trade iguanas is evident, especially given that their value is driven by variety and rarity, which is further intensified by recent taxonomic changes. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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14. Geographic patterns of genetic diversity from the native range of Cactoblastis cactorum (Berg) support the documented history of invasion and multiple introductions for invasive populations
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Marsico, Travis D., Wallace, Lisa E., Ervin, Gary N., Brooks, Christopher P., McClure, Jessica E., and Welch, Mark E.
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- 2011
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15. Variable populations within variable populations: quantifying mitochondrial heteroplasmy in natural populations of the gynodioecious plant Silene vulgaris
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Welch, Mark E., Darnell, Michael Z., and McCauley, David E.
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Angiosperms -- Distribution ,Angiosperms -- Genetic aspects ,Plant mitochondria -- Research ,Company distribution practices ,Biological sciences - Abstract
Populations of mitochondria reside within individuals. Among angiosperms, these populations are rarely considered as genetically variable entities and typically are not found to be heteroplasmic in nature, leading to the widespread assumption that plant mitochondrial populations are homoplasmic. However, empirical studies of mitochondrial variation in angiosperms are relatively uncommon due to a paucity of sequence variation. Recent greenhouse studies of Silene vulgaris suggested that heteroplasmy might occur in this species at a level that it is biologically relevant. Here, we use established qualitative methods and a novel quantitative PCR method to study the intraindividual population genetics of mitochondria across two generations in natural populations of S. vulgaris. We show incidences of heteroplasmy for mitochondrial atpA and patterns of inheritance that are suggestive of more widespread heteroplasmy at both atpA and cox1. Further, our results demonstrate that quantitative levels of mitochondrial variation within individuals are high, constituting 26% of the total in one population. These findings are most consistent with a biparental model of mitochondrial inheritance. However, selection within individuals may be instrumental in the maintenance of variation because S. vulgaris is gynodioecious. Male sterility is, in part, regulated by the mitochondrial genome, and strong selection pressures appear to influence the frequency of females in these populations.
- Published
- 2006
16. Mitochondrial Heteroplasmy and Paternal Leakage in Natural Populations of Silene vulgaris, a Gynodioecious Plant
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Pearl, Stephanie A., Welch, Mark E., and McCauley, David E.
- Published
- 2009
17. The identification of watermilfoil, discovery of hybrid watermilfoil, and their implications for aquatic plant management in the Clark Fork River, Western MT, USA.
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Madsen, John D., Wersal, Ryan M., Schmid, Samuel A., Thum, Ryan A., Welch, Mark E., and Phuntumart, Vipaporn
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AQUATIC plants ,EURASIAN watermilfoil ,POTAMOGETON ,MYRIOPHYLLUM ,MACROPHYTES ,HERBICIDES - Abstract
Eurasian watermilfoil (Myriophyllum spicatum) is an invasive submersed macrophyte that has infested many waters in North America since its introduction. Eurasian watermilfoil has the ability to alter the structure and function of the ecosystems that it invades. Eurasian watermilfoil was first surveyed in the Clark Fork River, MT in 2008, alongside the native northern watermilfoil (Myriophyllum sibiricum). Three reservoirs (Cabinet Gorge, Noxon Rapids and Thompson Falls) on the lower Clark Fork River had entire lake surveys conducted using the point intercept method. Morphological data from these surveys showed that only Eurasian watermilfoil and northern watermilfoil were present during the time of the surveys in 2008. The results of the morphological identification were supported by molecular identification at three different laboratories. In 2015, a genetic survey of watermilfoil species was conducted on the Noxon Rapids Reservoir and found that hybrid watermilfoil (Myriophyllum spicatum × sibiricum) was present. This hybridization event poses a number of issues for aquatic plant management. Hybrid watermilfoil is much more difficult to identify morphologically than its parent types. The hybrid is also more invasive and may be differentially susceptible to some herbicides than the parental type Eurasian watermilfoil. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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18. A more precise way to localize animals using drones.
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Hui, Nathan T., Lo, Eric K., Moss, Jen B., Gerber, Glenn P., Welch, Mark E., Kastner, Ryan, and Schurgers, Curt
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RADIO telemetry ,DIRECTIONAL antennas ,ANIMAL mechanics ,DRONE aircraft - Abstract
Radio telemetry is a commonly used technique in conservation biology and ecology, particularly for studying the movement and range of individuals and populations. Traditionally, most radio telemetry work is done using handheld directional antennae and either direction‐finding and homing techniques or radio‐triangulation techniques. Over the past couple of decades, efforts have been made to utilize unmanned aerial vehicles to make radio‐telemetry tracking more efficient, or cover more area. However, many of these approaches are complex and have not been rigorously field‐tested. To provide scientists with reliable quality tracking data, tracking systems need to be rigorously tested and characterized. In this paper, we present a novel, drone‐based, radio‐telemetry tracking method for tracking the broad‐scale movement paths of animals over multiple days and its implementation and deployment under field conditions. During a 2‐week field period in the Cayman Islands, we demonstrated this system's ability to localize multiple targets simultaneously, in daily 10 min tracking sessions over a period of 2 weeks, generating more precise estimates than comparable efforts using manual triangulation techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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19. Transcribed microsatellite allele lengths are often correlated with gene expression in natural sunflower populations.
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Ranathunge, Chathurani, Wheeler, Gregory L., Chimahusky, Melody E., Perkins, Andy D., Pramod, Sreepriya, and Welch, Mark E.
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GENE expression ,COMMON sunflower ,MICROSATELLITE repeats ,SUNFLOWERS ,EUKARYOTIC genomes ,ALLELES ,CIS-regulatory elements (Genetics) - Abstract
Microsatellites are common in genomes of most eukaryotic species. Due to their high mutability, an adaptive role for microsatellites has been considered. However, little is known concerning the contribution of microsatellites towards phenotypic variation. We used populations of the common sunflower (Helianthus annuus) at two latitudes to quantify the effect of microsatellite allele length on phenotype at the level of gene expression. We conducted a common garden experiment with seed collected from sunflower populations in Kansas and Oklahoma followed by an RNA‐Seq experiment on 95 individuals. The effect of microsatellite allele length on gene expression was assessed across 3,325 microsatellites that could be consistently scored. Our study revealed 479 microsatellites at which allele length significantly correlates with gene expression (eSTRs). When irregular allele sizes not conforming to the motif length were removed, the number of eSTRs rose to 2,379. The percentage of variation in gene expression explained by eSTRs ranged from 1%–86% when controlling for population and allele‐by‐population interaction effects at the 479 eSTRs. Of these eSTRs, 70.4% are in untranslated regions (UTRs). A gene ontology (GO) analysis revealed that eSTRs are significantly enriched for GO terms associated with cis‐ and trans‐regulatory processes. Our findings suggest that a substantial number of transcribed microsatellites can influence gene expression. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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20. Conditional female strategies influence hatching success in a communally nesting iguana.
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Moss, Jeanette B., Gerber, Glenn P., Laaser, Tanja, Goetz, Matthias, Oyog, TayVanis, and Welch, Mark E.
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EGG incubation ,BRITISH West Indies ,IGUANAS ,POSTNATAL care ,BODY size ,SQUAMATA ,NESTS - Abstract
The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring‐rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high‐density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low‐density nesting areas. Although larger females were not more likely than smaller females to nest in high‐density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late‐season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg‐filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high‐density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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21. Heterozygosity–Fitness Correlations Reveal Inbreeding Depression in Neonatal Body Size in a Critically Endangered Rock Iguana.
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Moss, Jeanette B, Gerber, Glenn P, and Welch, Mark E
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INBREEDING ,HETEROZYGOSITY ,BODY size ,GENETIC load ,NATURAL selection ,IGUANAS ,HOMOZYGOSITY - Abstract
Inbreeding depression, though challenging to identify in nature, may play an important role in regulating the dynamics of small and isolated populations. Conversely, greater expression of genetic load can enhance opportunities for natural selection. Conditional expression concentrates these opportunities for selection and may lead to failure of detection. This study investigates the possibility for age-dependent expression of inbreeding depression in a critically endangered population of rock iguanas, Cyclura nubila caymanensis. We employ heterozygote-fitness correlations to examine the contributions of individual genetic factors to body size, a fitness-related trait. Nonsignificant reductions in homozygosity (up to 7%) were detected between neonates and individuals surviving past their first year, which may reflect natural absorption of inbreeding effects by this small, fecund population. The majority of variation in neonate body size was attributed to maternal or environmental effects (i.e. clutch identity and incubation length); however, heterozygosity across 22 microsatellite loci also contributed significantly and positively to model predictions. Conversely, effects of heterozygosity on fitness were not detectable when adults were examined, suggesting that inbreeding depression in body size may be age dependent in this taxon. Overall, these findings emphasize the importance of taking holistic, cross-generational approaches to genetic monitoring of endangered populations. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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- View/download PDF
22. Genetic structure at three spatial scales is consistent with limited philopatry in Ricord's Rock Iguanas (Cyclura ricordii).
- Author
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Carreras‐De León, Rosanna, Pasachnik, Stesha A., Gerber, Glenn P., Brooks, Christopher P., Rupp, Ernst, and Welch, Mark E.
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PHILOPATRY ,IGUANAS ,HABITAT destruction ,GENETIC distance ,NESTS ,SEA turtles - Abstract
Cyclura ricordii is an endemic iguana from Hispaniola Island and is threatened on the IUCN Red List. The main threats are predation by introduced mammals, habitat destruction, and hunting pressure. The present study focused on two nesting sites from Pedernales Province in the Dominican Republic. The hypothesis that natal philopatry influences dispersal and nest‐site selection was tested. Monitoring and sampling took place in 2012 and 2013. Polymorphic markers were used to evaluate whether natal philopatry limits dispersal at multiple spatial scales. Ripley's K revealed that nests were significantly clustered at multiple scales, when both nesting sites were considered and within each nesting site. This suggests a patchy, nonrandom distribution of nests within nest sites. Hierarchical AMOVA revealed that nest‐site aggregations did not explain a significant portion of genetic variation within nesting sites. However, a small but positive correlation between geographic and genetic distance was detected using a Mantel's test. Hence, the relationship between geographic distance and genetic distance among hatchlings within nest sites, while detectable, was not strong enough to have a marked effect on fine‐scale genetic structure. Spatial and genetic data combined determined that the nesting sites included nesting females from multiple locations, and the hypothesis of "natal philopatry" was not supported because females nesting in the same cluster were no more closely related to each other than to other females from the same nesting site. These findings imply that nesting aggregations are more likely associated with cryptic habitat variables contributing to optimal nesting conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
23. Evidence for dominant males but not choosy females in an insular rock iguana.
- Author
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Moss, Jeanette B, Gerber, Glenn P, Schwirian, Aumbriel, Jackson, Anna C, and Welch, Mark E
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CYCLURA carinata ,INBREEDING ,PROMISCUITY ,REPTILE populations ,ANIMAL courtship - Abstract
In natural populations susceptible to inbreeding depression, behaviors such as female promiscuity and disassortative mating may enhance the production of outbred progeny and help maintain genetic variation at the population-level. However, empirical tests of such hypotheses have largely focused on mating systems in which female choice is known to play a large role. In insular reptile populations, cryptic choice may be important for overcoming constraints on precopulatory choice and diversifying breeder representation. We carried out pedigree reconstructions of 50 clutches of critically endangered Cyclura nubila caymanensis (Sauria: Iguanidae) to investigate the prevalence and efficacy of strategies theorized to optimize genetic compatibility among mate pairs. We found that females mating disassortatively and multiply, but not with respect to male heterozygosity, tended to produce more heterozygous offspring on average. Pair relatedness also had a negative effect on hatching success, whereas additional sires positively influenced clutch size. Despite evidence for direct and indirect benefits, females did not mate with more outbred or genetically dissimilar males than expected by chance. Our data imply strong reproductive skew among males, with geographic proximity and body size largely predicting siring success. Multiple-paternity occurred in a minimum of 38% of clutches. Paradoxically, females were not more promiscuous when confronted with more males, as demonstrated at a site supporting high local densities. Our data imply that while female-mating behaviors have the potential to confer adaptive benefits in this small population, the trajectory of mating system evolution may be largely constrained by sexual conflict. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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24. The complete mitochondrial genome of the critically endangered Lesser Antillean iguana (Iguana delicatissima; Squamata: Iguanidae).
- Author
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Miller, Aryeh H., C. Jackson, Anna, van den Burg, Matthijs P., Knapp, Charles R., Welch, Mark E., and Reynolds, R. Graham
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IGUANAS ,SQUAMATA ,INTROGRESSION (Genetics) ,TANDEM repeats ,TRANSFER RNA ,MICROSATELLITE repeats ,GENETIC transcription in plants - Abstract
The Lesser Antillean iguana, Iguana delicatissima Laurenti 1768, is one of the most endangered vertebrate taxa in the West Indies. This species faces significant threats, including introgressive hybridization with the introduced congener Iguana iguana. We deploy a combination of off-target sequence capture obtained from Illumina
® reads and targeted Sanger reads to assemble the mitochondrial genome of I. delicatissima. The mitogenome is 16,616 bp in length and is comprised of 13 protein-coding genes, two ribosomal subunits (rRNAs), 22 transfer RNAs, and a control region. Gene order is identical to that of congener I. iguana and other closely related taxa, absent of any tandem repeat regions. We show the phylogenetic utility of the mitogenome with a maximum-likelihood analysis, which yields a topology concordant with previous studies of iguanine taxa. We are hopeful that this genomic resource will be useful in further informing applied conservation and management for this critically endangered species. [ABSTRACT FROM AUTHOR]- Published
- 2019
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25. The Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius: Genetically Depauperate and Threatened by Ongoing Hybridization.
- Author
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van den Burg, Matthijs P., Meirmans, Patrick G., van Wagensveld, Timothy P., Kluskens, Bart, Madden, Hannah, Welch, Mark E., and Breeuwer, Johannes A. J.
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ENDANGERED species ,ANTILLEANS ,GREEN iguana ,HABITATS ,MARINE species diversity - Abstract
The Lesser Antillean Iguana (Iguana delicatissima) is an endangered species threatened by habitat loss and hybridization with non-native Green Iguanas (Iguana iguana). Iguana delicatissima has been extirpated on several islands, and the Green Iguana has invaded most islands with extant populations. Information is essential to protect this species from extinction. We collected data on 293 iguanas including 17 juveniles from St. Eustasius, one of the few remaining I. delicatissima strongholds. Genetic data were leveraged to test for hybridization presence with the Green Iguana using both mitochondrial and nuclear genes, including 16 microsatellite loci. The microsatellites were also analyzed to estimate genetic diversity, population structure, and effective population size. Using molecular and morphological data, we identified 286 I. delicatissima individuals captured during our first fieldwork effort, and 7 non-native iguanas captured during a second effort, showing hybridization occurs within this population. Comparing homologous microsatellites used in studies on Dominica and Chancel, the I. delicatissima population on St. Eustatius has extremely low genetic diversity (HO = 0.051; HE = 0.057), suggesting this population is genetically depauperate. Furthermore, there is significant evidence for inbreeding (FIS = 0.12) and weak spatial genetic structure (FST = 0.021, P = 0.002) within this population. Besides immediate threats including hybridization, this population's low genetic diversity, presence of physiological abnormalities and low recruitment could indicate presence of inbreeding depression that threatens its long-term survival. We conclude there is a continued region-wide threat to I. delicatissima and highlight the need for immediate conservation action to stop the continuing spread of Green Iguanas and to eliminate hybridization from St. Eustatius. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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26. First evidence for crossbreeding between invasive <italic>Iguana iguana</italic> and the native rock iguana (Genus <italic>Cyclura</italic>) on Little Cayman Island.
- Author
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Moss, Jeanette B., Welch, Mark E., Burton, Frederic J., Vallee, Michael V., Houlcroft, Edward W., Laaser, Tanja, and Gerber, Glenn P.
- Abstract
Green iguanas (
Iguana iguana ) are invasive throughout the West Indies and co-occur on several islands with native rock iguanas (GenusCyclura ). In August 2016, three hybrid hatchlings were captured on Little Cayman Island, providing the first evidence for a successful crossbreeding event betweenI. iguana and anyCyclura rock iguana species in the wild. Hybrid status was confirmed with morphological and genetic character analysis. This discovery prompts new concerns for biosecurity in the Caribbean. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
27. Transcriptome profiles of sunflower reveal the potential role of microsatellites in gene expression divergence.
- Author
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Ranathunge, Chathurani, Wheeler, Gregory L., Chimahusky, Melody E., Kennedy, Meaghan M., Morrison, Jesse I., Baldwin, Brian S., Perkins, Andy D., and Welch, Mark E.
- Subjects
COMMON sunflower ,GENE expression ,MICROSATELLITE repeats ,CHROMOSOMES ,NUCLEOTIDE sequencing - Abstract
Abstract: The mechanisms by which natural populations generate adaptive genetic variation are not well understood. Some studies propose that microsatellites can function as drivers of adaptive variation. Here, we tested a potentially adaptive role for transcribed microsatellites with natural populations of the common sunflower (
Helianthus annuus L.) by assessing the enrichment of microsatellites in genes that show expression divergence across latitudes. Seeds collected from six populations at two distinct latitudes in Kansas and Oklahoma were planted and grown in a common garden. Morphological measurements from the common garden demonstrated that phenotypic variation among populations is largely explained by underlying genetic variation. An RNA‐Seq experiment was conducted with 96 of the individuals grown in the common garden and differentially expressed (DE) transcripts between the two latitudes were identified. A total number of 825 DE transcripts were identified. DE transcripts and nondifferentially expressed (NDE) transcripts were then scanned for microsatellites. The abundance of different motif lengths and types in both groups were estimated. Our results indicate that DE transcripts are significantly enriched with mononucleotide repeats and significantly depauperate in trinucleotide repeats. Further, the standardized mononucleotide repeat motif A and dinucleotide repeat motif AG were significantly enriched within DE transcripts while motif types, C, AT, ACC and AAC in DE transcripts, are significantly differentiated in microsatellite tract length between the two latitudes. The tract length differentiation at specific microsatellite motif types across latitudes and their enrichment within DE transcripts indicate a potential functional role for transcribed microsatellites in gene expression divergence in sunflower. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
28. Phylogeographic evidence for a Florida panhandle-peninsula discontinuity in the distribution of Melitara prodenialis Walker (Lepidoptera: Pyralidae), a native cactus-boring moth.
- Author
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Marsico, Travis D., Sauby, Kristen E., Brooks, Christopher P., Welch, Mark E., Ervin, Gary N., R. Leather, Simon, and Ribera, Ignacio
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PHYLOGEOGRAPHY ,OPUNTIA ,PYRALIDAE ,SPECIES diversity ,SPECIES distribution - Abstract
Insects are highly underrepresented in the phylogeographic literature of the coastal plain region of the southeastern U.S., but they may contribute much to understanding the phylogeographic history of the area., The present study uses Melitara prodenialis Walker, a cactus-boring moth, to test two alternative hypotheses: Pleistocene changes in environment and coastline associated with population geographic change resulted in (i) a homogeneous Florida, USA, population of M. prodenialis or (ii) isolated subpopulations that gave rise to genetic divergence between regions., Melitara prodenialis larvae were collected from 23 sites ( n = 42 larvae sampled). For each larva, a 791 bp sequence of the COI mitochondrial gene was sequenced. Bayesian and parsimony approaches were used to investigate relationships among haplotypes. Phylogeographic and demographic analyses were conducted to identify geographic patterns in haplotype diversity distribution and infer population dynamics over time. Bioclim climate variables from the last interglacial period and the present were used to assess the potential contribution of environmental conditions to phylogeographic patterns observed., Melitara prodenialis populations in the Florida panhandle and peninsula are distinct, and the geographic segregation between these regions is correlated with current and historic climate patterns., Results suggest that populations of M. prodenialis in the Florida peninsula have more recently expanded than those in the panhandle. These findings are consistent with M. prodenialis populations changing in size and distribution following land area and climatic shifts associated with North American cycles of glaciation, with panhandle and peninsula populations remaining segregated over the relevant timeframes. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
29. Inferred vs Realized Patterns of Gene Flow: An Analysis of Population Structure in the Andros Island Rock Iguana.
- Author
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Colosimo, Giuliano, Knapp, Charles R., Wallace, Lisa E., and Welch, Mark E.
- Subjects
CYCLURA carinata ,EMIGRATION & immigration ,ENDANGERED species ,GENE flow ,DATA analysis ,ANALYSIS of variance - Abstract
Ecological data, the primary source of information on patterns and rates of migration, can be integrated with genetic data to more accurately describe the realized connectivity between geographically isolated demes. In this paper we implement this approach and discuss its implications for managing populations of the endangered Andros Island Rock Iguana, Cyclura cychlura cychlura. This iguana is endemic to Andros, a highly fragmented landmass of large islands and smaller cays. Field observations suggest that geographically isolated demes were panmictic due to high, inferred rates of gene flow. We expand on these observations using 16 polymorphic microsatellites to investigate the genetic structure and rates of gene flow from 188 Andros Iguanas collected across 23 island sites. Bayesian clustering of specimens assigned individuals to three distinct genotypic clusters. An analysis of molecular variance (AMOVA) indicates that allele frequency differences are responsible for a significant portion of the genetic variance across the three defined clusters (F
st = 0.117, p0.01). These clusters are associated with larger islands and satellite cays isolated by broad water channels with strong currents. These findings imply that broad water channels present greater obstacles to gene flow than was inferred from field observation alone. Additionally, rates of gene flow were indirectly estimated using BAYESASS 3.0. The proportion of individuals originating from within each identified cluster varied from 94.5 to 98.7%, providing further support for local isolation. Our assessment reveals a major disparity between inferred and realized gene flow. We discuss our results in a conservation perspective for species inhabiting highly fragmented landscapes. [ABSTRACT FROM AUTHOR]- Published
- 2014
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30. Microsatellites as Agents of Adaptive Change: An RNA-Seq-Based Comparative Study of Transcriptomes from Five Helianthus Species.
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Ranathunge, Chathurani, Pramod, Sreepriya, Renaut, Sébastien, Wheeler, Gregory L., Perkins, Andy D., Rieseberg, Loren H., and Welch, Mark E.
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MICROSATELLITE repeats ,SUNFLOWERS ,TRANSCRIPTOMES ,CHANGE agents ,SINGLE nucleotide polymorphisms ,CIS-regulatory elements (Genetics) - Abstract
Mutations that provide environment-dependent selective advantages drive adaptive divergence among species. Many phenotypic differences among related species are more likely to result from gene expression divergence rather than from non-synonymous mutations. In this regard, cis-regulatory mutations play an important part in generating functionally significant variation. Some proposed mechanisms that explore the role of cis-regulatory mutations in gene expression divergence involve microsatellites. Microsatellites exhibit high mutation rates achieved through symmetric or asymmetric mutation processes and are abundant in both coding and non-coding regions in positions that could influence gene function and products. Here we tested the hypothesis that microsatellites contribute to gene expression divergence among species with 50 individuals from five closely related Helianthus species using an RNA-seq approach. Differential expression analyses of the transcriptomes revealed that genes containing microsatellites in non-coding regions (UTRs and introns) are more likely to be differentially expressed among species when compared to genes with microsatellites in the coding regions and transcripts lacking microsatellites. We detected a greater proportion of shared microsatellites in 5′UTRs and coding regions compared to 3′UTRs and non-coding transcripts among Helianthus spp. Furthermore, allele frequency differences measured by pairwise F
ST at single nucleotide polymorphisms (SNPs), indicate greater genetic divergence in transcripts containing microsatellites compared to those lacking microsatellites. A gene ontology (GO) analysis revealed that microsatellite-containing differentially expressed genes are significantly enriched for GO terms associated with regulation of transcription and transcription factor activity. Collectively, our study provides compelling evidence to support the role of microsatellites in gene expression divergence. [ABSTRACT FROM AUTHOR]- Published
- 2021
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31. GENE EXPRESSION ASSAYS FOR ACTIN, UBIQUITIN, AND THREE MICROSATELLITE-ENCODING GENES IN HELIANTHUS ANNUUS (ASTERACEAE).
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Pramod, Sreepriya, Downs, Katharyn E., and Welch, Mark E.
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ASTERACEAE ,COMMON sunflower ,MICROSATELLITE repeats in plants ,GENE expression ,ACTIN ,UBIQUITIN - Abstract
* Premise of the study: The "tuning knob" model of King et al. (Endeavor 21: 36-40, 1997) postulates that microsatellite mutations can alter phenotypes in a stepwise fashion. Some proposed mechanisms involve regulation of gene expression. To study the effect of microsatellites harbored in untranslated regions on gene expression in Helianthus annuus, we have developed TaqMan assays for three microsatellite-encoding genes, and two constitutively expressed genes, actin and ubiquitin, to serve as standards. * Methods and Results: All five TaqMan assays yielded strong log-linear relationships between cycle threshold (C
T ) values and cDNA concentrations (R² = 0.98-0.99). Standard curves were based on five concentrations for each of five individuals. Efficiencies ranged from 0.83 to 1.03. * Conclusions: The developed tools will allow for relative quantification of gene expression across individuals. Genotyping these loci will allow for testing the "tuning knob" hypothesis. Further, the actin and ubiquitin assays should be generally applicable to gene expression studies in H. annuus. [ABSTRACT FROM AUTHOR]- Published
- 2012
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32. CHARACTERIZATION OF LONG TRANSCRIBED MICROSATELLITES IN HELIANTHUS ANNUUS (ASTERACEAE).
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Pramod, Sreepriya, Rasberry, Armed B., Butler, Tiffini G., and Welch, Mark E.
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MICROSATELLITE repeats in plants ,PLANT genetics ,COMMON sunflower ,HETEROZYGOSITY ,NUCLEOTIDE sequence - Abstract
* Premise of the study: Research on the evolutionary role of exonic microsatellites currently lacks an understanding of the evolutionary pressures that promote or limit their expansion. Contrasting levels of variability and genetic structures at anonymous and transcribed microsatellite loci of varying lengths are likely to provide useful insights regarding the relative strength of selection acting on different classes of microsatellites. We have developed primers for long transcribed microsatellites in Helianthus annuus to make these comparisons. * Methods and Results: Eight relatively long microsatellites from sequences in the expressed sequence tag database of H. annuus were characterized. A total of 63 individuals from three populations in Kansas were genotyped. The number of alleles per locus ranged from four to 11 with an average observed heterozygosity of 0.723. * Conclusions: Our study has generated suitable tools for studying the population genetics of long transcribed microsatellites that are potentially influenced by selection. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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33. Evaluating the Potential for Differential Susceptibility of Common Reed (Phragmites australis) Haplotypes I and M to Aquatic Herbicides
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Cheshier, Joshua C., Madsen, John D., Wersal, Ryan M., Gerard, Patrick D., and Welch, Mark E.
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- 2012
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34. Phylogenomics and historical biogeography of West Indian Rock Iguanas (genus Cyclura).
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Reynolds, R. Graham, Miller, Aryeh H., Pasachnik, Stesha A., Knapp, Charles R., Welch, Mark E., Colosimo, Giuliano, Gerber, Glenn P., Drawert, Brian, and Iverson, John B.
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IGUANAS , *SQUAMATA , *BIOGEOGRAPHY , *BASE pairs , *ANOLES - Abstract
[Display omitted] • Targeted sequence capture to yield partial annotated mitogenomes and thousands of nuclear loci for West Indian Cyclura iguanas. • All taxa (species and subspecies) of the entire genus are represented, as well as outgroups. • Gene tree/species tree analyses and divergence time analyses with biogeographic discussion. • Well resolved phylogenomic hypothesis with important conservation implications. The genus Cyclura includes nine extant species and six subspecies of West Indian Rock Iguanas and is one of the most imperiled genera of squamate reptiles globally. An understanding of species diversity, evolutionary relationships, diversification, and historical biogeography in this group is crucial for implementing sound long-term conservation strategies. We collected DNA samples from 1 to 10 individuals per taxon from all Cyclura taxa (n = 70 ingroup individuals), focusing where possible on incorporating individuals from different populations of each species. We also collected 1–2 individuals from each of seven outgroup species of iguanas (Iguana delicatissima ; five Ctenosaura species) and Anolis sagrei (n = 12 total outgroup individuals). We used targeted genomic sequence capture to isolate and to sequence 1,872 loci comprising of 687,308 base pairs (bp) from each of the 82 individuals from across the nuclear genome. We extracted mitochondrial reads and assembled and annotated mitogenomes for all Cyclura taxa plus outgroup species. We present well-supported phylogenomic gene tree/species tree analyses for all extant species of Cyclura using ASTRAL-III, SVDQuartets, and StarBEAST2 methods, and discuss the taxonomic, biogeographic, and conservation implications of these data. We find a most recent common ancestor of the genus 9.91 million years ago. The earliest divergence within Cyclura separates C. pinguis from a clade comprising all other Cyclura. Within the latter group, a clade comprising C. carinata from the southern Lucayan Islands and C. ricordii from Hispaniola is the sister taxon to a clade comprising the other Cyclura. Among the other Cyclura , the species C. cornuta and C. stejnegeri (from Hispaniola and Isla Mona) form the sister taxon to a clade of species from Jamaica (C. collei), Cuba and Cayman Islands (C. nubila and C. lewisi), and the eastern (C. rileyi) and western (C. cychlura) Lucayan Islands. Cyclura cychlura and C. rileyi form a clade whose sister taxa are C. nubila and C. lewisi. Cyclura collei is the sister taxon to these four species combined. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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