Publications by authors named "James D Austin"

26 Publications

  • Page 1 of 1

Dispersal and Land Cover Contribute to Pseudorabies Virus Exposure in Invasive Wild Pigs.

Ecohealth 2021 Jan 14. Epub 2021 Jan 14.

Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, USA.

We investigated the landscape epidemiology of a globally distributed mammal, the wild pig (Sus scrofa), in Florida (U.S.), where it is considered an invasive species and reservoir to pathogens that impact the health of people, domestic animals, and wildlife. Specifically, we tested the hypothesis that two commonly cited factors in disease transmission, connectivity among populations and abundant resources, would increase the likelihood of exposure to both pseudorabies virus (PrV) and Brucella spp. (bacterial agent of brucellosis) in wild pigs across the Kissimmee Valley of Florida. Using DNA from 348 wild pigs and sera from 320 individuals at 24 sites, we employed population genetic techniques to infer individual dispersal, and an Akaike information criterion framework to compare candidate logistic regression models that incorporated both dispersal and land cover composition. Our findings suggested that recent dispersal conferred higher odds of exposure to PrV, but not Brucella spp., among wild pigs throughout the Kissimmee Valley region. Odds of exposure also increased in association with agriculture and open canopy pine, prairie, and scrub habitats, likely because of highly localized resources within those land cover types. Because the effect of open canopy on PrV exposure reversed when agricultural cover was available, we suggest that small-scale resource distribution may be more important than overall resource abundance. Our results underscore the importance of studying and managing disease dynamics through multiple processes and spatial scales, particularly for non-native pathogens that threaten wildlife conservation, economy, and public health.
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http://dx.doi.org/10.1007/s10393-020-01508-6DOI Listing
January 2021

Urbanization and Population Genetic Structure of the Panama City crayfish (Procambarus econfinae).

J Hered 2020 04;111(2):204-215

Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL.

For species with geographically restricted distributions, the impacts of habitat loss and fragmentation on long-term persistence may be particularly pronounced. We examined the genetic structure of Panama City crayfish (PCC), Procambarus econfinae, whose historical distribution is limited to an area approximately 145 km2, largely within the limits of Panama City and eastern Bay County, FL. Currently, PCC occupy approximately 28% of its historical range, with suitable habitat composed of fragmented patches in the highly urbanized western portion of the range and managed plantations in the more contiguous eastern portion of the range. We used 1640 anonymous single-nucleotide polymorphisms to evaluate the effects of anthropogenic habitat modification on the genetic diversity and population structure of 161 PCC sampled from across its known distribution. First, we examined urban habitat patches in the west compared with less-developed habitat patches in the east. Second, we used approximate Bayesian computation to model inferences on the demographic history of eastern and western populations. We found anthropogenic habitat modifications explain the genetic structure of PCC range-wide. Clustering analyses revealed significant genetic structure between and within eastern and western regions. Estimates of divergence between east and west were consistent with urban growth in the mid-20th century. PCC have low genetic diversity and high levels of inbreeding and relatedness, indicating populations are small and isolated. Our results suggest that PCC have been strongly affected by habitat loss and fragmentation and management strategies, including legal protection, translocations, or reintroductions, may be necessary to ensure long-term persistence.
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http://dx.doi.org/10.1093/jhered/esz072DOI Listing
April 2020

The number of breeders explains genetic connectivity in an endangered bird.

Mol Ecol 2019 06 18;28(11):2746-2756. Epub 2019 Jun 18.

Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida, USA.

Connectivity is central to ecology and evolution as it focuses on the movement of individuals or genes across landscapes. Genetic connectivity approaches aim to understand gene flow but often estimate it indirectly based on metrics of genetic differentiation, which can also be affected by other evolutionary forces such as genetic drift. Gene flow and genetic drift are driven by separate ecological mechanisms with potentially differing effects on genetic differentiation and interpretations of genetic connectivity. The ecological mechanisms contributing to gene flow and genetic drift are primarily effective dispersal, or movement followed by successful reproduction, and the number of breeders in a local population, N , respectively. Yet, rarely are these ecological mechanisms and genetic connectivity measured simultaneously across landscapes. We examine the roles of effective dispersal and N on genetic connectivity across the entire range of the endangered snail kite (Rostrhamus sociabilis plumbeus), between 2006-2015. We find that both N and effective dispersal are important predictors of genetic connectivity across this landscape, but that N has a 3 × stronger effect on genetic connectivity. Furthermore, N is positively correlated with heterozygosity and allelic richness within patches, suggesting a potentially important role of genetic drift, in addition to gene flow, on genetic connectivity. These results emphasize that conservation efforts should focus on not only between-patch processes of movement but also within-patch processes regarding habitat quality and local population size for increasing genetic connectivity.
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http://dx.doi.org/10.1111/mec.15109DOI Listing
June 2019

Integrative taxonomy resolves taxonomic uncertainty for freshwater mussels being considered for protection under the U.S. Endangered Species Act.

Sci Rep 2018 10 26;8(1):15892. Epub 2018 Oct 26.

Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32601, USA.

Objectively delimiting species boundaries remains an important challenge in systematics and becomes urgent when unresolved taxonomy complicates conservation and recovery efforts. We examined species boundaries in the imperiled freshwater mussel genus Cyclonaias (Bivalvia: Unionidae) using morphometrics, molecular phylogenetics, and multispecies coalescent models to help guide pending conservation assessments and legislative decisions. Congruence across multiple lines of evidence indicated that current taxonomy overestimates diversity in the C. pustulosa species complex. The only genetically and morphologically diagnosable species in the C. pustulosa species complex were C. pustulosa and C. succissa and we consider C. aurea, C. houstonensis, C. mortoni, and C. refulgens to be synonyms of C. pustulosa. In contrast, all three species in the C. nodulata complex (C. necki, C. nodulata, and C. petrina) were genetically, geographically, and morphologically diagnosable. Our findings have important conservation and management implications, as three nominal species (C. aurea, C. houstonensis, and C. petrina) are being considered for protection under the Endangered Species Act.
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http://dx.doi.org/10.1038/s41598-018-33806-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203750PMC
October 2018

Isolating the roles of movement and reproduction on effective connectivity alters conservation priorities for an endangered bird.

Proc Natl Acad Sci U S A 2018 08 6;115(34):8591-8596. Epub 2018 Aug 6.

School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611-0430.

Movement is important for ecological and evolutionary theory as well as connectivity conservation, which is increasingly critical for species responding to environmental change. Key ecological and evolutionary outcomes of movement, such as population growth and gene flow, require effective dispersal: movement that is followed by successful reproduction. However, the relative roles of movement and postmovement reproduction for effective dispersal and connectivity remain unclear. Here we isolate the contributions of movement and immigrant reproduction to effective dispersal and connectivity across the entire breeding range of an endangered raptor, the snail kite (). To do so, we unite mark-resight data on movement and reproduction across 9 years and 27 breeding patches with an integrated model that decomposes effective dispersal into its hierarchical levels of movement, postmovement breeding attempt, and postmovement reproductive success. We found that immigrant reproduction limits effective dispersal more than movement for this endangered species, demonstrating that even highly mobile species may have limited effective connectivity due to reduced immigrant reproduction. We found different environmental limitations for the reproductive component of effective dispersal compared with movement, indicating that different conservation strategies may be needed when promoting effective dispersal rather than movement alone. We also demonstrate that considering immigrant reproduction, rather than movement alone, alters which patches are the most essential for connectivity, thereby changing conservation priorities. These results challenge the assumption that understanding movement alone is sufficient to infer connectivity and highlight that connectivity conservation may require not only fostering movement but also successful reproduction of immigrants.
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http://dx.doi.org/10.1073/pnas.1800183115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6112689PMC
August 2018

Mixing rates in weakly differentiated stocks of greater amberjack (Seriola dumerili) in the Gulf of Mexico.

Genetica 2018 Oct 25;146(4-5):393-402. Epub 2018 Jul 25.

Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA.

The greater amberjack (Seriola dumerili) is a commercially and recreationally important marine fish species in the southeastern United States, where it has been historically managed as two non-mixing stocks (Gulf of Mexico and Atlantic). Mark-recapture studies and analysis of mitochondrial DNA have suggested the two stocks are demographically independent; however, little is currently known about when and where spawning occurs in Gulf of Mexico amberjack, and whether stock mixture occurs on breeding grounds. The primary objective of this study was to quantify stock mixture among breeding populations of amberjack collected from the Atlantic and Gulf of Mexico. Genetic data based on 11 loci identified very low, though statistically significant differentiation among Gulf of Mexico samples (G = 0.007, [Formula: see text] = 0.009; all P = 0.001) and between reproductive adults collected from two spawning areas (G = 0.007, [Formula: see text] = 0.014; all P = 0.001). Naïve Bayesian mixture analysis supported a single genetic cluster [p(S|data) = 0.734] whereas trained clustering (using Atlantic and Gulf spawning fish) gave the highest support to a two-cluster model (p(S|data) = 1.0). Our results support the argument that the genetic structuring of greater amberjack is more complex than the previously assumed two, non-mixing stock model. Although our data provide evidence of limited population structure, we argue in favour of non-panmixia among reproductive fish collected from the Gulf of Mexico and Florida Keys.
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http://dx.doi.org/10.1007/s10709-018-0031-1DOI Listing
October 2018

Did Late Pleistocene climate change result in parallel genetic structure and demographic bottlenecks in sympatric Central African crocodiles, Mecistops and Osteolaemus?

Mol Ecol 2017 Nov 1;26(22):6463-6477. Epub 2017 Nov 1.

Department of Wildlife Ecology & Conservation, University of Florida, Gainesville, FL, USA.

The mid-Holocene has had profound demographic impacts on wildlife on the African continent, although there is little known about the impacts on species from Central Africa. Understanding the impacts of climate change on codistributed species can enhance our understanding of ecosystem dynamics and for formulating restoration objectives. We took a multigenome comparative approach to examine the phylogeographic structure of two poorly known Central African crocodile species-Mecistops sp. aff. cataphractus and Osteolaemus tetraspis. In addition, we conducted coalescent-based demographic reconstructions to test the hypothesis that population decline was driven by climate change since the Last Glacial Maximum, vs. more recent anthropogenic pressures. Using a hierarchical Bayesian model to reconstruct demographic history, we show that both species had dramatic declines (>97%) in effective population size in the 'period following the Last Glacial Maximum 1,500-18,000 YBP. Identification of genetic structuring showed both species have similar regional structure corresponding to major geological features (i.e., hydrologic basin) and that small observed differences between them are best explained by the differences in their ecology and the likely impact that climate change had on their habitat needs. Our results support our hypothesis that climatic effects, presumably on forest and wetland habitat, had a congruent negative impact on both species.
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http://dx.doi.org/10.1111/mec.14378DOI Listing
November 2017

Microsatellite Mutation Rate in Atlantic Sturgeon (Acipenser oxyrinchus).

J Hered 2017 Sep;108(6):686-692

Museum and Institute of Zoology, Polish Academy of Sciences, Warsaw, Poland; Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland; Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611; Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611; Institute of Genetics and Biotechnology, Department of Biology, University of Warsaw, Warsaw, Poland; University of Newcastle, Callaghan, Australia; Centre of New Technologies, University of Warsaw, Warsaw, Poland.

Understanding mutation rates can greatly extend the utility of population and conservation genetic analyses. Herein, we present an estimate of genome-wide microsatellite mutation rate in Atlantic sturgeon (Acipenser oxyrinchus) based on parent-offspring transmission patterns. We screened 307 individuals for parentage and mutation-rate analysis applying 43 variable markers. Out of 13228 allele transfers, 11 mutations were detected, producing a mutation rate of 8.3 × 10-4 per locus per generation (95% confidence interval: 1.48 × 10-3, 4.15 × 10-4). Single-step mutations predominated and there were trends toward mutations in loci with greater polymorphism and allele length. Two of the detected mutations were most probably cluster mutations, being identified in 12 and 28 sibs, respectively. Finally, we observed evidences of polyploidy based on the sporadic presence of 3 or 4 alleles per locus in the genotyped individuals, supporting previous reports of incomplete diploidization in Atlantic sturgeon.
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http://dx.doi.org/10.1093/jhered/esx057DOI Listing
September 2017

The causes of dispersal and the cost of carry-over effects for an endangered bird in a dynamic wetland landscape.

J Anim Ecol 2017 07 17;86(4):857-865. Epub 2017 May 17.

Department of Wildlife Ecology and Conservation, University of Florida, PO Box 110430, 110 Newins-Ziegler Hall, Gainesville, FL, 32611-0430, USA.

The decision to disperse or remain philopatric between breeding seasons has important implications for both ecology and evolution, including the potential for carry-over effects, where an individual's previous history affects its current performance. Carry-over effects are increasingly documented although underlying mechanisms remain unclear. Here we test for potential carry-over effects and their mechanisms by uniting hypotheses for the causes and consequences of habitat selection and dispersal across space and time. We linked hypotheses regarding different types of factors and information (environmental conditions, personal and public information) predicted to impact reproductive success and dispersal for an endangered, wetland-dependent bird, the snail kite (Rostrhamus sociabilis plumbeus). To do so, we coupled structural equation modelling with 20 years of mark-recapture and nesting data across the breeding range of this species to isolate potential direct and indirect effects of these factors. We found that water depth at nest sites explained subsequent emigration rates via an indirect path through the use of personal, not public, information. Importantly, we found that these dispersers tended to initiate nests later the following breeding season. This pattern explained a phenological mismatch of nesting with hydrological conditions, whereby immigrants tended to nest later, late nesters tended to experience lower water depths, higher nest failure occurred at lower water depths and higher nest failure explained subsequent breeding dispersal. These results identified a novel potential mechanism for carry-over effects: a phenological mismatch with environmental conditions (water depth) that occurred potentially due to time costs of dispersal. Our results also highlighted a substantial benefit of philopatry - earlier initiation of reproduction - which allows philopatric individuals to better coincide with environmental conditions that are beneficial for successful reproduction. These results have implications for our mechanistic understanding and prediction of carryover effects, and emphasize that local conservation strategies, such as water management, can explain future demography at distant sites connected through dispersal.
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http://dx.doi.org/10.1111/1365-2656.12676DOI Listing
July 2017

Affinity for natal environments by dispersers impacts reproduction and explains geographical structure of a highly mobile bird.

Proc Biol Sci 2015 Sep;282(1814)

Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA.

Understanding dispersal and habitat selection behaviours is central to many problems in ecology, evolution and conservation. One factor often hypothesized to influence habitat selection by dispersers is the natal environment experienced by juveniles. Nonetheless, evidence for the effect of natal environment on dispersing, wild vertebrates remains limited. Using 18 years of nesting and mark-resight data across an entire North American geographical range of an endangered bird, the snail kite (Rostrhamus sociabilis), we tested for natal effects on breeding-site selection by dispersers and its consequences for reproductive success and population structure. Dispersing snail kites were more likely to nest in wetlands of the same habitat type (lacustrine or palustrine) as their natal wetland, independent of dispersal distance, but this preference declined with age and if individuals were born during droughts. Importantly, dispersing kites that bred in natal-like habitats had lower nest success and productivity than kites that did not. These behaviours help explain recently described population connectivity and spatial structure across their geographical range and reveal that assortative breeding is occurring, where birds are more likely to breed with individuals born in the same wetland type as their natal habitat. Natal environments can thus have long-term and large-scale effects on populations in nature, even in highly mobile animals.
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http://dx.doi.org/10.1098/rspb.2015.1545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4571708PMC
September 2015

Rigorous approaches to species delimitation have significant implications for African crocodilian systematics and conservation.

Proc Biol Sci 2014 Feb 11;281(1776):20132483. Epub 2013 Dec 11.

Department of Wildlife Ecology and Conservation, University of Florida, , 110 Newins-Ziegler Hall, Gainesville, FL 32611, USA, SFM Safari Gabon, , BP 1107, Libreville, Gabon, Department of Biology, University of Florida, , 220 Bartram Hall, Gainesville, FL 32611, USA.

Accurate species delimitation is a central assumption of biology that, in groups such as the Crocodylia, is often hindered by highly conserved morphology and frequent introgression. In Africa, crocodilian systematics has been hampered by complex regional biogeography and confounded taxonomic history. We used rigorous molecular and morphological species delimitation methods to test the hypothesis that the slender-snouted crocodile (Mecistops cataphractus) is composed of multiple species corresponding to the Congolian and Guinean biogeographic zones. Speciation probability was assessed by using 11 mitochondrial and nuclear genes, and cranial morphology for over 100 specimens, representing the full geographical extent of the species distribution. Molecular Bayesian and phylogenetic species delimitation showed unanimous support for two Mecistops species isolated to the Upper Guinean and Congo (including Lower Guinean) biomes that were supported by 13 cranial characters capable of unambiguously diagnosing each species. Fossil-calibrated phylogenetic reconstruction estimated that the species split ± 6.5-7.5 Ma, which is congruent with intraspecies divergence within the sympatric crocodile genus Osteolaemus and the formation of the Cameroon Volcanic Line. Our results underscore the necessity of comprehensive phylogeographic analyses within currently recognized taxa to detect cryptic species within the Crocodylia. We recommend that the community of crocodilian researchers reconsider the conceptualization of crocodilian species especially in the light of the conservation ramifications for this economically and ecologically important group.
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http://dx.doi.org/10.1098/rspb.2013.2483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871313PMC
February 2014

Network modularity reveals critical scales for connectivity in ecology and evolution.

Nat Commun 2013 ;4:2572

Department of Wildlife Ecology and Conservation, PO Box 110430, 110 Newins-Ziegler Hall, University of Florida, Gainesville, Florida 32611-0430, USA.

For nearly a century, biologists have emphasized the profound importance of spatial scale for ecology, evolution and conservation. Nonetheless, objectively identifying critical scales has proven incredibly challenging. Here we extend new techniques from physics and social sciences that estimate modularity on networks to identify critical scales for movement and gene flow in animals. Using four species that vary widely in dispersal ability and include both mark-recapture and population genetic data, we identify significant modularity in three species, two of which cannot be explained by geographic distance alone. Importantly, the inclusion of modularity in connectivity and population viability assessments alters conclusions regarding patch importance to connectivity and suggests higher metapopulation viability than when ignoring this hidden spatial scale. We argue that network modularity reveals critical meso-scales that are probably common in populations, providing a powerful means of identifying fundamental scales for biology and for conservation strategies aimed at recovering imperilled species.
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http://dx.doi.org/10.1038/ncomms3572DOI Listing
May 2014

A relict lineage and new species of green palm-pitviper (Squamata, Viperidae, Bothriechis) from the Chortís Highlands of Mesoamerica.

Zookeys 2013 13(298):77-106. Epub 2013 May 13.

Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705-1081, USA ;  Centro Zamorano de Biodiversidad, Escuela Agrícola Panamericana Zamorano, Departamento de Francisco Morazán, Honduras.

A new species of palm-pitviper of the genus Bothriechis is described from Refugio de Vida Silvestre Texíguat in northern Honduras. The new species differs from congeners by having 19 dorsal scale rows at midbody, a bright green dorsal coloration in adults, the prelacunal scale fused to the second supralabial, and in representing a northern lineage that is sister to Bothriechis lateralis, which is distributed in Costa Rica and western Panama and is isolated from the new taxon by the Nicaraguan Depression. This represents the 15th endemic species occurring in Refugio de Vida Silvestre Texíguat, one of the richest herpetofaunal sites in Honduras, itself being the country with the highest degree of herpetofaunal endemism in Central America. We name this new species in honor of a Honduran conservationist slain in fighting against illegal logging, highlighting the sacrifices of rural activists in battling these issues and the critical importance of conservation in these areas.
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http://dx.doi.org/10.3897/zookeys.298.4834DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3689108PMC
June 2013

A new Nototriton (Caudata: Plethodontidae) from Parque Nacional Montaña de Botaderos in northeastern Honduras.

Zootaxa 2013 ;3666:358-68

Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705-1081, USA.

The highlands of northeastern Honduras remain under-characterized in terms of biological diversity, as exemplified by the regularity of new amphibian and reptile taxa discoveries. Following the recent description of a new species of Nototriton from the Sierra de Agalta in northeastern Honduras, we report the discovery of a second new species of Nototriton from the nearby Parque Nacional Montaña de Botaderos. This new taxon, Nototriton mime sp. nov., is distinguished from other Nototriton by its distinctive pale brown dorsal coloration in adult males, relatively large nares, a relatively broad head, mitochondrial sequence divergence, and phylogenetic relationships, and is geographically isolated from other populations of Nototriton.
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http://dx.doi.org/10.11646/zootaxa.3666.3.6DOI Listing
August 2015

An ancient icon reveals new mysteries: mummy DNA resurrects a cryptic species within the Nile crocodile.

Mol Ecol 2011 Oct 9;20(20):4199-215. Epub 2011 Sep 9.

Department of Biological Sciences, Fordham University, New York, NY, USA.

The Nile crocodile (Crocodylus niloticus) is an ancient icon of both cultural and scientific interest. The species is emblematic of the great civilizations of the Nile River valley and serves as a model for international wildlife conservation. Despite its familiarity, a centuries-long dispute over the taxonomic status of the Nile crocodile remains unresolved. This dispute not only confounds our understanding of the origins and biogeography of the 'true crocodiles' of the crown genus Crocodylus, but also complicates conservation and management of this commercially valuable species. We have taken a total evidence approach involving phylogenetic analysis of mitochondrial and nuclear markers, as well as karyotype analysis of chromosome number and structure, to assess the monophyletic status of the Nile crocodile. Samples were collected from throughout Africa, covering all major bioregions. We also utilized specimens from museum collections, including mummified crocodiles from the ancient Egyptian temples at Thebes and the Grottes de Samoun, to reconstruct the genetic profiles of extirpated populations. Our analyses reveal a cryptic evolutionary lineage within the Nile crocodile that elucidates the biogeographic history of the genus and clarifies long-standing arguments over the species' taxonomic identity and conservation status. An examination of crocodile mummy haplotypes indicates that the cryptic lineage corresponds to an earlier description of C. suchus and suggests that both African Crocodylus lineages historically inhabited the Nile River. Recent survey efforts indicate that C. suchus is declining or extirpated throughout much of its distribution. Without proper recognition of this cryptic species, current sustainable use-based management policies for the Nile crocodile may do more harm than good.
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http://dx.doi.org/10.1111/j.1365-294X.2011.05245.xDOI Listing
October 2011

Permanent genetic resources added to Molecular Ecology Resources Database 1 February 2011-31 March 2011.

Mol Ecol Resour 2011 Jul 31;11(4):757-8. Epub 2011 May 31.

Molecular Ecology Resources Editorial Office, 6270 University Blvd, Vancouver, BC V6T 1Z4, Canada.

This article documents the addition of 111 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acipenser oxyrinchus desotoi, Anopheles nuneztovari sensu lato, Asellus aquaticus, Calopteryx splendens, Calopteryx virgo, Centaurea aspera, Centaurea seridis, Chilina dombeyana, Proctoeces cf. lintoni and Pyrenophora teres f. teres.
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http://dx.doi.org/10.1111/j.1755-0998.2011.03028.xDOI Listing
July 2011

When technology meets conservation: increased microsatellite marker production using 454 genome sequencing on the endangered Okaloosa Darter (Etheostoma okaloosae).

J Hered 2010 Nov-Dec;101(6):784-8. Epub 2010 Jul 11.

Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611-0430, USA.

High-throughput sequencing affords a cost and time effective means of obtaining large numbers of genetic markers for conservation studies. Here, we present thousands of novel microsatellite loci developed for the Okaloosa darter, Etheostoma okaloosae, an endangered percid fish. We sequenced more than 29 million bp using 454 whole genome shotgun sequencing and employed free user-friendly bioinformatics tools to screen for microsatellite loci and design appropriate primers. We tested 39 primer sets for polymorphism and ran population-level analyses on a population of Okaloosa darters. Of these, 30 markers were variable with an observed and expected heterozygosity of 0.382 and 0.430, respectively, and allele numbers ranging from 2 to 13. Comparisons against the zebra fish reference genome, Danio rerio, revealed that these loci represent an adequate chromosomal coverage of the darter genome, although total genomic coverage was only 2.4-3.3%. We also tested these loci on the brown darter, E. edwini, and identified loci that will be useful for hybridization studies between these taxa.
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http://dx.doi.org/10.1093/jhered/esq080DOI Listing
January 2011

Genetic estimates of contemporary effective population size in an endangered butterfly indicate a possible role for genetic compensation.

Evol Appl 2010 Jan 10;3(1):28-39. Epub 2009 Aug 10.

McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History Gainesville, FL, USA ; Department of Entomology and Nematology, University of Florida Gainesville, FL, USA.

The effective population size (N e ) is a critical evolutionary and conservation parameter that can indicate the adaptive potential of populations. Robust estimates of N e of endangered taxa have been previously hampered by estimators that are sensitive to sample size. We estimated N e on two remaining populations of the endangered Miami blue butterfly, a formerly widespread taxon in Florida. Our goal was to determine the consistency of various temporal and point estimators on inferring N e and to determine the utility of this information for understanding the role of genetic stochasticity. We found that recently developed 'unbiased estimators' generally performed better than some older methods in that the former had more realistic N e estimates and were more consistent with what is known about adult population size. Overall, N e /N ratios based on census point counts were high. We suggest that this pattern may reflect genetic compensation caused by reduced reproductive variance due to breeding population size not being limited by resources. Assuming N e and N are not heavily biased, it appears that the lack of gene flow between distant populations may be a greater genetic threat in the short term than the loss of heterozygosity due to inbreeding.
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http://dx.doi.org/10.1111/j.1752-4571.2009.00096.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352457PMC
January 2010

Admixture of ephedrine to offset side effects of propofol: a randomized, controlled trial.

J Clin Anesth 2009 Feb;21(1):44-9

Department of Anaesthetics, Royal Berkshire Hospital, Reading, United Kingdom.

Study Objective: To determine whether adding ephedrine to propofol is as effective as adding lidocaine at reducing injection pain, and its effects on hemodynamics.

Design: Randomized, double-blinded, controlled trial.

Setting: District general hospital in the United Kingdom.

Patients: 156 adult, ASA physical status I, II, and III patients undergoing elective or emergency general anesthesia.

Interventions: Patients were randomized to one of three groups to receive one mL of 1% lidocaine per 20 mL of 1% propofol (Group L), 15 mg of ephedrine per 20 mL of propofol (Group E15), or 30 mg of ephedrine per 20 mL of propofol (Group E30).

Measurements And Main Results: Pain on injection, heart rate, and blood pressure at one-minute intervals for ten minutes were recorded. There was no significant difference in injection pain among groups. Group E30 had the least amount of hemodynamic change.

Conclusion: Adding 30 mg of ephedrine to 20 mL of 1% propofol is as effective as adding lidocaine in preventing injection pain, and it results in a more stable hemodynamic profile.
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http://dx.doi.org/10.1016/j.jclinane.2008.06.018DOI Listing
February 2009

Incongruence in the pattern and timing of intra-specific diversification in bronze frogs and bullfrogs (Ranidae).

Mol Phylogenet Evol 2008 Sep 24;48(3):1041-53. Epub 2008 Jun 24.

Wildlife Ecology & Conservation, 110 Newins-Ziegler Hall, P.O. Box 110430, University of Florida, Gainesville, Florida 32611, USA.

We compare patterns of lineage divergence in mitochondrial DNA (mtDNA) sequences of two protein-encoding mitochondrial genes (cyt b and ND2) in two ecologically similar, co-distributed, and closely related ranid frogs (Rana clamitans and Rana catesbeiana), that are geographically widespread, and frequently syntopic. We identified three lineages in R. clamitans, separated by 0.5% to 2.1% net corrected sequence divergence, comparable to two R. catesbeiana lineages separated by 0.6%. The geographic pattern of lineage distribution differed notably between the two species. In R. clamitans, we found a Coastal Plain-Appalachian (CPA) lineage restricted to south and east of the Appalachian Mountains and a widespread lineage that encompassing nearly all the sampled range. A third distinct and divergent lineage was detected in one location in the southwest portion of the range (Louisiana). This pattern contrasts with the east-west pattern in R. catesbeiana, and reflects possible differences in refugial dynamics and patterns of range expansion. Although both species have undergone range expansion and population growth, coalescent reconstruction of N(e) reflects larger lineages but more recent divergence in R. clamitans relative to R. catesbeiana, reflecting significant differences in population history or divergent patterns of molecular evolution at mtDNA.
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http://dx.doi.org/10.1016/j.ympev.2008.06.010DOI Listing
September 2008

Life-threatening hyperkalemia following partial pancreatectomy for neonatal hyperinsulinism.

Pediatr Crit Care Med 2008 May;9(3):e17-9

Department of Anaesthesia, Starship Hospital, Auckland, New Zealand.

Objective: To alert readers to the possibility of rebound hyperkalemia following pancreatic resection for neonatal hyperinsulinism.

Design: Case report.

Setting: Intensive care unit of tertiary pediatric hospital.

Patient: A term neonate with severe hyperinsulinism complicated by hypokalemia, fluid overload, and necrotizing enterocolitis.

Interventions: Preoperative management consisted of glucose 20.8 mg/kg/min, diazoxide 15 mg/kg/day, octreotide 27 mug/kg/day, and potassium (>10 mmol/kg/day) to maintain normoglycemia and normokalemia. The large glucose requirement, administered as 20% glucose, contributed to congestive heart failure, which was treated with frusemide. Attempts to feed enterally were abandoned because of necrotizing enterocolitis. Partial colectomy and subtotal pancreatectomy were performed on day 20.

Measurements And Main Results: Serum potassium rose rapidly within 2 hrs of surgery to reach 12.3 mmol/L, causing ventricular tachycardia (240 beats/min) on electrocardiogram. There was no evidence of renal failure or adrenal insufficiency. Management consisted of insulin 0.1 units/kg intravenously, 10% calcium gluconate 0.1 mmol/kg intravenously, sodium bicarbonate 3 mmol/kg intravenously, frusemide 2 mg/kg intravenously, and resonium 0.6 g/kg per rectum with good outcome.

Conclusions: This report highlights the rapid electrolyte shifts possible after sudden cessation of hormones regulating Na/K-ATPase activity.
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http://dx.doi.org/10.1097/PCC.0b013e3181728c82DOI Listing
May 2008

Multi-character perspectives on the evolution of intraspecific differentiation in a neotropical hylid frog.

BMC Evol Biol 2006 Mar 15;6:23. Epub 2006 Mar 15.

Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada.

Background: Multi-character empirical studies are important contributions to our understanding of the process of speciation. The relatively conserved morphology of, and importance of the mate recognition system in anurans, combined with phylogenetic tools, provide an opportunity to address predictions about the relative role of each in the process of speciation. We examine the relationship among patterns of variation in morphology, call characters, and 16S gene sequences across seven populations of a neotropical hylid frog, Hyla leucophyllata, to infer their relative importance in predicting the early stages of population differentiation.

Results: Multivariate analyses demonstrate that both morphological and call characteristics were significantly variable among populations, characterized by significantly lower intra-population dispersion in call space than morphological space, and significantly greater among-population variation in call structure. We found lack of concordance between a 16S DNA phylogeny of Hyla leucophyllata and the significant population-level differentiation evident in both external morphology and male advertisement call. Comparisons of the reconstructed gene trees to simulated lineages support the notion that variation in call cannot be simply explained by population history.

Conclusion: Discordance among traits may reflect sampling biases (e.g. single genetic marker effects), or imply a decoupling of evolution of different suites of characters. Diagnostic differences among populations in call structure possibly reflect local selection pressures presented by different heterospecific calling assemblages and may serve as a precursor of species-wide differentiation. Differentiation among populations in morphology may be due to ecophenotypic variation or to diversifying selection on body size directly, or on frequency attributes of calls (mediated by female choice) that show a strong relationship to body size.
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http://dx.doi.org/10.1186/1471-2148-6-23DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1434785PMC
March 2006

Controlling for the effects of history and nonequilibrium conditions in gene flow estimates in northern bullfrog (Rana catesbeiana) populations.

Genetics 2004 Nov;168(3):1491-506

Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6.

Nonequilibrium conditions due to either allopatry followed by secondary contact or recent range expansion can confound measurements of gene flow among populations in previously glaciated regions. We determined the scale at which gene flow can be estimated among breeding aggregations of bullfrogs (Rana catesbeiana) at the northern limit of their range in Ontario, Canada, using seven highly polymorphic DNA microsatellite loci. We first identified breeding aggregations that likely share a common history, determined from the pattern of allelic richness, factorial correspondence analysis, and a previously published mtDNA phylogeography, and then tested for regional equilibrium by evaluating the association between pairwise F(ST) and geographic distance. Regional breeding aggregations in eastern Ontario separated by <100 km were determined to be at or near equilibrium. High levels of gene flow were measured using traditional F-statistics and likelihood estimates of Nm. Similarly high levels of recent migration (past one to three generations) were estimated among the breeding aggregations using nonequilibrium methods. We also show that, in many cases, breeding aggregations separated by up to tens of kilometers are not genetically distinct enough to be considered separate genetic populations. These results have important implications both for the identification of independent "populations" and in assessing the effect of scale in detecting patterns of genetic equilibrium and gene flow.
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http://dx.doi.org/10.1534/genetics.104.027987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448790PMC
November 2004

Discordant temporal and geographic patterns in maternal lineages of eastern North American frogs, Rana catesbeiana (Ranidae) and Pseudacris crucifer (Hylidae).

Mol Phylogenet Evol 2004 Sep;32(3):799-816

Department of Biology, Queen's University, Kingston, Ont. K7L 3N6, Canada.

Whether the Pleistocene has had a disproportionate impact on the recent diversification of temperate species, or played a lesser role in a more protracted process, has been a prominent evolutionary debate for the past decade. We used cytochrome b sequences to reconstruct the evolutionary histories of two widely co-distributed, and ecologically divergent frogs (Rana catesbeiana and Pseudacris crucifer) to examine the role of the Pleistocene in structuring these species. Results for R. catesbeiana reflect a pattern of allopatric fragmentation, likely in Coastal Plain refugia on either side of the Mississippi River dating to the mid to early Pleistocene. In contrast, P. crucifer contains numerous divergent lineages, including one west of the Mississippi River in the Interior Highlands, and in the east, multiple lineages that likely expanded from a number of southern Appalachian refugia with lineage sundering originating in the late Pliocene. Large-scale phylogeographic comparisons between these and other eastern North American species reflect both congruent and independent patterns of diversification, possibly reflecting the relative importance of dispersal ability and habitat associations. Although intra-lineage diversification has been structured by repeated Pleistocene glaciations, lineage sundering likely dates at least to the Pliocene in most (but not all) northern temperate amphibian and reptile species studied to date.
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http://dx.doi.org/10.1016/j.ympev.2004.03.006DOI Listing
September 2004

Genetic evidence for female-biased dispersal in the bullfrog, Rana catesbeiana (Ranidae).

Mol Ecol 2003 Nov;12(11):3165-72

dagger Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.

Sex-biased dispersal is an important but unexplored area of amphibian ecology. We predicted female-biased dispersal in the bullfrog (Rana catesbeiana) based on aspects of their mating system and tested this prediction using data from seven polymorphic DNA microsatellite loci. Allelic (F-statistics) and genotypic [assignment index, (AIc)] frequencies from nine Ontario populations support our prediction, although significant sex differences in inbreeding and variance of AIc were not detected. The diversity of mating systems found in amphibians represents an important avenue for investigating the relationship between reproductive systems, dispersal and phylogeny.
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http://dx.doi.org/10.1046/j.1365-294x.2003.01948.xDOI Listing
November 2003

Cryptic lineages in a small frog: the post-glacial history of the spring peeper, Pseudacris crucifer (Anura: Hylidae).

Mol Phylogenet Evol 2002 Nov;25(2):316-29

Department of Biology, Queen's University, Kingston, Ont, Canada K7L 3N6.

The spring peeper (Pseudacris crucifer) is believed to have been a primary herpetological invader of eastern North America following the most recent period of glacial retreat. We examined the phylogeographic pattern and population structure of P. crucifer to determine whether the distribution of haplotypic variants reflect post-Pleistocene recolonization dynamics. A number of geographically isolated evolutionary lineages were supported by both maximum parsimony and neighbor-joining analyses, and by coalescence approaches applied to mtDNA. South-western Ontario represents a high level of genotypic diversity (pi) due to the presence of two divergent lineages. The geographic distribution of these lineages are interpreted as reflecting post-glacial recolonization dynamics from separate, isolated refugia during the late Pleistocene that have come into secondary contact in SW Ontario. The phylogenetic placement of haplotypes from the range of P. crucifer bartramiana (Florida and South Carolina) does not allow for monophyly of P. crucifer crucifer, and therefore the bartramiana subspecies designation does not reflect a separate evolutionary lineage.
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http://dx.doi.org/10.1016/s1055-7903(02)00260-9DOI Listing
November 2002