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Charles R Knapp - One of the best experts on this subject based on the ideXlab platform.
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Host sex, size, and hemoparasite infection influence the effects of ectoparasitic burdens on free-ranging iguanas.
Ecology and evolution, 2019Co-Authors: Charles R Knapp, Caro Perez-heydrich, Trevor T. Zachariah, Jill Jollay, Amy N. Schnelle, Sandra D. Buckner, Christine R. Lattin, L. Michael RomeroAbstract:Investigations focusing on host-ectoparasite interactions in animals have revealed asymptomatic to severe health and fitness consequences suggesting that species mobilize different interspecific response mechanisms. Fewer studies, however, have examined intraspecific responses to ectoparasitic burdens. In this study, we analyzed host health and fitness responses to increasing ectoparasite burdens along with the presence/absence of hemoparasites of free-ranging insular rock iguanas (Cyclura cychlura) in The Bahamas. Using hematology, plasma biochemistry, as well as body condition and growth rate comparisons, we failed to find significant associations of tick burdens with annual growth rate, corticosterone, packed cell volume, total white blood cell, and heterophil, monocyte, eosinophil or hemoglobin measures. We did, however, find mixed and significant associations of tick burdens with lymphocyte and basophil counts, heterophil-to-lymphocyte ratios, and body condition indices. These associations varied by sex, size, and hemoparasite infection status suggesting that different life stages of iguanas may invest differently in immune responses, and impacts may be modulated based on size and sex of hosts, and coinfection status.
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Influence of morphological, chemical and physical leaf traits on food selection of a herbivorous iguana from The Bahamas
Journal of Tropical Ecology, 2015Co-Authors: Charles R Knapp, Silvia Alvarez-clareAbstract:Herbivores are predicted to forage on a variety of plants in order to obtain a nutritionally sufficient diet. Most herbivores, however, forage non-randomly and may be influenced by morphological, chemical and physical traits in their food. We examined the influence of several leaf traits on food selection for the Exuma rock iguana ( Cyclura cychlura figginsi ). We expected the iguana to prefer leaves with higher nutrient concentration and lower physical defences, such as reflected by high N, P, Ca, K, Mg concentrations and low leaf density and per cent concentrations of cellulose, hemicellulose and lignin, respectively. We quantified selection by examining 30 faecal samples and analysing traits of leaves from the 10 most common plants on the island. Our results showed substantial variability in all measured traits among species but food preference only for less-dense leaves, a good indicator of low leaf toughness. Our results are the first to demonstrate that physical leaf traits can influence food selection in a true herbivorous lizard and offer a basis for future testing.
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Reptile-Associated Ticks from Dominica and the Bahamas With Notes on Hyperparasitic Erythraeid Mites
The Journal of parasitology, 2014Co-Authors: Lance A. Durden, Charles R Knapp, Lorenza Beati, Stephanie DoldAbstract:Ticks were collected or recorded from 522 individual reptiles on Dominica and from 658 reptiles from the Bahamas. Two species of ticks were collected on Dominica: Amblyomma antillorum and Amblyomma rotundatum. Similarly, 2 species were collected in the Bahamas: Amblyomma albopictum and Amblyomma torrei. On Dominica, A. antillorum was recorded from 517 Lesser Antillean iguanas (Iguana delicatissima), 2 boa constrictors (Boa nebulosa), 1 Antilles snake (Alsophis sibonius), and 1 Dominican ground lizard (Ameiva fuscata), whereas A. rotundatum was recorded from 1 Lesser Antillean skink (Mabuya mabouya). In the Bahamas, A. albopictum was recorded from 131 Andros iguanas (Cyclura cychlura cychlura), 271 Exuma Island iguanas (Cyclura cychlura figginsi), and 1 Andros curlytail lizard (Leiocephalus carinatus coryi), whereas A. torrei was recorded from 255 Exuma Island iguanas. In the Bahamas, A. albopictum parasitized iguanas on Andros Island and the central Exuma Islands, and A. torrei parasitized iguanas in the southern Exumas. An exception to this trend was that A. torrei was collected from iguanas on Pasture Cay in the central Exumas, an anomaly that is explained by the fact that iguanas (with attached ticks) on Pasture Cay were introduced by humans in the past from islands further south. External hyperparasitic larval erythraeid mites (Leptus sp.) were recorded from A. torrei in the Bahamas. Reptiles in the Caribbean region are parasitized by a unique suite of amblyommine ticks, including Amblyomma albopictum Neumann, Amblyomma antillorum Kohls, Amblyomma cruciferum Neumann, Amblyomma dissimile Koch, Amblyomma quadricavum (Schulze), Amblyomma rotundatum Koch, and Amblyomma torrei Vigeuras (Robinson, 1926; Whittick, 1939; Clifford and Kohls, 1962; Cern ´ y, 1969a; Kohls, 1969a, 1969b; Keirans, 1985; Keirans and Garris, 1986; Keirans and Klompen, 1996; Guglielmone et al., 2003; Durden and Knapp, 2005). Of these species, A. albopictum, A. antillorum, A. cruciferum, and A. torrei are known to be ectoparasitic specialists of iguanas (Robinson, 1926; Keirans, 1985; Guglielmone et al., 2003). However, the geograph- ical distribution of these tick species on the various Caribbean islands and their host associations are incompletely known. Additionally, to our knowledge, no external hyperparasites of any of these iguana-associated ticks have been reported previously. In this paper, we document the host associations for 2 of the above-listed tick species, A. albopictum and A. torrei, from the Bahamas, and for 1 congener, A. antillorum, from Dominica. We also document A. rotundatum from a skink in Dominica and report ectoparasitic erythraeid mites from A. torrei in the Bahamas. We also briefly discuss the known geographical distributions of the Caribbean iguana-associated ticks, including the intriguing apparently segregated distributions of A. albopic- tum and A. torrei in the Bahamas.
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inferred vs realized patterns of gene flow an analysis of population structure in the andros island rock iguana
PLOS ONE, 2014Co-Authors: Giuliano Colosimo, Charles R Knapp, Lisa E Wallace, Mark E. WelchAbstract: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 (Fst= 0.117, p%0.01). 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.
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ocular health assessment tear production and intraocular pressure in the andros island iguana Cyclura cychlura cychlura
Journal of Zoo and Wildlife Medicine, 2013Co-Authors: Kimberlee B Wojick, Lisa M Naples, Charles R KnappAbstract:Abstract: The purpose of this study was to assess the ocular health of a wild population of Andros Island iguanas (Cyclura cychlura cychlura) and determine reference values for tear production and intraocular pressure (IOP) for this species. Fifty-two iguanas, 20 males and 32 females, ranging in size from 11.1- to 51.0-cm snout-to-vent length (SVL), were included in the sample set, with measurements obtained from each eye. No abnormalities were found on ophthalmic examination, with the exception of mild, focal chemosis in one individual and periocular ticks in 52% of iguanas. Tear production was measured using the phenol red thread test, and IOP was measured using the TonoVet® rebound tonometer set on the P (undefined species) setting. No significant difference was found between males and females for either measurement. No significant difference was found between right and left eyes for intraocular pressure; however, a significant difference was found between eyes for tear production values. The mean (±S...
Mark E. Welch - One of the best experts on this subject based on the ideXlab platform.
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Contrasting Patterns of Movement across Life Stages in an Insular Iguana Population
Journal of Herpetology, 2020Co-Authors: Jeanette B. Moss, Tanja Laaser, Glenn P. Gerber, Matthias Goetz, Jane Ebert Haakonsson, Jessica C. Harvey, Mark E. WelchAbstract:West Indian rock iguanas (genus Cyclura) represent the most endangered group of lizards in the world, with most taxa restricted to few or single islands. In addition to distribution and availability of resources, factors influencing optimal use of insular space in these large vertebrates may include a combination of social, ontogenetic, and long-term demographic factors. Life stage-specific dispersal and habitat use patterns have previously been characterized in Cyclura, but assessments across the lifespan are lacking. This study evaluates shifting patterns of movement in a single taxon, Cyclura nubila caymanensis. We used mark–recapture and radio tracking simultaneously to assess age- and sex-dependent variation in spatial ecology. Evidence for prolonged site fidelity among adults was consistent with territoriality-modulating space use in this long-lived taxon. Over 5–10 yr, some females were never resighted or recaptured outside of an 80-m perimeter. A notable exception was that gravid females migrated 1.17 ± 0.91 km to utilize coastal areas during the nesting season. In contrast, neonates dispersed farther (2.32 ± 2.26 km) and their trajectories were often nonlinear. Radio-tracked brother–sister pairs exhibited no tendency to disperse together during their first 4 wk, settling into final known locations at pairwise distances of 2.16 ± 1.74 km. Annual net displacement remained high over the first 1–3 yr of life. Our data are consistent with studies of related taxa wherein individual spatial requirements vary with population density and island size. Notably, panmixis of small island iguana populations appears largely driven by pre-reproductive movements.
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First evidence for crossbreeding between invasive Iguana iguana and the native rock iguana (Genus Cyclura) on Little Cayman Island
Biological Invasions, 2018Co-Authors: Jeanette B. Moss, Mark E. Welch, Michael V. Vallee, Edward W. Houlcroft, Tanja Laaser, Frederic J Burton, Glenn P. GerberAbstract:Green iguanas ( Iguana iguana ) are invasive throughout the West Indies and co-occur on several islands with native rock iguanas (Genus Cyclura ). In August 2016, three hybrid hatchlings were captured on Little Cayman Island, providing the first evidence for a successful crossbreeding event between I. iguana and any Cyclura 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.
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Inferred vs Realized Patterns of Gene Flow: An Analysis of Population Structure in the Andros Island Rock Iguana
2016Co-Authors: Giuliano Colosimo, Lisa E Wallace, Mark E. WelchAbstract: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 (Fst = 0.117, p%0.01). 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 conservatio
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Genetic diversity and structure in the Endangered Allen Cays Rock Iguana, Cyclura cychlura inornata
PeerJ, 2016Co-Authors: Andrea C. Aplasca, Mark E. Welch, John B. Iverson, Giuliano Colosimo, Evon R. HekkalaAbstract:The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (
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genetic diversity and structure in the endangered allen cays rock iguana Cyclura cychlura inornata
PeerJ, 2016Co-Authors: Mark E. Welch, John B. Iverson, Andrea C. Aplasca, Giuliano Colosimo, Evon R. HekkalaAbstract:The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (<4 ha each). However, populations of unknown origin were recently discovered on four additional cays. To investigate patterns of genetic variation among these populations, we analyzed nuclear and mitochondrial markers for 268 individuals. Analysis of three mitochondrial gene regions (2,328 bp) and data for eight nuclear microsatellite loci indicated low genetic diversity overall. Estimates of effective population sizes based on multilocus genotypes were also extremely low. Despite low diversity, significant population structuring and variation in genetic diversity measures were detected among cays. Genetic data confirm the source population for an experimentally translocated population while raising concerns regarding other, unauthorized, translocations. Reduced heterozygosity is consistent with a documented historical population decline due to overharvest. This study provides the first range-wide genetic analysis of this subspecies. We suggest strategies to maximize genetic diversity during ongoing recovery including additional translocations to establish assurance populations and additional protective measures for the two remaining natural populations.
Allison C. Alberts - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of 23 polymorphic microsatellite loci for a West Indian iguana (Cyclura pinguis) from the British Virgin Islands.
Molecular ecology resources, 2009Co-Authors: Jennie Lau, Glenn P. Gerber, Allison C. Alberts, Leona G. Chemnick, Kenneth C. Jones, Adele A. Mitchell, Oliver A. RyderAbstract:Twenty-three polymorphic microsatellite markers were identified and characterized for Cyclura pinguis, a critically endangered species of lizard (Sauria: Iguanidae) native to Anegada Island in the British Virgin Islands. We examined variation at these loci for 39 C. pinguis, finding up to five alleles per locus and an average expected heterozygosity of 0.55. Allele frequency estimates for these microsatellite loci will be used to characterize genetic diversity of captive and wild C. pinguis populations and to estimate relatedness among adult iguanas at the San Diego Zoo that form the nucleus of a captive breeding programme for this critically endangered species.
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Surgical technique for permanent intracoelomic radiotransmitter placement in Anegada iguanas (Cyclura pinguis).
Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2005Co-Authors: Shannon T. Ferrell, Allison C. Alberts, Annajane B. Marlar, Lee A. Young, Kelly Bradley, Sandra L. Hurlbut, Nancy P. LungAbstract:Twenty-four juvenile to subadult Anegada iguanas (Cyclura pinguis), captive-reared in a propagation facility, were designated by a coordinated recovery program for release in the summer of 2003. To facilitate postrelease monitoring, a radiotransmitter device was placed within the coelomic cavity of each animal under general anesthesia before release. The equipment sterilization technique and the method of attachment of the transmitters to the coelomic body wall resulted in functional transmitters and acceptably low rates of mortality associated with the procedure.
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Temporary alteration of local social structure in a threatened population of Cuban iguanas (Cyclura nubila)
Behavioral Ecology and Sociobiology, 2002Co-Authors: Allison C. Alberts, Jeffrey M. Lemm, Andrew M. Perry, Lisa A. Morici, John A. PhillipsAbstract:In small, insular populations, behavioral patterns that lead to increased variance in individual reproductive success can accelerate loss of genetic variation. Over a 1-year period, we documented behavior and hormone levels in a breeding group of adult Cuban iguanas ( Cyclura nubila ) at Guantánamo Bay. Male dominance was associated with body and head size, display behavior, testosterone levels, home-range size, and proximity to females. Based on their success in agonistic encounters, we ranked males in a linear dominance hierarchy. During the subsequent breeding season, we conducted a removal experiment in which the five highest-ranking males were temporarily relocated from the study site. Although we were unable to assess reproductive success directly, previously lower-ranking males assumed control of vacated territories, won more fights, and increased their proximity to females in the absence of the dominant males. When it results in greater mating opportunities for otherwise socially suppressed individuals, temporary alteration of local social structure may help limit erosion of genetic variation in small, insular populations.
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Temporary alteration of local social structure in a threatened population of Cuban iguanas (Cyclura nubila)
Behavioral Ecology and Sociobiology, 2002Co-Authors: Allison C. Alberts, Jeffrey M. Lemm, Andrew M. Perry, Lisa A. Morici, John A. PhillipsAbstract:In small, insular populations, behavioral patterns that lead to increased variance in individual reproductive success can accelerate loss of genetic variation. Over a 1-year period, we documented behavior and hormone levels in a breeding group of adult Cuban iguanas (Cyclura nubila) at Guantanamo Bay. Male dominance was associated with body and head size, display behavior, testosterone levels, home-range size, and proximity to females. Based on their success in agonistic encounters, we ranked males in a linear dominance hierarchy. During the subsequent breeding season, we conducted a removal experiment in which the five highest-ranking males were temporarily relocated from the study site. Although we were unable to assess reproductive success directly, previously lower-ranking males assumed control of vacated territories, won more fights, and increased their proximity to females in the absence of the dominant males. When it results in greater mating opportunities for otherwise socially suppressed individuals, temporary alteration of local social structure may help limit erosion of genetic variation in small, insular populations.
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Use of statistical models based on radiographic measurements to predict oviposition date and clutch size in rock iguanas (Cyclura nubila)
Zoo Biology, 1995Co-Authors: Allison C. AlbertsAbstract:The ability to noninvasively estimate clutch size and predict oviposition date in reptiles can be useful not only to veterinary clinicians but also to managers of captive collections and field researchers. Measurements of egg size and shape, as well as position of the clutch within the coelomic cavity, were taken from diagnostic radiographs of 20 female Cuban rock iguanas, Cyclura nubila, 81 to 18 days prior to laying. Combined with data on maternal body size, these variables were entered into multiple regression models to predict clutch size and timing of egg laying. The model for clutch size was accurate to 0.53 ± 0.08 eggs, while the model for oviposition date was accurate to 6.22 ± 0.81 days. Equations were generated that should be applicable to this and other large Cyclura species. © 1995 Wiley-Liss, Inc.
Glenn P. Gerber - One of the best experts on this subject based on the ideXlab platform.
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Contrasting Patterns of Movement across Life Stages in an Insular Iguana Population
Journal of Herpetology, 2020Co-Authors: Jeanette B. Moss, Tanja Laaser, Glenn P. Gerber, Matthias Goetz, Jane Ebert Haakonsson, Jessica C. Harvey, Mark E. WelchAbstract:West Indian rock iguanas (genus Cyclura) represent the most endangered group of lizards in the world, with most taxa restricted to few or single islands. In addition to distribution and availability of resources, factors influencing optimal use of insular space in these large vertebrates may include a combination of social, ontogenetic, and long-term demographic factors. Life stage-specific dispersal and habitat use patterns have previously been characterized in Cyclura, but assessments across the lifespan are lacking. This study evaluates shifting patterns of movement in a single taxon, Cyclura nubila caymanensis. We used mark–recapture and radio tracking simultaneously to assess age- and sex-dependent variation in spatial ecology. Evidence for prolonged site fidelity among adults was consistent with territoriality-modulating space use in this long-lived taxon. Over 5–10 yr, some females were never resighted or recaptured outside of an 80-m perimeter. A notable exception was that gravid females migrated 1.17 ± 0.91 km to utilize coastal areas during the nesting season. In contrast, neonates dispersed farther (2.32 ± 2.26 km) and their trajectories were often nonlinear. Radio-tracked brother–sister pairs exhibited no tendency to disperse together during their first 4 wk, settling into final known locations at pairwise distances of 2.16 ± 1.74 km. Annual net displacement remained high over the first 1–3 yr of life. Our data are consistent with studies of related taxa wherein individual spatial requirements vary with population density and island size. Notably, panmixis of small island iguana populations appears largely driven by pre-reproductive movements.
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First evidence for crossbreeding between invasive Iguana iguana and the native rock iguana (Genus Cyclura) on Little Cayman Island
Biological Invasions, 2018Co-Authors: Jeanette B. Moss, Mark E. Welch, Michael V. Vallee, Edward W. Houlcroft, Tanja Laaser, Frederic J Burton, Glenn P. GerberAbstract:Green iguanas ( Iguana iguana ) are invasive throughout the West Indies and co-occur on several islands with native rock iguanas (Genus Cyclura ). In August 2016, three hybrid hatchlings were captured on Little Cayman Island, providing the first evidence for a successful crossbreeding event between I. iguana and any Cyclura 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.
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Twenty-nine polymorphic microsatellite loci in Cyclura carinata, the Turks and Caicos Iguana, a critically endangered island endemic
Conservation Genetics Resources, 2011Co-Authors: Mark E. Welch, Glenn P. Gerber, G. June Long, Jamen W. Berk, Angela H. Getz, Lisa E WallaceAbstract:Cyclura carinata , a critically endangered Caribbean rock iguana, now occupies less than 5% of its historic range. Remaining populations are genetically structured, but available tools are insufficient to identify taxonomic units. Ten polymorphic microsatellites isolated from C. carinata , and 19 loci developed for congeners are identified. All 29 loci were screened for variation in two populations with 20 or more individuals from each of two island populations, as well as 24 individuals that are representative of the species range.
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Isolation and characterization of 23 polymorphic microsatellite loci for a West Indian iguana (Cyclura pinguis) from the British Virgin Islands.
Molecular ecology resources, 2009Co-Authors: Jennie Lau, Glenn P. Gerber, Allison C. Alberts, Leona G. Chemnick, Kenneth C. Jones, Adele A. Mitchell, Oliver A. RyderAbstract:Twenty-three polymorphic microsatellite markers were identified and characterized for Cyclura pinguis, a critically endangered species of lizard (Sauria: Iguanidae) native to Anegada Island in the British Virgin Islands. We examined variation at these loci for 39 C. pinguis, finding up to five alleles per locus and an average expected heterozygosity of 0.55. Allele frequency estimates for these microsatellite loci will be used to characterize genetic diversity of captive and wild C. pinguis populations and to estimate relatedness among adult iguanas at the San Diego Zoo that form the nucleus of a captive breeding programme for this critically endangered species.
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Re-evaluating the Taxonomic Status of the Booby Cay Iguana, Cyclura Carinata Bartschi
Copeia, 2007Co-Authors: Jason J. Bryan, Mark E. Welch, Glenn P. Gerber, Catherine L. StephenAbstract:Abstract Cyclura carinata, a Bahamian rock iguana, currently has two recognized subspecies. Cyclura c. carinata is found on numerous islands and cays throughout the Turks and Caicos Islands. The second subspecies, C. c. bartschi, is now only known to exist on Booby Cay, a small island off of Mayaguana Island, Bahamas, which is also within the subspecies historic range. Support for subspecific status is weak. Geographic isolation appears to be the only strong indicator of genetic isolation. Recent conservation attempts made on the species behalf have raised questions regarding the validity of subspecific designations. We used mtDNA sequence data to ask whether there is any genetic variation that distinguishes C. c. bartschi from ten sampled populations of C. c. carinata. Our findings show that the Booby Cay population is fixed for a common mtDNA haplotype found in Caicos Island populations of C. carinata. In contrast, four different haplotypes were found among populations designated C. c. carinata. We conc...
John B. Iverson - One of the best experts on this subject based on the ideXlab platform.
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Marine subsidies likely cause gigantism of iguanas in the Bahamas
Oecologia, 2019Co-Authors: Kristen M. Richardson, John B. Iverson, Carolyn M. KurleAbstract:We utilized natural experiment opportunities presented by differential conditions (presence/absence of seabirds and invasive species) on cays in the Bahamas to study whether interisland variations in food resources contributed to gigantism in Allen Cays Rock Iguanas ( Cyclura cychlura inornata ). We analyzed the stable carbon ( δ ^13C) and nitrogen ( δ ^15N) isotope values from iguana tissues and resources from each island food web to test the predictions that (1) food webs on islands with seabirds exhibit the influence of marine subsidies from seabird guano, whereas those from non-seabird islands do not, and (2) size differences in iguanas among cays were due to either (a) supplemental food availability from mice and/or seabird carcasses killed by barn owls ( Tyto alba ) and/or (b) access to more nutrient-rich vegetation fertilized by seabird guano. Food web components from the seabird island (Allen Cay) had 5–9‰ higher δ ^15N values than those on the other cays and Allen Cay plants contained nearly two times more nitrogen. Bayesian stable isotope mixing models indicated that C_3 plants dominated iguana diets on all islands and showed no evidence for consumption of mice or shearwaters. The iguanas on Allen Cay were ~ 2 times longer (48.3 ± 11.6 cm) and ~ 6 times heavier (5499 ± 2847 g) than iguanas on other cays and this was likely from marine-derived subsidies from seabird guano which caused an increase in nitrogen concentration in the plants and a resultant increase in the δ ^15N values across the entire food web relative to non-seabird islands.
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Genetic diversity and structure in the Endangered Allen Cays Rock Iguana, Cyclura cychlura inornata
PeerJ, 2016Co-Authors: Andrea C. Aplasca, Mark E. Welch, John B. Iverson, Giuliano Colosimo, Evon R. HekkalaAbstract:The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (
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genetic diversity and structure in the endangered allen cays rock iguana Cyclura cychlura inornata
PeerJ, 2016Co-Authors: Mark E. Welch, John B. Iverson, Andrea C. Aplasca, Giuliano Colosimo, Evon R. HekkalaAbstract:The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (<4 ha each). However, populations of unknown origin were recently discovered on four additional cays. To investigate patterns of genetic variation among these populations, we analyzed nuclear and mitochondrial markers for 268 individuals. Analysis of three mitochondrial gene regions (2,328 bp) and data for eight nuclear microsatellite loci indicated low genetic diversity overall. Estimates of effective population sizes based on multilocus genotypes were also extremely low. Despite low diversity, significant population structuring and variation in genetic diversity measures were detected among cays. Genetic data confirm the source population for an experimentally translocated population while raising concerns regarding other, unauthorized, translocations. Reduced heterozygosity is consistent with a documented historical population decline due to overharvest. This study provides the first range-wide genetic analysis of this subspecies. We suggest strategies to maximize genetic diversity during ongoing recovery including additional translocations to establish assurance populations and additional protective measures for the two remaining natural populations.
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physiological effects of tourism and associated food provisioning in an endangered iguana
Conservation Physiology, 2013Co-Authors: Charles R Knapp, John B. Iverson, Trevor T. Zachariah, Sandra D. Buckner, Christine R. Lattin, Kirsten N Hines, Caro Perezheydrich, Shelley C Halach, Michael L RomeroAbstract:Deliberately feeding wildlife is an increasingly popular tourism-related activity despite a limited understanding of long-term impacts on the species being fed. As a result, tourist behaviours that may have adverse impacts on imperiled species have often been encouraged without the necessary evaluation or oversight. Here, we report the responses of Northern Bahamian Rock Iguanas (Cyclura cychlura) to human-visitation pressure and associated food provisioning. We compared a variety of blood chemistry parameters of iguanas subjected to supplemental feeding at popular tourist destinations with iguanas occurring on islands where supplemental feeding does not take place. We demonstrate that male and female iguanas inhabiting tourist-visited islands where supplemental feeding occurs do not differ in body condition or baseline stress and stress response (determined by corticosterone levels) compared with iguanas from non-visited islands. Both males and females from tourist-visited sites experienced a greater incidence of endoparasitic infection and atypical loose faeces. Indicators of dietary nutrition, including glucose, potassium, and uric acid values, also differed for both sexes from tourist-visited and unvisited islands. Male iguanas from visited islands differed significantly from those on non-visited islands in calcium, cholesterol, cobalt, copper, magnesium, packed cell volume, selenium, and triglyceride concentrations, whereas female iguanas from visited islands differed significantly in ionized calcium. Although the interpretation of these differences is challenging, chronic biochemical stressors could compromise individual health over time or decrease survivorship during periods of environmental stress. We suggest protocols that can be adopted throughout the region to ensure that supplemental feeding has fewer impacts on these long-lived iguanas.
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Conservation Of Amphibians And Reptiles In The Bahamas
Conservation of Caribbean Island Herpetofaunas Volume 2: Regional Accounts of the West Indies, 2011Co-Authors: Charles R Knapp, John B. Iverson, Sandra D. Buckner, Shelley V. CantAbstract:The native herpetofauna of The Bahamas is derived primarily from Cuba and Hispaniola, and numbers 46 species comprised of three frogs, 25 lizards, 11 snakes, two freshwater turtles, and five sea turtles. Currently, there are few legislative laws directly protecting the herpetofauna of The Bahamas although all three rock iguanas ( Cyclura ) are technically given full protection under the Wild Animals (Protection) Act of 1968. In 2009, the Bahamian Ministry of Agriculture and Marine Resources amended the Fisheries Regulations governing marine turtles in order to give full protection to all sea turtles found in its waters. Major threats to the Bahamian herpetofauna include inappropriate development, apathy, over-exploitation of wildlife, lack of law enforcement, hurricanes, introduced species, and disturbance by tourist activities. This chapter explores the challenges for long-term conservation of the Bahamian herpetofauna and provides suggestions to help mitigate pressures on amphibian and reptile populations. Keywords: Bahamas; Cyclura ; herpetofauna
