Biology and Impacts of Pacific Island Invasive Species: 8. Eleutherodactylus planirostris, the Greenhouse Frog (Anura: Eleutherodactylidae)

The greenhouse frog, Eleutherodactylus planirostris, is a direct-developing (i.e., no aquatic stage) frog native to Cuba and the Bahamas. It was introduced to Hawaii via nursery plants in the early 1990s and then subsequently from Hawaii to Guam in 2003. The greenhouse frog is now widespread on five Hawaiian Islands and Guam. Infestations are often overlooked due to the frog’s quiet calls, small size, and cryptic behavior, and this likely contributes to its spread. Because the greenhouse frog is an insectivore, introductions may reduce invertebrates. In Hawaii, the greenhouse frog primarily consumes ants, mites, and springtails, and obtains densities of up to 12,500 frogs ha-1. At this density, it is estimated that they can consume up to 129,000 invertebrates ha-1 night-1. They are a food source for the non-native brown tree snake in Guam and may be a food source for other non-native species. They may also compete with other insectivores for available prey. The greatest direct economic impacts of the invasions are to the nursery trade that must treat infested shipments. Although various control methods have been developed to control frogs in Hawaii, and citric acid, in particular, is effective in reducing greenhouse frogs, the frog’s inconspicuous nature often prevents populations from being identified and managed

The Welfare Implications of Using Exotic Tortoises as Ecological Replacements

<div><h3>Background</h3><p>Ecological replacement involves the introduction of non-native species to habitats beyond their historical range, a factor identified as increasing the risk of failure for translocations. Yet the effectiveness and success of ecological replacement rely in part on the ability of translocatees to adapt, survive and potentially reproduce in a novel environment. We discuss the welfare aspects of translocating captive-reared non-native tortoises, <em>Aldabrachelys gigantea</em> and <em>Astrochelys radiata</em>, to two offshore Mauritian islands, and the costs and success of the projects to date.</p> <h3>Methodology/Principal Findings</h3><p>Because tortoises are long-lived, late-maturing reptiles, we assessed the progress of the translocation by monitoring the survival, health, growth, and breeding by the founders. Between 2000 and 2011, a total of 26 <em>A. gigantea</em> were introduced to Ile aux Aigrettes, and in 2007 twelve sexually immature <em>A. gigantea</em> and twelve male <em>A. radiata</em> were introduced to Round Island, Mauritius. Annual mortality rates were low, with most animals either maintaining or gaining weight. A minimum of 529 hatchlings were produced on Ile aux Aigrettes in 11 years; there was no potential for breeding on Round Island. Project costs were low. We attribute the success of these introductions to the tortoises’ generalist diet, habitat requirements, and innate behaviour.</p> <h3>Conclusions/Significance</h3><p>Feasibility analyses for ecological replacement and assisted colonisation projects should consider the candidate species’ welfare during translocation and in its recipient environment. Our study provides a useful model for how this should be done. In addition to serving as ecological replacements for extinct Mauritian tortoises, we found that releasing small numbers of captive-reared <em>A. gigantea</em> and <em>A. radiata</em> is cost-effective and successful in the short term. The ability to release small numbers of animals is a particularly important attribute for ecological replacement projects since it reduces the potential risk and controversy associated with introducing non-native species.</p> </div

Sequencing three crocodilian genomes to illuminate the evolution of archosaurs and amniotes

The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator (Alligator mississippiensis), saltwater crocodile (Crocodylus porosus) and Indian gharial (Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described

Short heatwaves during fluctuating incubation regimes produce females under temperature-dependent sex determination with implications for sex ratios in nature

Abstract Patterns of temperature fluctuations in nature affect numerous biological processes, yet, empirical studies often utilize constant temperature treatments. This can limit our understanding of how thermally sensitive species respond to ecologically relevant temperatures. Research on turtles with temperature-dependent sex determination (TSD) provides good examples of this, since nest temperatures from many populations rarely exceed those necessary to produce females under constant laboratory conditions. We hypothesized that exposure to brief periods of warm temperatures (i.e., heat waves) are integral to sex determination in species with TSD, which requires tests that move beyond constant temperatures. We exposed Trachemys scripta embryos from multiple populations and across the nesting season to heat waves of variable durations and quantified sex ratios. We found that embryos from all populations were highly sensitive to brief exposures to female producing temperatures; only 7.9 days of exposure produced a 50:50 sex ratio, but the response varied across the nesting season. From these findings, a model was developed to estimate sex ratios from field temperature traces, and this model outperformed traditional methods. Overall, these results enhance our understanding of TSD and emphasize the importance of using biologically relevant temperatures when studying thermally sensitive processes

Dietary Selenomethionine Administration and Its Effects on the American Alligator (Alligator mississippiensis): Oxidative Status and Corticosterone Levels

Selenium (Se) is an essential nutrient which in excess causes toxicity. The disposal of incompletely combusted coal, which often is rich in Se, into aquatic settling basins is increasing the risk of Se exposure worldwide. However, very few studies have looked at the physiological effects of Se exposure on long-lived, top trophic vertebrates, such as the American alligator (Alligator mississippiensis). During a 7-week period, alligators were fed one of three dietary treatments: mice injected with deionized water or mice injected with water containing 1000 or 2000 ppm selenomethionine (SeMet). One week after the last feeding alligators were bled within 3 min of capture for plasma corticosterone (CORT). A few days later, all alligators were euthanized and whole blood and tail tissue were harvested to measure oxidative damage, an antioxidant-associated transcription factor, and antioxidant enzymes [glutathione peroxidase-1 (GPX1), superoxide dismutase-1 (SOD1), and SOD2] by Western blotting. There was a dose-dependent increase in baseline CORT levels in alligators administered SeMet. Except for blood SOD2 levels, SeMet treatment had no effect (p \u3e 0.05 for all) on oxidative status: oxidative damage, GPX1, SOD1, and muscle SOD2 levels were similar among treatments. Our results illustrate that high levels of Se may act as a stressor to crocodilians. Future studies should investigate further the physiological effects of Se accumulation in long-lived, top-trophic vertebrates

Effects of head-starting on multi-year space use and survival of an at-risk tortoise

A major challenge in the recovery of long-lived at-risk taxa like turtles is low juvenile recruitment. Head-starting—the raising of juveniles to larger sizes to improve survival—is one tool that can be used in circumstances where juvenile recruitment is limited. Due to declining populations and difficulty detecting juveniles, however, lack of knowledge of the ecology of juveniles can hinder efforts to develop and evaluate head-starting programs for many turtle species. We sought to inform recovery efforts of Mojave desert tortoises by quantifying multi-year space use and survival of head-started juveniles after release. We radio-tracked tortoises head-started under three different husbandry treatments that varied in rearing duration (from two to over six years) and whether head-starting included an indoor rearing component the first year. We compared post-release space use and survival as a function of treatment, release size, and time since release. We found that space use, including home range size and site fidelity, varied by husbandry treatment, with smaller and younger tortoises having smaller home ranges and higher site fidelity. Additionally, home range size decreased and site fidelity increased with time since release across treatments. Tortoises with an indoor-rearing component experiencing increased risk of mortality as movement increased compared to tortoises reared solely outdoors. Nevertheless, survival did not differ among treatments or with tortoise age or size. Regardless of husbandry treatment, head-started tortoises exhibited similar space-use and survival overall. Our study provides insight into juvenile tortoise behavior and head-starting as a tool for tortoise conservation

Preface - the interdisciplinary workshop on "Gastrointestinal tomours"

Identifying geographic barriers that define genetic structure within a species is crucial in formulating an effective conservation plan. The identification of appropriate management units is critical for the protection and recovery of the gopher tortoise Gopherus polyphemus, which have declined across their entire range. Previous molecular work at various spatial scales has identified distinct population assemblages of the gopher tortoise. The goal of this study was to assess the genetic structure in gopher tortoises through a more complete sampling of the federally listed as threatened portion of the range and evaluate the extent of genetic isolation imposed by several potential geographic barriers. We sequenced a 712–base-pair portion of a mitochondrial gene (NADH dehydrogenase 4) for 322 individuals from 42 sites across the range. We found two major assemblages of haplotypes separated by a modest phylogenetic break (average uncorrected p distance  =  0.015). The biogeographic barrier that best explained the geographic partitioning of genetic variation was the Apalachicola–Chattahoochee rivers and not the one used to delimit the federally listed as threatened portion of the range (Tombigbee–Mobile). However, the presence of distinct (group 1 and 2) haplotypes on either side of Apalachicola–Chattahoochee rivers indicates that the two lineages experienced historical isolation and divergence, after which they came back into contact. If one were to define genetic units of conservation for gopher tortoises, then the Apalachicola–Chattahoochee rivers delineation would be the most appropriate based on the analysis of molecular variance of the mitochondrial sequence data. However, a model that combines the Apalachicola–Chattahoochee and Tombigbee–Mobile rivers as geographic breaks was the second-best model in this analysis, which suggests that the federally listed as threatened portion of the range also contains important geographic structure. Thus, we recommend that making management decisions on the basis of mitochondrial data alone is premature, and that prior to any status review additional work that examines finer scale patterns of genetic structure by using microsatellite loci is required