ABSTRACT Understanding which factors predict species sensitivity to climate change requires comparative studies conducted under standardized conditions. Reptiles are particularly vulnerable to climate shifts due to their reliance on external temperatures to regulate body temperature. As such, available environmental temperatures may influence their behavior as they seek more optimal conditions. In this study, we measured thermal habitat use in 73 individuals across nine turtle species housed under semi‐natural conditions at a single location. Ambient temperatures within each enclosure were also recorded every 20 min for 3 months to determine the range of thermal options available, yielding over 650,000 data points. We then compared experienced habitat temperatures to environmental conditions across the native range of each species. Experienced habitat temperatures generally aligned with native conditions. However, several species—including Terrapene carolina, Chelonoidis denticulata, and Indotestudo elongata—experienced habitat temperatures near the lower limit of what was available in enclosures and showed little individual variation, suggesting limited capacity for behavioral adjustment under future warming. Experienced habitat temperatures differed among species and were influenced by body mass, but not sex. By providing the first large‐scale, cross‐species dataset on experienced habitat temperatures in turtles under standardized conditions, this study offers a framework for assessing thermal vulnerability and adaptive capacity in response to climate change. These findings also inform conservation efforts, including the design of captive environments that reflect species‐specific thermal needs.

Abstract Background Comparative oncology can uncover novel mechanisms of cancer resistance and progression across animals. Non-traditional model organisms with naturally high or low cancer prevalence may provide further insights into metastasis or cancer resistance. In this context, the “lemon frost” morph of the leopard gecko (Eublepharis macularius) shows high prevalence of iridophoromas, exceeding 80%. These tumors can recur and metastasize, presenting a unique opportunity to study pigment cell cancer and tumor progression in a non-mammalian vertebrate. Results We performed high-coverage whole-genome sequencing on matched tumor and non-tumor samples from three lemon frost individuals. A shared missense mutation in the TATA-box binding protein (TBP) suggests possible disruption to transcriptional regulation in tumor samples. Additionally, a recurrent gene fusion between IARS1 and RNF213 was identified across all tumor samples. Copy number neutral loss of heterozygosity events were observed in three mutated genes that have a role in cancer: MAP3K13, TENM4, and OR2AT4-like, while copy number gains were observed in four genomic regions. Pathway analysis revealed dysregulation in actin filament organization, a hallmark of metastatic potential. These findings suggest a multifaceted genomic basis for tumorigenesis in this model, including transcriptional misregulation, chromatin remodeling defects, and cytoskeletal disruption. Conclusions This study provides the first characterization of genomic changes associated with iridophoroma in a reptilian species and establishes the lemon frost gecko as a promising model for cancer research. Our findings identify candidate pathways of tumor progression and metastasis in a non-traditional system, highlighting both conserved and novel mechanisms relevant to human disease.

Turtles are renowned for their extreme longevity and tremendous range in body size. Theoretically, large, long-lived organisms should face higher cancer risks because of increased cell numbers and lifetime cellular turnover, yet cancer appears to be exceptionally rare in turtles. In the present article, we synthesize the current knowledge on cancer prevalence in turtles, drawing from zoo necropsies, pathology reports, and comparative oncology studies, and present new data spanning additional species that reinforce this pattern. Emerging molecular evidence suggests that turtles possess high resistance to oxidative stress and protein dysregulation, which may contribute to cancer resistance. Given their extreme lifespans and unique physiology, turtles represent a promising but underexplored model for studying the evolution of longevity and natural cancer suppression mechanisms.

Globally, the disease ecology of reptiles remains understudied, even for threatened and iconic species such as the Galápagos marine iguana (Amblyrhynchus cristatus). Although marine iguanas are parasitized by distinct species of ticks and mites, research on vector-borne diseases for this species is limited. In this study, we detected 16S ribosomal RNA (rRNA) sequences of Candidatus Allocryptoplasma in transcriptomic data from marine iguana blood samples. These 16S rRNA sequences were further characterized through phylogenetic analysis and a haplotype network. Our analysis revealed the first molecular evidence for the infection of marine iguanas with Candidatus Allocryptoplasma, a candidate genus in the family Anaplasmataceae with unknown pathogenic potential, likely transmitted by ticks. Phylogenetic analysis of the novel 16S rRNA sequences together with available Anaplasmataceae sequences confirmed their assignment to this candidate genus. A haplotype network analysis indicated that the agent infecting the marine iguana represents a distinct lineage within the known Ca. Allocryptoplasma diversity. Candidatus Allocryptoplasma had a high prevalence within marine iguanas, infecting individuals across most of the geographical range of this species. To elucidate the transmission dynamics of this bacterium in the Galápagos ecosystem, ectoparasites of the marine iguana and shared vertebrate hosts should be screened for infection with Ca. Allocryptoplasma.

Evaluating pesticide ecological risk is essential for regulation, but traditional vertebrate testing is resource-intensive and ethically challenging. New approach methodologies, such as high-throughput assays (HTAs), offer cost-effective, mechanistically explicit alternatives that reduce animal use. The US EPA's ToxCast program houses HTA data for chemical screening, but its use in ecological risk assessment (ERA) remains underutilized. We applied ToxCast data directly to ERA metrics, comparing assay-derived exposure-activity ratios to in vivo risk quotients (RQs) from regulatory assessments. Uniquely, our study focuses on pesticides and is risk-focused rather than hazard-focused, leveraging data drawn directly from the same standardized regulatory risk assessments that inform decision-making. While ToxCast assays generally underestimated risks compared to in vivo RQs-particularly for chronic endpoints-certain assays, such as cytochrome P450 assays, demonstrated strong alignment for herbicides and fungicides. In contrast, assay performance was weaker for neurotoxic insecticides and herbicides targeting photosynthesis, reflecting gaps in HTA coverage for these modes of action. Our findings underscore the potential of HTAs as complementary tools for ERA, particularly for screening and prioritization, though further assay development is needed for chronic and mode-of-action-specific risks. Integrating HTA data into risk metrics lays the groundwork for promoting more accurate, efficient, and ethical approaches to pesticide evaluation.

We evaluated the feasibility of using the high-throughput CometChip to assess DNA damage in non-model species. Specifically, we measured UVA-induced damage in fibroblasts from five turtle and four mammalian species with diverse life histories and cancer rates. Turtles exhibited significantly higher endogenous DNA damage than mammals but showed lower UVA-induced damage after both 2-min and 5-min exposures. At 5 min, bats exhibited the most DNA damage (21.3

In this study, we compared a wide range of cell-based bioassays to the use of chemical analysis followed by exposure-activity ratio (EAR) and Toxicological Prioritization index (ToxPi) for prioritizing chemicals, sites, and hazard concerns in water samples. Surface water samples were collected from nine sites in three Central Pennsylvania streams and analyzed for a forty-six contaminants of emerging concern (CECs), including pesticides, personal care products, and pharmaceuticals. Cell-based reporter assays evaluated human and zebrafish molecular initiating events (MIEs) in endocrine and metabolic disruption, altered lipid metabolism, and oxidative stress. Bioassays showed that 12 out of 40 assays had at least one site with activity over the effect-based trigger (EBT) values. The receptors that exhibited the highest number of samples above the EBT that would be expected to cause toxicity were Aryl hydrocarbon receptor (AhR, human and zebrafish), Pregnane X Receptor (PXR), Estrogen Receptor-beta (ERB), and Androgen Receptor (AR). Characterizing the collection sites by their bioactivity aligned closely with the stream in which samples were collected. The sum of all EARs for each chemical indicated that the pharmaceutical Carbamazepine and the pesticides Carbaryl and Atrazine posed the greatest concern. However, predicted activity and site prioritization based on individual chemical analysis and calculated EAR were different than those measured by bioassay, indicating that biologically active chemicals are present in the samples that were not included in the targeted analytes. Taken together, these data show that chemical analysis and EAR analysis are beneficial for prioritization of chemicals, whereas mechanism-based bioassays are more inclusive of known as well as unknown chemical contaminants and thus of more use for overall water quality analysis and site prioritization.

RNA sequencing (RNA-Seq) is becoming a popular method for measuring gene expression in non-model organisms, including wild populations sampled in the field. While RNA-Seq can be used to measure gene expression variation among wild-caught individuals and can yield important biological insights into organismal function, technical variables may also influence gene expression estimates. We examined the influence of multiple technical variables on estimated gene expression in a non-model fish species, the westslope cutthroat trout (Oncorhynchus clarkii lewisi), using two RNA-Seq methods: 3’ RNA-Seq and whole mRNA-Seq. We evaluated the effects of dip netting versus electrofishing, and of harvesting tissue immediately versus 5 minutes after euthanasia on estimated gene expression in blood, gill, muscle, and liver. We found higher RNA degradation in the liver compared to the other tissues. There were fewer expressed genes in blood compared to gill and muscle. We found no difference in gene expression among sampling methods or due to a delay in tissue collection. However, we detected fewer genes with 3’ RNA-Seq than with whole mRNA-Seq and found statistically significant differences in gene expression between 3’ RNA-Seq and whole mRNA-Seq. The magnitude and direction of these differences does not appear to be dependent on gene type or length. Our findings indicate that RNA-Seq is robust to the technical variables related to the field sampling techniques tested here but varies based on the tissue sampled and the RNA-Seq library used. This study advances understanding of usefulness of RNA-Seq to study gene expression variation in evolution, ecology, and conservation.

Surveys assessing attitudes and values about the environment can help predict human behavior toward wildlife and develop effective conservation goals alongside local communities. Coastal Alabama, in the southeastern United States, is a hotspot for biodiversity and endemism and needs protection. Land and wildlife management practices in Alabama have moved from indigenous-led, which is more in harmony with the environment, to larger-scale exploitative uses for agriculture and plantations. We therefore predicted that a large proportion of the population has a dominant view of the environment in which land and wildlife are primarily for human benefit. To test this hypothesis, we surveyed over 1300 residents in Mobile and Baldwin counties-the two southernmost counties in Alabama-to assess attitudes toward local vertebrate wildlife, knowledge of the region's biodiversity, and whether individuals value protected areas where they live and/or work. As hunting is generally considered a dominant behavior, we used self-identified hunters versus non-hunters to examine the relationship between humans and the environment. Overall, hunters would kill or kill to eat more often than non-hunters, and would kill even when it is not for food. Furthermore, regardless of hunting status, most participants in our survey would kill a snake, indicating that targeted environmental education is needed for this group. Both hunters and non-hunters, independently of demographic differences including education and income levels, were not familiar with the especially rich biodiversity of the area and would not be willing to invest money to protect it. Our results indicate that targeted education about the unique and rich biodiversity of southern Alabama compared to the rest of the United States is needed to support successful environmental management, conservation actions, and local participation.

Pharmaceuticals and personal care products (PPCPs) are incredibly diverse in terms of chemical structures, physicochemical properties, and modes of action, making their environmental impacts challenging to assess. New chemical prioritization methodologies have emerged that compare contaminant monitoring concentrations to multiple toxicity data sources, including whole organism and high-throughput data, to develop a list of "high priority" chemicals requiring further study. We applied such an approach to assess PPCPs in Hunting Creek, an urban tributary of the Potomac River near Washington, DC, which has experienced extensive human population growth. We estimated potential risks of 99 PPCPs from surface water and sediment collected upstream and downstream of a major wastewater treatment plant (WWTP), nearby combined sewer overflows (CSO), and in the adjacent Potomac River. The greatest potential risks to the aquatic ecosystem occurred near WWTP and CSO outfalls, but risk levels rapidly dropped below thresholds of concern - established by previous chemical prioritization studies - in the Potomac mainstem. These results suggest that urban tributaries, rather than larger rivers, are important to monitor because their lower or intermittent flow may not adequately dilute contaminants of concern. Common psychotropics, such as fluoxetine and venlafaxine, presented the highest potential risks, with toxicity quotients often > 10 in surface water and > 1000 in sediment, indicating the need for further field studies. Several ubiquitous chemicals such as caffeine and carbamazepine also exceeded thresholds of concern throughout our study area and point to specific neurotoxic and endocrine modes of action that warrant further investigation. Since many "high priority" chemicals in our analysis have also triggered concerns in other areas around the world, better coordination is needed among environmental monitoring programs to improve global chemical prioritization efforts.

Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.

Glucocorticoids are steroid hormones that are often used to evaluate vertebrate population health. However, glucocorticoid levels can vary widely among individuals and over time, making it challenging to unravel the factors influencing their expression. We examined the relationship between corticosterone – the primary glucocorticoid in reptiles – and various biological and ecological factors in Galapagos marine iguanas (Amblyrhynchus cristatus). Marine iguanas are ideal for studying drivers of physiological stress since they inhabit many isolated islands with varying ecological conditions. We found that baseline corticosterone levels differed among marine iguana populations throughout the Galapagos archipelago, and that females had significantly higher corticosterone values than males. However, we did not find strong relationships between corticosterone and other assessed factors, including body condition, food availability, and blood parasite infection. Our results differ from previous studies, which found that corticosterone is strongly linked to body condition and a good predictor of individual survival probability in marine iguanas. This discrepancy is likely because prior studies were conducted during periods of acute environmental stress, such as an El Niño or oil spill, whereas our work took place during typical non-El Niño conditions when food was abundant. Thus, baseline corticosterone in marine iguanas appears to be a good surrogate for individual health and survival during times of extreme stress but should be used with caution for routine monitoring. Our results add to a growing understanding of the applicability of glucocorticoids for assessing population health.

The Anatomical RecordVolume 306, Issue 3 p. 688-691 COMMENTARY A rare case of caudal bifurcation in a miniaturized gecko from Puerto Rico Juan D. Daza, Corresponding Author Juan D. Daza [email protected] orcid.org/0000-0002-5651-0240 Department of Biological Sciences, Sam Houston State University, Huntsville, Texas, USA Correspondence Juan D. Daza, Department of Biological Sciences, Sam Houston State University, Huntsville, TX, USA. Email: [email protected]Search for more papers by this authorYlenia Chiari, Ylenia Chiari orcid.org/0000-0003-2338-8602 Department of Biology, George Mason University, Manassas, Virginia, USASearch for more papers by this authorEmilia Daza-Herrera, Emilia Daza-Herrera Scott Johnson Elementary and Huntsville Intermediate School, Huntsville, Texas, USASearch for more papers by this authorMayim S. Glaberman, Mayim S. Glaberman Laurel Ridge Elementary School, Fairfax, Virginia, USASearch for more papers by this authorScott Glaberman, Scott Glaberman orcid.org/0000-0003-0594-4732 Department of Environmental Science and Policy, George Mason University, Fairfax, Virginia, USASearch for more papers by this authorOlivia A. Heide, Olivia A. Heide orcid.org/0000-0002-3992-9533 Department of Biological Sciences, Sam Houston State University, Huntsville, Texas, USASearch for more papers by this authorAlexandra Herrera-Martínez, Alexandra Herrera-Martínez orcid.org/0000-0001-5774-2863 Diagnostic Laboratory for Human Health, Sam Houston State University, Huntsville, Texas, USASearch for more papers by this authorRichard Thomas, Richard Thomas Biology Department, University of Puerto Rico, Río Piedras Campus, Río Piedras, Puerto RicoSearch for more papers by this author Juan D. Daza, Corresponding Author Juan D. Daza [email protected] orcid.org/0000-0002-5651-0240 Department of Biological Sciences, Sam Houston State University, Huntsville, Texas, USA Correspondence Juan D. Daza, Department of Biological Sciences, Sam Houston State University, Huntsville, TX, USA. Email: [email protected]Search for more papers by this authorYlenia Chiari, Ylenia Chiari orcid.org/0000-0003-2338-8602 Department of Biology, George Mason University, Manassas, Virginia, USASearch for more papers by this authorEmilia Daza-Herrera, Emilia Daza-Herrera Scott Johnson Elementary and Huntsville Intermediate School, Huntsville, Texas, USASearch for more papers by this authorMayim S. Glaberman, Mayim S. Glaberman Laurel Ridge Elementary School, Fairfax, Virginia, USASearch for more papers by this authorScott Glaberman, Scott Glaberman orcid.org/0000-0003-0594-4732 Department of Environmental Science and Policy, George Mason University, Fairfax, Virginia, USASearch for more papers by this authorOlivia A. Heide, Olivia A. Heide orcid.org/0000-0002-3992-9533 Department of Biological Sciences, Sam Houston State University, Huntsville, Texas, USASearch for more papers by this authorAlexandra Herrera-Martínez, Alexandra Herrera-Martínez orcid.org/0000-0001-5774-2863 Diagnostic Laboratory for Human Health, Sam Houston State University, Huntsville, Texas, USASearch for more papers by this authorRichard Thomas, Richard Thomas Biology Department, University of Puerto Rico, Río Piedras Campus, Río Piedras, Puerto RicoSearch for more papers by this author First published: 06 July 2022 https://doi.org/10.1002/ar.25034 Funding information: Department of Biological Sciences Sam Houston State Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume306, Issue3March 2023Pages 688-691 RelatedInformation

Animals are exposed to different visual stimuli that influence how they perceive and interact with their environment. Visual information such as shape and colour can help animals detect, discriminate, and make appropriate behavioural decisions for mate selection, communication, camouflage, and foraging. Previous research indicates that at least some species within all major vertebrate groups prefer and can discriminate among certain colours and that colour may increase the response to a stimulus. However, since colour is often studied together with other potentially confounding factors such as movement and scent, it is still unclear what role colour plays in the perception of and attention to different stimuli. In this study, we test whether colour influences the response that an animal has to an object, and whether this influence changes depending on the type of object shown to the animal. We assessed the response of three gecko species, Correlophus ciliatus , Eublepharis macularius, and Phelsuma laticauda, to familiar and novel objects presented as colour or grayscale images. Our results indicate that colour does not change the response to objects. Specifically, we found that while all species responded more often to novel than to the familiar images, colour did not influence the response. We also found that the duration of interaction with images was significantly longer for the diurnal species, P. laticauda , than for the two nocturnal species, but this was also independent of colouration. Finally, no differences among sexes were observed within or between species. Our results show that geckos discriminate between 2D images of different content independent of colouration, suggesting that colour may not increase detectability or intensity of the response. These results are essential for uncovering which visual stimuli produce responses in animals.

Ecological risk assessments of chemicals are frequently based on laboratory toxicity data from a small number of model species that may be reared in labs for years or decades. These populations can undergo many processes in the lab including artificial selection, founder effect, and genetic drift, and may not adequately represent their wild counterparts, potentially undermining the goal of protecting natural populations. Here we measure variation in lethality to copper chloride among strains of an emerging model species in toxicology, Caenorhabditis elegans. We tested four wild strains from Chile, Germany, Kenya, and Madeira (Portugal) against several versions of the standard laboratory N2 strain from Bristol, UK used in molecular biology. The four wild strains were more sensitive than any of the N2 strains tested with copper. We also found that the standard N2 strain cultured in the laboratory for >1 year was less sensitive than a recently cultured N2 strain as well as a cataloged ancestral version of the N2 strain. These results suggest that toxicologists should be cognizant of performing toxicity testing with long-held animal cultures, and should perhaps use multiple strains as well as renew cultures periodically in the laboratory. This study also shows that multi-strain toxicity testing with nematodes is highly achievable and useful for understanding variation in intra- and interspecific chemical sensitivity.

Pharmaceuticals and personal care products (PPCPs) are incredibly diverse in terms of chemical structures, physicochemical properties, and modes of action, making it challenging to assess their environmental impacts. Many PPCPs also lack regulatory benchmarks and toxicity data, and are not efficiently removed by wastewater treatment. New chemical prioritization methodologies have emerged that compare PPCP monitoring concentrations to multiple toxicity data sources, including whole organism and high-throughput data, to develop a list of “high priority” chemicals requiring further study. We applied such an approach to assess PPCPs in Hunting Creek, an urban tributary of the Potomac River near Washington, DC, which has experienced extensive human population growth. We estimated potential risks of 99 PPCPs from surface water and sediment collected upstream and downstream of a major wastewater treatment plant (WWTP) discharging into Hunting Creek, nearby combined sewer overflows (CSO), and in the adjacent Potomac River. Most “high priority” PPCPs we identified, including acetaminophen, caffeine, carbamazepine, metoprolol, sulfamethoxazole, and venlafaxine, were also flagged in a similar study in the Great Lakes. The greatest potential risks occurred near the WWTP and CSO outfalls, but risk levels rapidly dropped below thresholds of concern in the Potomac mainstem, likely due to increased flow. Common psychotropics, such as fluoxetine and venlafaxine, presented the greatest potential risks, with toxicity quotients often >10. Several ubiquitous chemicals such as caffeine and carbamazepine also exceeded thresholds of concern throughout our study area and point to specific neurotoxic and endocrine modes of action that warrant further laboratory or field study.

Identifying species with lower-than-expected cancer prevalence can help establish new models for understanding cancer resistance. Most studies of cancer prevalence have focused on mammals. Yet, other vertebrate groups vary tremendously in genetics, physiology, and ecology, which can all influence mechanisms of cancer resistance and may hold new keys to understanding cancer biology. Here, we present data on cancer prevalence in tetrapods, which includes all major vertebrate groups except fish, using necropsies from over a thousand different species. We investigated cancer prevalence within and among amphibians, birds, crocodilians, mammals, squamates, and turtles in relationship to body mass and lifespan. We are the first to (1) analyze non-avian reptile groups separately, (2) conduct statistical analyses appropriate for this type of discontinuous data, (3) more accurately use raw cancer occurrence data instead of species averages, and (4) look at how data resampling influences the robustness of results. We found remarkably low cancer prevalence in turtles and high prevalence in squamates and mammals. In contrast to previous studies, lifespan in mammals was negatively associated with neoplasia but positively associated with malignancy. We recovered the same results by reanalyzing data from these previous studies with our statistical approach. We also found that neoplasia prevalence was positively associated with body mass in amphibians and squamates. Overall, our results demonstrate a clear relationship between life history and neoplasia in most tetrapod groups. Our findings also indicate that choice of analytical methods is critical when examining cancer prevalence data. Finally, the exceptionally low cancer prevalence in turtles and extensive variation in cancer prevalence among tetrapod families hold particular promise for identifying species with novel mechanisms of cancer resistance.

Pseudemys alabamensis is one of the most endangered freshwater turtle species in the United States due to its restricted geographic distribution in coastal Alabama and Mississippi. Populations of P. alabamensis are geographically isolated from one another by land and saltwater, which could act as barriers to gene flow. It is currently unknown how differentiated these populations are from one another and whether they have experienced reductions in population size. Previous work found morphological differences between Alabama and Mississippi populations, suggesting that they may be evolutionarily distinct. Other Pseudemys turtles such as P. concinna and P. floridana occur naturally within the same geographic area as P. alabamensis and are known to hybridize with each other. These more abundant species could threaten the unique genetic identity of P. alabamensis through introgression. In order to evaluate the endangered status of P. alabamensis and the level of hybridization with other species, we used mitochondrial and nuclear microsatellite markers to assess genetic variation within and among populations of P. alabamensis throughout its range and estimate admixture with co-occurring Pseudemys species. In P. alabamensis, we found no variation in mitochondrial DNA and an excess of homozygosity in microsatellite data. Our results show genetic differentiation between Alabama and Mississippi populations of P. alabamensis, and low estimated breeding sizes and signs of inbreeding for two populations (Fowl River, Alabama and Biloxi, Mississippi). We also found evidence of admixture between P. alabamensis and P. concinna/P. floridana. Based on our results, P. alabamensis is highly endangered throughout its range and threatened by both low population sizes and hybridization. In order to improve the species' chances of survival, focus should be placed on habitat preservation, maintenance of genetic diversity within both the Mississippi and Alabama populations, and routine population-monitoring activities such as nest surveillance and estimates of recruitment.

The Galapagos Archipelago is recognized as a natural laboratory for studying evolutionary processes. San Cristóbal was one of the first islands colonized by tortoises, which radiated from there across the archipelago to inhabit 10 islands. Here, we sequenced the mitochondrial control region from six historical giant tortoises from San Cristóbal (five long deceased individuals found in a cave and one found alive during an expedition in 1906) and discovered that the five from the cave are from a clade that is distinct among known Galapagos giant tortoises but closely related to the species from Española and Pinta Islands. The haplotype of the individual collected alive in 1906 is in the same clade as the haplotype in the contemporary population. To search for traces of a second lineage in the contemporary population on San Cristóbal, we closely examined the population by sequencing the mitochondrial control region for 129 individuals and genotyping 70 of these for both 21 microsatellite loci and >12,000 genome-wide single nucleotide polymorphisms [SNPs]. Only a single mitochondrial haplotype was found, with no evidence to suggest substructure based on the nuclear markers. Given the geographic and temporal proximity of the two deeply divergent mitochondrial lineages in the historical samples, they were likely sympatric, raising the possibility that the lineages coexisted. Without the museum samples, this important discovery of an additional lineage of Galapagos giant tortoise would not have been possible, underscoring the value of such collections and providing insights into the early evolution of this iconic radiation.

The Kemp's ridley (Lepidochelys kempii) is the world's most endangered sea turtle species. Predominately nesting at only one beach in Mexico, this species declined to an estimated 300 females in the mid-1980s. Conservation efforts in the United States and Mexico, including a head start programme in southern Texas in which hatchlings were reared in captivity for several months before being released into the wild, resulted in the recovery of this species. Although genetic data have previously been used to assess the success of the head start programme and dispersal of individual adults, data on immature turtles sampled at foraging areas and adult females sampled at the main nesting beach in Mexico are lacking. Genetic characterization of immature individuals is important for understanding recruitment, survival, and population demography, while genetic data on individuals from Mexico are essential for understanding dispersal and overall genetic diversity in this species. To address these gaps, mitochondrial DNA data were collected from 106 immature individuals sampled at four different foraging sites in the northern Gulf of Mexico and from 18 nesting females at the primary nesting beach in Mexico. Two previously unknown mitochondrial DNA haplotypes were discovered among the immature individuals. Except for these two new haplotypes, the genetic diversity of immature individuals in the northern Gulf of Mexico closely corresponds to that of adults sampled in Mexico, which suggests that much of the diversity within the nesting population can be found among immature animals dispersing to foraging grounds, including locations in the northern Gulf of Mexico. Continued monitoring of the genetic variation of different life stages of this species across its distribution range will help assess the success of conservation programmes by ensuring the maintenance of genetic diversity and representation of this diversity across the species' distribution range.