The Last Survivors: current status and conservation of the non-volant land mammals of the insular Caribbean

The insular Caribbean is among the few oceanic-type island systems colonized by non-volant land mammals. This region also has experienced the world’s highest level of historical mammal extinctions, with at least 29 species lost since AD 1500. Representatives of only 2 land-mammal families (Capromyidae and Solenodontidae) now survive, in Cuba, Hispaniola, Jamaica, and the Bahama Archipelago. The conservation status of Caribbean land mammals is surprisingly poorly understood. The most recent IUCN Red List assessment, from 2008, recognized 15 endemic species, of which 13 were assessed as threatened. We reassessed all available baseline data on the current status of the Caribbean land-mammal fauna within the framework of the IUCN Red List, to determine specific conservation requirements for Caribbean land-mammal species using an evidence-based approach. We recognize only 13 surviving species, one of which is not formally described and cannot be assessed using IUCN criteria; 3 further species previously considered valid are interpreted as junior synonyms or subspecies. Of the 12 reassessed species, 5 have undergone a change in threat status since 2008, with 3 species (Capromys pilorides, Geocapromys brownii, Mesocapromys angelcabrerai) increasing in extinction risk by 1 IUCN category, and 2 species (Plagiodontia aedium, Solenodon paradoxus) decreasing in extinction risk by 2 categories. Only 1 change in threat status represents a genuine change; all other changes are mainly associated with new information becoming available. Hunting, habitat loss, and invasive species represent major threats to surviving species, and conservation of the highly threatened Caribbean land-mammal fauna will require a range of targeted management strategies

The impact of habitat quality inside protected areas on distribution of the Dominican Republic's last endemic non-volant land mammals

The Hispaniolan solenodon, Solenodon paradoxus, and Hispaniolan hutia, Plagiodontia aedium, are the Dominican Republic’s only surviving endemic non-volant land mammals, and are high priorities for conservation. The country has an extensive protected area (PA) network designed to maintain habitats and benefit biodiversity, but which faces significant anthropogenic threats likely to detrimentally impact both species. We examined how differences in habitats, forest structure, topography, and human activity influence presence of solenodons and hutias across the Dominican Republic. Systematic surveys of seven PAs were undertaken to record indirect signs, with presence-absence data analyzed using a multi-model inference approach incorporating ecological variables from both field and GIS data. Solenodons were detected relatively frequently, whereas detections of hutias were uncommon. Lower elevations, increased surrounding tree cover, canopy closure, and reduced levels of low vegetation are all associated with increased probability of detecting solenodons, whereas agriculture and mangrove represent poor-quality habitat. Increased canopy closure, tree basal area (indicating older-growth forest), and increased rock substrate (providing more den sites) are associated with increased probability of detecting hutias. Our findings indicated that human activities within PAs are likely to negatively affect both species, and conservation activities should focus on preventing encroachment and conversion of forest to agriculture to maintain high-quality forest habitats. / El solenodonte de la Hispaniola, Solenodon paradoxus, y la hutia de la Hispaniola, Plagiodontia aedium, son los únicos mamíferos endémicos terrestres no voladores que sobreviven en la República Dominicana, su conservación es de alta prioridad. El país tiene una extensa red de áreas protegidas (AP) diseñada para mantener hábitats y beneficiar la biodiversidad, pero se enfrenta a amenazas antropogénicas. Sin embargo, no existen datos cuantitativos para evaluar las presiones antropogénicas que amenazan a los solenodontes y las hutias. Examinamos cómo las diferencias en los hábitats, la estructura del bosque, la topografía y la actividad humana influyen la presencia de solenodontes y hutias en toda la República Dominicana. Se realizaron encuestas sistemáticas de siete AP para registrar los signos indirectos de ambas especies, los datos de presencia/ausencia fueron analizados mediante inferencia multimodelo que incorpora variables ecológicas de los datos de campo y Sistema de Información Geográfica. Los Solenodontes se detectaron relativamente frecuentemente, mientras que las detecciones de hutias fueron menos comunes. Las elevaciones más bajas, el aumento de la cubierta arbórea circundante, el cierre del dosel y los niveles reducidos de vegetación baja se asocian con una mayor probabilidad de detectar solenodones. Mientras que la agricultura y los manglares representan un hábitat de mala calidad para el solenodonte. Aumento del cierre del dosel, área basal del árbol (que indica un bosque más antiguo) y un sustrato con mayor proporcion de roca (que proporciona más sitios para madrigueras) se asocian con una mayor probabilidad de detectar hutias. Nuestros hallazgos indican que las actividades humanas dentro de las AP pueden afectar negativamente a ambas especies. Las actividades de conservación deberían enfocarse en mantener hábitats forestales de alta calidad por medio de prevenir la invasión y la conversión de los bosques a agricultura

Independent evolutionary histories in allopatric populations of a threatened Caribbean land mammal

Aim: To determine the evolutionary history, relationships and distinctiveness of allopatric populations of Hispaniolan solenodon (Solenodon paradoxus), a highly threatened Caribbean 'relict' mammal, to understand spatio-temporal patterns of gene flow and the distribution of diversity across complex large island landscapes and inform spatial conservation prioritization. Location: Historical and modern-day solenodon specimens were analysed from sampling localities across Hispaniola, representing this geotectonically complex island's distinct northern, south-eastern and south-western biogeographic provinces. Methods: We successfully amplified mitochondrial cytochrome b and control region sequences from 34 solenodon samples. Bayesian phylogenetic analyses were applied to assess the relationship between these sequence data, and coalescent simulation and approximate Bayesian computation were used to identify which model of solenodon intra-island demographic history best explains the observed patterns of variation. We also conducted morphometric analysis of 110 solenodon specimens to investigate whether allopatric Hispaniolan populations can be differentiated using craniodental characteristics. Results: Unique haplotypes were identified in solenodon samples from each biogeographic region, with no haplotype sharing between regions. Higher marginal posterior probability values were found for a three-population model comprising allopatric northern, south-eastern and south-western Hispaniolan populations, with exceptionally low migration rates inferred between all populations, indicating that they are genetically isolated. Modal estimates of long-term effective female population size are extremely low for south-western and south-eastern populations. Morphometric differentiation is observed between all three populations. Main conclusions: Evolutionary differentiation of Hispaniolan solenodons into three distinct populations is congruent with phylogenetic patterns observed in several other Hispaniolan species, with population isolation possibly associated with past marine transgression. We interpret these populations as distinct subspecies, with the two genetically impoverished southern subspecies particularly vulnerable to environmental change. Our improved understanding of Hispaniolan solenodon evolutionary history provides an important baseline for identifying wider patterns of intra-island diversification and prioritizing conservation attention for evolutionarily significant populations

Assessing congruence of opportunistic records and systematic surveys for predicting Hispaniolan mammal species distributions

Comparative assessment of the relative information content of different independent spatial data types is necessary to evaluate whether they provide congruent biogeographic signals for predicting species ranges. Opportunistic occurrence records and systematically collected survey data are available from the Dominican Republic for Hispaniola’s surviving endemic non‐volant mammals, the Hispaniolan solenodon (Solenodon paradoxus) and Hispaniolan hutia (Plagiodontia aedium); opportunistic records (archaeological, historical and recent) exist from across the entire country, and systematic survey data have been collected from seven protected areas. Species distribution models were developed in maxent for solenodons and hutias using both data types, with species habitat suitability and potential country‐level distribution predicted using seven biotic and abiotic environmental variables. Three different models were produced and compared for each species: (a) opportunistic model, with starting model incorporating abiotic‐only predictors; (b) total survey model, with starting model incorporating biotic and abiotic predictors; and (c) reduced survey model, with starting model incorporating abiotic‐only predictors to allow further comparison with the opportunistic model. All models predict suitable environmental conditions for both solenodons and hutias across a broadly congruent, relatively large area of the Dominican Republic, providing a spatial baseline of conservation‐priority landscapes that might support native mammals. Correlation between total and reduced survey models is high for both species, indicating the substantial explanatory power of abiotic variables for predicting Hispaniolan mammal distributions. However, correlation between survey models and opportunistic models is only moderately positive. Species distribution models derived from different data types can provide different predictions about habitat suitability and conservation‐priority landscapes for threatened species, likely reflecting incompleteness and bias in spatial sampling associated with both data types. Models derived using both opportunistic and systematic data must therefore be applied critically and cautiously