Using the past to contextualize anthropogenic impacts on the present and future distribution of an endemic Caribbean mammal.

Island species are difficult to conserve because they face the synergy of climate change, invasive species, deforestation, and increasing human population densities in areas where land mass is shrinking. The Caribbean island of Hispaniola presents particular challenges because of geopolitical complexities that span 2 countries and hinder coordinated management of species across the island. We employed species distribution modeling to evaluate the impacts of climatic change and anthropogenic activities on the distribution of an endemic mammal of conservation concern, the Hispaniolan solenodon (Solenodon paradoxus). We aggregated occurrence points for this poorly known species for the Last Glacial Maximum (LGM) and the present (1975-2016) based on museum collections, online biodiversity databases, and new field surveys. We quantified degree of overlap between periods and scenarios with Schoener's D. Through a conservation paleobiology lens, we found that over time humans played an increasing role in shaping the distribution of S. paradoxus, thus, providing a foundation for developing conservation strategies on appropriate spatiotemporal scales. Human population density was the single most important predictor of S. paradoxus occurrence. Densities >166 people/km2 corresponded to a near-zero probability of occurrence. Models that accounted for climate but not anthropogenic variables falsely identified suitable habitat in Haiti, where on-the-ground surveys confirm habitat is unavailable. Climate-only models also significantly overestimated the potential for habitat connectivity between isolated populations. Our work highlights that alternative fates for S. paradoxus in the Anthropocene exist across the political border between the Dominican Republic and Haiti due to the fundamentally different economic and political realities of each country. Relationships in the fossil record confirm that Hispaniola's sociopolitical boundary is not biologically significant but instead represents one imposed on the island's fauna in the past 500 years by colonial activity. Our approach reveals how a paleontological perspective can contribute to concrete management insights.

Uso del Pasado para Contextualizar los Impactos Antropogénicos en la Distribución Presente y Futura de un Mamífero Endémico del Caribe Resumen Las especies insulares son difíciles de conservar ya que enfrentan la sinergia del cambio climático, las especies invasoras, la deforestación y la densidad creciente de la población humana en áreas en donde la masa de tierra se está encogiendo. La isla caribeña de La Española representa un reto particular debido a las complejidades geopolíticas que abarcan a dos países y obstaculizan el manejo coordinado de las especies en toda la isla. Empleamos el modelado de distribución de especies para evaluar los impactos del cambio climático y las actividades antropogénicas sobre la distribución de un mamífero endémico de importancia para la conservación: el solenodonte de La Española (Solenodon paradoxus). Agregamos puntos de presencia para esta especie muy poco conocida durante el Último Máximo Glacial (LGM, en inglés) y durante el presente (1975-2016) con base en colecciones de museos, bases de datos de biodiversidad en línea y nuevos censos de campo. A través de este lente de paleobiología de la conservación encontramos que con el tiempo los humanos tuvieron un papel cada vez mayor en la distribución de S. paradoxus, proporcionando así los cimientos para el desarrollo de estrategias de conservación a escalas espacio-temporales adecuadas. La densidad de la población humana fue el pronosticador más importante de la presencia de S. paradoxus. Las densidades mayores a 166 personas/km2 correspondieron con una probabilidad cercana a cero de la presencia de este mamífero. Los modelos que consideraron al cambio climático pero no a las variables antropogénicas identificaron falsamente hábitats aptos en Haití, en donde los censos de campo confirman que no hay hábitat disponible. Los modelos que sólo consideraron el clima también sobreestimaron significativamente el potencial para la conectividad de hábitat entre poblaciones aisladas. Nuestro trabajo resalta que existen destinos alternativos para S. paradoxus en el Antropoceno, que además traspasan la frontera política entre Haití y la República Dominicana causada por las realidades económica y política fundamentalmente diferentes de cada país. Las relaciones en el registro fósil confirman que la frontera socio-política de La Española no es significativa biológicamente, sino que representa una frontera impuesta sobre la fauna de la isla durante los últimos 500 años por la actividad colonial. Nuestra estrategia revela cómo la perspectiva paleontológica puede contribuir para concretar la percepción del manejo.

Dispersal provided resilience to range collapse in a marine mammal: insights from the past to inform conservation biology.

Population loss is often a harbinger of species extinction, but few opportunities exist to follow a species' demography and genetics through both time and space while this occurs. Previous research has shown that the northern fur seal (Callorhinus ursinus) was extirpated from most of its range over the past 200-800 years and that some of the extirpated populations had unique life history strategies. In this study, widespread availability of subfossils in the eastern Pacific allowed us to examine temporal changes in spatial genetic structure during massive population range contraction and partial recovery. We sequenced the mitochondrial control region from 40 ancient and 365 modern samples and analyzed them through extensive simulations within a serial Approximate Bayesian Computation framework. These analyses suggest that the species maintained a high abundance, probably in subarctic refugia, that dispersal rates are likely 85% per generation into new breeding colonies, and that population structure was not higher in the past. Despite substantial loss of breeding range, this species' high dispersal rates and refugia appear to have prevented a loss of genetic diversity. High dispersal rates also suggest that previous evidence for divergent life history strategies in ancient populations likely resulted from behavioral plasticity. Our results support the proposal that panmictic, or nearly panmictic, species with large ranges will be more resilient to future disturbance and environmental change. When appropriately verified, evidence of low population structure can be powerful information for conservation decision-making.

Bartonellae are Prevalent and Diverse in Costa Rican Bats and Bat Flies.

Species in the bacterial genus, Bartonella, can cause disease in both humans and animals. Previous reports of Bartonella in bats and ectoparasitic bat flies suggest that bats could serve as mammalian hosts and bat flies as arthropod vectors. We compared the prevalence and genetic similarity of bartonellae in individual Costa Rican bats and their bat flies using molecular and sequencing methods targeting the citrate synthase gene (gltA). Bartonellae were more prevalent in bat flies than in bats, and genetic variants were sometimes, but not always, shared between bats and their bat flies. The detected bartonellae genetic variants were diverse, and some were similar to species known to cause disease in humans and other mammals. The high prevalence and sharing of bartonellae in bat flies and bats support a role for bat flies as a potential vector for Bartonella, while the genetic diversity and similarity to known species suggest that bartonellae could spill over into humans and animals sharing the landscape.

Calibration and error in placental molecular clocks: a conservative approach using the cetartiodactyl fossil record.

The nature of the molecular and fossil record and their limitations must be ascertained in order to gain the most precise and accurate evolutionary timescale using genetic information. Yet the majority of such timescales are based on point estimates using fossils or the molecular clock. Here we document from the primary literature minimum and maximum fossil age estimates of the divergence of whales from artiodactyls, a commonly used anchor point for calibrating both mitogenomic and nucleogenomic placental timescales. We applied these reestimates to the most recently established placental timescale based on mitochondrial rRNA and several nuclear loci, and present an attempt to account for both genetic and fossil uncertainty. Our results indicate that disregard for fossil calibration error may inflate the power of the molecular clock when testing the time of ordinal diversification in context with the K-T boundary. However, the early history of placentals, including their superordinal diversification, remained in the Cretaceous despite a conservative approach. Our conclusions need corroboration across other frequently used fossil anchor points, but also with more genetic partitions on the linear relationship between molecular substitutions and geologic time.

A genetic record of population isolation in pocket gophers during Holocene climatic change.

A long-standing question in Quaternary paleontology is whether climate-induced, population-level phenotypic change is a result of large-scale migration or evolution in isolation. To directly measure genetic variation through time, ancient DNA and morphologic variation was measured over 2,400 years in a Holocene sequence of pocket gophers (Thomomys talpoides) from Lamar Cave, Yellowstone National Park, Wyoming. Ancient specimens and modern samples collected near Lamar Cave share mitochondrial cytochrome b sequences that are absent from adjacent localities, suggesting that the population was isolated for the entire period. In contrast, diastemal length, a morphologic character correlated with body size and nutritional level, changed predictably in response to climatic change. Our results demonstrate that small mammal populations can experience the long-term isolation assumed by many theoretical models of microevolutionary change.