Comparative Phylogeography of a Coevolved Community: Concerted Population Expansions in Joshua Trees and Four Yucca Moths

Comparative phylogeographic studies have had mixed success in identifying common phylogeographic patterns among co-distributed organisms. Whereas some have found broadly similar patterns across a diverse array of taxa, others have found that the histories of different species are more idiosyncratic than congruent. The variation in the results of comparative phylogeographic studies could indicate that the extent to which sympatrically-distributed organisms share common biogeographic histories varies depending on the strength and specificity of ecological interactions between them. To test this hypothesis, we examined demographic and phylogeographic patterns in a highly specialized, coevolved community – Joshua trees (Yucca brevifolia) and their associated yucca moths. This tightly-integrated, mutually interdependent community is known to have experienced significant range changes at the end of the last glacial period, so there is a strong a priori expectation that these organisms will show common signatures of demographic and distributional changes over time. Using a database of >5000 GPS records for Joshua trees, and multi-locus DNA sequence data from the Joshua tree and four species of yucca moth, we combined paleaodistribution modeling with coalescent-based analyses of demographic and phylgeographic history. We extensively evaluated the power of our methods to infer past population size and distributional changes by evaluating the effect of different inference procedures on our results, comparing our palaeodistribution models to Pleistocene-aged packrat midden records, and simulating DNA sequence data under a variety of alternative demographic histories. Together the results indicate that these organisms have shared a common history of population expansion, and that these expansions were broadly coincident in time. However, contrary to our expectations, none of our analyses indicated significant range or population size reductions at the end of the last glacial period, and the inferred demographic changes substantially predate Holocene climate changes

High proportion of cactus species threatened with extinction

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Consejo Nacional de Ciencia y Tecnologí

Colonización en las tierras áridas de Norteamérica: El viaje de Agarito (Berberis trifoliolata) revelado por datos moleculares multilocus y restos fósiles de Packrat Midden

Here we conduct research to understand the evolutionary history of a shrubby species known as Agarito (Berberis trifoliolata), an endemic species to the Chihuahuan Desert. We identify genetic signatures based on plastid DNA and AFLP markers and perform niche modelling and spatial connectivity analyses as well as niche modelling based on records in packrats to elucidate whether orogenic events such as mountain range uplift in the Miocene or the contraction/expansion dynamics of vegetation in response to climate oscillations in the Pliocene/Pleistocene had an effect on evolutionary processes in Agarito. Our results of current niche modelling and palaeomodelling showed that the area currently occupied by Berberis trifoliolata is substantially larger than it was during the Last Interglacial period and the Last Glacial Maximum. Agarito was probably confined to small areas in the Northeastern and gradually expanded its distribution just after the Last Glacial Maximum when the weather in the Chihuahuan Desert and adjacent regions became progressively warmer and drier. The most contracted range was predicted for the Interglacial period. Populations remained in stable areas during the Last Glacial Maximum and expanded at the beginning of the Holocene. Most genetic variation occured in populations from the Sierra Madre Oriental. Two groups of haplotypes were identified: the Mexican Plateau populations and certain Northeastern populations. Haplogroups were spatially connected during the Last Glacial Maximum and separated during interglacial periods. The most important prediction of packrat middens palaeomodelling lies in the Mexican Plateau, a finding congruent with current and past niche modelling predictions for agarito and genetic results. Our results corroborate that these climate changes in the Pliocene/Pleistocene affected the evolutionary history of agarito. The journey of agarito in the Chihuahuan Desert has been dynamic, expanding and contracting its distribution range and currently occupying the largest area in its history.Aquí realizamos una investigación para comprender la historia evolutiva de una especie arbustiva conocida como Agarito (Berberis trifoliolata), una especie endémica del desierto de Chihuahua. Identificamos firmas genéticas basadas en marcadores de ADN plastidial y AFLP y realizamos análisis de modelado de nicho y de conectividad espacial, así como de modelado de nicho basado en registros en packrats para dilucidar si los eventos orogénicos como el levantamiento de la cordillera en el Mioceno o la dinámica de contracción/expansión de la vegetación en respuesta a las oscilaciones climáticas en el Plioceno/Pleistoceno tuvieron un efecto en los procesos evolutivos de Agarito. Nuestros resultados de la modelización del nicho actual y de la paleomodelización mostraron que el área ocupada actualmente por Berberis trifoliolata es sustancialmente mayor de lo que era durante el último período interglacial y el último máximo glacial. El agarito estaba probablemente confinado en pequeñas zonas del noreste y amplió gradualmente su distribución justo después del Último Máximo Glacial, cuando el clima en el desierto de Chihuahua y las regiones adyacentes se volvió progresivamente más cálido y seco. El área de distribución más contraída se predijo para el periodo interglaciar. Las poblaciones permanecieron en zonas estables durante el Último Máximo Glacial y se expandieron a principios del Holoceno. La mayor variación genética se produjo en las poblaciones de la Sierra Madre Oriental. Se identificaron dos grupos de haplotipos: las poblaciones de la Meseta Mexicana y ciertas poblaciones del Noreste. Los haplogrupos estuvieron conectados espacialmente durante el Último Máximo Glacial y se separaron durante los periodos interglaciares. La predicción más importante de la paleomodelación de los muladares de las ratas de carga se sitúa en la Meseta Mexicana, un hallazgo congruente con las predicciones actuales y pasadas de la modelización del nicho del agarito y los resultados genéticos. Nuestros resultados corroboran que estos cambios climáticos en el Plioceno/Pleistoceno afectaron a la historia evolutiva del agarito. El recorrido del agarito en el Desierto Chihuahuense ha sido dinámico, expandiendo y contrayendo su rango de distribución y ocupando actualmente la mayor área de su historia.Fil: Angulo, Diego F. Universidad Autónoma de Yucatán; México.Fil: Amarilla, Leonardo D. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Amarilla, Leonardo D. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Anton, Ana M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Anton, Ana M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Sosa, Victoria. Instituto de Ecología. Departamento de Biología Evolutiva; México