Early adaptive radiations of Aplodontoidea (Rodentia, Mammalia) on the Holarctic region: systematics, and phylogenetic and paleobiogeographic implications

International audienceThe Aplodontoidea, now restricted to only oneNorth American species (Aplodontia rufa), have shown awide Holarctic extension since the Upper Eocene. As theirfossil record is poor, their phylogenetic relationships andthe origins of their successive radiations remain unclear.We perform here phylogenetic analyses, primarily based ondental evidence (94 dental of 97 characters), restricted toPaleogene and early Miocene taxa (46 taxa) in order toavoid biases introduced by substantially derived (divergent)taxa. We confirm the inclusion of some problematicgenera such as Cedromus or Douglassciurus withinSciuroidea rather than in Aplodontoidea. Ephemeromysand Lophallomys appear as the most basal members of theAplodontoidea, and Epeiromys is the closest outgroup ofthe Sciuroidea-Aplodontoidea clade. The relationshipsamong the ‘‘prosciurines’’ remain unclear, with paraphyleticgenera such as Prosciurus and Haplomys. Theirdiagnoses are reevaluated and a new genus is described.The Aplodontidae, including the clade of the latter, andHaplomys liolophus display a dichotomy betweenAnsomyinae and Aplodontinae, the two crown groups. Thefirst clade formed by the European species argoviensis anddescendens (referred to a new genus) can be proposed as asister group of the species of Ansomys. The second branchof the dichotomy includes the European Plesispermophilusand Sciurodon as basal groups. The species of Parallomysdo not form a clade, and the genus appears paraphyletic.The last dichotomy separates the Allomys clade from the‘meniscomyine’ clade. Comparisons of the selected speciesallow consideration of their patterns of dental evolution(e.g. enlargement of P4, development of a metaloph—protoloph disto-mesial connection, of crescentic shape inmain cusps and ectoloph, of a buccal protruding compressedmesostyle, of a metastylid crest or an anterior spurof the hypoconid, etc.). The split between sciuroids andaplodontoids occurred in North America, and then aplodontoidsdispersed rapidly throughout the whole Holarcticregion. The first aplodontid adaptive radiation took placeeither in North America or in Asia. Periodic exchangesoccurred between Europe, Asia and North America, andthe last radiations (meniscomyines) were restricted inNorth America

Spatio-Temporal Patterns of Beaked Whale Echolocation Signals in the North Pacific

At least ten species of beaked whales inhabit the North Pacific, but little is known about their abundance, ecology, and behavior, as they are elusive and difficult to distinguish visually at sea. Six of these species produce known species-specific frequency modulated (FM) echolocation pulses: Baird’s, Blainville’s, Cuvier’s, Deraniyagala’s, Longman’s, and Stejneger’s beaked whales. Additionally, one described FM pulse (BWC) from Cross Seamount, Hawai’i, and three unknown FM pulse types (BW40, BW43, BW70) have been identified from almost 11 cumulative years of autonomous recordings at 24 sites throughout the North Pacific. Most sites had a dominant FM pulse type with other types being either absent or limited. There was not a strong seasonal influence on the occurrence of these signals at any site, but longer time series may reveal smaller, consistent fluctuations. Only the species producing BWC signals, detected throughout the Pacific Islands region, consistently showed a diel cycle with nocturnal foraging. By comparing stranding and sighting information with acoustic findings, we hypothesize that BWC signals are produced by ginkgo-toothed beaked whales. BW43 signal encounters were restricted to Southern California and may be produced by Perrin’s beaked whale, known only from Californian waters. BW70 signals were detected in the southern Gulf of California, which is prime habitat for Pygmy beaked whales. Hubb’s beaked whale may have produced the BW40 signals encountered off central and southern California; however, these signals were also recorded off Pearl and Hermes Reef and Wake Atoll, which are well south of their known range

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