Documenting the biogeographic history ofMicrotus cabreraethrough its fossil record

Abstract

Microtus cabrerae is an Iberian endemic vole species with specific adaptations to the subhumid Mediterranean climate. Its living populations are under a regressive trend. The earliest known records of Microtus cabrerae date from the late Middle Pleistocene, and it originated from Microtus brecciensis. We describe changes in the geographic distribution of Microtus cabrerae throughout its history based on its palaeontological record, and link them to environmental changes that have taken place since the appearance of Microtus cabrerae. A series of successive chronological intervals comprising the recorded existence of the species was established, so that the majority of the published fossil records of Microtus cabrerae could be used for analysis. For each interval, a map with the inferred distribution of the species was created. The maps were used to establish variations in the species' distribution through time. A first regression in the extent of the distribution of Microtus cabrerae took place in Marine Isotope Stage 2, when the species abandoned south‐eastern France and central Spain, where it had been present since the beginning of the Late Pleistocene. This range contraction was probably due to the global decline in temperatures and rainfall that took place in this period. After a rapid recolonization of most of the previously abandoned areas at the beginning of the Holocene and a remarkable increase in records during the Neolithic, a new gradual decrease of records is observed from the Neolithic to the Roman period, intensifying from c. 2000 years ago onwards and ending with the final disappearance of the species from south‐western France and north‐eastern Iberia. This second decline is linked to the aridification of the Mediterranean entourage that started in the mid‐Holocene and has been enhanced by human modification of the landscape. The species is shown to be sensitive to climate change.

Global climate changes drive ecological specialization of mammal faunas: trends in rodent assemblages from the Iberian Plio-Pleistocene

“…This global radiation is evidenced within the Iberian fossil record by local speciation (e.g. development of the endemic lineage Iberomys within Microtus [62-64]) as well as by immigration of new species from other Eurasian regions, being both processes spurred by global environmental change. Overall, such ecological reorganization of assemblages appears to be triggered by global climatic changes and modulated by the differences in ecological specialization of the implied species, similarly to what was observed in earlier periods of faunal replacement in Spain [36,65].…”

Cold-climate rodent indicators for the Late Pleistocene of Central Iberia: New data from the Buena Pinta Cave (Pinilla del Valle, Madrid Region, Spain)

“…These species are characteristic of the Middle Pleistocene (Brunet-Lecomte, 1988;Laplana and Sevilla, 2013) and have never been cited for younger sediments. Their presence in levels 2-5 is incongruent with their dating, and with the presence in the same levels of Microtus cabrerae, a descendent of M. brecciensis.…”

Revisión a nivel ibérico de la distribución del topillo de Cabrera o iberón, Iberomys cabrerae (Thomas, 1906)

“…Estos datos fueron integrados en una base de datos Access a partir de la cual se generó la correspondiente cartografía digital mediante un SIG manejado con el programa ArcGIS 10. Para ofrecer una perspectiva paleobiológica de los cambios en la distribución de la especie, en el mapa de cUTM2500 se incluyó tambien la distribución de restos fósiles y subfósiles del Holoceno (Garrido- García & Soriguer 2011, Laplana & Sevilla 2013, aunque para diferenciarlos claramente de los datos de presencia actuales se localizaron directamente con las coordenadas UTM de los yacimientos.…”

“…Según los datos paleobiológicos ( Fig. 2; Garrido- García & Soriguer 2012, Laplana & Sevilla 2013, esta situación se configuró a lo largo del Holoceno, debido a extinciones que habrían reducido la extensión del área de distribución original y desconectado los núcleos actuales entre sí. Así, su desaparición en Cataluña y el sureste de Francia habría separado los actuales núcleos Prepirenaico y Montibérico, y la pérdida de las poblaciones de los tercios central y occidental de las cordilleras Béticas habría reducido mucho el núcleo Bético.…”

“…Así, su desaparición en Cataluña y el sureste de Francia habría separado los actuales núcleos Prepirenaico y Montibérico, y la pérdida de las poblaciones de los tercios central y occidental de las cordilleras Béticas habría reducido mucho el núcleo Bético. En el oeste peninsular, la escasez de sustratos geológicos adecuados para la fosilización no permite documentar con precisión el proceso de retracción (Laplana & Sevilla 2013), y los registros disponibles sólo indican pérdidas significativas en los extremos occidental y septentrional del núcleo Luso-Carpetano (Estremadura portuguesa, centro de Lugo).…”