RESUMEN
Quaternary climate fluctuations can affect speciation in regional biodiversity assembly in two non-mutually exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation in underused adaptive zones during ice-free periods. We detected biogeographic and genetic signatures associated with both mechanisms in the assembly of the biota of the European Alps. Age distributions of endemic and widespread species within aquatic and terrestrial taxa (amphipods, fishes, amphibians, butterflies and flowering plants) revealed that endemic fish evolved only in lakes, are highly sympatric, and mainly of Holocene age, consistent with adaptive radiation. Endemic amphipods are ancient, suggesting preglacial radiation with limited range expansion and local Pleistocene survival, perhaps facilitated by a groundwater-dwelling lifestyle. Terrestrial endemics are mostly of Pleistocene age and are thus more consistent with the glacial species pump. The lack of evidence for Holocene adaptive radiation in the terrestrial biome is consistent with faster recolonization through range expansion of these taxa after glacial retreats. More stable and less seasonal ecological conditions in lakes during the Holocene may also have contributed to Holocene speciation in lakes. The high proportion of young, endemic species makes the Alpine biota vulnerable to climate change, but the mechanisms and consequences of species loss will likely differ between biomes because of their distinct evolutionary histories.
Asunto(s)
Mariposas Diurnas , Emigración e Inmigración , Animales , Biodiversidad , Ecosistema , Peces , Especiación Genética , Filogenia , Refugio de FaunaRESUMEN
A phylogeny of the main lineages of dung beetles (Coleoptera: Scarabaeinae) from the Iberian Peninsula was based on partial nucleotide sequences (about 1221 bp) of the mitochondrial cytochrome oxidase I and II genes of 33 taxa. Our phylogenetic analyses confirmed the validity and composition of most of the recognized tribes within the subfamily. Interestingly, the Onitini showed an evolutionary rate significantly higher than that of the other tribes. The molecular phylogeny supports a sister-group relationship of the tribes Onitini and Oniticellini + Onthophagini. A close relationship of Scarabaeini, Gymnopleurini, and Sisyphini is also suggested but lacks bootstrap support. Surprisingly, the Coprini, which had always been related to the Oniticellini and Onthophagini, were placed closer to the Scarabaeini, Gymnopleurini, and Sisyphini. The inferred molecular phylogeny was used to assess the main evolutionary trends of nesting behavior. Our results suggest tentative single origins for both the tunneling and the rolling behaviors, and the possibility that the rolling behavior could have been lost secondarily in Copris.
Asunto(s)
Escarabajos/clasificación , Escarabajos/genética , Evolución Molecular , Filogenia , Conducta Social , Animales , Secuencia de Bases , Cartilla de ADN , Complejo IV de Transporte de Electrones/genética , GeografíaRESUMEN
Este trabajo investiga la sucesión de especies de mosquitos que utilizan espatas caídas de palma llenas con agua de lluvia para completar sus fases preadultas en un bosque nublado tropical en Venezuela, e investiga el papel de las interacciones bióticas como condicionantes del proceso sucesional. Para caracterizar el proceso de reemplazo de especies en el tiempo se asignó un rango de edad relativa a las espatas, que correspondía con su estado de descomposición. En total se muestrearon 71 espatas en 6 oportunidades desde mayo de 1989 hasta marzo de 1990, para determinar los cambios en las espatas y especies de mosquitos. Las interacciones bióticas entre las 2 especies más comunes y contiguas en la sucesión se evaluaron utilizando experimentos en espatas. La sucesión comienza con la colonización de Trichoprospon evansae en las espatas recién caídas. Esta especie resultó ser depredador facultativo de otros mosquitos. Tres especies le siguen en el orden sucesional y presentan gran superposición temporal: culex rausseoi, anopheles eiseni y limatus sp. tr. evansae presentó correlaciones negativas con la edad relativa de las espatas y con cada una de las restantes especies, entre las cuales se detectaron correlaciones positivas. Los experimentos de interacciones demostraron un impacto negativo de tr. evansae sobre cx. rausseoi y se caracterizó esta sucesión como un caso de inhibición, de acuerdo con la hipótesis de Connell y Slatyer (1977).
