Publication: Filogenia, filogeografía y biogeografía histórica de las especies mediterráneas del género Squalius Bonaparte, 1837 (Actinopterygii, Cyprinidae)
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2018-09-21
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Universidad Complutense de Madrid
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Abstract
El género Squalius Bonaparte 1837, es uno de los géneros más diversificados y ampliamente distribuidos en la región Mediterránea, además, es uno de los géneros de ciprínidos más antiguo de la península ibérica ya que se conocen fósiles desde el Oligoceno. Por tanto, su historia evolutiva debe estar fuertemente ligada a los procesos históricos y climáticos de la región Mediterránea durante la mayor parte del Terciario y Cuaternario. El género Squalius presenta dos linajes evolutivos desde un punto de vista genético separados por la cordillera alpina como principal barrera generadora de patrones vicariantes entre ambos linajes. La presente tesis ha tenido como objetivo estudiar los distintos patrones de diversificación de las especies que pertenecen al linaje mediterráneo así como de los procesos que los originan y que han dado lugar a la alta diversidad que aparece actualmente en las penínsulas mediterráneas. De esta forma, se estudian las relaciones filogenéticas entre las distintas especies mediterráneas del género. Nuestros resultados sugieren que, a pesar de los estudios previos sobre estas especies, todavía quedan cuestiones evolutivas de gran interés por resolver, especialmente en la península ibérica, donde la diversidad de linajes evolutivos es más alta de lo que se consideraba previamente. A través del análisis filogenético de estas especies ibéricas del género, esta tesis también muestra que las aproximaciones bayesianas de delimitación de especies, que tienen en consideración la coalescencia de las poblaciones, resuelven las relaciones filogenéticas entre las especies de forma más precisa que otros métodos filogenéticos, aunque estos últimos manifiestan de forma más evidente las incongruencias entre las topologías de los árboles. De esta forma, cuando existen procesos de hibridación y especiación reticulada los árboles bayesianos de especies no pudieron ser generados como ocurrió en el caso de las especies griegas en las que existe una captura mitocondrial. Por otro lado, los resultados de esta tesis muestran un patrón de especiación alopátrica reciente en las especies del género de la vertiente oriental del Adriático guiado por la finalización de la formación del karst Dinárico, indicando la influencia de los procesos geomorfológicos en la historia evolutiva de los organismos vivos. En esta tesis también se evaluó la estructura geográfica y los patrones de diversidad genética de las especies ibéricas del género Squalius demostrando la importancia de los factores climáticos en la generación de estos patrones, siendo los dos factores climáticos más relevantes la estacionalidad del clima mediterráneo y las glaciaciones pleistocenicas. Así, se encuentra un patrón de diversidad genética en la península ibérica congruente con estudios previos de forma que las poblaciones del sur presentan mayor diversidad genética que las poblaciones del norte. En las poblaciones del sur pertenecientes a S. pyrenaicus, la estacionalidad mediterránea ha favorecido una estructura metapoblacional como consecuencia de continuos cuellos de botella y fragmentación de las poblaciones. En las poblaciones del norte adscritas a S. carolitertii, la pérdida de variabilidad genética puede ser una consecuencia de fuertes reducciones poblacionales e incluso extinción local de poblaciones provocada por el efecto de las glaciaciones. Un patrón de diversidad genética diferente se halla en las poblaciones del levante español de S. valentinus, donde la mayor diversidad genética aparece en los tramos bajos de los grandes ríos y en pequeños ríos que presentan manantiales de caudal y temperatura constantes. Estos ambientes proporcionan una mayor estabilidad ambiental para las poblaciones. Por tanto, en este caso, la variabilidad genética parece estar influenciada no solo por factores climáticos sino también por la estructura y geomorfología de los ríos donde habitan estas especies, como también se observa en el sur de la península ibérica donde la laguna de la Janda posiblemente actuó como un reservorio de variabilidad genética de la fauna de peces de agua dulce de esta región.
The genus Squalius Bonaparte 1837, is one of the most diversified and widely distributed genus of the Mediterranean region. Besides, it is one of the oldest cyprinid genera in the Iberian Peninsula and fossils from the Oligocene period are known. Therefore, its evolutionary history is strongly linked to the Cenozoic historical and climatic processes of the Mediterranean region. The genus Squalius is represented by two different evolutionary lineages isolated by the biogeographic barrier that supposed the Alpine range. The main focus of this thesis is studying the species that belong to the Mediterranean lineage as well as the processes that have giving rise to the high current diversity of this lineage in the Mediterranean peninsulas. Thus, the results of the present thesis suggests that in spite of the number of scientific studies focus on these Mediterranean species there are still many interesting evolutionary questions to be resolved, especially in the Iberian Peninsula, where diversity of genetic lineages is higher than previous knowledge. This thesis also shows that Bayesian species delimitation approaches are more powerful for deciphering relationships within species than other phylogenetic methods, although these latter methods are also important to highlight incongruences between tree topologies. Therefore, when hybridization processes or reticulated hybridization were present, species trees could not be generated, as was the case of the mitochondrial capture inferred in the Peloponeso. On the other hand, results from this thesis showed a recent process of allopatric speciation drove by the final episodes of the Dinaric karst configuration, indicating the influence of geomorphological processes in the evolutionary history of organisms. The genetic structure and diversity patterns of the Iberian species of the genus Squalius were also inferred; demonstrating the importance of climatic factors in the generation of those processes and being the two most relevant climatic factors are the Mediterranean seasonality and the Pleistocene glaciations. Thus, a genetic diversity pattern congruent with previous studies was found. This pattern showed that southern populations presented higher values of genetic diversity than northern populations. In the southern populations, belonging to the species S. pyrenaicus, the Mediterranean seasonality has favoured a metapopulation structure as consequences of continuous bottlenecks and fragmentation of populations. In northern populations belonging to S. carolitertii, the loss of genetic variability could be a consequence of drastic population declines or even local extinction of populations caused by the effect of Pleistocene glaciations. A different pattern of genetic diversity is found in the populations of the Spanish Levant region, where the highest genetic diversity was found in populations from the lower reaches of the larger rivers and in small karstic springs with permanent caudal and stable climatic conditions. These environments provide a higher stability for these populations. Therefore, in this case, the genetic variability is also influenced by geomorphological features of the rivers inhabited by these populations. This is also observed in the south of the Iberian Peninsula where the Janda Lagoon probably acted as a reservoir of genetic variability for the freshwater fish fauna of this region.
The genus Squalius Bonaparte 1837, is one of the most diversified and widely distributed genus of the Mediterranean region. Besides, it is one of the oldest cyprinid genera in the Iberian Peninsula and fossils from the Oligocene period are known. Therefore, its evolutionary history is strongly linked to the Cenozoic historical and climatic processes of the Mediterranean region. The genus Squalius is represented by two different evolutionary lineages isolated by the biogeographic barrier that supposed the Alpine range. The main focus of this thesis is studying the species that belong to the Mediterranean lineage as well as the processes that have giving rise to the high current diversity of this lineage in the Mediterranean peninsulas. Thus, the results of the present thesis suggests that in spite of the number of scientific studies focus on these Mediterranean species there are still many interesting evolutionary questions to be resolved, especially in the Iberian Peninsula, where diversity of genetic lineages is higher than previous knowledge. This thesis also shows that Bayesian species delimitation approaches are more powerful for deciphering relationships within species than other phylogenetic methods, although these latter methods are also important to highlight incongruences between tree topologies. Therefore, when hybridization processes or reticulated hybridization were present, species trees could not be generated, as was the case of the mitochondrial capture inferred in the Peloponeso. On the other hand, results from this thesis showed a recent process of allopatric speciation drove by the final episodes of the Dinaric karst configuration, indicating the influence of geomorphological processes in the evolutionary history of organisms. The genetic structure and diversity patterns of the Iberian species of the genus Squalius were also inferred; demonstrating the importance of climatic factors in the generation of those processes and being the two most relevant climatic factors are the Mediterranean seasonality and the Pleistocene glaciations. Thus, a genetic diversity pattern congruent with previous studies was found. This pattern showed that southern populations presented higher values of genetic diversity than northern populations. In the southern populations, belonging to the species S. pyrenaicus, the Mediterranean seasonality has favoured a metapopulation structure as consequences of continuous bottlenecks and fragmentation of populations. In northern populations belonging to S. carolitertii, the loss of genetic variability could be a consequence of drastic population declines or even local extinction of populations caused by the effect of Pleistocene glaciations. A different pattern of genetic diversity is found in the populations of the Spanish Levant region, where the highest genetic diversity was found in populations from the lower reaches of the larger rivers and in small karstic springs with permanent caudal and stable climatic conditions. These environments provide a higher stability for these populations. Therefore, in this case, the genetic variability is also influenced by geomorphological features of the rivers inhabited by these populations. This is also observed in the south of the Iberian Peninsula where the Janda Lagoon probably acted as a reservoir of genetic variability for the freshwater fish fauna of this region.
Description
Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, Departamento de Zoología y Antropología Física, leída el 3 de Julio de 2017. Tesis formato europeo (compendio de artículos)