Hybridization and invasive species in a threatened freshwater fish community under environmental pressures: Morphometric and molecular evidence

Mediterranean freshwater systems are under threat owing to increased drought driven by climate change, intensive human land uses and non-native species. This is causing increased fish hybridization in isolated watercourses. The genetic and morphological characteristics of hybrids of sympatric native and non-native fish species were studied in four streams of the Mediterranean Guadalquivir basin (south-west Spain). Fish morphology was analysed using geometric morphometrics, and molecular determination of parenthood was inferred through one mitochondrial gene (cytb) and one nuclear gene (Beta-actin) for all hybrids and a subset of pure parental specimens. Molecular analyses confirmed hybrids between the native Squalius alburnoides and non-native Alburnus alburnus in a stream with continuous flow. Haplotype analyses suggested that they originated from backcrossing of hybrid offspring. Intergeneric crosses between native species S. alburnoides and Pseudochondrostoma willkommii, and S. alburnoides and Iberochondrostoma lemmingii were detected in streams under reduced connectivity scenarios. Morphometrics revealed that hybrid phenotypes were similar to S. alburnoides. In some cases, molecular markers uncovered hybridization events that were neither detected in the field nor by morphometric analyses, potentially supporting a backcrossing/introgression scenario. Hybridization is likely to be increasing in Mediterranean rivers where S. alburnoides are present owing to increased fragmentation caused by summer drought exacerbated by climate change and human land uses and pressures. This can become a problem for these endemic vulnerable species if genetic diversity is lost, morphological homogenization occurs and hybrids cannot be easily detected in the field. The potential risks could be addressed by monitoring and eradication of non-native species and segregation from natives. To avoid native–native crosses, habitat quality and desiccation risk could be tackled by improved water quality and riparian reforestation to provide shade and reduce evapotranspiration. This would need increased coordination and intervention between the institutions that share conservation responsibilities in the area

Lepomis gibbosus (Linnaeus, 1758) (Teleostei, Centrachidae) en la península Ibérica: variabilidad genética, origen y expansión de sus poblaciones

Trabajo de Fin de Máster presentado en la Facultad de Ciencias Biológicas (Departamento de Biodiversidad, Ecología y Evolución) de la Universidad Complutense de Madri

Genetic and Ecological Approaches to Introduced Populations of Pumpkinseed Sunfish (Lepomis gibbosus) in Southwestern Europe

Freshwater systems are among the most affected by the introduction of exotic species. The pumpkinseed sunfish Lepomis gibbosus, a centrarchid native to eastern North America, is listed among the top ten introduced freshwater fishes with the greatest ecological impact globally. Despite this, genetic and evolutionary studies of the species are still scarce. Here, we analyzed the genetic variability of introduced populations of L. gibbosus using three mitochondrial genes (COI, d-loop, and ND1). In addition, we used species distribution modeling to compare the niche of introduced versus native populations to assess the present and potential future distribution of the species under different climate change scenarios. Compared with the native populations, introduced ones present a lower level of genetic variability, indicating these populations originated from a small number of individuals from the native (Atlantic) population in the USA and Canada. The low variability was likely driven by a founder effect and subsequent bottleneck, as often occurs in invasive species. Our modeling results suggest not only that L. gibbosus modified its niche during the invasion process in Europe but also the possible global expansion of the species under future climatic conditions, which could facilitate its establishment in almost all continents

Genetic and Ecological Approaches to Introduced Populations of Pumpkinseed Sunfish (Lepomis gibbosus) in Southwestern Europe

Freshwater systems are among the most affected by the introduction of exotic species. The pumpkinseed sunfish Lepomis gibbosus, a centrarchid native to eastern North America, is listed among the top ten introduced freshwater fishes with the greatest ecological impact globally. Despite this, genetic and evolutionary studies of the species are still scarce. Here, we analyzed the genetic variability of introduced populations of L. gibbosus using three mitochondrial genes (COI, d-loop, and ND1). In addition, we used species distribution modeling to compare the niche of introduced versus native populations to assess the present and potential future distribution of the species under different climate change scenarios. Compared with the native populations, introduced ones present a lower level of genetic variability, indicating these populations originated from a small number of individuals from the native (Atlantic) population in the USA and Canada. The low variability was likely driven by a founder effect and subsequent bottleneck, as often occurs in invasive species. Our modeling results suggest not only that L. gibbosus modified its niche during the invasion process in Europe but also the possible global expansion of the species under future climatic conditions, which could facilitate its establishment in almost all continents.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Estudio de la dispersión del gobio de boca súpera, pseudirasbora parva (Teleostei: Cyprinidae), en los ríos y embalses de la Península Ibérica utilizando caracteres moleculares

Esta comunicación en formato panel tuvo lugar en este congreso organizado en la facultad de Ciencias de la Universidad de Navarra del 20 al 23 de abril de 2022 por la Plataforma de Especies Exóticas Invasoras.Pseudorasbora parva o pseudorasbora es una especie invasora de pez dulceacuícola, que se ha expandido de forma vertiginosa por Europa en las últimas décadas. Su área de distribución nativa es el este de Asia (Japón, China, Taiwán, Corea, Rusia). Esta especie se detectó por primera vez en Europa en el año 1961, en Rumanía, y desde entonces, se ha ido introduciendo en diferentes cuencas hidrográficas europeas. En España apareció décadas más tarde siendo inicialmente detectada en la cuenca del Ebro en el 2001, punto desde el que se ha ido expandiendo a otras cuencas de la Península Ibérica. Con la finalidad de identificar el origen de los ejemplares de P. parva llegados a España, su dispersión y su relación con otras poblaciones introducidas y nativas, se utilizarán dos genes mitocondriales ampliamente estudiados, D-LOOP y COI, de ejemplares de poblaciones de la Península Ibérica junto con individuos de otras zonas invadidas y aquellos procedentes de zonas nativas recopilados del GENBANK. En general, observamos que las poblaciones europeas e ibéricas proceden de poblaciones nativas de China. Sin embargo, otras áreas invadidas como Irán, encontramos que las poblaciones invasoras de P. parva tienen un origen predominantemente de las poblaciones nativas de Japón. La introducción reciente de esta especie en la Península Ibérica, ha provocado que esta especie aún no se haya distribuido por todas las masas de agua que potencialmente pudiera habitar. Es por este motivo que se han realizado diversos modelos de distribución potencial de esta especie, basados en la distribución de la misma en su área nativa, en las áreas invadidas a nivel europeo y también en las áreas invadidas en la Península Ibérica, empleando para ello el programa MAXENT. Se emplean estos modelos para localizar las zonas más susceptibles a ser invadidas en el futuro, de cara a poner en marcha medidas de prevención y alerta temprana.Peer reviewe