Nucella Lapillus L. : Imposex after Tributyltin (TBT) Ban and Population Connectivity Studies

Programa Oficial de Doutoramento en Ciencias Mariñas, Tecnoloxía e Xestión. 564V01[Abstract] The gastropod Nucella lapillus is the most common predator in the European Atlantic intertidal rocky shores. Its populations have been exposed to the pollutant tributyltin (TBT) for years, which induced the development of male sexual characters onto females (imposex). At high concentrations, it produces sterility and can cause population to collapse. The use of TBT has been regulated until its total ban in 2003. N. lapillus is the sentinel organism for its biomonitoring. This thesis add new information to the data collected in Galician coast since 1996, and explores the effectiveness of the legislation. Furthermore, population recovery in the marine environment greatly rely on the arrival of new individuals. N. lapillus is a direct-developer and is assumed to have a limited dispersal. Here, AFLP markers were used to investigate the population genetic structure of N. lapillus to elucidate its actual dispersal capacity and thus its ability to recover. Sampling was designed to test if hydrodynamic conditions have an influence on the resulting genetic pattern. In addition, a genome scan for outlier loci was performed among the AFLP markers to explore if wave-exposure conditions were promoting local adaptation under isolation. Finally, the temporal genetic stability was investigated by sampling several generations.[Resumen] El gasterópodo Nucella lapillus es el depredor más común del intermareal rocoso del Atlántico Europeo. Sus poblaciones han estado expuestas durante años al tributilestaño (TBT), un contaminante que induce el desarrollo de caracteres sexuales masculinos en hembras de gasterópodos (imposex). A altas concentraciones conduce a la esterilidad, y finalmente a la extinción de las poblaciones. En 2003, y tras sucesivas regulaciones, se prohíbe su uso. N. lapillus es la especie bioindicadora oficial para su biomonitorización. Esta tesis añade nuevos datos a los recopilados en la costa gallega desde 1996 y comprueba la eficacia de la legislación implementada. En el medio marino, la recuperación de las poblaciones depende de la llegada de nuevos individuos. N.lapillus es una especie de desarrollo directo con una capacidad de dispersión limitada. Mediante el uso de marcadores AFLP, se investigó su estructura genética poblacional para deducir su capacidad real de dispersión y por tanto sus opciones de recuperación. El muestreo se diseñó para testar si las condiciones hidrodinámicas influyen en el patrón genético resultante. Además, se realizó un escaneo genómico en busca de loci atípicos entre los AFLPs para averiguar si la exposición al oleaje está promoviendo adaptación local bajo aislamiento. Por último, se investigó la estabilidad genética temporal mediante el muestreo de diferentes generaciones.[Resumo] O gasterópodo Nucella lapillus é o depredador máis común do intermareal rochoso do Atlántico Europeo. As súas poboacións víronse durante anos expostas ó tributilestaño (TBT), un contaminante que induce o desenvolvemento de caracteres sexuais maculinos en femias de gasterópodos (imposex). A altas concentracións leva á esterilidade e finalmente á extinción das poboacións. No 2003, e tras sucesivas regulacións, prohíbese o seu uso. N. lapillus é a especie bioindicadora oficial para a súa biomonitorización. Esta tese engade novos datos ós recollidos na costa galega dende o 1996 e comproba a eficacia da lexislación implementada. No medio mariño, a recuperación das poboacións depende da chegada de novos individuos. N. lapillus é unha especie de desenvolvemento directo cunha capacidade de dispersión limitada. Mediante o uso de marcadores AFLP, investigouse a súa estrutura xenética de poboacións para deducir a súa verdadeira capacidade de dispersión e polo tanto as súas opcións de recuperación. A mostraxe deseñouse para testar se as condicións hidrodinámicas inflúen no patrón xenético resultante. Ademais, realizouse un escaneo xenómico na procura de loci atípicos entre os AFLPs para pescudar se a exposición á ondada promove adaptación local baixo illamento. Por último, investigouse a estabilidade xenética temporal mediante a mostraxe de diferentes xeracións

Epigenetic and phenotypic responses to experimental climate change of native and invasive Carpobrotus edulis

Despite the recent discoveries on how DNA methylation could help plants to adapt to changing environments, the relationship between epigenetics and climate change or invasion in new areas is still poorly known. Here, we investigated, through a field experiment, how the new expected climate scenarios for Southern Europe, i.e., increased temperature and decreased rainfall, might affect global DNA methylation in relation to phenotypic variation in individuals of clonal plant, Carpobrotus edulis, from its native (Southern African) and invaded (northwestern Iberian Peninsula) area. Our results showed that changes in temperature and rainfall induced phenotypic but not global DNA methylation differences among plants, and the climatic effects were similar for plants coming from the native or invaded areas. The individuals from the Iberian Peninsula showed higher levels of global methylation than their native counterparts from South Africa. We also observed differences between natives and invasive phenotypes in traits related to the pattern of biomass partitioning and to the strategies for water uptake and use and found an epigenetic contribution to phenotypic changes in some leaf traits, especially on the nitrogen isotopic composition. We conclude that the increased temperature and decreased rainfall projected for Southern Europe during the course of the twenty-first century may foster phenotypic changes in C. edulis, possibly endowing this species with a higher ability to successful cope the rapid environmental shifts. The epigenetic and phenotypic divergence that we observed between native and invasive plants suggests an intraspecific functional variation during the process of invasion. This result could indicate that phenotypic plasticity and global DNA methylation are related to the colonization of new habitats. Our findings reinforce the importance of epigenetic plasticity on rapid adaptation of invasive clonal plantsFunding for this study was provided by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF; grant Ref. CGL2013-48885-C2-2-R and Ref. CGL2017-87294-C3-1P awarded to RR) and by the Autonomous Government of Galicia (grant ref. I2CB awarded to MS)S