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Conectividade genética em ambientes aquáticos - implicações para a conservação
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Advisor(s)
Abstract(s)
A evolução dos peixes primários na Península Ibérica encontra-se correlacionada com
a evolução paleogeomorfológica das bacias hidrográficas e o movimento orogénico de sistemas
montanhosos, como o Maciço Calcário Estremenho (MCE). Esta elevação separa duas regiões
biogeográficas para a ictiofauna nativa: vertente ocidental com pequenos rios costeiros e
ligações antigas ao rio Mondego; e oriental, zonas de cabeceira de sub-bacias do Tejo. Por
terem maior declive, menor caudal e carácter intermitente, as nascentes do MCE eram
consideradas desprovidas de ictiofauna. Os objetivos deste estudo foram: (1) conhecer as
espécies aquáticas (peixes e gastrópodes) presentes nas nascentes; (2) avaliar a conetividade
genética entre zonas de cabeceira e a jusante para duas espécies-alvo nas vertentes opostas do
MCE (Achondrostoma oligolepis e Squalius pyrenaicus); e (3) confirmação genética da
identidade taxonómica de gastrópodes. Os resultados demonstraram que as nascentes têm vida
aquática (8 espécies nativas de peixes e 4 espécies nativas de gastrópodes) e podem ser locais
prioritários para a conservação da Biodiversidade. Como esperado, encontraram-se diferenças
interpopulacionais entre as populações de peixes dos diferentes rios. Foram ainda detetadas
diferenças intrapopulacionais, entre locais de amostragem de um mesmo rio, demonstrando
que, em ecossistemas fluviais, a determinação da diversidade genética populacional pode ser
afetada pelo esquema de amostragem. Além disso, ficou claro que as características destes
ecossistemas podem afetar a conetividade genética das populações de peixes, sendo importante
investir em estudos de genética de paisagem para avaliar a conetividade e a diversidade genética
das espécies ameaçadas, relacionando-as com as características dos habitats fluviais onde
ocorrem.
ABSTRACT: The evolution of primary fish in the Iberian Peninsula is correlated with the paleogeomorphological evolution of hydrographic basins and the orogenic movement of mountain systems, such as the Maciço Calcário Estremenho (MCE). This elevation separates two biogeographic regions for the native ichthyofauna: western slope with small coastal rivers and old connections to the Mondego River; and eastern, headwaters of Tagus sub-basins. Due to their higher slope, lower flow and intermittent character, the springs of the MCE were considered devoid of ichthyofauna. The objectives of this study were: (1) to know the aquatic species (fish and gastropods) present in the springs; (2) to evaluate the genetic connectivity between headwater and downstream zones for two target species on opposite slopes of the MCE (Achondrostoma oligolepis and Squalius pyrenaicus); and (3) genetic confirmation of the taxonomic identity of gastropods. The results showed that the springs have aquatic life (8 native species of fish and 4 native species of gastropods) and may be priority sites for the conservation of Biodiversity. As expected, interpopulation differences were found between fish populations from different rivers. Intrapopulation differences were also detected, between sampling sites of the same river, demonstrating that, in fluvial ecosystems, the determination of population genetic diversity can be affected by the sampling scheme. In addition, it became clear that the characteristics of these ecosystems can affect the genetic connectivity of fish populations, making it important to invest in landscape genetic studies to assess the connectivity and genetic diversity of threatened species, relating them to the characteristics of river habitats where they occur.
ABSTRACT: The evolution of primary fish in the Iberian Peninsula is correlated with the paleogeomorphological evolution of hydrographic basins and the orogenic movement of mountain systems, such as the Maciço Calcário Estremenho (MCE). This elevation separates two biogeographic regions for the native ichthyofauna: western slope with small coastal rivers and old connections to the Mondego River; and eastern, headwaters of Tagus sub-basins. Due to their higher slope, lower flow and intermittent character, the springs of the MCE were considered devoid of ichthyofauna. The objectives of this study were: (1) to know the aquatic species (fish and gastropods) present in the springs; (2) to evaluate the genetic connectivity between headwater and downstream zones for two target species on opposite slopes of the MCE (Achondrostoma oligolepis and Squalius pyrenaicus); and (3) genetic confirmation of the taxonomic identity of gastropods. The results showed that the springs have aquatic life (8 native species of fish and 4 native species of gastropods) and may be priority sites for the conservation of Biodiversity. As expected, interpopulation differences were found between fish populations from different rivers. Intrapopulation differences were also detected, between sampling sites of the same river, demonstrating that, in fluvial ecosystems, the determination of population genetic diversity can be affected by the sampling scheme. In addition, it became clear that the characteristics of these ecosystems can affect the genetic connectivity of fish populations, making it important to invest in landscape genetic studies to assess the connectivity and genetic diversity of threatened species, relating them to the characteristics of river habitats where they occur.
Description
Dissertação de Mestrado realizada sob a
orientação da Doutora Carla Sousa Santos,
apresentada no Ispa – Instituto Universitário
para obtenção de grau de Mestre na especialidade
de Biologia Marinha e Conservação.
Keywords
Ictiofauna dulciaquícola Gastrópodes aquáticos Espécies ameaçadas Zonas de nascente Diversidade genética Freshwater ichthyofauna Gastropods Protection zones Spring threatened species Genetic diversity