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Impacts of anthropogenic pressure on genetic and phenotypic diversity of the African elephant (Loxodonta africana) in southern Africa
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Resumo(s)
A pressão antropogénica é uma força evolutiva cada vez mais influente e que pode moldar as caraterísticas genéticas e fenotípicas das populações e das espécies. O elefante da savana africana (Loxodonta africana) é uma espécie emblemática e carismática com a qual os seres humanos têm interagido directamente desde há milénios. Os elefantes têm sofrido especialmente com a fragmentação do habitat e a caça para obtenção de marfim. Uma das regiões africanas que, no passado recente, foi afetada por estas acções é a África Austral. As populações desta região sofreram alterações demográficas consideráveis mediadas pelo homem, e o comércio ilegal de animais selvagens ainda ocorre na região. Porém, a África Austral detém actualmente algumas das maiores populações do continente, que são indiscutivelmente muito importantes para a sobrevivência a longo prazo da espécie. Esta tese tem como objetivo investigar os impactos genómicos e fenotípicos das acções humanas nas populações de elefantes selvagens na África Austral e fornecer informação para acções de conservação. Especificamente, descrevemos a diversidade genómica contemporânea das populações da África do Sul e mostrámos que uma rápida velocidade de recuperação demográfica pode travar a erosão genómica. Também identificámos novas sequências de mitogenoma para áreas com informação genómica limitada em Angola e Moçambique, e verificámos uma diminuição do tamanho das presas obtidas através da caça de troféus na maior parte do continente. Por último, investigámos os artefactos e as fontes de enviesamento que podem surgir quando se combinam conjuntos de dados genómicos para realizar análises genómicas temporais. Esta tese oferece informações para esforços de conservação como translocações e identificação da proveniência de marfim, bem como sobre as melhores práticas na realização de estudos genómicos que recorrem a várias técnicas de sequenciação genómica.
Anthropogenic pressure is an increasingly influential evolutionary force that can shape genetic and phenotypic traits of populations and species. The African savanna elephant (Loxodonta africana) is a charismatic flagship species with which humans have directly interacted with for millenia. Elephants have especially suffered from habitat fragmentation and hunting for ivory. One of the African regions that has been impacted in the recent past from these actions is southern Africa. Populations therein underwent considerable human-mediated demographic changes, and illegal wildlife trade still occurs in the region. Nonetheless, southern Africa currently holds some of the largest populations in the continent, which are arguably highly important for the long-term survival of the species. This thesis aims to investigate genomic and phenotypic impacts of human actions on wild elephant populations in southern Africa and offer information for conservation actions. Specifically, we described contemporary genomic diversity for populations in South Africa, and showed that a rapid demographic recovery speed can halt genomic erosion. We also identified novel mitogenome sequences for areas with limited genomic information in Angola and Mozambique, and found a decrease in the size of tusks obtained through trophy hunting in most of the continent. Lastly, we investigated artefacts and bias sources that are liable to arise when combining genomic datasets to perform temporal genomic analyses. This thesis offers insights into such conservation efforts as translocations and the identification of ivory provenance, as well as into best practices when conducting genomic studies that resort to various genomic sequencing techniques.
Anthropogenic pressure is an increasingly influential evolutionary force that can shape genetic and phenotypic traits of populations and species. The African savanna elephant (Loxodonta africana) is a charismatic flagship species with which humans have directly interacted with for millenia. Elephants have especially suffered from habitat fragmentation and hunting for ivory. One of the African regions that has been impacted in the recent past from these actions is southern Africa. Populations therein underwent considerable human-mediated demographic changes, and illegal wildlife trade still occurs in the region. Nonetheless, southern Africa currently holds some of the largest populations in the continent, which are arguably highly important for the long-term survival of the species. This thesis aims to investigate genomic and phenotypic impacts of human actions on wild elephant populations in southern Africa and offer information for conservation actions. Specifically, we described contemporary genomic diversity for populations in South Africa, and showed that a rapid demographic recovery speed can halt genomic erosion. We also identified novel mitogenome sequences for areas with limited genomic information in Angola and Mozambique, and found a decrease in the size of tusks obtained through trophy hunting in most of the continent. Lastly, we investigated artefacts and bias sources that are liable to arise when combining genomic datasets to perform temporal genomic analyses. This thesis offers insights into such conservation efforts as translocations and the identification of ivory provenance, as well as into best practices when conducting genomic studies that resort to various genomic sequencing techniques.
Descrição
Tese de doutoramento em Biodiversidade, Genética e Evolução, Universidade de Lisboa, Faculdade de Ciências, 2026
Palavras-chave
Population genomics phylogeography museomics sequencing bias selective removal Genómica populacional filogeografia museómica enviesamento de sequenciação remoção selectiva