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Resumo(s)
As ilhas têm, desde há muito, servido como laboratórios naturais para o estudo dos mecanismos que moldam a biodiversidade, as interações ecológicas e a evolução adaptativa. Esta tese explora de que forma o isolamento, a heterogeneidade ambiental e a estrutura trófica influenciam a organização, o funcionamento e o potencial adaptativo das comunidades de artrópodes, comparando ecossistemas de pastagens costeiras do Arquipélago dos Açores e de Portugal continental. Através de uma abordagem integradora que combina análises taxonómicas, funcionais e genéticas, este trabalho examina como a simplificação ecológica e a limitada diversidade de recursos moldam a dinâmica comunitária e a adaptabilidade das espécies em ambientes insulares.
Na primeira parte do estudo, as comunidades de artrópodes foram amostradas de forma sistemática em pastagens costeiras de ambas as regiões. Aplicaram-se protocolos padronizados para garantir a comparabilidade dos dados, que foram estruturados de acordo com os padrões Darwin Core e disponibilizados publicamente através da plataforma GBIF. Estes conjuntos de dados constituíram a base para as análises de biodiversidade e abundância, que revelaram diferenças marcadas entre os dois sistemas. As comunidades continentais apresentaram maior riqueza específica, em consonância com uma maior heterogeneidade ambiental e diversidade de recursos, enquanto as comunidades insulares exibiram menor riqueza, mas uma compensação de abundância em algumas espécies, além de uma forte dominância de poucos taxa adaptáveis, particularmente dentro dos Coccinellidae. Estes resultados confirmam que o isolamento ecológico promove a simplificação comunitária e reduz a redundância funcional.
As análises subsequentes centraram-se na estrutura trófica e nas interações funcionais entre joaninhas, formigas, afídeos e plantas hospedeiras. As redes continentais revelaram um maior número de ligações, ao passo que as redes insulares se caracterizaram por menos conexões e maior dependência de espécies dominantes. Esta simplificação sugere que os ecossistemas insulares, embora estáveis a curto prazo, poderão ser mais vulneráveis a perturbações e à perda de espécies devido à sua reduzida capacidade de amortecimento ecológico.
Para avaliar o potencial adaptativo a nível populacional, foram realizados ensaios laboratoriais com Scymnus nubilus, uma espécie predadora-chave. Os indivíduos foram criados em condições controladas e alimentados com afídeos de diferente adequação nutricional. Os resultados revelaram uma clara plasticidade fenotípica — a capacidade de um único genótipo expressar fenótipos distintos sob diferentes condições ambientais — em características de desenvolvimento e reprodução, permitindo o ajustamento a diversos recursos alimentares. Contudo, estas respostas foram acompanhadas por compromissos evolutivos (trade-offs): indivíduos com melhor desempenho em presas ótimas demonstraram menor flexibilidade quando expostos a recursos alternativos. Estes resultados evidenciam a interação entre variabilidade genética e flexibilidade fenotípica como motores fundamentais da adaptação.
No seu conjunto, as evidências demonstram que o isolamento ecológico e a filtragem ambiental moldam tanto a composição das comunidades como a sua capacidade adaptativa. A plasticidade fenotípica surge como um mecanismo compensatório que permite a persistência sob condições ecológicas restritas, mas que simultaneamente impõe constrangimentos evolutivos em sistemas simplificados. A integração das perspetivas ecológica, funcional e genética nesta tese contribui para uma compreensão mais profunda de como a insularidade influencia os padrões de biodiversidade e a resiliência, oferecendo valiosos contributos para os processos que regem a adaptação, a conservação e a estabilidade dos ecossistemas num mundo em mudança.
ABSTRACT: Islands have long served as natural laboratories for studying the mechanisms that shape biodiversity, ecological interactions, and adaptive evolution. This thesis explores how isolation, environmental heterogeneity, and trophic structure influence the organisation, functioning, and adaptive potential of arthropod communities, comparing coastal grassland ecosystems from the Azores Archipelago and mainland Portugal. Through an integrative approach combining taxonomic, functional, and genetic analyses, this work examines how ecological simplification and limited resource diversity shape community dynamics and species adaptability in insular environments. In the first part of the study, arthropod communities were systematically sampled across coastal grasslands in both regions. Standardised protocols were applied to ensure data comparability, and all records were structured according to Darwin Core standards and made publicly available through the GBIF platform. These datasets formed the basis for biodiversity and abundance analyses, which revealed marked differences between the two systems. Mainland communities exhibited higher species richness, consistent with greater environmental heterogeneity and resource diversity, whereas insular communities displayed lower richness but showed an abundance compensation for certain species, along with a strong dominance of a few adaptable taxa, particularly within the Coccinellidae. These findings confirm that ecological isolation promotes community simplification and reduces functional redundancy. Subsequent analyses focused on the trophic structure and functional interactions among ladybirds, ants, aphids, and host plants. Continental networks revealed a greater number of connections, whereas insular networks were characterised by fewer links and higher dependence on dominant species. This simplification suggests that island ecosystems, though stable in the short term, may be more vulnerable to disturbance and species loss due to their limited ecological buffering capacity. To assess adaptive potential at the population level, laboratory assays were conducted using Scymnus nubilus, a key predatory species. Individuals were reared under controlled conditions and fed aphids of different nutritional suitability. The results revealed clear phenotypic plasticity—the ability of a single genotype to express distinct phenotypes under varying environmental conditions—in developmental and reproductive traits, allowing adjustment to diverse food resources. However, these responses were accompanied by evolutionary trade-offs: individuals performing better on optimal prey showed reduced flexibility when exposed to alternative resources. These results highlight the interaction between genetic variability and phenotypic flexibility as fundamental drivers of adaptation. Taken together, the evidence demonstrates that ecological isolation and environmental filtering shape both community composition and adaptive capacity. Phenotypic plasticity emerges as a compensatory mechanism that enables persistence under restricted ecological conditions, while simultaneously imposing evolutionary constraints in simplified systems. The integration of ecological, functional, and genetic perspectives in this thesis provides a deeper understanding of how insularity influences biodiversity patterns and resilience, offering valuable insights into the processes that govern adaptation, conservation, and ecosystem stability in a changing world.
ABSTRACT: Islands have long served as natural laboratories for studying the mechanisms that shape biodiversity, ecological interactions, and adaptive evolution. This thesis explores how isolation, environmental heterogeneity, and trophic structure influence the organisation, functioning, and adaptive potential of arthropod communities, comparing coastal grassland ecosystems from the Azores Archipelago and mainland Portugal. Through an integrative approach combining taxonomic, functional, and genetic analyses, this work examines how ecological simplification and limited resource diversity shape community dynamics and species adaptability in insular environments. In the first part of the study, arthropod communities were systematically sampled across coastal grasslands in both regions. Standardised protocols were applied to ensure data comparability, and all records were structured according to Darwin Core standards and made publicly available through the GBIF platform. These datasets formed the basis for biodiversity and abundance analyses, which revealed marked differences between the two systems. Mainland communities exhibited higher species richness, consistent with greater environmental heterogeneity and resource diversity, whereas insular communities displayed lower richness but showed an abundance compensation for certain species, along with a strong dominance of a few adaptable taxa, particularly within the Coccinellidae. These findings confirm that ecological isolation promotes community simplification and reduces functional redundancy. Subsequent analyses focused on the trophic structure and functional interactions among ladybirds, ants, aphids, and host plants. Continental networks revealed a greater number of connections, whereas insular networks were characterised by fewer links and higher dependence on dominant species. This simplification suggests that island ecosystems, though stable in the short term, may be more vulnerable to disturbance and species loss due to their limited ecological buffering capacity. To assess adaptive potential at the population level, laboratory assays were conducted using Scymnus nubilus, a key predatory species. Individuals were reared under controlled conditions and fed aphids of different nutritional suitability. The results revealed clear phenotypic plasticity—the ability of a single genotype to express distinct phenotypes under varying environmental conditions—in developmental and reproductive traits, allowing adjustment to diverse food resources. However, these responses were accompanied by evolutionary trade-offs: individuals performing better on optimal prey showed reduced flexibility when exposed to alternative resources. These results highlight the interaction between genetic variability and phenotypic flexibility as fundamental drivers of adaptation. Taken together, the evidence demonstrates that ecological isolation and environmental filtering shape both community composition and adaptive capacity. Phenotypic plasticity emerges as a compensatory mechanism that enables persistence under restricted ecological conditions, while simultaneously imposing evolutionary constraints in simplified systems. The integration of ecological, functional, and genetic perspectives in this thesis provides a deeper understanding of how insularity influences biodiversity patterns and resilience, offering valuable insights into the processes that govern adaptation, conservation, and ecosystem stability in a changing world.
Descrição
Tese de Doutoramento, Biologia, 16 de abril de 2026, Universidade dos Açores.
Palavras-chave
Life-history traits Phenotypic plasticity Ladybirds Aphids Trophic networks Species diversity Specialization Density compensation Coastal grasslands Insular ecosystems
Contexto Educativo
Citação
CALADO, Hugo Renato Marques Garcia. (2025). Phenotypic Plasticity of Pest and Biological Control Agents: Contrasting Mainland and Insular Coastal Ecosystems. Ponta Delgada, Universidade dos Açores, 2025. 142 p. Tese de Doutoramento em Biologia. Disponível em http://hdl.handle.net/10400.3/8970