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Orientador: Fernando Fernandes Mendonça / Resumo: A atividade pesqueira desempenha um importante papel ambiental e socioeconômico, pois é fonte de renda e alimento para milhões de pessoas no mundo. Entretanto, falhas em sua gestão e lacunas nos dados biológicos para muitas espécies, tem resultado na sobreexplotação de seus estoques, o que pode impactar diversos ecossistemas marinhos. Neste contexto, os peixes-de-bico, grupo formado pelas famílias Xiphiidae e Istiophoridae, são considerados valiosos recursos pesqueiros, porém ainda não há consenso sobre o número e a validade das espécies da família Istiophoridae e também há incertezas sobre a avaliação atual de seus estoques. Sendo assim, o objetivo deste estudo é o de delimitar as espécies da família Istiophoridae e os estoques genéticos do agulhão-vela Istiophorus platypterus no Oceano Atlântico utilizando marcadores moleculares mitocondriais. Entre os resultados dos testes de delimitação de espécies, o número variou entre 6 e 12 táxons possíveis, dependendo do teste aplicado. Em relação a delimitação dos estoques genéticos de I. platypterus no Atlântico, assumindo-se apenas uma espécie no gênero Istiophorus, nossos resultados apontam a existência de alta diversidade genética, componde um único estoque genético no Atlântico (ΦST=0,01121, p=0,02438), apresentando um alto fluxo gênico. Porém, pela análise da rede de haplótipos e da inferência bayesiana observa-se a existência de diferentes linhagens mitocondriais simpátricas, que divergiram durante o Mioceno Superior e foram ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Fishing activity plays an important environmental and socio-economic role, as it is a source of income and food for millions of people worldwide. Although, shortcomings in management and gaps in biological data for many species resulted in the overexploitation of their stocks, which may impact several marine ecosystems. In this context, billfishes, a group compounded by the Xiphiidae and Istiophoridae families, are considered valuable fish resources, but there is still no consensus on the number and validity of the species of Istiophoridae family and there are also uncertainties about the current fisheries stocks assessments. Thus, the main objectives of this study are to delimit the species of the Istiophoridae family and the genetic stocks of the sailfish, Istiophorus platypterus, in the Atlantic Ocean using mitochondrial molecular markers. Among the species delimitation tests results, the number ranged from 6 to 12 possible taxa depending on the test applied. In order to determine the genetic stock of I. platypterus in the Atlantic Ocean, assuming only one species in the genus Istiophorus, our results point to the existence of high genetic diversity, comprising a single genetic stock in the Atlantic (ΦST = 0.01121, p = 0.02438), presenting a high gene flow. However, the analysis of the network of haplotypes and Bayesian inference shows the existence of different sympatric mitochondrial lines, which diverged during the Upper Miocene and were re-approximated, interrupting th... (Complete abstract click electronic access below) / Doutor

Migratory insects are vital components of global ecosystems and provide important ecosystem services, yet the migration phenomenon is understudied in insects compared to vertebrates. In this thesis, I aim to deepen our understanding of insect migration, using the monarch butterfly Danaus plexippus (L.) and the painted lady butterfly Vanessa cardui (L.) as model systems. Studying insect migration is notoriously difficult given the small size, high abundance, and short lifespans of insects. Isotope geolocation has shown promise for overcoming these obstacles. Here, I develop and apply metals and metal isotopes, specifically strontium isotope ratios (⁸⁷Sr/⁸⁶Sr), to increase the spatial precision of isotope geolocation and demonstrate how isotopic geolocation tools can advance our understanding of insect migration at the population level. In the first chapter, I test the validity of using ⁸⁷Sr/⁸⁶Sr, lead isotopes, and a suite of 23 metals and metalloids to estimate the natal origins of migratory insects, by investigating the pathways of metal incorporation into butterfly wing tissues. Using an 8-week diet-switching experiment, I show that the concentrations of many metals in insect wings can be altered through the adult diet or dust deposition, making them poor candidates for geolocation but potentially interesting tools to study insect physiology, diet, or toxicology. For example, lead was found to accumulate on butterfly wings from external sources, and lead isotopes could potentially be used to quantify the exposure of migratory insects to metal pollution. Some metals, including Ba, Cs, Mg, Na, Rb, Sr, Ti, Tl, and U, are good candidates for developing geolocation tools. I focused on ⁸⁷Sr/⁸⁶Sr and demonstrated that, despite some caveats, this tool is valid for isotope geolocation. In the second chapter, I outline the steps required to use ⁸⁷Sr/⁸⁶Sr for the geolocation of insects, including the calibration of a spatial model of isotopic variation (i.e., an isoscape) using random forest regression. I then combine hydrogen isotope values (δ²H) and ⁸⁷Sr/⁸⁶Sr into a dual assignment framework to estimate the natal origins of a single generation of monarch butterflies in eastern North America. I demonstrate that combining these two isotopes provides a more spatially constrained estimate of natal origin than using either isotope alone. In the third chapter, I apply this framework to characterize the migratory patterns and migratory connectivity of an insect species across a geographical barrier, the Sahara. Painted ladies journeying northwards across the Sahara appear to do so in a gradual progression, although spatiotemporal sampling limitations prevented a complete characterization of this movement. In contrast, painted ladies migrating southwards appear to journey in a broad front, parallel migration pattern with little longitudinal movement. Evidence for a leapfrog migration pattern was found in the western region, wherein butterflies of northernmost origin journey farther south than butterflies bred in more southerly regions. This leapfrog migration pattern suggests distinct migratory behaviours within painted lady butterflies wherein some individuals migrate longer distances than others. In the fourth chapter, I apply isotope geolocation to characterize the migration distances of multiple individuals and assess the potential genetic differentiation of butterflies migrating distinct distances. I use δ²H and ⁸⁷Sr/⁸⁶Sr-based geographic assignment to confirm that some painted ladies migrate up to 4,000 km from Europe to sub-Saharan Africa, while others migrate shorter distances from Europe to the circum-Mediterranean region. Despite these differences in migration distance, genome-wide analysis revealed a lack of adaptive variation between short- and long-distance migrants. Instead, variation in migration distance in painted lady butterflies is likely the result of a plastic response to environmental conditions. Overall, the methodological developments presented in this thesis are a step forward in studying insect migration. The development and application of metals and metal isotopes for insect geolocation opens new avenues to study the migration phenomenon at different scales with widespread relevance for conservation and pest management.