North Atlantic and South Atlantic swordfish (Xiphias gladius L.) are currently managed as two stocks separated at 5°N. While previous studies of genetic population structure using both mitochondrial and nuclear DNA confirm two genetically distinct stocks, sampling coverage has not been uniform or representative of all areas and estimates of admixture in areas of contact have not been provided. In this study, we examined: 1) the applicability of high-resolution melting analysis (HRMA) in population genetic studies of non-model organisms, 2) the use of nuclear markers in Atlantic swordfish and the methodology whereby nuclear gene variation can be quickly screened, identified, and genotyped using short-amplicon (SA) HRMA and unlabeled probe (UP) HRMA, and 3) the use of HRMA to characterize nuclear markers to study the genetic population structure of Atlantic swordfish using representative samples of the entire basin to provide an estimation of population admixture by means of Bayesian individual assignment. High resolution melting analysis (HRMA) is shown to be a highly sensitive, rapid, closed-tube genotyping method amenable to high throughput and, though until recently primarily confined to clinical studies, suitable for population studies in non-model species. Ten nuclear markers were genotyped primarily by SA- and UP-HRMA in North Atlantic (n=419), South Atlantic (n=296), and Mediterranean (n=59) swordfish. Comparisons of pairwise FST, AMOVA, PCoA, and Bayesian individual assignments were congruent with previous finding of three discrete populations with comparatively low levels of estimated gene flow for a marine organism (FST = 0.039-0.126). Population admixture was identified and estimated in the Northeast Atlantic and appeared to be asymmetrical, with swordfish from the South Atlantic found among North Atlantic localities but no North Atlantic migrants identified in the South Atlantic. The Mediterranean boundary currently at the Strait of Gibraltar is found to extend west into Atlantic waters to approximately 8°W. Similarly, the boundary between North and South Atlantic swordfish should be revised to a line that extends north from 0°N 45°W to 25°N 45°W and from that position, as a nearly horizontal line, eastwards to the African coast. Finally, I show that Bayesian individual assignment using the developed marker set can be used for mixed stock allocation in the Northeast Atlantic.

The cotton fleahopper, Pseudatomoscelis seriatus (Reuter) is a widely distributed insect across the United States. Although, it feeds on several native wild hosts, its agricultural importance lies as an economic pest of cotton in several states in the southern United States. No studies have addressed intraspecific genetic and phenotypic variation of this insect pest at a large geographic scale. I examined genetic variation among cotton fleahopper populations associated with cotton in different geographic locations across the southern United States (Chapter II). Using dominant, neutral, nuclear molecular markers (AFLP, amplified fragment length polymorphism) and mitochondrial DNA sequences, I found that overall genetic differentiation among different geographic populations, collected from cotton in eleven cotton growing states, was low but significant. AFLP revealed the presence of three regional groups representing western (Arizona), central (Texas, Oklahoma, Arkansas, Louisiana, Mississippi and Alabama), and eastern (Florida, Georgia, South Carolina and North Carolina) populations. I examined if there were distinct lineages of cotton fleahoppers associated with three of its host plant species: cotton (Gossypium hirsutum), horsemint (Monarda punctata) and woolly croton (Croton capitatus) in five different locations of Texas by using AFLP markers (Chapter III). I found two distinct host-associated lineages at three locations and local panmixia in the other two locations. I tested if host preference of cotton fleahoppers were affected by geographic variation and prior experience. Conducting choice tests with a Y-tube olfactometer, I found that host preference in cotton fleahoppers for horsemint (one of its native host plants) is conserved and unaffected by individual?s prior experience with cotton (Chapter IV). Finally, I explored the role of host-plant species in morphological differentiation of the cotton fleahopper in two locations that differ in presence of distinct host-associated lineages. Using a geometric-morphometric approach, I detected significant effect of host plant and geography on body morphology and wing shape of cotton fleahopper populations (Chapter V). Length of antenna and rostrum were two important traits associated with morphological divergence of cotton and horsemint associated insect populations. Cotton associated individuals had relatively longer antenna and rostrum compared to individuals associated with horsemint.

The dusky shark, Carcharinus obscurus, is a globally distributed, coastal-pelagic species subject to an apparent high level of exploitation. The International Union for the Conservation of Nature (IUCN) lists this species as “Vulnerable” globally, and “Endangered” within western North Atlantic and Gulf of Mexico waters due to an over 80% decline in this region, with no evidence of population recovery. The extensive exploitation of dusky sharks may partly be attributed to the high market value of its fins, but the contribution of individual dusky shark stocks to the fin markets is unknown. This knowledge would be helpful to detect if specific stocks are experiencing disproportionate levels of exploitation. Due to its susceptibility to overfishing, current dire conservation status and need for additional information on its population dynamics, we analyzed the genetic population structure and genetic diversity of the dusky shark (n = 415) across 8 globally distributed locations utilizing 10 nuclear microsatellite loci. The nuclear marker analyses support and extend previously published mitochondrial marker work, identifying a strong divergence among Atlantic and Indo-Pacific samples. Furthermore, nuclear marker results indicate the presence of six genetically discrete management units for dusky sharks, with significant genetic differentiation between the western North Atlantic, South African, and each of three Australian site collections (N, E and W coasts). Discovery of these nuclear microsatellite-defined, smaller geographic scale management units provides a basis for the assignment of market-derived fins to their population of origin with the use of genetic assignment techniques.

Discerning the extent and patterns of genetic connectivity and understanding population demographic processes is essential for framing proper management and conservation measures for species of concern. Although genetic connectivity may be influenced by numerous biotic and abiotic factors, habitat utilization and dispersal potential are often key factors driving connectivity, especially in marine fishes. While dispersal potential is of key importance with respect to shaping connectivity, other extrinsic (e.g., oceanographic processes) and intrinsic (e.g., reproductive behavior) factors may also influence connectivity; however, the relative influence of such factors is immensely variable across species and life-stages. This dissertation explores genetic connectivity and demographic history in marine fishes with diverse dispersal potentials to determine which processes, in addition to the known dispersal potential of the species, may be shaping connectivity. Genetic connectivity and demographic history is assessed for four marine fishes: two shark species with juxtaposing dispersal potentials, the highly migratory tiger shark (Galeocerdo cuvier) and the reef associated Caribbean reef shark (Carcharhinus perezi), which possess high and low dispersal potentials, respectively, and two teleost species, the pelagic roundscale spearfish (Tetrapturus georgii) and the Nassau grouper (Epinephelus striatus), which possess high and low adult dispersal potentials, respectively. This work demonstrates that dispersal potential does, in fact, play a key role in delineating genetic structure for these species; however, other factors, such as contemporary oceanographic currents (e.g., upwelling and temperature), habitat availability (e.g., coral cover), and historical events, such as cyclical glacial cycles, also influence genetic connectivity across variable spatial scales, thereby creating complex patterns of genetic population structure, requiring composite management strategies to ensure the persistence of these species.

Os aspectos da pesca do espada, Trichiurus lepturus (Linnaeus, 1758) (Trichiuridae), foram descritos e analisados para as artes de pesca artesanal de linha-de-mão em Arraial do Cabo (RJ) e cerco flutuante em Porto Belo (SC), e da pesca comercial de arrasto de fundo com parelhas na costa de São Paulo. Verificaram-se tendências crescentes na produção da espécie, principalmente na pesca artesanal. Foram utilizados marcadores moleculares tipo RAPD para analisar a estrutura genético-populacional da espécie com exemplares de Belém (PA), Natal (RN), Arraial do Cabo (RJ), Guarujá (SP), Porto Belo (SC) e Rio Grande (RS), evidenciando-se uma população distinta em Belém, enquanto as demais não apresentaram estruturação definida. A dinâmica de populações foi analisada para exemplares de Arraial do Cabo, São Paulo e Porto Belo, coletados mensalmente de janeiro/2002 a julho/2003. A desova da espécie é parcelada com período reprodutivo ocorrendo do verão ao início do inverno. As fêmeas maduras migram para a plataforma encontrando-se com os machos maduros que ali permanecem, retornando à costa após a desova. O comprimento médio de primeira maturação sexual variou de 647 a 670mm (Lt) para fêmeas, e de 526 a 650mm para machos. As estimativas dos parâmetros de crescimento foram as seguintes: para fêmeas Loo de 1740 a 2010mm; k de 0,12 a 0,15/ano e t0 de -1,642 a -2,517 anos; para machos Loo de 1373 a 1580mm; k de 0,17 a 0.25/ano e t0 de -1,662 a -1,866 anos. A longevidade foi cerca de 14 anos. As taxas de mortalidade natural variaram de 0,20 a 0,29/ano. O modelo de rendimento relativo por recruta indicou que as taxas de mortalidade por pesca do espada estão próximas ou já ultrapassam os limites do rendimento máximo sustentável. / The fishery aspects of the cutlassfish, Trichiurus lepturus (Linnaeus, 1758) (Trichiuridae), were analyzed for the artisanal fishery of line and hook of Arraial do Cabo (RJ) and floating encirclement of Porto Belo (SC), and of the commercial paired bottom trawlers in the coast of São Paulo. Tendencies in increasing yields were detected, mainly in the artisanal fishery. RAPD markers techniques were employed in order to analyze the genetic-population structure of the cutlassfish from Belém (PA), Natal (RN), Arraial do Cabo (RJ), Guarujá (SP), Porto Belo (SC) and Rio Grande (RS), showing a different population in Belém, while the others did not show a clearly defined structure. The population dynamics were analyzed for fishes of Arraial do Cabo, São Paulo and Porto Belo, collected monthly of January/2002 to July/2003. The cutlassfish spawning is parceled with reproductive period from the summer to the beginning of the winter. Ripe females migrate offshore to mate with ripe males that stay there, returning to the coast just after spawning. The length of first sexual maturity varied from 647 to 670mm (Lt) for females, and 526 to 650mm for males. The estimates of growth parameters were: for females Loo from 1740 to 2010mm; k from 0,12 to 0,15/year and t0 from -1,642 to -2,517 years, and for males Loo from 1373 to 1580mm; k from 0,171 0.255/year and t0 from -1,662 to -1,866 years. The longevity was about 14 years. The natural mortality rate varied from 0,20 to 0,29/year. The relative yield per recruit model showed that fishing mortality rates of the cutlassfish are close or just exceeding the limits of the maximum sustainable yield.

Os aspectos da pesca do espada, Trichiurus lepturus (Linnaeus, 1758) (Trichiuridae), foram descritos e analisados para as artes de pesca artesanal de linha-de-mão em Arraial do Cabo (RJ) e cerco flutuante em Porto Belo (SC), e da pesca comercial de arrasto de fundo com parelhas na costa de São Paulo. Verificaram-se tendências crescentes na produção da espécie, principalmente na pesca artesanal. Foram utilizados marcadores moleculares tipo RAPD para analisar a estrutura genético-populacional da espécie com exemplares de Belém (PA), Natal (RN), Arraial do Cabo (RJ), Guarujá (SP), Porto Belo (SC) e Rio Grande (RS), evidenciando-se uma população distinta em Belém, enquanto as demais não apresentaram estruturação definida. A dinâmica de populações foi analisada para exemplares de Arraial do Cabo, São Paulo e Porto Belo, coletados mensalmente de janeiro/2002 a julho/2003. A desova da espécie é parcelada com período reprodutivo ocorrendo do verão ao início do inverno. As fêmeas maduras migram para a plataforma encontrando-se com os machos maduros que ali permanecem, retornando à costa após a desova. O comprimento médio de primeira maturação sexual variou de 647 a 670mm (Lt) para fêmeas, e de 526 a 650mm para machos. As estimativas dos parâmetros de crescimento foram as seguintes: para fêmeas Loo de 1740 a 2010mm; k de 0,12 a 0,15/ano e t0 de -1,642 a -2,517 anos; para machos Loo de 1373 a 1580mm; k de 0,17 a 0.25/ano e t0 de -1,662 a -1,866 anos. A longevidade foi cerca de 14 anos. As taxas de mortalidade natural variaram de 0,20 a 0,29/ano. O modelo de rendimento relativo por recruta indicou que as taxas de mortalidade por pesca do espada estão próximas ou já ultrapassam os limites do rendimento máximo sustentável. / The fishery aspects of the cutlassfish, Trichiurus lepturus (Linnaeus, 1758) (Trichiuridae), were analyzed for the artisanal fishery of line and hook of Arraial do Cabo (RJ) and floating encirclement of Porto Belo (SC), and of the commercial paired bottom trawlers in the coast of São Paulo. Tendencies in increasing yields were detected, mainly in the artisanal fishery. RAPD markers techniques were employed in order to analyze the genetic-population structure of the cutlassfish from Belém (PA), Natal (RN), Arraial do Cabo (RJ), Guarujá (SP), Porto Belo (SC) and Rio Grande (RS), showing a different population in Belém, while the others did not show a clearly defined structure. The population dynamics were analyzed for fishes of Arraial do Cabo, São Paulo and Porto Belo, collected monthly of January/2002 to July/2003. The cutlassfish spawning is parceled with reproductive period from the summer to the beginning of the winter. Ripe females migrate offshore to mate with ripe males that stay there, returning to the coast just after spawning. The length of first sexual maturity varied from 647 to 670mm (Lt) for females, and 526 to 650mm for males. The estimates of growth parameters were: for females Loo from 1740 to 2010mm; k from 0,12 to 0,15/year and t0 from -1,642 to -2,517 years, and for males Loo from 1373 to 1580mm; k from 0,171 0.255/year and t0 from -1,662 to -1,866 years. The longevity was about 14 years. The natural mortality rate varied from 0,20 to 0,29/year. The relative yield per recruit model showed that fishing mortality rates of the cutlassfish are close or just exceeding the limits of the maximum sustainable yield.

Abstract Many plant species inhabiting the seashore meadows of the Bothnian Bay, especially early successional ones, have become threatened. Isostatic land uplift creates virgin land for early successional species to colonise. However, at the same time it gradually elevates the habitat and eventually makes the habitat unsuitable for them. Disturbances of the waterfront may slow down succession and create new empty sites. In order to persist on the shores, pioneer species have to be able to colonise new sites by seeds, vegetative propagules or growth. In this thesis I studied the status of an endangered early successional grass species, A. fulva var. pendulina, at the Liminka Bay. According to a matrix population model based on eight years of observations (1992–1999), the population seemed not to be in immediate danger of extinction. However, simulations based on four-year field observations (2000–2003) indicated that if the current trend continues, the species will decrease considerably in area in the next 30 years. In the field studies no seedlings or viable seeds of A. fulva were found. In spite of this, high genotypic diversity was found in the A. fulva population, suggesting that sexual reproduction has taken place at some time during the history of the population. Analysis of the population structure revealed a low level of genotypic differentiation between subpopulations and significant sub-structuring within subpopulations. The overall pattern of genetic variation suggests that the population has characters of both stepping-stone and metapopulation models. The results of the study on the ability of a seashore plant Potentilla anserina ssp. egedii to change its allocation of resources to sexual and vegetative reproduction according to competitive stress implied that the species can modify the allocation of resources to different life-history traits. For a plant living in disturbance-prone environment, it may be beneficial to be able to rapidly track the competition-free space formed by disturbances by changing its reproductive pattern. Management studies on three endangered seashore plant species showed that deterioration of suitable habitats of A. fulva and Primula nutans var. jokelae could be slowed down by management, and the vegetative and/or sexual reproduction of these species was enhanced. However, in the case of Puccinellia phryganodes, no positive response to management was observed.

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