Freshwater lake ecosystems often exhibit strong oxygen, and temperature gradients across which many zooplankton species live. Daphnia sp. vary in their ability to up-regulate hemoglobin in response to low oxygen environments. However; the role that hemoglobin up-regulation plays in diel vertical migration, and how it might mediate coexistence of Daphnia within lakes is still unclear. Using an oligotrophic lake in Ontario, I studied three distinct phenotypes of Daphnia pulicaria, which differed in the ability to up-regulate hemoglobin (classified as red, pink, and pale). Twenty-four hour surveys were conducted during the fall of 2012 and samples were drawn at 1m intervals to monitor changes in diel vertical migration. At each 1m interval Daphnia were color indexed, photographed, and preserved for genetic analysis using cellulose acetate electrophoresis. Red and pink Daphnia showed little change in distribution over the water column through time, suggesting individuals experienced little vertical migration. Pale individuals showed strong changes in vertical distribution through time suggesting vertical migration. The phenotypes are strongly correlated with multi-locus genotypes, suggesting genetic differences in migration behavior. Mesocosm experiments were used to manipulate migration over heterogeneous environments to test the hypothesis that vertical migration impacts genetic and phenotypic diversity in Daphnia pulicaria. The first mesocosm experiment contained two treatment groups; a migrating and non-migrating treatment containing the three phenotypes. The migrating treatment permitted unrestricted movement throughout the water column, and the non-migrating treatment restricted Daphnia to discrete 1m intervals. The second mesocosm experiment comprised two non-migrating treatments; red non-migrating and pale non-migrating. Results from the first set of mesocosm experiments indicate decreased genetic and phenotypic diversity in the migrating treatment. Shifts in hemoglobin up-regulation between pales and reds in the second mesocosm experiments suggest hemoglobin up-regulation is plastic, whereby pale, pink, and red individuals have the ability to up and down regulate hemoglobin. The differences in Daphnia migration patterns and the plastic response in hemoglobin up-regulation permits migrating genotypes to withstand low oxygen conditions. Overall implications of this study suggest that migration over a strong environmental gradient plays a key role in fostering phenotypic plasticity and genetic diversity in organisms living in heterogeneous environments. / Thesis (Master, Biology) -- Queen's University, 2014-04-08 12:07:42.757

La dynamique et le fonctionnement des écosystèmes forestiers dépendent fortement de la reproduction des arbres. Ainsi de nombreux travaux se sont intéressés aux fortes fluctuations interannuelles à la fois synchrones et non prévisibles des productions de graines, mais très peu d’études ont pu caractériser la sensibilité aux variables climatiques et le déterminisme des traits de reproduction. Dans le cadre de cette thèse nous avons étudié la reproduction de deux espèces de chênes tempérés européens (Quercus petraea et Quercus robur) avec pour objectifs (i) d’évaluer l’évolution des traits de reproduction au cours des deux dernières décennies, notamment vis-à-vis des changements de température, (ii) d’estimer la contribution des facteurs génétiques et environnementaux à la variation de ces traits le long de gradients environnementaux et enfin (iii) d’estimer l’héritabilité des traits de reproduction ainsi que d’identifier les régions du génome qui leurs sont associées. A partir de suivis long-termes de l’effort de reproduction « in situ » sur tout le territoire de France métropolitaine, nous avons pu mettre en évidence une augmentation significative de la production fruitière des chênes au cours des 14 dernières années. Ces accroissements du nombre et de la taille des glands sont fortement corrélés à l’augmentation des températures printanières. Cette sensibilité à la température a par ailleurs pu être confirmée grâce à un dispositif indépendant installé le long de gradients altitudinaux dans les Pyrénées. Nos résultats montrent également une différenciation génétique entre les populations provenant du gradient altitudinal et une opposition de signes entre les clines génétique et phénotypique « contre-gradient » pour les deux traits de reproduction étudiés. Contrairement aux traits de croissance pour lesquels nous observons un « co-gradient », le « contre gradient » observé pour la reproduction suggère que les variations génétiques contrecarrent en partie la forte plasticité environnementale, minimisant ainsi la tendance (ou patron) de l’effort de reproduction avec la température. Enfin, nous avons observé une forte héritabilité pour chacun des traits de reproduction chez le chêne pédonculé dans une famille de pleins frères, confirmant l’existence d’un déterminisme génétique évoqué précédemment. De plus, nous avons identifié pour la première fois chez les arbres forestiers, des locus à caractère quantitatif (QTLs) associés à la reproduction du chêne. Ces résultats suggèrent qu’en réponse à des changements environnementaux, les traits de reproduction ont la capacité de répondre à la sélection et de faciliter l'adaptation locale, et ainsi apportent de nouvelles perspectives dans l’étude de la réponse des arbres forestiers aux changements climatiques. / Forest ecosystem dynamics closely depend on tree reproduction. Many studies have investigated the synchronous and non-predictable year-to-year variability of seed production, characteristic of masting species. However, little is known about the sensitivity of tree reproduction to climate variables and to which extent this phenotypic variability is genetically and/or environmentally driven. We intensively studied the reproduction of two European temperate oaks and our aims were (i) to characterize the change in reproductive traits over the last two decades, (ii) to assess the determinism of their variations along environmental gradients and (iii) to estimate the heritability of reproductive traits and identify the regions of their genome related to reproduction. We were able to show a dramatic increase in seed production over the last 14 years. This increase in seed production and size was significantly correlated with increasing spring temperatures. We then confirmed this sensitivity to temperature by studying the reproduction of oak populations growing along the elevation gradient of the Pyrenees. Based on a common garden approach, we then showed significant genetic differentiation between oak provenances and demonstrated that the genetic and phenotypic clines for the reproductive traits observed along the environmental gradient have opposite signs (counter-gradient). Contrary to growth traits, for which genetic variation parallels phenotypic variation, the counter-gradient observed for reproduction-related traits suggested that genetic variation partly counteracts the phenotypic effect of temperature, moderating the change in reproductive effort according to temperature. Finally, using a full-sib family where reproduction was monitored during four consecutive years, we found a high heritability of reproductive traits and showed high genetic differentiation between trees of a same population, which confirms the significant genetic determinism observed earlier. Furthermore, we were able to identify for the first time in forest trees quantitative trait loci (QTLs) associated with seed production and size. Our findings show that reproduction-related traits may undergo evolutionary changes under selective pressure and may be determinant for tree adaptation in response to environmental changes.

Made available in DSpace on 2016-12-08T15:50:05Z (GMT). No. of bitstreams: 1 PGCS15DA024.pdf: 1709565 bytes, checksum: 102e8c7963b170e39ba16b5decf01861 (MD5) Previous issue date: 2015-03-06 / Upper montane ecosystems have been highlighted by environmental functionality, supplying ecosystem services due to its high capacity of water and carbon storage besides the endemism of species. From the edaphic perspective, these regions stand out for lower decomposition rate of organic material and the predominance of less developed and acid soils with high capacity of carbon storage. Its soil variability and properties related to the upper layer as carbon and nutrients cycling and water dynamics are related to the slope. Associated with these characteristics, according to the steep slope, upper montane ecosystems show lower resilience and fragility to unplanned human interventions. The objectives of this research was: to characterize slope and morphology of the soil related to drainage and total organic carbon content; to describe physical and chemical properties of the soil according to slope gradient and contents and fractions of soil organic carbon, in a fragment of upper montane mixed-rain forest, in Urupema SC. This research is presented in three chapters; firstly, presents relationship between slope, soil morphology and organic carbon contents; secondly, characterizes soil physical and chemical properties; and finally, analyzes contents and fractions of soil organic carbon in slope gradient under native forest areas. Soil was sampled into four transects across the slope, subdivided in plots of 10 m x 20 m, amounting 55 plots. The evaluated attributes werealtitude, slope, drainage, depth, stoniness and soil color, in surface horizon. For the chemical analysis were determined pH in CaCl2, extracting acidity (Al+3 e H+), exchangeable cations (Ca⁺², Mg⁺² and K⁺), available phosphorus and total organic carbon (TOC). The sum of exchangeable bases (SB) and cation exchange capacity (CEC) were calculated. The particulate fraction of carbon (POC) was determined and the fraction associated to minerals (COAM), was calculated by the difference between TOC and COP. Physical analysis were macro, micro and total porosity and soil resistance to penetration. The analysis of humin fractions (H), humic acid (HA), fulvic acids (FA) was performed in the layer 0 to 10 cm. It was calculated the relation among humin fractions, C humic acid and C fulvic acid (FAH-C/ C-FAF) and, the C alkaline extract (AE-C = C+C fulvic acid humic acid) with C from humin fraction (C-EA/ C-HUM). To evaluate the litterfall, composed litter samples from each plot of the four transect were collected. Relations among variables were determined through principal compounds analysis (PCA). The studied soils mainly occurred under steep slope areas, and that condition justifies the occurrence of rocky and shallow soils. Thinner soils were classified as Humic Lithic Dystrudept. Soils from higher altitudes with lower slope and better drainage showed higher TOC values, being classified as Humic Dystrupept. Soils from higher areas, with lower slope have lower acidity level and fertility when compared with soils under steep slope condition, lower altitude and moderately deep soil profile. The Humic Dystrupept are more fertile, showed high organic carbon content and had more litter quantity. They presented predominance of humin, indicating greater organic material humification, so reflecting the influence of weather conditions, altitude, slope and vegetation on total organic carbon dynamics / Ecossistemas alto-montanos têm sido destacados pela funcionalidade ambiental, podendo suprir serviços ecossistêmicos, devido à elevada capacidade de armazenamento de água e carbono, além do endemismo de espécies. Do ponto de vista edáfico, essas regiões se destacam pela menor taxa de decomposição da matéria orgânica e predomínio de solos pouco desenvolvidos e ácidos, com alta capacidade de estoques de carbono. Nestes, a variabilidade de solo e atributos relacionados à camada superficial, como ciclagem de carbono e nutrientes e dinâmica da água é condicionada pelo relevo. Associado a essas características, em função do relevo ondulado, os ecossistemas alto-montanos apresentam baixa resiliência e fragilidade as intervenções antrópicas não planejadas. Os objetivos do trabalho foram: caracterizar relevo e morfologia do solo, relacionados à drenagem e ao teor de carbono orgânico total; caracterizar os atributos físicos e químicos do solo em função do gradiente de declividade e caracterizar os teores e frações do carbono orgânico do solo em fragmento de Floresta Ombrófila Mista Alto-Montana, no município de Urupema SC. Este trabalho e foi apresentado em três capítulos, sendo o primeiro abordando relações entre relevo, morfologia e teores de carbono orgânico do solo, o segundo caracterizando atributos físicos e químicos do solo e o terceiro analisando teores e frações do carbono orgânico do solo em gradiente de relevo em áreas de floresta nativa. Os solos foram amostrados em quatro transectos, subdividos em parcelas de 10 m x 20 m, totalizando 55 parcelas. Para as análises químicas e físicas o solo foi coletado nas profundidades de 0 a 10, 10 a 30 e 30 a 50 cm. Os atributos avaliados foram altitude, declividade, drenagem, profundidade, pedregosidade e cor do solo, no horizonte superficial. As análises químicas foram pH em CaCl2, acidez extraível (Al+3 e H+), cátions trocáveis (Ca⁺², Mg⁺² e K⁺), fósforo disponível e carbono orgânico total (COT). A soma de bases trocáveis (S) e capacidade de troca catiônica (CTC) foram calculadas. Foi determinada a fração do carbono particulado (COP) e a fração associada aos minerais (COAM), calculada pela diferença entre o COT e o COP. As análises físicas foram macro e microporosidade, porosidade total e resistência à penetração do solo. As frações huminas (H), ácidos húmicos (AH), ácidos fúlvicos (AF) foram analisadas apenas na camada de 0 a 10 cm. Foram calculadas as relações C ácido húmico e C ácido fúlvico (C-AH/C-AF) e, C do extrato alcalino (C-EA= C ácido fúlvico + C ácido húmico) com o C da fração humina (C-EA/CH). Para estimar a serapilheira foram coletadas amostras compostas em cada parcela. As relações entre as variáveis foram determinadas pela análise de componentes principais (ACP). Os solos estudados ocorrem predominantemente em relevo ondulado. Essa condição justifica a ocorrência de solos rasos, com afloramentos de rocha. Os solos mais rasos foram enquadrados como Neossolos Litólicos Distróficos. Os solos nas cotas mais elevadas, menos declivosas e com boa drenagem apresentaram mais COT e foram classificados como Cambissolos Húmicos Distróficos. Os solos das áreas de maior altitude, em topografia mais plana são menos ácidos e tem baixa fertilidade, quando comparados com os solos localizados em topografia mais inclinada, com menor altitude e maior profundidade. Os Cambissolos são mais férteis apresentam maior teor de COT e serapilheira. Além disso, apresentaram predomínio de humina, indicando maior humificação da matéria orgânica, o que denota a influencia das condições climáticas, altitude, topografia e vegetação na dinâmica do carbono orgânico total

Submitted by dayse paz (daysepaz@hotmail.com) on 2016-04-06T18:25:56Z No. of bitstreams: 1 Disserta_o_Mestrado_Gabriela_Guerra_PPGBAC.pdf: 2204919 bytes, checksum: 182150838d9e5538ccbbc7e9a89712a4 (MD5) / Approved for entry into archive by cleuza maria medina dos santos (cleuzamai@yahoo.com.br) on 2016-05-10T20:07:01Z (GMT) No. of bitstreams: 1 Disserta_o_Mestrado_Gabriela_Guerra_PPGBAC.pdf: 2204919 bytes, checksum: 182150838d9e5538ccbbc7e9a89712a4 (MD5) / Made available in DSpace on 2016-05-10T20:07:01Z (GMT). No. of bitstreams: 1 Disserta_o_Mestrado_Gabriela_Guerra_PPGBAC.pdf: 2204919 bytes, checksum: 182150838d9e5538ccbbc7e9a89712a4 (MD5) Previous issue date: 2014 / O estudo da estrutura trófica de comunidades biológicas nos fornece uma descrição da organização e funcionamento do ecossistema e das interações entre as comunidades. Comparar a estrutura trófica das comunidades ao longo de gradientes ambientais pode fornecer novas interpretações em relação a sua organização trófica e serve de base para avaliar impactos antrópicos presentes e futuros. Um dos métodos mais comuns atualmente para se avaliar relações tróficas é a análise dos isótopos estáveis (AIE), o qual vem sendo utilizado para estimar os fluxos de matéria orgânica entre consumidores bem como sua posição trófica na cadeia alimentar. O objetivo principal dessa dissertação foi investigar a estrutura trófica da assembleia de peixes de zonas rasas ao longo de um gradiente estuarino–límnico, a partir da AIE de carbono (13C/12C) e nitrogênio (15N/14N) de fontes alimentares basais (i.e., plantas com fotossíntese C3 e C4 e matéria orgânica particulada em suspensão, POM) e peixes dominantes em cada sistema. Amostras de fontes alimentares basais, peixes e invertebrados foram coletados na primavera e verão entre 2009 e 2010 no estuário da Lagoa dos Patos, Canal São Gonçalo e Lagoa Mirim no extremo sul do Rio Grande do Sul. Biplots e métricas isotópicas (Convex hull e nicho isotópico) foram utilizadas para descrever e comparar a estrutura trófica da ictiofauna entre os ambientes. Análises de correlação foram realizadas para analisar a relação entre o comprimento total (CT) da ictiofauna e a posição trófica (PT). Modelos bayesianos de mistura isotópica foram empregados para avaliar a variabilidade no uso de recursos alimentares ao longo do gradiente ambiental para o barrigudinho Jenynsia multidentata, uma das únicas espécies frequentes ao longo de todo gradiente. A área total (Convex hull) e o nicho isotópico ocupado pela assembleia de peixes variaram marcadamente entre os ambientes, com o estuário apresentando uma área total duas vezes maior (CH: 50,28) do que o Canal e a Lagoa (17,51 e 20,29, respectivamente). Já o nicho isotópico, que é robusto aos efeitos de possíveis diferenças no número amostral, apresentou diferenças estatísticas entre estuário e os dois ambientes de água doce (p<0,00), porém esses dois últimos não apresentaram diferenças entre si (p>0,30). A AIE dos peixes no Canal sugere que a fragmentação de habitat ocasionada pela presença de uma barragem-eclusa afetou também a conectividade trófica entre o estuário da Lagoa dos Patos e Lagoa Mirim. Variações na razão isotópica do nitrogênio da comunidade também sugerem que impactos antrópicos como a eutrofização são mais acentuados no estuário da Lagoa dos Patos e Canal. As análises de correlações não mostraram correlação positiva entre o CT e PT. O modelo de mistura mostrou que as principais fontes alimentares basais para J. multidentata no canal foi POM, enquanto na lagoa foram principalmente plantas C4 e POM e no estuário houve uma maior sobreposição nos intervalos de credibilidade, não sendo possível distinguir diferenças significativas na contribuição relativa das fontes basais para a espécie. Nossos resultados mostraram que há diferenças na estrutura trófica e no uso de recursos alimentares ao longo do gradiente ambiental e que impactos antrópicos, como construção de barragem e eutrofização, afetam a ictiofauna nesses ambientes. / Trophic structure analyses of biological communities provide insights on ecosystem organization and functioning and also on communities’ interactions. Comparing the trophic structure of communities considering environmental gradients allows new interpretations of their trophic organization and evaluation of current and future anthropic impacts. One of the most common methods to evaluate trophic relationships is the stable isotope analysis (SIA), which has been used to estimate the flow of organic matter among consumers as well as its trophic position in the food chain. The main objective of this Master Thesis was to investigate the trophic structure of shallow areas fish assemblage along a freshwater-estuarine gradient, using the analysis of carbon (13C/12C) and nitrogen (15N/14N) isotope ratios of basal food sources (i.e., plants with C3 and C4 photosynthesis and particulate organic matter POM) and dominant fishes in each system. Basal food sources, fishes and invertebrates were collected at Lagoa dos Patos estuary, São Gonçalo Channel and Lagoa Mirim, located in the southern most in Brazil, during spring and summer seasons of 2009 and 2010. Biplots and isotopic metrics (Convex hull and isotopic niche) were used to describe and compare the trophic structure obtained in the three environments. Correlation analyzes were conducted to examine the relationship between total length (TL) of the ichthyofauna and trophic position (TP). Bayesian models of isotopic mixing were used to evaluate the variability in food resource use by the one-sided livebearer Jenynsia multidentata along the environmental gradient, which was one of the only species found along the entire gradient. The total area (Convex hull) and the isotopic niche occupied by the fish assemblage showed an marked variation among environments. The Convex hull total area of the estuary (CH: 50.28) was two-fold higher than the Channel and Lagoa Mirim areas (17,51 and 20.29, respectively). The isotopic niche, which is not affected by differences in sample sizes, showed statistical differences between the estuary and the two freshwater systems ( (p<0.00), but there were no statistical differences when the freshwater systems were compared with each other (p>0.30). The SIA analysis of fishes in the Channel suggests that the habitat fragmentation caused by a dam also affected the trophic connectivity between the Lagoa dos Patos estuary and the Lagoa Mirim. Comparison of the nitrogen isotope ratio values among communities also suggested that anthropogenic impacts (e.g., eutrophication) were more evident in the Lagoa dos Patos estuary and Channel. The analysis of correlations didn't show any positive correlation between TL and TP. The mixing model showed that the main basal food sources sustaining J. multidentata in the Channel was POM, whereas in the Lagoa Mirim was mainly C4 plants and POM. Moreover, in the estuary, it was found a greater overlap on the credibility intervals of basal food sources and it was not possible to distinguish statistical differences between their relative contributions to the specie. Our results showed that there are differences on the trophic structure and on the use of food resources along the environmental gradient. Also, anthropogenic impacts, such as dam constructions and eutrophication, have an affect on the ichthyofauna of these environments.

Full thesis document accompanied by all data files and R scripts to reproduce analyses in both data chapters (2 & 3). / Animals should favour breeding locations that maximize their lifetime reproductive output. Parents ought to rear young in sites that positively affect offspring but sometimes these same sites inflict costs on parents. How parents balance their own needs against those of their offspring when selecting a site for reproduction remains unclear, particularly in animals that provide extended parental care at one location. Further, few studies have linked variation in life history traits to reproductive site choices within a single species. In this thesis, I addressed both knowledge gaps by studying the plainfin midshipman (Porichthys notatus), a marine toadfish where fathers provide sole parental care to broods of young in intertidal and shallow subtidal nests for up to two months. In Chapter 2, I measured the costs incurred by caring males and the benefits conferred to offspring in nest sites along a tidal gradient. Males suffered similar rates of body condition deterioration in all nests across the intertidal gradient. Young developed more quickly in intertidal nests compared to subtidal nests, but broods in the highest intertidal nests suffered the highest mortality rates, despite receiving more parental care from the males at these nest sites. We found the most competitive males in lower intertidal nests, a trend that agrees with life history theory—in species with relatively slow offspring development, parents should accrue greater reproductive benefits from nest sites where offspring benefits are highest. In Chapter 3, I describe a laboratory experiment designed to examine how warm water and air exposure (two abiotic conditions that vary dramatically within the intertidal) affect development and survival of plainfin midshipman young, and how these effects vary with maternal traits. Exposure to warm water enhanced embryonic and larval development rates; this effect was attenuated by air exposure. Juveniles raised in warm water also exhibited superior swimming performance, while air-exposed young suffered higher mortality rates. Although larger juveniles emerged from larger eggs, development rates were similar across egg sizes. Offspring survival increased with maternal body condition in cold water but decreased with maternal body condition in warm water. Juvenile body sizes increased with maternal condition in cold water without emersion, and in warm water with emersion—the two ecologically relevant rearing environments. Thus, low condition mothers might accrue greater benefits by depositing their eggs in nests at higher tidal elevations—where development is more rapid—further supporting the idea that among-individual variation in the expression of life history traits might influence nest site preferences in these fish. In sum, my research (Chapters 2 & 3) elucidates the link between life history traits and the spatial component of animal reproductive strategies. / Thesis / Master of Science (MSc)

The trait based approach has been proposed as a way to reconcile community ecology. Despite recent advances in trait based ecology, such as the development of global trait databases and standardized methodology for trait collections, it remains unclear to what degree traits vary across individuals, species, and communities. In addition, the drivers of trait variation may shed light on the underlying processes that maintain species diversity and community assembly at local to continental scales yet these have been poorly studied. In this study, I examine both the magnitude of trait variation as well as the patterns of trait variation at local to continental scales in order to understand the drivers of diversity patterns across environmental gradients. First, I quantified the magnitude of trait variation at local scales in a dry tropical forest and determined that intraspecific variation is not negligible and can be quite large for compound-leaved species. However, I showed that the sample sizes necessary for quantifying trait variation are tractable and should encourage the adoption of trait variation in trait based ecology. Second, I tested whether climatic variables are predominantly responsible for observed trait variation across dry tropical forests in the Americas. I showed that climatic variability, specifically variability in precipitation, explained a large degree of observed trait variation across dry tropical forests and may provide a unique approach for classifying dry tropical forests based on their inherent degree of climatic seasonality. Third, I quantified patterns of trait variation at continental scales across elevational gradients at high to low latitudes. I showed that climatic variables largely drive patterns of trait variation at high latitudes while biotic factors largely drive patterns of trait variation at low, tropical latitudes. This finding has implications for understanding large-scale patterns of species diversity across elevational and latitudinal gradients. Finally, I apply trait variation to life history theory by quantifying variation in two life history traits (growth and reproduction) in a tropical tree species using a legacy dataset. I showed that variation in these two life history traits is due to both resource availability and allometric related effects on both traits. In sum, this study advances our understanding of the magnitude and underlying drivers of trait variation at local to continental scales.

Environmental gradients can help shed light on the evolution of life history strategies such as parental investment. Parental investment is crucial for the fitness of many species. In this thesis, I examine reproductive investment dynamics in the Eurasian blue tit (Cyanistes caeruleus) in the French Pyrenees and assess potential differences in reproductive measures across an altitudinal gradient that creates variation in environmental “harshness”. Further, I investigate fine-scale aspects of bi-parental care, such as investment tactics in current reproduction, and sex differences in contributions to offspring care. To do so, I used a mixture of observational and experimental data, collected over a total of six breeding seasons from over 500 blue tits nests. I showed that breeding conditions are “harsher” due to colder temperatures with increasing elevation, leading to changes in reproductive timing and output. I found that increasing altitude leads to decreased hatching success. Nevertheless, clutch size and brood mortality is comparable across the gradient. A shift to a lower, but qualitatively comparable reproductive output may be part of a slower “pace of life” strategies pursued at high relative to low altitudes. From experimental data, I also found that parental investment is positively linked across different phases within one reproductive attempt. Finally, in line with theory, a temporary brood manipulation revealed that parents balance the benefits and costs of reproduction by partially compensating for changes in brood size. Parents also responded in similar ways to brood size. Overall, the findings presented in this thesis highlight the importance of mechanisms to fine-tune reproduction to maximise reproductive fitness. I suggest that initial reproductive decisions such as timing and amount of offspring produced heavily shape the success of a reproductive attempt. These results have implications for current versus future reproductive trade-offs in life history theory, in particular for short-lived species.

The aim of this thesis was to study patterns of reproduction of Betula pendula and B. pubescens coll. along an altitudinal, coastal-inland, gradient in northern Sweden. The altitudinal variation was related to the distribution of the birch taxa along the gradient. Six years field data showed a steep decrease of seed germinability of B. pendula towards its altitudinal range limit in the Scandes every year. In contrast, B. pubescens ssp. pubescens showed significant positive correlations between seed germinability and altitude in three of the six years. Furthermore, there was a highly significant positive correlation between seed weight and altitude for B. pubescens coll., but not for B. pendula. Production of viable seeds fluctuated strongly between years in most populations, except in marginal B. pendula populations in the mountain area where it was constantly very low. On average 15 - 41 % of the seeds produced in B. pendula populations above 400 m altitude were attacked by gall midges (Semudobia ssp.). Corresponding values for B. pendula populations below 400 m altitude were 4 - 7 %. In B. pubescens populations, the seeds attacked by Semudobia ssp. never exceeded 3 %. The high frequency of Semudobia attackes in high altitude marginal B. pendula populations was suggested to be due to limited resources for defense against the seed predator. A 3-yr study documented large variations in pollination and seed quality between taxa, high and low altitude populations, and between years. Empty seeds (without embryos) dominated among the sampled seeds in most cases. This proportion was decreased by pollen addition, in both B. pendula and B. pubescens, in mountain populations, but not in coastal populations. The high percentage of empty seeds was therefore suggested to be partly caused by pollen-limitation, but failure of pollen tube penetration - fertilisation, or maternal resource supply could also have had an influence. A laboratory experiment showed increased pollen germination and length of the longest pollen tube per style after increased pollination. The correlations between number and length of pollen tubes per style were however mostly low in natural populations, suggesting low probability of pollen competition in the natural situation. Sowing experiments indicated that differences in initial seedling density between B. pendula and B. pubescens was more affected by interspecific differences in seed quality than by interspecific differences in survival of seedlings after establishment A study of the age structure of a B. pendula stand, planted about 250 m above its natural altitudinal limit, indicated that this birch may reproduce above its recent range limit during temporally warmer periods. It was concluded that the level of accumulated resources in B. pendula in marginal sites in the Scandes would mostly be too low for completion of the reproductive cycle. In contrast, B. pubescens ssp. pubescens is able to accumulate enough rescources for reproduction also at relative high altitudes. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 5 uppsatser.</p> / digitalisering@umu

Besides spatial heterogeneity, an important component of diversity of the protist communities is also the variation in species assemblages through time (temporal turnover). Spatial and temporal variation in patterns of distribution and abundance of lentic microphytobenthos assemblages is often large and occurs at relatively small spatial scale. Desmids (Zygnematophyceae) often constitute a characteristic part of the microphytobenthos of peat bogs. Despite their important role in primary production and fact that they are useful indicators of ecosystem uniqueness, investigations of their seasonality and spatial distribution are scarce. In my thesis I have investigated if desmid epipelic communities are driven rather by neutral or niche-based processes, and I also focused on the factors affecting their diversity, seasonal dynamics and spatial patterns at the local spatial scale. The study was conducted at the two different types of biotopes - minerotrophic lowland peat bogs (Doksy region) and ombrotrophic raised bogs (Jizera Mountains region). Seasonal changes in species composition and diversity of assemblages were not evident. This may be affected by a monopolization effect and also that local abundance of species was positively correlated with population persistence, which suggests that high local...

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-06-20T18:42:06Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação (G. Ferreira).pdf: 2368229 bytes, checksum: e7d27dd236d3848f67692455d0a94426 (MD5) / Made available in DSpace on 2016-06-20T18:42:06Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação (G. Ferreira).pdf: 2368229 bytes, checksum: e7d27dd236d3848f67692455d0a94426 (MD5) Previous issue date: 2016-02-01 / Capes / Este estudo avalia a influência espaço-temporal nos padrões de distribuição, ecologia alimentar e ingestão de microplástico da espécie Cynoscion acoupa (Pescada Amarela) ao longo da sua ontogenia, no estuário do rio Goiana, localizado no nordeste do Brasil. A área de estudo se trata de um estuário tropical, com altas médias de temperatura anual e pequenas oscilações. O ambiente está submetido a um regime de mesomaré semi-diurna. As principais alterações encontradas no estuário são oriundas do ciclo sazonal, que está diretamente ligado à pluviometria, divida em quatro estações (início da chuva, fim da chuva, início da seca e fim da seeca), com o intuito de se ter uma maior precisão na avaliação dos processos abiológicos e na comunidade aquática. Os espécimes foram coletados em diferentes porções estuarinas (estuário superior, intermediário e inferior) e nos canais de maré. Simultaneamente a coleta dos dados biológicos foram obtidas informações a respeito dos parâmetros físico-químicos. Os padrões de distribuição e alimentação da espécie estudada ocorrem de forma distinta em relação à ontogenia, sazonalidade e áreas do estuário. A fase juvenil de C. acoupa ocupa a porção superior do estuário durante todas as estações do ano, em busca de baixos valores de salinidade, onde encontram condições ideais apara evitar predadores marinhos. As principais presas dos juvenins no estuário superior foram filamentos de microplástico (FO=63%), amphipoda (FO=28%) e mysidacea (FO=22%). Além disso, no início do período chuvoso, o estuário superior apresenta um papel crucial para o ciclo de vida da espécie, por se caracterizar como uma área berçário para C. acoupa (grande densidade 228,4 ind. ha-1 e baixa biomassa 46 g ha-1 de juvenis), pois a sua contribuição de indivíduos juvenis para a população adulta é muito maior que nos outros hábitats. No ambiente de berçário os juvenis se alimentaram principalmente de filamentos de microplástico (FO=48%), camarão (FO=28%), mysidacea (FO=22%) e amphipoda (FO=21%). Nas demais porções estuarinas, também são registrados indivíduos juvenis, sobretudo nos períodos chuvosos (início da chuva 115 ind ha-1 e fim da chuva 7,3 ind. ha-1), porém em menor escala. Os subadultos de C. acoupa utilizam principalmente o estuário superior durante o início da seca (1,7 ind. ha-1), fim da seca (1,6 ind. ha-1) e início da chuva (6,5 ind. ha-1) como área de alimentação. Predando no estuário superior, no início da seca, principalmente peixes não identificados (FO=50%), no fim da seca, filamentos de microplástico (FO=60%), mysidacea (FO=20%) e syllidae (FO=20%) e no início da chuva, filamentos de nylon FO=100% e peixes não identificados (FO=20%). Durante o fim do período chuvoso os indivíduos subadultos migram para o estuário intermediário (2,3 ind. ha-1) para evitar grandes estresses osmorregulatórios e predaram principalmente amphipoda (FO=75%), Cathorops spixii (FO=50%), Anchovia clupeoides (FO=25%) e peixes não identificados (FO=25%). A fase adulta de C. acoupa foi registrada somente nas porções mais externas do estuário inferior, por se tratar de uma espécie de hábitos costeiros quando completamente desenvolvida. Os indivíduos adultos de C. acoupa predaram principalmente filamentos de nylon (FO=100%), C. spixii (FO=18%), Achirus lineatus (FO=15%), Stellifer stellifer (FO=15%) e camarão (FO=15%). C. acoupa apresentou uma variação no padrão de distribuição em relação a sua ontogenia, sazonalidade e diferentes porções estuarinas. Ao longo do seu desenvolvimento ontogenético C. acoupa também apresentou uma alteração na sua guilda trófica, os juvenis e os subadultos foram classificados como oportunistas e os indivíduos adultos como piscívoros. A grande quantidade de fragmentos e microplástico encontrada na espécie estudada, demostra que ela é particularmente vulnerável a esse tipo de contaminante, sobre tudo os espécimes adultos, que registraram os maiores níveis de contaminação, provavelmente em razão do seu nível trófico, como predadores de topo. / This study assess the spatio-temporal distribution patterns, feeding ecology and microplastic ingestion of the Cynoscion acoupa (Acoupa weakfish) during its ontogeny in the Goianna Estuary, located in northeast Brazil. The study area is a tropical estuary, with high mean temperatures and narrow annual temperature variations. The environment is classified as a semi-diurnal mesotidal estuary. The major environmental dynamics are caused by the seasonal regime, which is related to the rainfall, according to the pluviometry, the area was divided in four different seasons (early dry, late dry, early rainy and late rainy). Biological samples were performed in different estuarine reaches (upper, middle and lower estuary) and in tidal creeks. During the fish sampling, environmental parameters were also recorded. The distribution and feeding patters of the studied species occur in a distinctive form according to the ontogeny, seasonality and estuarine area. The juveniles of C. acoupa occupy the upper estuary, during all seasons, seeking low salinity that provide ideal conditions to avoid marine predators. The main juveniles prey in the upper estuary were microplastic threads (FO=63%), amphipoda (FO=28%) and mysidacea (FO=22%). Moreover in the early rainy season, the upper estuary is crucial for the life ciclo of the species, because it is a nursery ground for C. acoupa (high density 228.4 ind. ha-1 and low biomass 46 g ha-1 of juveniles), as a result of the higher contribution of juveniles for to the adult population than in the other habitats. In the nursery ground, the juveniles of C. acoupa fed mainly on plastic threads (FO=48%), penaeid shrimps (FO=28%), mysidacea (FO=22%) and amphipoda (FO=21%). In other estuarine areas juveniles were also recorded, mainly on the rainy seasons (early rainy 115 ind. ha-1 and late rainy 7.3 ind. ha-1), however with lower densities. The subadults of C. acoupa inhabited mostly the upper estuary, during the early dry (1.7 ind. ha-1), late dry (1.6 ind. ha-1) and early rainy seasons (6.5 ind. ha-1) as a feeding ground. In the upper estuary, during the early season they fed mainly on unidentified fish (FO=50%), in the late dry, plastic threads (FO=60%), mysidacea (FO=20%) and syllidae (FO=20%) and in the early rainy, plastic threads (FO=100%) and unidentified fish (FO=20%). During the late rainy season the subadults of C. acoupa migrated to the middle estuary (2.3 ind. ha-1) to avoid osmoregulatory stress, the subadults and fed mainly on amphipoda (FO=75%), Cathorops spixii (FO=50%), Anchovia clupeoides (FO=25%) and non-identified fish (FO=25%). The adults of C. acoupa were recorded only in seaward areas of the lower estuary, as a result of C. acoupa being a coastal/marine species when fully developed. The adults preyed mostly plastic threads (FO=100%), C. spixii (FO=18%), Achirus lineatus (FO=15%), Stellifer stellifer (FO=15%) and penaeid shrimp (FO=15%). During the ontogenetic process, C. acoupa showed a trophic guild shift, the juveniles and subadults were assigned as opportunistic and the adults as psicivores. C. acoupa showed a variation in the distribution pattern in relation to the ontogeny, seasonality and different estuarine reaches. During the ontogenetic development, C. acoupa showed a trophic guild shift, the juveniles and subadults were assigned as opportunistic and the adults as psicivores. The high occurrence of microplastic threads in the species, evince that C. acoupa is particularly vulnerable to this contaminant, especially the adult phase that registered highest contamination levels, probably due its trophic level, as a top predator.