Orientadores: Sergio Furtado dos Reis, Glauco Machado / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-09T02:04:21Z (GMT). No. of bitstreams: 1 Araujo_MarcioSilva_D.pdf: 2407731 bytes, checksum: 8775de8c335558a4381e1293aad0f17e (MD5) Previous issue date: 2007 / Resumo: A teoria ecológica clássica, em especial a teoria de nicho, foi construída sob a suposição de que os indivíduos de uma população são equivalentes em termos da utilização de recursos. Entretanto, é sabido que os indivíduos de uma população podem variar no uso de recursos e que essa variação pode ter importantes implicações ecológicas e evolutivas. Essa variação interindividual pode dar origem a morfotipos discretos (¿polimorfismo de recursos¿) ou ser contínua (¿especialização individual¿). O presente estudo teve como objetivo investigar a variação interindividual no uso de recursos em quatro populações de rãs do Cerrado brasileiro (Leptodactylus sp., L. fuscus, Eleutherodactylus cf. juipoca e Proceratophrys sp.), uma população de vespas-caçadoras de uma área de Mata Atlântica (Trypoxylon albonigrum) e uma população do peixe lacustre Gasterosteus aculeatus da Columbia Britânica, Canada. Houve evidência de variação interindividual em todas as populações estudadas, indicando que esse fenômeno não é exclusivo de comunidades temperadas de baixa diversidade. Houve uma associação entre a amplitude dos nichos populacionais e o grau de variação interindividual, indicando que os nichos individuais permanecem estreitos apesar da expansão do nicho populacional. Esse padrão é consistente com a presença de trade-offs funcionais associados ao uso dos recursos. A base dos trade-offs permanece desconhecida no caso das rãs e das vespas, mas é provavelmente comportamental. No caso de G. aculeatus, os trade-offs têm base morfológica, mas são mediados pelo comportamento. Além disso, foi identificado um padrão de partição de recursos inédito nesses peixes, em que os indivíduos formam microguildas que representam subdivisões dos recursos litorâneos e pelágicos. São propostos dois novos métodos para a investigação da variação intrapopulacional no uso de recursos, um deles baseado no uso de isótopos estáveis de carbono (d13C) e o outro na teoria de redes complexas / Abstract: Ecological theory, and specially niche theory, was built on the assumption that individuals are equivalent in terms of resource use. However, the individuals in a population may vary in their resources, and this interindividual variation may have important ecological and evolutionary implications. Such variation may give rise to discrete morphological groups (¿resource olymorphism¿) or it may be more continuous (¿individual specialization¿). In the present study, we investigated interindividual variation in resource use in four populations of frogs inhabiting the Brazilian Cerrado (Leptodactylus sp., L. fuscus, Eleutherodactylus cf. juipoca e Proceratophrys sp.), one population of hunting-wasp of the Atlantic Rainforest (Trypoxylon albonigrum), and one population of sticklebacks (Gasterosteus aculeatus) from British Columbia, Canada. We found evidence of interindividual diet variation in all studied populations, indicating that such variation is not restricted to temperate, depauperate comunities. There was an association between niche width and the degree of interindividual variation, indicating that individual niches remain constrained as the population niche expands. This pattern is consistent with the presence of functional trade-offs associated with resource use. In the case of the frogs and the wasps, the nature of the trade-offs remains unknown, but are likely to be behavioral. In the sticklebacks, the trade-offs have a morphological basis, but are mediated by behavior. We found that individual sticklebacks partition resources within littoral and within pelagic prey, which represents a finer pattern of resource partitioning than the traditional ¿littoral-pelagic¿ dichotomy. Two new methods for the quantification of interindividual diet variation are proposed, one based on carbon stable isotopes (d13C) and another based on complex-network theory / Doutorado / Ecologia / Doutor em Ecologia

No description available.

Thesis (Ph. D.)--Miami University, Dept. of Botany, 2008. / Title from second page of PDF document. Includes bibliographical references (p. 86-88).

Orientadores: Sergio Furtado dos Reis, Marcio Silva Araujo. / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-11T20:53:34Z (GMT). No. of bitstreams: 1 Costa_JoaoCarlosLopes_M.pdf: 677158 bytes, checksum: b1c8a350aeb6b46bf7f5c1573c624dec (MD5) Previous issue date: 2008 / Resumo: A dieta é um dos principais atributos do nicho ecológico de qualquer espécie animal. Geralmente nos estudos ecológicos os indivíduos de uma população são considerados ecologicamente equivalentes em relação ao uso de recurso. Contudo, esta abordagem tem se mostrada inadequada na descrição da utilização de recurso para várias espécies, como demonstrado por dados empíricos. A variação intrapopulacional pode ser ocasionada por fatores exógenos ou fenômenos endógenos ocasionados pelas diferenças sexuais e/ou ontogenéticas. Além disso, indivíduos pertencentes à mesma classe etária, ao mesmo sexo e dentro da mesma localidade podem também exibir variação no nicho. Esse fenômeno é denominado de "especialização individual" e sua ocorrência tem sido descrita para comunidades temperadas ou depauperadas até o presente momento. Para verificar quais fenômenos podem produzir a variação no nicho de lagartos tropicais foi utilizado como modelo Tropidurus hispidus. Os objetivos deste estudo foram: descrever a composição da dieta; investigar a existência de variação intrapopulacional no nicho trófico; determinar em que níveis essa variação se expressa; e testar se a morfologia é um mecanismo subjacente ao uso de recursos alimentares nesta espécie. Dentre os fenômenos analisados, a variação intrapopulacional parece ser ocasionada unicamente pela especialização individual. Os itens mais consumidos por T. hispidus, formigas, besouros e cupins, produzem uma variedade de substâncias químicas tóxicas que podem impor um alto custo para desintoxicação e gerar preferências alimentares individuais. Outra possível fonte de variação é a ocorrência de diferentes comportamentos de forrageio por indivíduos da mesma população. Este é o primeiro registro da ocorrência de especialização individual em lagartos tropicais e reforça a percepção de que esse fenômeno esta presente em comunidades tropicais de alta diversidade, contrariando o padrão estabelecido na literatura, relacionando à ocorrência da especialização individual a comunidades temperadas e depauperadas. / Abstract: The diet is one of the main atributes of the ecological niche of animal species. Generally, the individuals of a population are considered ecologically equivalent in ecological studies that focus on resource use. Nevertheless, this approach has been inadequate to correctly describe resource use by various species, as demonstrated by empirical data. Intrapopulation variation may be caused by exogenous factors or endogenous phenomena such as sexual and/or ontogenetic differences. Additionally, individuals belonging to the same age or sex, and within a single site or time can also show differences in niche. This phenomenon has been defined as "individual specialization" and its occurrence is related to temperate and/or depauperate communities. To verify which phenomena produce niche variation in tropical lizards, we used Tropidurus hispidus as a model system. The aims of this study were to describe the diet composition; to investigate the existence of intrapopulational variation in trophic niche; to determine at which levels this variation is expressed, and test if the morphology is an underlying mechanism in food resource use in this species. The intrapopulation variation seems to be caused uniquely by individual specialization. The most consumed items by T. hispidus, ants, beetles and termites, produce a variety of toxic chemical substances that can impose a high cost for desintoxication and generate individual alimentary preferences. Another possible source of variation is the occurrence of different forage behaviors by individuals of the same population. This is the first record of the occurrence of individual specialization in tropical lizards, which suggests the presence of this phenomenon in highly diverse tropical communities, contradicting the established literature relating the occurrence of individual specialization to temperate and depauperate communities. / Mestrado / Mestre em Ecologia

Thesis (M.S.)--North Carolina State University, 2003. / Title from PDF t.p. (viewed on Aug. 21, 2004). Includes vita. Includes bibliographical references (p. 88-94).

Orientadores: Fernando Roberto Martins, Roque Cielo Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T19:33:19Z (GMT). No. of bitstreams: 1 Azevedo_MarioJoseMarques_M.pdf: 1374222 bytes, checksum: 6cfc592a0f568c5e7abef9efd6a9adeb (MD5) Previous issue date: 2013 / Resumo: O padrão de utilização de recursos e a teoria de nichos ecológicos constituem elementos importantes na compreensão de como comunidades ecológicas são estruturadas. A maneira como os recursos são partilhados entre as espécies é refletida na sua distribuição de abundância. Abundância e diversidade de espécie são resultantes de processos que determinam as comunidades. Um padrão frequentemente observado é a relação unimodal entre diversidade e produtividade. Processos competitivos são inferidos na determinação da diversidade ao longo do gradiente de produtividade. Devido à abundância das espécies serem resultantes de interações biológicas, os modelos de distribuição de abundância de espécies (DAE) permitem inferir na maneira como o espaço de nicho é partilhado. Utilizamos os modelos de DAE proposto por Tokeshi e índices de concentração de dominância e equabilidade para testar por meio de regressões como a riqueza, biomassa e equabilidade variam ao longo de um gradiente de estresse nutricional definido pela concentração de alumínio no solo. Verificamos um padrão linear negativo entre a riqueza e gradiente de estresse nutricional com fragmentos de floresta estacional semidecídua no extremo de menor estresse e cerradão no extremo oposto do gradiente. A biomassa apresentou um padrão em forma de "U" quando relacionado ao mesmo gradiente. Os índices e os modelos foram condizentes na verificação da concentração de dominância por poucas espécies nos extremos do gradiente, porém somente o índice Evar verificou a maior equabilidade nos valores intermediários do gradiente. Nossos resultados permitiram inferir que tal gradiente foi importante na determinação da riqueza e biomassa das comunidades. Os modelos e índices permitiram verificar o padrão de partilha de nicho, porém não foi possível afirmar o processo que resultou tal partilha / Abstract: The resource utilization patterns and ecological niche theory are important in understand how communities are assembled. The way how resources are apportioned between species are showed in its abundance distribution. Abundance and diversity are outcome of process that structure communities. The pattern frequently found is a "hump-back" relationship between diversity and productivity. Competitive processes are inferred in determination of diversity along productivity gradient. Due to species abundance are outcome of biological interaction, models of species abundance distribution (SAD) allow us to infer how niche are apportioned. We use Tokeshi's SADs models and dominance and evenness index to test, using regression, how richness, biomass and evenness change along stress nutrition gradient defined by aluminium concentration in soil. We verified a negative linear pattern between richness and nutrition stress gradient with semideciduous forest fragment at extreme of lesser stress gradient and cerradão at opposite extreme gradient. The biomass showed a "U" shape pattern along the same gradient. The index and SADs models showed similar result measuring dominance of few species at extremes of gradient, however only Evar index measured more evenness between extremes of gradient. Our results allow inferring that such gradient war important to define community richness and biomass. The models and index allowed testing the patterns of niche apportionment, however its do not allowed us confirm the process of niche apportionment / Mestrado / Ecologia / Mestre em Ecologia

At Cape Gantheaume, Kangaroo Island (South Australia), adult male, lactating female and juvenile New Zealand (NZ) and Australian fur seals regularly return to the same colony, creating the potential for intra- and inter-specific foraging competition in nearby waters. I hypothesised that these demographic groups would exhibit distinct foraging strategies, which reduce competition and facilitate their coexistence. I analysed the diet of adult male, adult female and juvenile NZ fur seals and adult male Australian fur seals and studied the diving behaviour of adult male and lactating female NZ fur seals and the at-sea movements of juvenile, adult male and lactating female NZ fur seals. Female diet reflected that of a generalist predator, influenced by prey availability and their dependant pups� fasting abilities. In contrast, adult male NZ and Australian fur seals used larger and more energy-rich prey, most likely because they could more efficiently access and handle such prey. Juvenile fur seals primarily utilised small lantern fish, which occur south of the shelf break, in pelagic waters. Juveniles undertook the longest foraging trips and adult males conducted more lengthy trips than lactating females, which perform relatively brief trips in order to regularly nurse their pups. Unlike lactating females, some adult males appeared to rest underwater by performing dives that were characterised by a period of passive drifting through the water column. The large body sizes of adult males and lactating females facilitated the use of both benthic and pelagic habitats, but adult males dived deeper and for longer than lactating females, facilitating vertical separation of their foraging habitats. Spatial overlap in foraging habitats among the age/sex groups was minimal, because lactating females typically utilised continental shelf waters and males used deeper water over the shelf break, beyond female foraging grounds. Furthermore, juveniles used pelagic waters, up to 1000 km south of the regions used by lactating females and adult males. The age and sex groups in this study employed dramatically different strategies to maximise their survival and reproductive success. Their prey and foraging habitats are likely to be shaped by body size differences, which determine their different physiological constraints and metabolic requirements. I suggest that these physiological constraints and the lactation constraints on females are the primary factors that reduce competition, thereby facilitating niche partitioning.

Thesis (Ph.D.)--University of Aberdeen, 2005. / Includes bibliographical references. Available in PDF format via the World Wide Web.

Meyer’s Parrot Poicephalus meyeri is the smallest of the nine Poicephalus parrots, forming the P. meyeri superspecies complex with five congeners. Their distributional range far exceeds any other African parrot, extending throughout subtropical Africa. Meyer’s Parrots had previously not been studied in the wild, and therefore, gathering high-quality empirical data on their behavioural ecology became a research and conservation priority. The primary aim of the study was to correlate environmental (e.g. rainfall, habitat availability, resource characteristics, food resource abundance and temperature) and social (e.g. inter- and intra-specific competition, predation, and human disturbance) variables with aspects of their ecology (e.g. flight activity, food item preferences, breeding activity, and group dynamics) to evaluate the degree of specialization in resource use (e.g. trophic, nesting and habitat niche metrics). African deforestation rates are the highest in the world, resulting in twelve out of the eighteen Meyer’s Parrot range states undergoing drastic loss of forest cover over the last 25 years. Most commentary on the population status of Meyer’s Parrots and other Poicephalus parrots pre-dates this period of rapid deforestation In addition, over 75 000 wild-caught Meyer’s Parrots and almost 1 million wild-caught Poicephalus parrots have been recorded in international trade since 1975. Empirical data from this study was used to identify ecological weaknesses (e.g. niche specialization or low breeding turnover) for evaluation within the context of deforestation in the African subtropics. Baseline data on the breeding biology and nest cavity requirements of Meyer’s Parrots was also necessary to assess the viability of applying the conservative sustained-harvest model to African parrots. A unifying goal of this study was to advance our knowledge of the ecology of African parrots and other Psittaciformes by assessing the validity of current hypotheses put forward in the literature. The Meyer’s Parrot Project was initiated in January 2004 on Vundumtiki Island in the north-eastern part of the Okavango Delta, Botswana. Due to high flood waters between March and July 2004, road transects were postponed till August 2004. Transects were conducted at Vundumtiki from August 2004 to July 2005 and February 2007 to August 2007, and at Mombo from August 2005 to January 2006. During 480 road transects over 24 months, food item preferences closely tracked fruiting and flowering phenology, resulting in significant positive correlations between Levins’ niche breadth, rainfall and food resource availability. Meyer’s Parrot can, therefore, be considered opportunistic generalists predispersal seed predator that tracks resource availability across a wide suite of potential food items, including 71 different food items from 37 tree species in 16 families. Meyer’s Parrots were, however, found to be habitat specialists preferring established galleries of riverine forest and associated Acacia-Combretum marginal woodland. These strong habitat associations facilitate their wide distribution throughout the Kavango Basin, Linyanti Swamps, down the Zambezi valley, up along the Rift Valley system in associations with the great lakes, through the Upper Nile and the Sudd, and west as far as Lake Chad through the Sahel. Seventy-five nest cavities were measured during this study, including 28 nest cavities utilized by Meyer’s Parrots within the 430ha sample area at Vundumtiki. Over 1700 hours of intensive nest observations at six nest cavities was undertaken. Meyer’s Parrots formed socially monogamous pair-bonds maintained over at least four breeding seasons. Breeding pairs established breeding territories up to an estimated 160ha within which there were 1–6 nest cavities. Eggs hatched asynchronously, yet nestlings fledged synchronously with similar body size and condition. There was evidence to support the incidence of extra-pair copulations, however, mitochondrial DNA sequence data are required to confirm the incidence of extra-pair fertilizations. Meyer’s Parrots had no preferences in regard to nest tree species beyond the incidence of suitable nest cavities, which are selected and further excavated to accommodate their non-random nest cavity preferences. There was a significant non-nesting Meyer’s Parrot population during the breeding season, likely due to this longlived cavity-nester delaying nesting until a suitable breeding territory becomes available. Meyer’s Parrots utilize communal roosts during summer and disperse from them according to the Foraging Dispersal Hypothesis. Due to the requirement to roost during the middle of the day to avoid heat stress, Meyer’s Parrots have bimodal flight and feeding activity patterns. The highest probability of locating Meyer’s Parrots is between 08h30 and 11h00 during summer when both adults are feeding on the seeds of fleshy-fruits in riverine forest communities. Due to the paucity of data on the current distribution and population status of Meyer’s Parrots and other African parrots, a continent-wide survey of all African parrots represents a conservation priority. Current deforestation rates in several Meyer’s Parrot range, their specialist habitat associations, and lack of evidence to support adaptability to a changing landscape mosaic necessitate the re-classification of Meyer’s Parrots as data deficient or nearthreatened. Based on low breeding population due to limited breeding opportunities, the CITES Appendix II wild-caught bird trade should also be halted until the sustainability of this trade has been evaluated and the relevant information made available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

At Cape Gantheaume, Kangaroo Island (South Australia), adult male, lactating female and juvenile New Zealand (NZ) and Australian fur seals regularly return to the same colony, creating the potential for intra- and inter-specific foraging competition in nearby waters. I hypothesised that these demographic groups would exhibit distinct foraging strategies, which reduce competition and facilitate their coexistence. I analysed the diet of adult male, adult female and juvenile NZ fur seals and adult male Australian fur seals and studied the diving behaviour of adult male and lactating female NZ fur seals and the at-sea movements of juvenile, adult male and lactating female NZ fur seals. Female diet reflected that of a generalist predator, influenced by prey availability and their dependant pups� fasting abilities. In contrast, adult male NZ and Australian fur seals used larger and more energy-rich prey, most likely because they could more efficiently access and handle such prey. Juvenile fur seals primarily utilised small lantern fish, which occur south of the shelf break, in pelagic waters. Juveniles undertook the longest foraging trips and adult males conducted more lengthy trips than lactating females, which perform relatively brief trips in order to regularly nurse their pups. Unlike lactating females, some adult males appeared to rest underwater by performing dives that were characterised by a period of passive drifting through the water column. The large body sizes of adult males and lactating females facilitated the use of both benthic and pelagic habitats, but adult males dived deeper and for longer than lactating females, facilitating vertical separation of their foraging habitats. Spatial overlap in foraging habitats among the age/sex groups was minimal, because lactating females typically utilised continental shelf waters and males used deeper water over the shelf break, beyond female foraging grounds. Furthermore, juveniles used pelagic waters, up to 1000 km south of the regions used by lactating females and adult males. The age and sex groups in this study employed dramatically different strategies to maximise their survival and reproductive success. Their prey and foraging habitats are likely to be shaped by body size differences, which determine their different physiological constraints and metabolic requirements. I suggest that these physiological constraints and the lactation constraints on females are the primary factors that reduce competition, thereby facilitating niche partitioning.