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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

INTERSPECIFIC COMPETITION AND MICROHABITAT SELECTION IN THE GOLDEN MOUSE (OCHROTOMYS NUTTALLI)

Hubert, Jay Bradley 01 August 2011 (has links)
The golden mouse (Ochrotomys nuttalli), a state-threatened species in Illinois, is sympatric throughout most of its geographic range with the ubiquitous white-footed mouse (Peromyscus leucopus). The degree of interspecific competitive interaction between these species has been investigated by previous researchers, with often conflicting results. I live trapped and marked both species on two grids from 21 May 2008 through 8 May 2009. One grid was the control area; from the second grid I removed white-footed mice. Habitat on the grids was very similar for six measured habitat variables. My objectives were to document the extent of competition between the two species as indicated by a population density or behavioral response of golden mice to removal of white-footed mice on the experimental grid, and to determine if white-footed mouse presence or habitat variables affected the capture of golden mice. During 6,528 trap nights per grid, I captured a total of 22 individual O. nuttalli and 66 P. leucopus on the control grid, and 48 O. nuttalli and 202 P. leucopus on the removal grid. Compared to previous studies (Rose, 2008), the number of individual golden mice captured on my two sites (n = 70) was very large. Whereas I expected an increase in numbers and space use of golden mice upon removal of Peromyscus, the only statistically significant change was an apparent decrease in space use--there was no population density change. These results, which may indicate a lack of interspecific competition, are more likely the result of experimental design flaws, especially considering the following results. The likelihood of trapping a golden mouse at any given station on the control site was unaffected by any of the six habitat variables. White-footed mouse presence significantly decreased the likelihood of capturing golden mice on both sites. These results were the same for both elevated and ground traps. On the experimental site, golden mice changed from predominantly arboreal space use before Peromyscus removal to equal space use between arboreal and ground habitat after Peromyscusremoval. These results illustrate a spatially segregated habitat with competitively superior white-footed mice dominating the ground level microhabitat and golden mice staying predominantly in elevated microhabitat. My study, and others, demonstrate that golden mice in southern Illinois are likely habitat generalists (Morzillo et al., 2003), competitively inferior to Peromyscus(Feldhamer and Maycroft, 1992), and excluded from certain microhabitat; although it may be they actually prefer different microhabitats.
12

Foraging ecology of Naja nivea and Dispholidus typus

Greuel, Janine January 2019 (has links)
Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / It is widely reported that snakes can be major predators of avian nests, but the use of a single avian prey type by competing species has rarely been examined. This study aimed to investigate predation of a single food resource by the sympatric snakes Naja nivea and Dispholidus typus. Specifically, I aimed to 1) identify factors influencing snake presence in sociable weaver colonies and 2) quantify snake predation and potential differences in the consumption of prey by the two competing snakes. I used repeated visual surveys of sociable weavers to obtain presence-absence data of cape cobra and boomslang in sociable weaver colonies over an entire breeding season. I related the presence-absence data of the two snake species to spatially- and temporally-variable factors using principal component analyses (PCA) and multiple logistic regression analyses. The presence of snakes in sociable weaver colonies is primarily influenced by temporal factors, but spatial factors also play a role.
13

The Effects of Interspecific Competition and Predation on Survival of Neonate Mule Deer

Sallee, Daniel W 02 June 2021 (has links)
Mule deer (Odocoileus hemionus) populations are influenced by multiple factors, including interspecific competition and predation. Interspecific competition can affect resource acquisition and survival through altering space use and access to preferred habitat. Mule deer in some areas alter space use in the presence of competing species, including bison (Bison bison), cattle (Box taurus), elk (Cervus canadensis), and feral horses (Equus caballus), however the influence of competition on survival of mule deer during specific life history stages, such as birthing and rearing of neonates, is largely unknown. In addition to competition, predation can influence mule deer populations and even limit population growth by reducing recruitment of neonates into the adult population. The effects of predation may increase within a complex predator community, as predator species differ in hunting strategies, which may influence timing of predation events. We investigated the effects of interspecific competition on space use by mule deer during birthing and rearing of young (Chapter 1) and analyzed temporal patterns of predator kills of neonate mule deer in a complex predator community (Chapter 2). We hypothesized that mule deer would avoid competing ungulate species during birth and rearing of young, and that survival of neonate mule deer would decrease in areas of with increased likelihood of competition. We also hypothesized that timing of kills and habitat characteristics of kill sites would differ by predator species due to different hunting strategies. We captured 98 neonate mule deer and fit them with mortality-sensing radiocollars to test our hypotheses. We did not observe any evidence of competitive interactions between mule deer and other ungulate species. Further, we observed a positive association between space use by mule deer and elk following parturition. We also observed an increase in probability of survival for neonate mule deer in areas with higher probability of use by elk (Hazard ratio= 0.185, SE=0.497). We observed differences in timing of kills among predator species (p=0.026), however habitat characteristics of kill sites did not differ for those species. It appears that resource availability and climatic conditions influence space use by mule deer more strongly than space use by competing species. Further, timing of kills of neonate mule deer differ by predator species, which may lead to an additive effect of predation within a complex predator community.
14

Systematics and reproductive biology of the genus Morus L. (Moraceae)

Nepal, Madhav P. January 1900 (has links)
Doctor of Philosophy / Department of Biology / Carolyn J. Ferguson / Morus L. (Moraceae) is a temperate and subtropical genus of ten to 15 species distributed in Asia, Africa, Europe, North, Central and South America. Despite its broad distribution and economic importance, it has received little attention from systematic botanists. Two species of this genus, the native M. rubra and the exotic M. alba, co-occur in eastern North America including the Flint Hills region of the Central Plains. In my dissertation research, I have conducted both species level and population level studies to obtain insights into the diversification of Morus. At the species level, my objectives were to re-evaluate the taxonomy and reconstruct the phylogeny of Morus. Based on herbarium and literature study as well as some field study, I recognize 13 species: eight species occurring in Asia, one in Africa and four in the New World. I used sequence data from the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and the trnL-trnF region of the chloroplast DNA to reconstruct the evolutionary history of Morus. The phylogenies were congruent and indicate a) a monophyletic core group of Morus with two well-supported geographical clades (one containing Asian taxa and one of New World taxa); and b) that Morus, as currently circumscribed, is non-monophyletic. At the population level, I studied sex expression pattern variation between the Morus native-exotic pair in the Flint Hills region, and assessed hybridization between these species at Konza Prairie Biological Station (KPBS). Both species are subdioecious, and Flint Hills populations exhibit significantly male-biased sex ratios, with sex expression being size independent. Approximately 10% of individuals of each species changed sex annually. In the population study at KPBS, I applied randomly amplified polymorphic DNA (RAPD) markers and microsatellites. The Morus species were moderately ([Theta]II = 0.079; RAPD data) to highly differentiated genetically (F[subscript]ST = 0.233; microsatellite data). Analysis of genetic structure suggested interspecific gene flow and indicated the presence of later generation hybrids. The presence of the exotic congener may affect the existence and genetic integrity of the native species. Overall, these studies contribute to our understanding of diversity in this interesting plant study system.
15

Endemický taxon Krkonoš Campanula bohemica: zhodnocení rizika hybridizace s C. rotundifolia / Risk assessment of interspecific hybridization between endemic Campanula bohemica and widespread C. rotundifolia s.l.

Hanušová, Kateřina January 2014 (has links)
The thesis deals with phenotypic, ploidy and genetic variation of two Campanula species occurring in the Krkonoše Mts., namely the endemic C. bohemica and widespread C. rotundifolia subsp. rotundifolia. For comparative purposes subspecies sudetica of the latter species was also included. The main aim was to get insight into population structure and assess the threat of interspecific hybridization to the survival of the endemic bluebell. Flow cytometry, distance-based morphometrics and molecular analysis were used to address these questions. Three distinct groups of fluorescence intensities were revealed by flow cytometry, corresponding to DNA diploids, tetraploids and pentaploids. While diploids morphologically matched the nominate subspecies of C. rotundifolia, tetraploids corresponded either to C. rotundifolia subsp. sudetica or C. bohemica. Most populations from the Krkonoše Mts. were uniform although a sympatric growth of diploids and tetraploids was encountered in 12 populations. Only two pentaploids individuals, most likely of hybrid origin, were found, which indicated that interspecific hybridization is much less common than previously assumed. The two tetraploid taxa were distinguished by molecular markers. A combination of flow cytometry and molecular analyses thus allowed reliable...
16

Detailní taxonomická a klonální struktura druhového komplexu Daphnia longispina na podélném gradientu přehradní nádrže Želivka / Detailed taxonomic and clonal structure of the Daphnia longispina species complex on the longitudinal gradient of the Želivka Reservoir

Stodola, Jakub January 2013 (has links)
Canyon shaped reservoirs are characteristic by specific environmental horizontal gradients, so they enable existence of several species of the Daphnia longispina complex in one water body. Due to preference of distinct environmental conditions Daphnia species occurre in the different localities. The aim of my thesis was to analyze detail taxonomical and clonal structure of Daphnia longispina group by ten microsatellite markers on longitudinal gradient and compare it between two consecutive seasons. Simultaneously I received newly discovered divergent mitochondrial lineage from Želivka reservoir. It was confirmed, that the distribution of species and their hybrids in water reservoir was non-concidental and the taxonomic spatial distribution is in two consecutive seasons relatively constant. On the contrary the spatial and temporal distribution of clones was very heterogeneous. Clonal diversity in the interspecific hybrids was lower than in the coexisting parental species. This finding supports the hypothesis, that there exist reproductive barriers between parental genomes. Most of the clones were substantively variable, but several clones that occurred in both seasons in similar localities were found. It is possible that some clones are able of overwintering in hypolimnion and in the spring...
17

Invasion potential and colonization dynamics of Fusarium proliferatum

Reyes Gaige, Andres Jose January 1900 (has links)
Doctor of Philosophy / Department of Plant Pathology / James Stack / The trade of food, plant, and animal products has increased the worldwide movement and establishment of exotic pathogens with dramatic negative impacts on plant systems. Fusarium proliferatum is a broad host-range pathogen and among the most common maize pathogens globally. It is often seed-borne and symptomless in maize, making it a high risk for introduction in maize and other grains. Considering the global distribution of maize and the wide host range and production of mycotoxins by F. proliferatum, a better understanding of its life history is needed. To provide markers for tracking F. proliferatum in laboratory experiments, strains of F. proliferatum were transformed to express a green fluorescent protein (GFP). Active dispersal (at least 1.5cm at 25°C and -50mb soil matric potential) and colonization of organic matter in nonsterile field soil was demonstrated in soil microcosms. Fusarium verticillioides is commonly isolated from maize seed also colonized by F. proliferatum. A red fluorescent (mRFP) F. verticillioides transformant was developed to study competition with F. proliferatum. For quantification in host tissues, a TaqMan multiplex qPCR protocol was developed using primer and probe sets targeting fragments of the green and red fluorescence genes to detect F. proliferatum and F. verticillioides, respectively. Prior colonization of maize tissues by F. verticillioides (p=0.6749) and other seed-borne microorganisms (p=0.1910) did not affect subsequent colonization by F. proliferatum. Genotyping-by-sequencing (GBS) was used to identify genetic markers in F. proliferatum. Primer sets based GBS markers were designed to allow detection of specific isolates in field experiments. F. proliferatum populations were characterized from maize seed prior to planting and again after harvest. End-point PCR identified F. proliferatum isolates containing the GBS marker. AFLP-fingerprinting indicated that 23 of the 817 F. proliferatum isolates contained the molecular marker and were genetically related to the original isolate. Based on the subclade and percentage similarity in UPGMA phylogenetic trees, and the population grouping observed in STRUCTURE and Principal Coordinate Analysis, these isolates could have a single origin and be clonal. Understanding the life cycle of F. proliferatum is critical for learning more about the risk of introducing seed-borne exotic isolates into new environments.
18

Effects of interspecific competition, salinity, and hurricanes on the success of an invasive fish, the Rio Grande cichlid (Herichthys cyanoguttatus)

Lorenz, O. Thomas 07 August 2008 (has links)
The Rio Grande cichlid (Herichthys cyanoguttatus) has been established in the Greater New Orleans Metropolitan Area (GNOMA) for at least 20 years. It is often the most common fish species in urban canals and has also been found in natural waterways outside of the GNOMA. The effects and potential for further spread of H. cyanoguttatus is uncertain. My research addressed how extensive the cichlids spread in the GNOMA, how H. cyanoguttatus interacted with L. macrochirus, a native fish, and what salinity tolerance this species has. Surveys on Lake Pontchartrain and in the GNOMA indicated that H. cyanoguttatus is well established in urban habitats. These surveys also indicate that H. cyanoguttatus has spread rapidly into Bayou Saint John and City Park in recent years and that H. cyanoguttatus populations were relatively unaffected by Hurricanes Katrina and Rita. There is little evidence that H. cyanoguttatus has become established outside of the GNOMA, but this lack of persistence cannot be explained by abiotic variables I measured. Salinity may be a factor and this was measured in growth trials of H. cyanoguttatus. Salinities up to 16 ppt, however, had no significant effect on H. cyanoguttatus growth. Interspecific behavioral experiments were conducted to examine potential biotic interactions with native fish species. Prior resident trials indicated that H. cyanoguttatus was aggressive whether holding territory or not, and that native bluegill (Lepomis macrochirus) was only aggressive while holding territory. Feeding experiments were performed to examine biotic interactions between H. cyanoguttatus and L. macrochirus. Lepomis macrochirus grew faster than H. cyanoguttatus when inter- and intraspecific trials were compared; however, no significant growth differences were seen when trials were structured with L. macrochirus as prior residents. The major findings of my research are a high salinity tolerance of H. cyanoguttatus, a potential mechanism for H. cyanoguttatus affecting native fishes through aggression as residents and invaders, and the presence of H. cyanoguttatus throughout the GNOMA, before and after the hurricanes.
19

Estrutura de comunidades de formigas do cerrado. / Ant community structure in the brazilian tropical dry forest (Cerrado).

Silvestre, Rogerio 09 June 2000 (has links)
O presente trabalho investiga três aspectos da estrutura de comunidades de formigas do bioma Cerrado: interações interespecíficas, riqueza e diversidade de espécies e guildas. Primeiramente, investiguei a influência dos comportamentos agressivos observados em interações interespecíficas nos levantamentos faunísticos que empregam iscas, verificando a existência de hierarquias de dominância dentro das comunidades de formigas e tentando responder se essa eventual dominância comportamental da fonte alimentar poderia alterar os resultados de freqüência relativa das espécies obtidos em levantamentos. Utilizei como modelo iscas de sardinha que mimetizam fontes de proteína. Registrei os atos comportamentais de formigas visitando 60 iscas oferecidas por 90 minutos sobre o solo de duas localidades de Cerrado. Setenta e duas espécies foram registradas realizando 682 atos comportamentais interativos, dos quais 352 foram agressivos, resultando na morte de 29 indivíduos. A maioria das espécies observadas monitora constantemente o habitat à procura de alimentos, sobrepondo as áreas de forrageamento das colônias que estão próximas, resultando assim na competição freqüentemente observada. A maioria das iscas (85%) foi visitada nos primeiros cinco minutos de exposição e em média 4,8 espécies (1-8) visitaram cada isca durante os 90 minutos. O comportamento mais comum registrado foi a visita oportunista das formigas nas iscas; nesta situação a operária encontra solitariamente a isca, coleta uma porção da sardinha e retorna ao ninho. Muitas vezes operárias foram observadas obstruindo o acesso das outras que visitavam as mesmas iscas, por utilizarem químicos repelentes, recrutamento de massa ou por serem agressivas. Minhas observações indicam que, embora a dominância da isca por determinadas espécies possa ocorrer, resultando na exclusão das espécies subordinadas, a ordem na hierarquia de dominância pode se inverter em outra ocasião, possivelmente como resultado da distância da fonte ao ninho, da composição de espécies interagindo na mesma isca e das diferentes estratégias de recrutamento empregadas em cada situação. Na segunda etapa do trabalho, realizei um levantamento da fauna de formigas em 7 localidades de Cerrado, utilizando métodos quantitativos e qualitativos. Para as coletas quantitativas, uma área de 1ha de Cerrado sensu stricto foi escolhida em cada localidade e 25 pontos foram sorteados de um total de 121 pontos demarcados em uma grade de coleta, formada por 11 transectos, separados 10m entre si, com 11 pontos separados, também 10m um do outro. Em cada localidade as iscas foram oferecidas por 90 minutos no solo e na vegetação nos períodos diurno e noturno. Um total de 4.400 iscas foram oferecidas em todas as 7 localidades, com o objetivo de comparar a similaridade faunística entre as áreas amostradas. Utilizei ainda, em cinco localidades, 500 iscas dispostas em Matas Ciliares (100 por localidade), no solo e na vegetação, apenas no período diurno, em transectos cobrindo 250m lineares. Para as amostragens qualitativas utilizei: coletas com pinça, frasco aspirador, escavação de cupinzeiros, o revirar de pedras, a abertura de troncos, galhos e gravetos caídos, amostras de serapilheira submetidas a funil de Berlese-Tüllgren e extrator de Winkler, a instalação de armadilhas do tipo pit-fall, bandejas com água e para a captura de alados Malaise e armadilha luminosa. Um total de 331 espécies foi registrado, somando todas as espécies de formigas amostradas nos levantamentos qualitativos e quantitativos nas 7 localidades de Cerrado. Neste levantamento foram registradas as subfamílias Formicinae, Myrmecinae, Dilichoderinae, Ecitoninae, Ponerinae, Pseudomyrmecinae e Cerapachyinae. Os gêneros Camponotus, Pheidole, Crematogaster e Solenopsis foram os mais ricos em número de espécies. Pseudomyrmex mostrou uma grande diversidade de espécies (29), incluindo espécies ainda não descritas. Muitas espécies foram registradas pela primeira vez nesta latitude como Blepharidatta conops, Gigantiops destructor, Paraponera clavata, Megalomyrmex acauna e Tingimyrmex mirabilis. Como última etapa do trabalho, analisei a comunidade amostrada no Cerrado, tentando revelar as guildas de formigas existentes, baseando-me na taxonomia, na preferência trófica, nos hábitos de nidificação, nas estratégias de forrageamento, no padrão de comportamento observado em interações interespecíficas, no tamanho das operárias, na agilidade relativa das espécies e no tamanho da população das colônias maduras. Selecionei para análise os táxons associados com os dados de observações de campo, considerando para este propósito um total de 110 espécies. Uma análise de agrupamento com distância Euclidiana e ligação completa orientou a formação de 12 guildas: predadoras grandes, patrulheiras, oportunistas, espécies crípticas, desfolheadoras, cultivadoras de fungos sobre carcaças, mirmicíneas generalistas, dolichoderíneas de recrutamento massivo, nômades, especialistas mínimas, cefalotíneas e dolichoderíneas coletoras de néctar. Por fim, eu comparo a estrutura da comunidade de uma localidade no “core" do Cerrado, com uma localidade “ilha" de Cerrado, utilizando o modelo de classificação das guildas, demonstrando que existe uma substituição de espécies dentro dos grupos e que as comunidades são funcionalmente semelhantes. / The present work investigates three aspects of ant community structure in the tropical dry forest of the Brazilian Central Plateau (Cerrado): interespecific interactions, richness and diversity of species and guilds. Firstly, I investigated the influence of aggressive behaviors in interspecific interactions on ant faunistic surveys that employ baits, assessing if the eventual behavioral dominance hierarchy on the food source influences the relative frequencies observed in surveys. I used as model sardine baits that mimic sources of protein, recording the behavioral acts of ants visiting 60 baits, offered for 90 minutes, on the soil of two Cerrado localities. Seventy-two ant species were registered performing 682 interactive behavioral acts, of which 352 were aggressive, resulting in the death of 29 individuals. Of the observed species, most constantly monitor the habitat searching for food, resulting in niche overlapping, and hence interespecific competition was quite frequent. Most baits (85%) were visited in the first five minutes after exposition, and in average 4,8 (1-8) species visited each bait during the 90 min. The most common behavior registered was the opportunistic visit of ants to baits, in which individuals find the bait alone, take some of it and leave the spot. Nevertheless some species were observed obstructing the access of others visiting the same bait, either by releasing irritating sprays, employing massive recruitment, or by agonistic behaviors. My observations indicate that although dominance may occur resulting in the exclusion of subordinate species, the order in dominance hierarchies may change, possibly as a result of the different distances from the nest to the food source, of the species composition interacting at a given bait, and of the different recruiting strategies employed by them in each situation. Secondly, I check the ant fauna through qualitative and quantitative surveys in seven Cerrado localities. For this purpose the samples include all species collected by different techniques. To perform the quantitative surveys, one area (1ha) of Cerrado sensu stricto was chosen before collecting events in each locality, and 25 points were randomly chosen among 121 points in a grid made by 11 transects, separated 10m either, with 11 points, also separated 10m from each other. At each locality sardine baits were offered for 90 minutes, over the soil and on the vegetation, at day and night periods. A total of 4400 baits in all seven localities were offered in order to compare the ant species composition in each surveyed area. I summed to this total 500 baits set in Forests bordering rivers, on transects covering 250m, in five localities. For the qualitative surveys, a set of general procedures was applied including general collecting using forceps and aspirator, excavations on termites nests, the turn of rocks and opening of rotting wood, tearing up logs and stumps, submitting litter samples to Berlese-Tüllgren funnels and Winkler extractors, the setting of pit-fall traps and yellow water trays, and Malaises and light-traps to capture winged forms. Summing all ants collected in qualitative and quantitative surveys I registered 331 species. In this survey I registered the subfamilies: Formicinae, Myrmicinae, Dolichoderinae, Ecitoninae, Ponerinae, Pseudomyrmecinae, and Cerapachyinae. The genera Camponotus, Pheidole, Crematogaster, and Solenopsis were the most rich in number of species. Pseudomyrmex showed a great diversity (29 species), including undescribed ones. Several species had their first record in this latitude as Blepharidatta conops, Gigantiops destructor, Paraponera clavata, Megalomyrmex acauna, and Tingimyrmex mirabilis. Finally, I analyzed the Cerrado ant community trying to classify the species in guilds based on taxonomy, throphic preference, nidification habits, foraging and recruitment strategies, behavioral patterns observed on interespecific interactions, size of workers, “readiness of movement" and estimated mature colony population. I selected for this analysis those taxa associated with field observation data, considering for this purposes a total of 110 species. A cluster analysis, with Euclidean distance, and with complete linkage oriented the formation of 12 guilds: big predators, patrollers, opportunistic, cryptic, leaf cuttings, fungus growers over carcass, generalist myrmicines, aggressive arboreal, nomads, minimal specialist, cephalotines, and nectars feed dolichoderines. After that I compared two Cerrado localities, utilizing the guild model, revealing as well which species substitute others in different localities, and that the communities are functionally similar.
20

Composição e estrutura vegetacional em diferentes formações na floresta Atlântica, sul de Santa Catarina, Brasil

Martins, Rafael January 2010 (has links)
Florestas pluviais tropicais, entre elas a Floresta Atlântica, são formações de elevada diversidade e riqueza o que as torna muito complexas. Elucidar os mecanismos que mantêm esta diversidade constitui o foco das abordagens ecológicas atuais. O objetivo do presente estudo, além de contribuir para o melhor conhecimento florístico-estrutural da Floresta Atlântica, foi o de avaliar as relações entre espécies e o ambiente, a partir da heterogeneidade florística em respostas a gradientes ambientais. O estudo foi conduzido em três formações florestais no sul Catarinense, compreendendo um fragmento de floresta brejosa, e dois de Floresta Ombrófila Densa, uma submontana e outra montana. Foram amostrados indivíduos arbustivo-arbóreos, com altura a partir de 0,20 m. Classes de tamanho foram estabelecidas, consistindo em (1) indivíduos iguais ou maiores a 0,20 m e menores que 1m; (2) maiores que 1 m e menores que 5 cm de DAP (diâmetro à altura do peito); e (3) iguais ou maiores a 5 cm de DAP. A análise de correspondência canônica aplicada à classe 3 mostrou a segregação das comunidades a partir de gradientes indiretos (altitude e topografia), ocasionando variação na disponibilidade de recursos (gradientes diretos) locais. A análise de nichos aplicada às três classes de tamanho demonstrou especialização de nichos por parte das espécies, conforme demonstrado pelo índice médio de marginalidade (OMI). As relações do ambiente com as fases ontogenéticas demonstraram que as espécies tendem a conservar seus nichos e que esta conservação é mais evidenciada no ambiente de sub-bosque, onde as espécies tendem a coexistir com sobreposição de nichos. / Tropical rain forests, including the Atlantic Forest, are made up of high diversity and richness which makes them very complex. Elucidating the mechanisms that maintain this diversity is the focus of current ecological approaches. The aim of this study also contributes to a better understanding of the floristic-structural Atlantic Forest, was to assess the relationships between species and the environment from the floristic heterogeneity in responses to environmental gradients. The study was conducted in three forests in southern Santa Catarina, including a remnant lowland peat forest and submontane rain forest and montane rain forest.We sampled tree species, height from 0.20 m. Size classes were established, consisting of (1) individuals equal to or greater than 0.20 m less than 1m, (2) greater than 1 m in less than 5 cm DBH (diameter at breast height), and (3) equal or larger than 5 cm DBH. A canonical correspondence analysis applied to the class 3 showed the segregation of communities from indirect gradients (altitude and topography), causing variation in the availability of resources (direct gradients) locations. The analysis of niche applied to three size classes demonstrated expertise in niches by species, as demonstrated by the average index of marginality (IMO). Relations on the environment and ontogenetic stages showed that the species tend to retain their niche and that conservation is more evident in the environment of the understory, where species tend to coexist with overlapping niches.

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