THE EFFECTS OF ZOOPLANKTON DISPERSAL ON COMMUNITY ASSEMBLY OF TEMPORARY PONDS. PDF Download
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Author: Lauren C McCarthy
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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The dispersal of individuals among habitat patches is thought to have an important effect on ecological communities as it can influence both population dynamics and community assembly. Though much work on dispersal has been completed, zooplankton offer an interesting opportunity to study dispersal. They can disperse not only among ponds, but they can also disperse within and among ponds through time as their eggs can remain dormant for long periods until environmental conditions initiate their hatching. The dissertation has focused on the role of temporal and spatial dispersal on the assembly of zooplankton communities, an assessment of whether predators weaken the effect of early dispersing zooplankton species on late dispersing zooplankton species through differences in zooplankton hatching phenology, and the effects of environment and space on temporary pond zooplankton communities in the Croatan National Forest, NC. Differences in spatial and temporal dispersal had a weak effect on the number of zooplankton species present. Nonetheless, both spatial and temporal dispersal strongly affected the total abundance and species composition of zooplankton present, but their effects were interdependent. When predation and the effects of zooplankton hatching phenology were considered predators and one zooplankton species that arrived early slowed the growth of the later arriving zooplankton species. Algal resources were not affected by predators, but were affected by the order of arrival of the different zooplankton species. Lastly, the role of environment and space on zooplankton temporary pond communities showed that spatial and environmental factors explained similar amounts of the variation in zooplankton composition in the Croatan National Forest, with environmental factors explaining more of the variation in the spring and summer than in the fall and winter. Together these results indicate that zooplankton composition in pond communities can be affected by interactions between spatial and temporal dispersal, the presence of predators and differences in hatching phenology, as well as by environmental factors such as temperature and spatial factors such as pond size and pond density. Thus, highlighting the importance of dispersal but also its interaction with other abiotic and biotic factors to form zooplankton communities.
Author: Lauren C McCarthy
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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Book Description
The dispersal of individuals among habitat patches is thought to have an important effect on ecological communities as it can influence both population dynamics and community assembly. Though much work on dispersal has been completed, zooplankton offer an interesting opportunity to study dispersal. They can disperse not only among ponds, but they can also disperse within and among ponds through time as their eggs can remain dormant for long periods until environmental conditions initiate their hatching. The dissertation has focused on the role of temporal and spatial dispersal on the assembly of zooplankton communities, an assessment of whether predators weaken the effect of early dispersing zooplankton species on late dispersing zooplankton species through differences in zooplankton hatching phenology, and the effects of environment and space on temporary pond zooplankton communities in the Croatan National Forest, NC. Differences in spatial and temporal dispersal had a weak effect on the number of zooplankton species present. Nonetheless, both spatial and temporal dispersal strongly affected the total abundance and species composition of zooplankton present, but their effects were interdependent. When predation and the effects of zooplankton hatching phenology were considered predators and one zooplankton species that arrived early slowed the growth of the later arriving zooplankton species. Algal resources were not affected by predators, but were affected by the order of arrival of the different zooplankton species. Lastly, the role of environment and space on zooplankton temporary pond communities showed that spatial and environmental factors explained similar amounts of the variation in zooplankton composition in the Croatan National Forest, with environmental factors explaining more of the variation in the spring and summer than in the fall and winter. Together these results indicate that zooplankton composition in pond communities can be affected by interactions between spatial and temporal dispersal, the presence of predators and differences in hatching phenology, as well as by environmental factors such as temperature and spatial factors such as pond size and pond density. Thus, highlighting the importance of dispersal but also its interaction with other abiotic and biotic factors to form zooplankton communities.
Author: Celia Claire Symons
Publisher:
ISBN:
Category :
Languages : en
Pages : 236
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Theoretical and empirical work has shown that community diversity and composition can be influenced by both local conditions and dispersal from a regional species pool. This may be especially true shortly after environmental disturbances, because perturbations can provide spatial or temporal niche opportunities for dispersers to establish. Theory predicts that after environmental disturbances tolerant functionally-redundant dispersing species can establish in disturbed communities, maintaining local community diversity and ecosystem function; however, this model relies on the successful establishment of dispersers (i.e., the community must be invasible). Invasibility is expected to decline as time-since-disturbance increases because the local community can use freed resources and increases in abundance. Although studies have acknowledged that timing may influence invasibility, very few studies have focused on how dispersal timing influences the role of dispersal in community response to disturbance. My thesis was conducted to test the role of crustacean zooplankton dispersal timing in the establishment success, and subsequent influence on diversity and ecosystem function of dispersers. To assess this, a field mesocosm study was completed in Churchill, Canada to test the effects of disturbance (nutrients and salinity) and immigration timing (from 51 regional ponds/pools) on invasibility, local community structure and ecosystem functioning (i.e., chl-a). Results show that invasibility was initially high following disturbance, but decreased with time- since-disturbance as the resident community exerted priority effects over dispersers. As a result community diversity was most influenced by immigration when dispersers were added shortly after disturbance. Many coarse measures of diversity were resistant to disturbance, but community composition and the relative abundance of functional groups shifted, and likely influence ecosystem function (i.e., chl-a). When dispersers were added to disturbed communities ecosystem function was recovered to undisturbed levels. Overall, my results suggest that dispersal timing can influence the role of dispersal in communities and the ability of species to capitalize on windows of invasion opportunity will influence their ability to establish in favorable local patches.
Author: Katelyn Louise Turner
Publisher:
ISBN:
Category :
Languages : en
Pages : 242
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The influence of regional processes, such as dispersal, on ecological communities has been the focal point of considerable ecological research. Evidence has shown that dispersal can impact community composition through interactions with predation, the introduction of keystone species, and maintenance of species lost due to competitive exclusion. Ecological communities can be characterized by several metrics including species richness, diversity, evenness, abundance and species co-occurrence patterns. Negative species co-occurrence patterns have historically been attributed to competitive interactions between species causing pairs of species to never co-occur. However, little attention has been paid to the contribution of dispersal on species co-occurrence patterns. I have experimentally investigated the influence of dispersal on species co-occurrence patterns in addition to local species richness, total species abundance, evenness, and Simpson's diversity. Local species richness significantly increased with dispersal, with variation in total local richness being mainly attributed to differences in the rotifer community. Local diversity, total abundance, and evenness were not significantly influenced by changes in the level of dispersal. Species co-occurrence patterns were greatly affected by changes in dispersal, with negative species co-occurrence patterns peaking at intermediate levels of dispersal. The potential for dispersal to increase the number of rare species within a community suggested that the presence of rare species could be behind the changes in the co-occurrence patterns between dispersal treatments. The effect size of the co-occurrence tests increased with the removal of rare species in the intermediate dispersal treatment and decreased in the remaining dispersal treatments. Likely, through mass effects, the presence of rare species, and the establishment of keystone predators changes in the level of dispersal strongly influenced species co-occurrence patterns. I conclude that external processes, like dispersal, can influence species co-occurrence patterns and that caution should be taken when interpreting the mechanisms driving species co-occurrence patterns across landscapes.
Author: Kim A. Medley
Publisher:
ISBN:
Category : Floodplain ecology
Languages : en
Pages : 130
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Author: Michael R. Allen
Publisher:
ISBN: 9781109570984
Category :
Languages : en
Pages : 135
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A recent focus on contemporary evolution and the connections between communities has sought to more closely integrate ecology with evolutionary biology. Studies of coevolutionary dynamics, life history evolution, and rapid local adaptation demonstrate that ecological circumstances can dictate evolutionary trajectories. Thus, variation in species identity, trait distributions, and genetic composition may be maintained among ecologically divergent habitats. New theories and hypotheses (E.G., metacommunity theory and the Monopolization hypothesis) seek to understand better the processes occurring in spatially structured environments and how dispersal contributes to ecology and evolution at broader scales. As few empirical studies of these theories exist, this work seeks to further test these concepts. Spatial and temporal dispersal are the mechanisms connecting habitats to one another. Both processes allow organisms to leave suboptimal or unfavorable conditions, and enable colonization and invasion, species range expansion, and gene flow among populations. Freshwater zooplankton typically develop resting stages as part of their life that allow organisms to disperse both temporally and spatially. Additionally, because many species are cyclically parthenogenetic, they make excellent model organisms to study in a controlled environment. Here, I use freshwater zooplankton communities to examine the mechanisms and consequences of dispersal and to test these nascent theories on the influence of spatial structure in natural systems. In Chapter one, I use field experiments and mathematical models to determine the movement vectors and range of adult zooplankton dispersal over land. Chapter two uses statistical models with field and mesocosm experiments to examine prolonged dormancy in "Daphnia pulex." I show that variation in dormant egg hatching is substantial among populations in nature and can be attributed to genetic differences among the populations. Chapters three and four explore the consequences of dispersal at multiple levels of biological diversity. Chapter three looks at population level consequences of dispersal over evolutionary time on current patterns of population genetic differentiation. I test two alternative hypotheses addressing why nearby populations of "Daphnia" exhibit high population genetic differentiation. Finally, chapter four is a case study of how dispersal has influenced patterns of variation at the community, trait and genetic levels of biodiversity in a lake metacommunity. [The dissertation citations contained here are published with the permission of ProQuest llc. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.].
Author: Jennifer Gail Howeth
Publisher:
ISBN:
Category : Biotic communities
Languages : en
Pages : 286
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Insights gained from metapopulation and metacommunity biology indicate that the connectivity of subpopulations and communities by species dispersal can profoundly impact population dynamics, community structure, and ecosystem attributes. Recent advancements in metacommunity theory further suggest that the rate of species dispersal among local communities can be important in altering local and regional species richness and ecosystem functioning. The role of species dispersal rates relative to patch-type heterogeneity and associated intrinsic community structuring mechanisms (competition, predation) in affecting diversity of multi-trophic communities, however, remains unknown. Here, I address the relative influence of regional and local processes in altering species richness and ecosystem functioning at multiple spatial scales in freshwater pond metacommunities. In a series of experiments, I employed pond mesocosm metacommunities to manipulate planktonic species dispersal rates and the incidence of top predators which differed in prey selectivity. The consequences of dispersal and predation to zooplankton species richness, trophic structure, ecosystem stability, and prey traits were evaluated. Generally, my findings support predictions from metacommunity models, and demonstrate that dispersal strongly affects community and ecosystem-level properties. In accord with dispersal-diversity theory, dispersal rate affected species richness and ecosystem stability at multiple spatial scales. The presence, but not the rate, of dispersal had strong effects on the partitioning of biomass amongst producers, grazers, and top predators. The relative influence of predation on local and metacommunity structure varied across experiments and largely depended upon predator identity and the degree of feeding specialization. The research presented herein is some of the first work to evaluate how species dispersal rates can affect dispersal-diversity relationships, diversity-stability relationships, trophic structure, and the distribution of prey traits in metacommunities. In addition to advancing ecological theory, the results have important implications for conservation as fragmented landscapes become increasingly prevalent, and local and regional biotas modified. Ultimately, it proves critical to identify drivers of local and regional species richness in order to maintain biotic integrity at the global scale.
Author: Jeffrey M. Schell
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
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Author: Joseph Clifton Bieberich
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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In recent years, there has been a growing desire among natural resource mangers to maintain and promote biodiversity in the built environment. Though some management practices are implemented extensively in developed landscapes, their ecological implications are not currently known. The goal of this study was to determine the effects of both dispersal and spatial variation in habitat conditions on biodiversity in urban zooplankton metacommunities. A five-week mesocosm experiment was performed in which human management and elevated zooplankton dispersal rates were manipulated in a series of four-pond metacommunities. Results indicate that dispersal had a significant negative effect on species turnover between communities but did not significantly affect local richness. It was also demonstrated that dispersal and the interaction of the dispersal and management treatments could significantly affect zooplankton density. These results highlight the importance of understanding the complex effects of dispersal and human management regimes on maintaining biodiversity in urban environments.
Author:
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Category :
Languages : en
Pages :
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Lentic community structure varies across a size gradient of ponds and lakes with physical factors, such as pond drying, and biotic factors, such as fish predation, determining the species assemblage. To test these concepts, I studied the effects of pond drying and consequent fish loss on crustacean zooplankton across a gradient of pond sizes in a Texas grassland following an exceptional drought where smaller ponds dried and lost their fish communities. After rains filled ponds in March, crustacean zooplankton were sampled in 20 temporary and 18 permanent ponds in April. Compared to permanent ponds, temporary ponds had fewer zooplankton species, more similar community assemblages and larger individual zooplankton. Thus, pond size mediated whether ponds dried during a drought, and drying determined the presence and absence of fish and its secondary trophic-level effects on zooplankton community structure.
Author: Daniel Walters Schneider
Publisher:
ISBN:
Category :
Languages : en
Pages : 416
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