Current Search: demography (x)
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(1 - 8 of 8)
- Title
- Using Molecular Genetic and Demographic Tools to Improve Management of Ex Situ Avian Populations.
- Creator
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Ferrie, Gina, Hoffman, Eric, Parkinson, Christopher, Quintana-Ascencio, Pedro, Bettinger, Tamara, University of Central Florida
- Abstract / Description
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Small populations, specifically those that are isolated from others, are more prone to extinction than larger inter-connected populations. The risks that these small isolated populations face include loss of genetic diversity due to founder effects and inbreeding due to population bottlenecks, as well as demographic uncertainty due to fluctuating fecundity and mortality rates and impacts of external environmental factors. Ex situ populations, including those managed as conservation breeding...
Show moreSmall populations, specifically those that are isolated from others, are more prone to extinction than larger inter-connected populations. The risks that these small isolated populations face include loss of genetic diversity due to founder effects and inbreeding due to population bottlenecks, as well as demographic uncertainty due to fluctuating fecundity and mortality rates and impacts of external environmental factors. Ex situ populations, including those managed as conservation breeding programs with species recovery aims, as well as those that do not have reintroduction goals but are managed for long term population sustainability, suffer from the same extinction risks as small and isolated natural populations. Using three separate avian species which have different life histories and population structures, I investigated impacts of multiple genetic and demographic management strategies on these ex situ populations. I examined the use of molecular genetic datasets including microsatellites and single nucleotide polymorphisms (SNPs) to determine their utility for reconstructing pedigrees, examining individual relatedness within populations, and compared results of measuring genetic diversity through theoretical methods verses those obtained from a molecular dataset. These methods can then ultimately be applied to improve future management including improving studbook datasets and to measure actual loss of genetic diversity. I also used analytical strategies including population viability analysis to determine how management practices influence demographic parameters and determine the future probability of population extinction. The genetic and demographic analyses of both the historic management of an ex situ population, and its current status, are a first step in hypothesizing the potential directions for future management and understanding the likelihood of survival of an ex situ population.
Show less - Date Issued
- 2017
- Identifier
- CFE0006940, ucf:51670
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006940
- Title
- Modeling Survival of Immature Loggerheads (Caretta caretta) and Green Turtles (Chelonia mydas) from 10 Years of Mark-Recapture Data at the Florida Power and Light St. Lucie Plant.
- Creator
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Sterner, Andrew, Weishampel, John, Ehrhart, Llewellyn, Walters, Linda, Breininger, David, University of Central Florida
- Abstract / Description
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Loggerheads (Caretta caretta) are listed as Threatened and green turtles (Chelonia mydas) are listed as Endangered under the United States Endangered Species Act. While green turtle nest production in Florida has increased markedly in recent years, loggerhead nest production has followed a more tenuous path. Reasons for these differences are unknown. Limited demographic information is available for these species of conservation concern. I used Barker models, which incorporated mark-recapture,...
Show moreLoggerheads (Caretta caretta) are listed as Threatened and green turtles (Chelonia mydas) are listed as Endangered under the United States Endangered Species Act. While green turtle nest production in Florida has increased markedly in recent years, loggerhead nest production has followed a more tenuous path. Reasons for these differences are unknown. Limited demographic information is available for these species of conservation concern. I used Barker models, which incorporated mark-recapture, live-resight and dead recovery data, implemented in Program MARK. These models were used to estimate apparent survival for immature loggerhead ((<)85cm SCL) and green turtle ((<)60cm SCL) populations foraging in the Atlantic Ocean adjacent to the Florida Power and Light St. Lucie Plant on Hutchinson Island, Florida between 2002 and 2011. My results indicated annual apparent survival was decreasing (from 0.75 to 0.59) for resident immature loggerheads and was stable (~0.81) for resident immature green turtles over the ten year study period. I found that permanent emigration models were better supported than no movement models for both species. Size (straight carapace length) was found to be an important covariate for survival and fidelity parameters in the green turtle analysis but not in the loggerhead analysis. My study is the first to compare survival of two species of immature marine turtles foraging at the same location in the Atlantic. These estimates are also the first available survival estimates for immature marine turtle populations in Florida based on modern mark-recapture techniques, filling a critical knowledge gap. This information is vitally important for managers when evaluating the long-term recovery of these endangered species.
Show less - Date Issued
- 2013
- Identifier
- CFE0004755, ucf:49770
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004755
- Title
- DEMOGRAPHIC CONSEQUENCES OF MANAGING FOR FLORIDA SCRUB-JAYS (APHELOCOMA COERULESCENS) ON AN ISOLATED PRESERVE.
- Creator
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Lyon, Casey, Stout, I. Jack, University of Central Florida
- Abstract / Description
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Many species naturally occupy discrete habitat patches within a mosaic of habitats that vary in quality. The Florida scrub-jay (Aphelocoma coerulescens) is endemic to Florida scrub, a habitat that is naturally patchy and greatly reduced in area over recent decades owing to development and urbanization. Because of this habitat loss, future management of Florida scrub-jays will focus on smaller, fragmented tracts of land. My study examines such a tract, Lyonia Preserve, southwest Volusia County...
Show moreMany species naturally occupy discrete habitat patches within a mosaic of habitats that vary in quality. The Florida scrub-jay (Aphelocoma coerulescens) is endemic to Florida scrub, a habitat that is naturally patchy and greatly reduced in area over recent decades owing to development and urbanization. Because of this habitat loss, future management of Florida scrub-jays will focus on smaller, fragmented tracts of land. My study examines such a tract, Lyonia Preserve, southwest Volusia County, FL. This preserve was unoccupied by scrub-jays prior to habitat restoration. The preserve is now frequently managed exclusively for scrub-jays as a habitat island surrounded by development. Management of the preserve includes roller chopping, root raking, timbering, and "oak stripping" where islands of oak patches are left intact while the rest of the area is roller chopped. I investigate what, if any, demographic consequences may be associated with the habitat management and the spatial setting of the preserve. I used population data collected in this area since 1992 to examine population growth and responses to habitat restoration within the preserve and habitat destruction outside the preserve. I mapped territories and measured survival and recruitment of scrub-jays, and dispersal into and out of the study area, for two and a half years. Since restoration, the population has shown logistic growth, with the area supporting higher than average densities of scrub-jay family groups. Observed density of the population and territory size varied between study years. Breeder survival values were positively related to territory size and significantly lower during periods of highest observed density. However, recruitment (yearling production) showed no relationship to territory size. Dispersal to isolated habitat patches was observed; likewise, several failed dispersal events were noted. No immigration into the study area was observed; however these data may be underrepresented since not all scrub-jays in and outside of the preserve were banded, and data collection was limited during the initial colonization period. High densities inside the preserve may therefore be both a result of frequent habitat management in the form of mechanical treatment as well as crowding of individuals due to outside habitat destruction. The results indicate that carrying capacity of habitat for scrub-jays may be raised by frequent, mechanical management; however, if the area is isolated, management may result in high densities and negative demographic consequences, e.g., reduced breeder survival. Negative effects of management may be avoided by subjecting smaller areas to mechanical treatment with increased time between treatments. Land managed for Florida scrub-jays should be contiguous or connected with other scrub habitats so that surplus birds from the managed areas have a refuge and do not contribute to increased densities. Regulatory officials should use caution when allowing for "take" of scrub-jay habitat as the effects may extend beyond the local habitat being destroyed.
Show less - Date Issued
- 2007
- Identifier
- CFE0001769, ucf:47280
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001769
- Title
- DOES HABITAT AFFECT CLONAL DEMOGRAPHY? AN EXPERIMENT WITH POLYGONELLA MYRIOPHYLLA IN ROADSIDE AND FLORIDA SCRUB.
- Creator
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Horn, Kristina, Quintana-Ascencio, Pedro, University of Central Florida
- Abstract / Description
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Polygonella myriophylla (Polygonaceae) is a clonal shrub listed as endangered and narrowly endemic to pyrogenic scrub ecosystems in central Florida. It is almost restricted to gaps within the matrix of shrubs in the scrub but also occurs along adjacent road-side habitats. I hypothesize that persistent disturbed microhabitats and more dynamic sand accretion in roadsides will increase rooting probabilities compared to more stable scrub habitats, affecting survival, growth and reproduction. In...
Show morePolygonella myriophylla (Polygonaceae) is a clonal shrub listed as endangered and narrowly endemic to pyrogenic scrub ecosystems in central Florida. It is almost restricted to gaps within the matrix of shrubs in the scrub but also occurs along adjacent road-side habitats. I hypothesize that persistent disturbed microhabitats and more dynamic sand accretion in roadsides will increase rooting probabilities compared to more stable scrub habitats, affecting survival, growth and reproduction. In April 2004- March 2006, I compared plant (genet) and basal branch (ramet) performance between experimentally manipulated plants in native scrub and roadside habitats at two locations within the Lake Wales Ridge State Forest in Polk County: LC01 and Old School. We completed a total of 6 evaluations in each site (April, July and November 2004, May and November 2005, and March 2006). Fifteen plants per replicated habitat in LCO1 and Old School were selected based on presence of four unrooted branches. Each unrooted branch within a plant randomly received one of four possible treatments: forced branch burial, branch lifting, procedural control, and no manipulation (total N= 60 genets and 240 ramets). Forced burial was implemented to mimic sand burial and evaluate rooting probability and performance in both habitats. Branch lifting was applied to prevent sand burial and evaluate demography of unrooted branches in both habitats. The procedural control served to evaluate wire effects on ramet demography. The control provided vital and rooting rates of branches in natural conditions. Road populations exhibited larger crown area and higher monthly diameter (controlled by initial diameter) and higher monthly length growth rates compared to scrub populations. Rooting probability was only affected by treatment one (buried wire) not habitat or site. Forced sand burial increased rooting (67 % after forced contact vs. 20-30 % for other treatments). Rooted branches did not exhibit variation in survival, growth, or fecundity compared to unrooted branches. Old School populations exhibited larger crown area, higher monthly diameter and monthly length growth rates compared to LC01 populations. Prescribed fires killed several plants explaining significantly higher branch survival at the unburned LC01 (66.1%) compared to recently burned Old School (36.2 %). LC01 populations exhibited higher fecundity and ramet survival compared to Old School populations. In February – December 2006, I describe the reproductive schedule at (LC01) in 10 road and 10 scrub plants. Monthly, I counted number of inflorescences and flowers per inflorescence (one inflorescence per plant) for each plant. Number of inflorescences per plant was highest between May and September and higher in road than in scrub. Our results indicate significant different demographic performance of P. myriophylla at plant and branch level between road and scrub habitats. A longer term study is needed to determine if the persistence of P. myriophylla is threatened by increasing roadside populations.
Show less - Date Issued
- 2007
- Identifier
- CFE0001982, ucf:47421
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001982
- Title
- INTEGRAL PROJECTION MODELS REVEAL INTERACTIVE EFFECTS OF BIOTIC FACTORS AND DISTURBANCE ON PLANT DEMOGRAPHY.
- Creator
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Tye, Matthew, Quintana-Ascencio, Pedro, Fauth, John, Nevai, Andrew, Menges, Eric, University of Central Florida
- Abstract / Description
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Understanding factors limiting population growth is crucial to evaluating species persistence in changing environments. I used Integral Projection Models (IPMs) to elucidate the role of biotic interactions and disturbance on population growth rate in two plants: Helianthemum squamatum, a perennial endemic to gypsum habitats in central Spain, and Liatris ohlingerae, a long-lived perennial endemic to the Lake Wales Ridge of central Florida. In H. squamatum, there was a strong positive effect of...
Show moreUnderstanding factors limiting population growth is crucial to evaluating species persistence in changing environments. I used Integral Projection Models (IPMs) to elucidate the role of biotic interactions and disturbance on population growth rate in two plants: Helianthemum squamatum, a perennial endemic to gypsum habitats in central Spain, and Liatris ohlingerae, a long-lived perennial endemic to the Lake Wales Ridge of central Florida. In H. squamatum, there was a strong positive effect of trampling in the site with the highest plant density and moderate positive effects of seed addition in the site with the lowest plant density. Differences in treatment effectiveness between sites may represent a shift from seed to microsite limitation at increasing densities. Additionally, a distinct drop in population growth rate occurred in the hottest and driest year (2009-10). In Liatris ohlingerae, roadside populations had consistently higher population growth rates than scrub populations. A modest negative effect of time-since-fire was observed in plants that did not experience herbivory. Both habitat and time-since-fire showed distinct interactions with vertebrate herbivory, with herbivory increasing the difference in growth rate between habitats and decreasing the difference between time-since-fire classes. The direct effect of herbivory was negative in all environmental combinations except in long unburned populations. These results demonstrate the importance of considering environmental interactions when constructing population models, as well as the validity of using IPMs to assess interactions in species with differing life histories.
Show less - Date Issued
- 2014
- Identifier
- CFE0005271, ucf:50558
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005271
- Title
- DEGREES OF CAUSALITY: AN ASSESSMENT OF ENDOGENOUS CONTRIBUTORS TO INSTABILITY IN JORDAN, SYRIA, & TURKEY.
- Creator
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Willman, Gabriel, Sadri, Houman, University of Central Florida
- Abstract / Description
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The political instability of the Middle East is often perceived to be derived primarily from the interaction of Middle Eastern nations with external forces; with significant emphasis placed upon the disruptive effects of modern colonialism and Westernization. While this study does not seek to directly contest the catalytic primacy of exogenous factors, it does seek to establish the necessary causality of pre-existing internal factors. Rather than approaching the situation from a linear causal...
Show moreThe political instability of the Middle East is often perceived to be derived primarily from the interaction of Middle Eastern nations with external forces; with significant emphasis placed upon the disruptive effects of modern colonialism and Westernization. While this study does not seek to directly contest the catalytic primacy of exogenous factors, it does seek to establish the necessary causality of pre-existing internal factors. Rather than approaching the situation from a linear causal perspective, this assessment is oriented around an interdisciplinary examination of confluent factors. By examining the political history, ethno sociology, and economy of the region, the analysis investigates the underlying variables which have contributed to the instability of the Jordan, Syria, and Turkey. The primary conclusion of this analysis is that the interactions of multiple endogenous variables provide a basis of necessary causality which may be of equal causal import to that of modern colonialism and Westernization.
Show less - Date Issued
- 2012
- Identifier
- CFH0004228, ucf:44965
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004228
- Title
- EXPLAINING CHURN: MASS SOCIETY, SOCIAL CAPITAL, & COMMUNITY CHURN.
- Creator
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Edelen, Delores, Wright, James, University of Central Florida
- Abstract / Description
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Population churn--the population turnover experienced by a community--can have differential effects on a community. Mass society theory suggests that because the churn rate experienced by communities can contribute to their uprooting, fragmentation, and isolation, churn is a potent threat to the stability of our modern day communities. Social capital theory, to the contrary, suggests otherwise. Social capital theory suggests that churn can have positive effects on communities by bringing new...
Show morePopulation churn--the population turnover experienced by a community--can have differential effects on a community. Mass society theory suggests that because the churn rate experienced by communities can contribute to their uprooting, fragmentation, and isolation, churn is a potent threat to the stability of our modern day communities. Social capital theory, to the contrary, suggests otherwise. Social capital theory suggests that churn can have positive effects on communities by bringing new migrants with valuable human capital skills and experiences to communities. These migrants bring to their new communities the potential for creating new jobs, spurring economic development, and for initiating housing starts that expand housing options for the poor and minorities. In so doing, they help create and sustain vibrant, growing modern day communities. Yet in spite of the significant role churn may play in determining the health and viability of modern day communities, it has been overlooked in the migration literature, which is mostly dominated by individual-level research on the causes and effects of migration, particularly the pecuniary benefits to movers. Using county-level data and multivariate analyses, this research seeks to fill this gap in the literature by examining the relationship between the community and churn, from the perspectives provided by social capital and mass society theories.
Show less - Date Issued
- 2004
- Identifier
- CFE0000224, ucf:46257
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000224
- Title
- Habitat selection in transformed landscapes and the role of novel ecosystems for native species persistence.
- Creator
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Sanchez Clavijo, Lina, Quintana-Ascencio, Pedro, Noss, Reed, Weishampel, John, Rodewald, Amanda, University of Central Florida
- Abstract / Description
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To understand native species persistence in transformed landscapes we must evaluate how individual behaviors interact with landscape structure through ecological processes such as habitat selection. Rapid, widespread landscape transformation may lead to a mismatch between habitat preference and quality, a phenomenon known as ecological traps that can have negative outcomes for populations. I applied this framework to the study of birds inhabiting landscapes dominated by forest remnants and...
Show moreTo understand native species persistence in transformed landscapes we must evaluate how individual behaviors interact with landscape structure through ecological processes such as habitat selection. Rapid, widespread landscape transformation may lead to a mismatch between habitat preference and quality, a phenomenon known as ecological traps that can have negative outcomes for populations. I applied this framework to the study of birds inhabiting landscapes dominated by forest remnants and shade coffee plantations, a tropical agroforestry system that retains important portions of native biodiversity. I used two different approaches to answer the question: What is the role of habitat selection in the adaptation of native species to transformed landscapes? First, I present the results of a simulation model used to evaluate the effects of landscape structure on population dynamics of a hypothetical species under two mechanisms of habitat selection. Then I present the analyses of seven years of capture-mark-recapture and resight data collected to compare habitat preference and quality between shade coffee and forest for twelve resident bird species in the Sierra Nevada de Santa Marta (Colombia). I provide evidence for the importance of including the landscape context in the evaluation of ecological traps and for using long-term demographic data when evaluating the potential of novel ecosystems and intermediately-modified habitats for biodiversity conservation. Beyond suggestions to improve bird conservation in shade coffee, my findings contribute to theory about ecological traps and can be applied to understand population processes in a wide variety of heterogeneous landscapes.
Show less - Date Issued
- 2016
- Identifier
- CFE0006494, ucf:51392
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006494
