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(1 - 11 of 11)
- Title
- Modeling and analysis of a three-species food web with facilitated and intraguild predation.
- Creator
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Castro, Joshua, Weishampel, John, Quintana-Ascencio, Pedro, Nevai, A, University of Central Florida
- Abstract / Description
-
Biotic interactions are known to shape natural community assemblages and biodiversity. Positive interactions such as facilitation have recently received attention in ecological food webs. Mechanistic models have improved our understanding of these complex food web interactions. Here, focus is given to a three-species food web system with a beach dune natural community in mind. In the last decade, there has been a series of studies investigating intraguild predation between two major...
Show moreBiotic interactions are known to shape natural community assemblages and biodiversity. Positive interactions such as facilitation have recently received attention in ecological food webs. Mechanistic models have improved our understanding of these complex food web interactions. Here, focus is given to a three-species food web system with a beach dune natural community in mind. In the last decade, there has been a series of studies investigating intraguild predation between two major loggerhead sea turtle nest predators, North American raccoons and Atlantic ghost crabs. Studies have also highlighted that ghost crab predation assists raccoons in finding nests (i.e., facilitated predation). However, the combined effects of these two intraguild interactions and their consequences on nests have not been examined explicitly. The aims of this study were to (i) develop a three-species, ordinary differential equation model (ii) implement a sensitivity analysis to understand the influence of facilitation and other factors in driving species richness and abundance and (iii) characterize the dynamic interactions between intraguild predators and their effects on a shared resource. Interactions between ghost crabs and sea turtle eggs and facilitation can yield a wide variety of species abundance responses and were influential factors in the model. I found that high secondary sea turtle egg depredation and low facilitated predation by raccoons led to three species co-existence regions in the model. Controlling for nest predators at higher abundance levels showed that ghost crabs had a larger negative effect on sea turtle egg abundance responses when compared to raccoons. This suggests that interactions between sea turtle eggs and ghost crabs appear to be important and potential sea turtle nest management implications are discussed such as the use of ghost crab exclusion devices.
Show less - Date Issued
- 2015
- Identifier
- CFE0005771, ucf:50074
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005771
- Title
- The ecology of central Florida's thief ants (Hymenoptera: Formicidae: Solenopsis).
- Creator
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Ohyama, Leo, King, Joshua, Jenkins, David, Fedorka, Kenneth, University of Central Florida
- Abstract / Description
-
Thief ants of the genus Solenopsis are a diverse group of ants that are found in ant communities throughout the world. They have long been purported to practice lestobiosis, an interaction between small and larger-bodied ants, where small ants cryptically tunnel into larger-bodied ant nests within the subterranean environment and steal brood or eggs for consumption. Thief ants are extremely small, measuring 1-2 mm in length and many of the species within this group practice a subterranean...
Show moreThief ants of the genus Solenopsis are a diverse group of ants that are found in ant communities throughout the world. They have long been purported to practice lestobiosis, an interaction between small and larger-bodied ants, where small ants cryptically tunnel into larger-bodied ant nests within the subterranean environment and steal brood or eggs for consumption. Thief ants are extremely small, measuring 1-2 mm in length and many of the species within this group practice a subterranean life history, where they live the entirety of their lives exclusively belowground. Due to these key characteristics, the ecology and natural history of this group of ants has remained largely unknown despite their noted high abundance within the southeastern United States, especially in upland ecosystems. The purpose of this thesis is to improve our understanding of the ecology of this enigmatic group, providing a solid foundation for future work on their behavior, biology, and natural history. Therefore, this project first attempts to identify key abiotic environmental variables that potentially drive the diversity and distribution of this group in upland ecosystems. Next a field manipulation experiment was conducted in areas of high thief ant density to determine biotic effects between thief ants and the aboveground ant community. This was done by removing thief ants using belowground toxic baits and monitoring co-occurring ant worker abundances throughout a period of approximately 1 year. We found evidence that thief ants dominate belowground and diversity. Our field experiment also yielded evidence indicating that thief ants exert potential top-down regulation on entire ant communities.
Show less - Date Issued
- 2019
- Identifier
- CFE0007696, ucf:52408
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007696
- Title
- FACTORS AFFECTING PREDATION OF MARINE TURTLE EGGS BY RACCOONS AND GHOST CRABS ON CANAVERAL NATIONAL SEASHORE, FL.
- Creator
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Brown, Justin, Roth, James, University of Central Florida
- Abstract / Description
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Changes in abundance of interactive species can have cascading, community-wide effects (Soulé et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons--the most obvious egg predator--which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost...
Show moreChanges in abundance of interactive species can have cascading, community-wide effects (Soulé et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons--the most obvious egg predator--which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost crab density on egg predation are well understood. I studied raccoon-ghost crab interactions and the effects of environmental variation on their activity during the 2007 marine turtle nesting season on Canaveral National Seashore, FL. My goal was to model predator activity and identify efficient management strategies to reduce egg predation. Raccoon activity increased with increasing habitat diversity and edge of the dominant cover type, coastal strand. Raccoon activity increased locally and became less variable near segments of beach accessed for human recreation, but activity was greater on undeveloped beach, where habitat diversity and edge were greater. Ghost crab density and size were primarily affected by sand characteristics and recreation but decreased with increasing raccoon activity in June, which may have contributed to sustained declines in ghost crab density. Hatching success of marine turtles decreased with increasing ghost crab egg predation, suggesting ghost crabs are an important cause of egg mortality and not merely scavengers on unhatched eggs. Egg predation by ghost crabs was unrelated to ghost crab density or size, likely a result of monitoring limitations, but raccoon activity increased with increasing egg predation by ghost crabs, supporting previous research and experimental evidence suggesting ghost crabs can facilitate secondary nest predation by raccoons. This indirect interaction has strong implications for marine turtle conservation, because its strength may increase with increasing ghost crab density, potentially negating the effects of raccoon removal.
Show less - Date Issued
- 2009
- Identifier
- CFE0002667, ucf:48235
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002667
- Title
- CASCADING EFFECTS OF PREDATOR REMOVAL ON THE ECOLOGY OF SEA TURTLE NESTING BEACHES.
- Creator
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Barton, Brandon, Roth, James, University of Central Florida
- Abstract / Description
-
Traditional views of food web dynamics have characterized species interactions as linear and direct. However, modern food web theory suggests that interactions can also be nonlinear and indirect, so that disturbance at one trophic level is transmitted throughout the community. Many previous studies have demonstrated that the removal of top predators from terrestrial ecosystems can have broad-scale impacts on community ecology. I examined the direct and indirect effects of raccoon removal from...
Show moreTraditional views of food web dynamics have characterized species interactions as linear and direct. However, modern food web theory suggests that interactions can also be nonlinear and indirect, so that disturbance at one trophic level is transmitted throughout the community. Many previous studies have demonstrated that the removal of top predators from terrestrial ecosystems can have broad-scale impacts on community ecology. I examined the direct and indirect effects of raccoon removal from sea turtle nesting beaches in east-central Florida during the summers of 2003 and 2004. Raccoon and ghost crab predation are among the highest causes of egg mortality for sea turtles in Florida and raccoons are intraguild predators of ghost crabs. Because of the damage done to sea turtle nests, raccoons have been removed from some beaches during the sea turtle nesting season. I compared the diet and demography of a raccoon population that had experienced two decades of raccoon removal to a population that had previously been unmanipulated. I found that long-term raccoon removal had created a significantly male-biased sex ratio in that population. I also examined the indirect effects of raccoon removal by comparing the abundances of raccoons and ghost crabs at four study sites using passive tracking plots. My data suggest intraguild predation by raccoons limits ghost crab abundance and that reduced raccoon abundance allowed ghost crab abundance to increase, resulting in a net increase in sea turtle egg predation. These results support my hypothesis that intraguild predation of ghost crabs by raccoons is an influential interaction on sea turtle nesting beach community dynamics.
Show less - Date Issued
- 2005
- Identifier
- CFE0000521, ucf:46466
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000521
- Title
- FLORIDA TEACHER PERCEPTIONS CONCERNING INTERNET DANGERS FOR STUDENTS.
- Creator
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Baker, Kathleen, McGee, Janet, University of Central Florida
- Abstract / Description
-
This research study was conducted to determine if there were significant differences or relationships between teachersÂÂ' perceptions of knowledge of Internet dangers to students and factors such as demographics, self-reported comfort levels with Internet use, and with knowledge of policies and laws regarding Internet safety. Three hundred seventy-two teachers from three central Florida school districts were surveyed using an adapted survey developed by authors Patchin...
Show moreThis research study was conducted to determine if there were significant differences or relationships between teachersÂÂ' perceptions of knowledge of Internet dangers to students and factors such as demographics, self-reported comfort levels with Internet use, and with knowledge of policies and laws regarding Internet safety. Three hundred seventy-two teachers from three central Florida school districts were surveyed using an adapted survey developed by authors Patchin and Hinduja (2006) and Willard (2006, 2009). The world of the Internet is constantly changing, and students will encounter harassment and dangers while pursuing their interests on line. Recent research on the types of Internet dangers involving youth (Hinduja & Patchin, 2009; Juvonen & Gross, 2008, Leichtling, 2008; Lenhart, Madden & Hitlin, 2005; Li, 2007; Willard, 2009), and evidence supporting limited adult knowledge of Internet dangers to youth (Finkelhor, Mitchell & Wolak, 2000; Hinduja & Patchin, 2009; Patchin & Hinduja, 2006; Willard, 2006,2009) provided the conceptual framework for this study. Descriptive and inferential statistics were performed to investigate each research question. These statistics included one-way ANOVA, Scheffe post-hoc analysis, chi-square tests of independence, independent T-tests, and Kruskal-Wallis tests. These findings demonstrated that the null hypotheses were rejected for each research question. Significant differences were found between teachersÂÂ' knowledge of Internet dangers and age, years of experience, level of school taught, and personal comfort with the Internet. Other significant relationships were found between personal Internet comfort and knowledge of laws and policies, specifically the Jeffrey Johnston Stand Up for All Students Act, and between male teachers and knowledge of victim behaviors. Gender was the only demographic variable found to be not significantly related to a teachersÂÂ' knowledge of Internet dangers to students. The implications of these results validate the importance of more teacher training to increase knowledge of Internet dangers, policies and programs, as well as increase teachersÂÂ' ability to identify victims and provide them with assistance. As technology expands, Internet dangers for children online expand and are a growing concern for parents, teachers, and administrators. Since technology will continue to grow, adults play a major role in educating children concerning the dangers of being online. However, adults struggle to play catch-up to the young digital natives, and are not really present to intervene when needed. We cannot cross the digital divide and help our students if we are not seeking out the information ourselves (Willard, 2009).
Show less - Date Issued
- 2010
- Identifier
- CFE0003307, ucf:48500
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003307
- Title
- INTERACTIONS BETWEEN THE NUDIBRANCH OKENIA ZOOBOTRYON AND ITS BRYOZOAN PREY ZOOBOTRYON VERTICILLATUM.
- Creator
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Robinson, Nicole, Kuhn, David, University of Central Florida
- Abstract / Description
-
In the Indian River Lagoon, the nudibranch Okenia zoobotryon and its egg masses are found attached to the bryozoan Zoobotryon verticillatum throughout the year. Okenia zoobotryon is thought to live, feed, and reproduce exclusively on Z. verticillatum, which would make this a very specialized predator-prey interaction. The primary goal of my study was to document certain aspects of the ecological and chemical relationships between Z. verticillatum and O. zoobotryon. Specifically, I wanted to...
Show moreIn the Indian River Lagoon, the nudibranch Okenia zoobotryon and its egg masses are found attached to the bryozoan Zoobotryon verticillatum throughout the year. Okenia zoobotryon is thought to live, feed, and reproduce exclusively on Z. verticillatum, which would make this a very specialized predator-prey interaction. The primary goal of my study was to document certain aspects of the ecological and chemical relationships between Z. verticillatum and O. zoobotryon. Specifically, I wanted to understand the cues used by the nudibranch to locate and remain on Z. verticillatum. Population surveys on Z. verticillatum, as well as other potential hosts, were performed. From these surveys, I found a small number of O. zoobotryon adults and egg masses on the red macroalga S. filamentosa mixed with Z. verticillatum (0.01 and 0.05 g/wet-weight, respectively), none on the bryozoan Amathia distans, and none on the red macroalga Gracilaria tikvahiae. To determine if prey identification was associated with an adult cue, I ran paired-choice trials. In these, the adults did not significantly prefer Z. verticillatum. Next, laboratory culture of larvae of O. zoobotryon was performed. During larval culture some aspects of this previously undocumented life-history were recorded; adults of this species developed from planktotrophic veliger larvae that hatched out of egg masses between 4 and 6 days, the time post-hatching to settlement was 7-8 days, and metamorphosis occurred approximately 24 hours after settlement. The final question addressed in this study was; "Does O. zoobotryon feed on and take up chemicals from Z. verticillatum?" To address this question, high-performance liquid chromatography was performed on extracts of Z. verticillatum and O. zoobotryon. Both organisms were compared and found to contain similar compounds, which suggest that the nudibranch is feeding on Z. verticillatum and taking up chemicals. Concentrations of compounds in Z. verticillatum varied between populations in the northern and southern regions of the Indian River Lagoon. There are, also, differences between the chemical composition of Z. verticillatum in the IRL (northern and southern) and the California species identified by Sato and Fenical (1983).
Show less - Date Issued
- 2004
- Identifier
- CFE0000309, ucf:46308
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000309
- Title
- PREDATION ON THE EASTERN OYSTER CRASSOSTREA VIRGINICA ON INTERTIDAL REEFS AFFECTED BY RECREATIONAL BOATING.
- Creator
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Stiner, Jennifer, Walters, Linda, University of Central Florida
- Abstract / Description
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Widely regarded as a keystone species and ecosystem engineer, the eastern oyster Crassostrea virginica plays a vital role in estuarine environments. Complex, three-dimensional oyster reefs act as havens for biodiversity and contribute to ecological processes. Recently, concern for this resource has arisen in Mosquito Lagoon, Florida, the southernmost limit along the Atlantic coast for undisturbed, intertidal reefs of C. virginica. Since the 1990s, intense recreational boating activity has...
Show moreWidely regarded as a keystone species and ecosystem engineer, the eastern oyster Crassostrea virginica plays a vital role in estuarine environments. Complex, three-dimensional oyster reefs act as havens for biodiversity and contribute to ecological processes. Recently, concern for this resource has arisen in Mosquito Lagoon, Florida, the southernmost limit along the Atlantic coast for undisturbed, intertidal reefs of C. virginica. Since the 1990s, intense recreational boating activity has caused atypical dead margins (mounds of disarticulated shells) to emerge on the seaward edges of oyster reefs located along major navigational channels. Once dead margins are formed, little is known about their influence on biotic composition and interactions on oyster reefs. This study focused on the affect of dead margins on: (1) mobile species biodiversity and distribution, (2) reef architecture, and (3) the affect of structural variables on predation of juvenile oysters. To determine if dead margins influenced the biodiversity of mobile species on oyster reefs, lift nets (1 m2) were deployed within Mosquito Lagoon for one year (June 2004 - June 2005). These nets (5/site) were deployed on the back-reef areas of six reefs (3 reference reefs and 3 reefs containing dead margins). To simulate reef habitat, one and a half liters of live oysters were placed within each net. Lift nets were checked monthly and surveyed for all mobile species. The resulting data were assimilated into a species inventory containing 65 species of fishes, mollusks, crustaceans, worms, and echinoderms. The two most abundant species present on reefs in Mosquito Lagoon were the big-claw snapping shrimp Alpheus heterochaelis, a filter-feeder, and the flat-back mud crab Eurypanopeus herbstii, a predator of oyster spat. Contrary to expections, analyses of community metrics showed that dead margins did not significantly affect the biodiversity of back-reef areas on oyster reefs. Modified lift nets (0.25 m2) were placed on six different oyster reefs (3 reference reefs and 3 containing dead margins) to test if dead margins affected the distribution of mobile species inhabiting oyster reefs. Nine nets were arranged to cover three separate areas of each reef: the fore-reef (3 nets), mid-reef (3 nets), and back-reef (3 nets). Half a liter of oyster shells were placed inside each net. These nets were checked weekly, for five weeks and species richness, density, and biomass were recorded. Analyses revealed that all community metrics were significantly higher on reference reefs than reefs affected with dead margins. Further, a significant drop in all three metrics was seen on the mid-reef area of affected reefs. The absence of species on this area is hypothesized to be due to a lack of water, shade, and habitat complexity. To document architectural differences, two types of transects were run along five reference reefs and five reefs with dead margins. First, quadrat transects determined the percent of live oysters, the percent of shell clusters, topographic complexity (using chain links), and the angle of shells on each reef type. Transect lines were stretched parallel to the water line and covered all three reef areas (fore-reef, mid-reef, and back-reef). The results showed reference reefs to have approximately four-fold more live oysters, approximately twice as many shell clusters, and significantly greater topographic complexity. Numbers of live oysters and shell clusters were greater on the fore-reef and back-reef areas of both reef types. Second, laser transects were used to record reef profiles and the slope of fore-reef areas. Transect lines were stretched perpendicular to the water line and every 20 cm the distance between the lagoon bottom and reef top was measured. Vertical reef profiles and fore-reef slopes were significantly different between reference reefs and reefs with dead margins. Dead margins compressed reef widths, increased center peaks, and increased slopes on the fore-reef area by two-fold. Lastly, field experiments were conducted to determine the affect of dead margins on the vulnerability of oyster spat to predation. Structural variables (e.g. shell orientation, single versus shell clusters, reef slope) were manipulated and effects on oyster mortality were observed. Three predators were tested: the blue crab Callinectes sapidus, the common mud crab Panopeus herbstii, and the Atlantic oyster drill Urosalpinx cinerea. Structural variables did not have a significant influence on oyster mortality; however, a significant difference was established between predators. Panopeus herbstii consumed the most juvenile oysters, followed by U. cinerea and then C. sapidus. Together, these findings document ecological implications of dead margins on C. virginica reefs and reinforce the urgent need for enhanced regulations and restoration. If the intensity of recreational boating remains unregulated, dead margins will continue to increase. Thus, in order to maintain the diversity and productivity of Mosquito Lagoon, it is crucial to fully understand how dead margins alter the biogenic habitat and biotic communities of oyster reefs.
Show less - Date Issued
- 2006
- Identifier
- CFE0001059, ucf:46790
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001059
- Title
- AN EXAMINATION OF THE HISTORY AND EFFECT OF AMERICAN SEX OFFENSE LAWS AND OFFENDER REGISTRATION.
- Creator
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Shabat-love, David, Milon, Abby, University of Central Florida
- Abstract / Description
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America's Sex Offense statutes and cases are some of the most controversial sections of modern law, both for the extreme sensitivity of their subject matter as well as the scope and application of those laws. This thesis is an analysis and overview of both the objective and subjective issues posed by the current state of those very laws: the subjective portion explored the development of current laws and the diverse attendant legal issues such as over-broadness and excessive or misdirected...
Show moreAmerica's Sex Offense statutes and cases are some of the most controversial sections of modern law, both for the extreme sensitivity of their subject matter as well as the scope and application of those laws. This thesis is an analysis and overview of both the objective and subjective issues posed by the current state of those very laws: the subjective portion explored the development of current laws and the diverse attendant legal issues such as over-broadness and excessive or misdirected effect as compared to the Legislative and public intent which directly led to the development of these laws. Additionally a more objective study of their efficacy was conducted through the use of data regarding offense rates by locality. This objective data was procured from both the United States Census and Bureau of Justice statistics, which contained national averages such as the overall violent crime rate, and from the Florida Department of Law Enforcement Statistics and was supplemented with additional data from other academic sources. It is both the subjective conclusion and the interpretation of objective data that while the rate of sex offenses has lowered in recent decades this effect is a part of the overall trend of reduction in all violent offenses, and that the extreme stance of modern sex offense laws have arguably resulted in the net-negative of creating a class of individuals ostracized from all but other sex offenders who are virtually incapable of supporting themselves or at times of even finding legal habitation post-release. With little to no chance of a productive life, there is the strong possibility of recidivism and little incentive to avoid re-offending.
Show less - Date Issued
- 2012
- Identifier
- CFH0004233, ucf:44915
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004233
- Title
- Fear and Loathing in the Super Organism: Foraging Strategy Doesn't Change Forager Response in a Landscape of Fear.
- Creator
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Schadegg, Philip, King, Joshua, De Bekker, Charissa, Fedorka, Kenneth, University of Central Florida
- Abstract / Description
-
Understanding how predators impact keystone species, like ants, is very important for our understanding of ecology because of ants' importance in shaping community dynamics and ecosystem functions. In this thesis I present research investigating the role of the ant-specialized spider Anasaitis canosa in influencing the foraging behavior of four ant species (Formica pallidefulva, Odontomachus ruginodis, Pheidole obscurithorax (&) Solenopsis invicta). Collectively, these four species use...
Show moreUnderstanding how predators impact keystone species, like ants, is very important for our understanding of ecology because of ants' importance in shaping community dynamics and ecosystem functions. In this thesis I present research investigating the role of the ant-specialized spider Anasaitis canosa in influencing the foraging behavior of four ant species (Formica pallidefulva, Odontomachus ruginodis, Pheidole obscurithorax (&) Solenopsis invicta). Collectively, these four species use foraging strategies exhibited by most ants. I conducted two experiments to quantify the impacts of spider predation on ant prey. The first used forty colonies of four ant species to investigate how A. canosa changed foraging behavior at both the individual and colony level. The second used 27 lab-reared S. invicta colonies to see if there was any evidence for innate predatory avoidance in foragers and if predatory avoidance was influenced by learning. A field study observed the density and prey choices of A. canosa in 3 sites within the UCF arboretum. In sum, no consistent change in foraging occurred in the presence of A. canosa, over time scales sufficient to detect colony-level impacts and thus colonies as a whole appear to be risk insensitive. Na(&)#239;ve colonies had more ants beginning foraging before a single ant would return in their first trial compared to the second trial. This suggests forager learning occurs as foragers respond to the perception of a predator, and that S. invicta can reduce individual risk through increasing forager numbers. A. canosa predation rates and density were calculated and based on these estimates an approximate impact upon a colony was made. Most importantly, 13 foragers/m2 inside each foraging cohort can be expected to have prior experience with the spider.
Show less - Date Issued
- 2019
- Identifier
- CFE0007859, ucf:52792
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007859
- Title
- Population dynamics and environmental factors influencing herbs in intact and degraded Florida Rosemary scrub.
- Creator
-
Stephens, Elizabeth, Quintana-Ascencio, Pedro, VonHolle, Mary, Fauth, John, Levey, Douglas, University of Central Florida
- Abstract / Description
-
Species have complex and contextual relationships with their environment; both the relative contributions of life-history stages to population growth and the effect of environmental factors on each stage can be different among co-existing species. Timing and extent of reproduction, survival, and mortality determine population growth, species distributions, and assemblage patterns. I evaluate the role of habitat (intact, degraded) and microsite (shrub, leaf litter, bare sand) on population...
Show moreSpecies have complex and contextual relationships with their environment; both the relative contributions of life-history stages to population growth and the effect of environmental factors on each stage can be different among co-existing species. Timing and extent of reproduction, survival, and mortality determine population growth, species distributions, and assemblage patterns. I evaluate the role of habitat (intact, degraded) and microsite (shrub, leaf litter, bare sand) on population dynamics of Florida scrub herbs. Isolated overgrown shrubs and extensive bare sand areas in degraded scrub were expected to decrease seed predation, reduce competition of herbs with shrubs, and provide larger habitat for recruitment. I provide evidence that habitat and microsite variation influenced demography of five endemic and two common native species through effects on seed removal, emergence, and establishment. Habitat and species affected seed removal: endemic species with large seeds were removed in higher frequency in degraded habitat, likely by vertebrates, while species with small seeds were removed in higher frequency in intact habitat, by invertebrates. There was no evidence of differences in individual seed production between habitats for the two common species, C. fasciculata and B. angustifolia. Invertebrates were primarily responsible for seed removal of both species, although peak season of removal and microsite varied with species. Removal of seeds, emergence, and establishment increased with seed density. Matrix modeling indicated that population growth of C. fasciculata was greater in degraded habitat and greatest in litter microsites, and population growth of B. angustifolia was similar between habitats and greatest in bare sand. Contrasting responses among species to environmental factors in intact and degraded scrub indicated that natural disturbances are not ecologically equivalent to anthropogenic disturbances. Idiosyncratic species dynamics in common environments suggest that understanding relationships between life-history traits and environmental conditions will be required to facilitate restoration.
Show less - Date Issued
- 2013
- Identifier
- CFE0004754, ucf:49791
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004754
- Title
- computational study of traveling wave solutions and global stability of predator-prey models.
- Creator
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Zhu, Yi, Qi, Yuanwei, Rollins, David, Shuai, Zhisheng, Zhai, Lei, University of Central Florida
- Abstract / Description
-
In this thesis, we study two types of reaction-diffusion systems which have direct applications in understanding wide range of phenomena in chemical reaction, biological pattern formation and theoretical ecology.The first part of this thesis is on propagating traveling waves in a class of reaction-diffusion systems which model isothermal autocatalytic chemical reactions as well as microbial growth and competition in a flow reactor. In the context of isothermal autocatalytic systems, two...
Show moreIn this thesis, we study two types of reaction-diffusion systems which have direct applications in understanding wide range of phenomena in chemical reaction, biological pattern formation and theoretical ecology.The first part of this thesis is on propagating traveling waves in a class of reaction-diffusion systems which model isothermal autocatalytic chemical reactions as well as microbial growth and competition in a flow reactor. In the context of isothermal autocatalytic systems, two different cases will bestudied. The first is autocatalytic chemical reaction of order $m$ without decay. The second is chemical reaction of order $m$ with a decay of order $l$, where $m$ and $l$ are positive integers and $m(>)l\ge1$. A typical system is $A + 2B \rightarrow3B$ and $B\rightarrow C$ involving three chemical species, a reactant A and an auto-catalyst B and C an inert chemical species.We use numerical computation to give more accurate estimates on minimum speed of traveling waves for autocatalytic reaction without decay, providing useful insight in the study of stability of traveling waves. For autocatalytic reaction of order $m = 2$ with linear decay $l = 1$, which hasa particular important role in biological pattern formation, it is shown numerically that there exist multiple traveling waves with 1, 2 and 3 peaks with certain choices of parameters.The second part of this thesis is on the global stability of diffusive predator-prey system of Leslie Type and Holling-Tanner Type in a bounded domain $\Omega\subset R^N$ with no-flux boundary condition. By using a new approach, we establish much improved global asymptotic stability of a unique positiveequilibrium solution. We also show the result can be extended to more general type of systems with heterogeneous environment and/or other kind of kinetic terms.
Show less - Date Issued
- 2016
- Identifier
- CFE0006519, ucf:51359
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006519
