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- Title
- LIMNOLOGICAL AND LANDSCAPE FACTORS AFFECTING USE OF MANUFACTURED PONDS BY THE INVASIVE CUBAN TREEFROG (OSTEOPILUS SEPTENTRIONALIS).
- Creator
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Nusinov, Terina, Fauth, John, University of Central Florida
- Abstract / Description
-
Exotic amphibians are often detrimental to native biotas. In Florida, the exotic Cuban Treefrog (Osteopilus septentrionalis) eats native frogs and may outcompete them for resources. Cuban Treefrogs thrive in disturbed areas and around buildings, and often breed in manufactured wetlands such as retention ponds and borrow pits. This study identified limnological, landscape, and biotic characteristics that discouraged pond use by Cuban Treefrogs and promoted use by native amphibian species. I...
Show moreExotic amphibians are often detrimental to native biotas. In Florida, the exotic Cuban Treefrog (Osteopilus septentrionalis) eats native frogs and may outcompete them for resources. Cuban Treefrogs thrive in disturbed areas and around buildings, and often breed in manufactured wetlands such as retention ponds and borrow pits. This study identified limnological, landscape, and biotic characteristics that discouraged pond use by Cuban Treefrogs and promoted use by native amphibian species. I sampled natural and manufactured ponds in Orange County, Florida, for one year, using standard methods to estimate the species richness and relative abundance of amphibians and their potential fish and macroinvertebrate predators. I determined the relationship between the presence of Cuban Treefrogs and twelve limnological (% vegetation, slope, pond age, pH, % dissolved oxygen, air temperature, water temperature, turbidity, conductivity, depth, perimeter, and area) and seven landscape characteristics (% canopy closure over ponds, building density, distance to nearest building, road density, distance to nearest road, distance to nearest forest stand, and % forest cover), plus five biotic factors (native amphibian richness and abundance, fish richness and abundance, and macroinvertebrate abundance). No relationship existed between native amphibian abundance or species richness and the presence or absence of Cuban Treefrogs. Ponds with a greater percentage of vegetation, large perimeters, and low pH and turbidity had greater native amphibian species richness. Cuban Treefrogs were more likely to be found in ponds with a greater percentage of aquatic vegetation and small perimeters. My results show that building large retention ponds containing low-turbidity water will restrict colonization by Cuban Treefrogs and maintain species richness of native amphibians.
Show less - Date Issued
- 2006
- Identifier
- CFE0001000, ucf:46837
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001000
- Title
- AEROMONAS HYDROPHILA IN AMPHIBIANS: HARMLESS BYSTANDER OR OPPORTUNISTIC PATHOGEN.
- Creator
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Rivas, Zachary P, Savage, Anna Evangeline, University of Central Florida
- Abstract / Description
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For several decades amphibian populations have been declining. Historically, the bacterium A. hydrophila (Ah) was hypothesized to be the causal factor in amphibian disease and population declines. However, with the discovery of a chytrid fungus, Batrachochytrium dendrobatidis (Bd) in 1998, which was identified on the skin of amphibians during documented mortality events, Ah research became of minor interest as focus shifted to Bd. Recent studies into the immunocompromising abilities of Bd,...
Show moreFor several decades amphibian populations have been declining. Historically, the bacterium A. hydrophila (Ah) was hypothesized to be the causal factor in amphibian disease and population declines. However, with the discovery of a chytrid fungus, Batrachochytrium dendrobatidis (Bd) in 1998, which was identified on the skin of amphibians during documented mortality events, Ah research became of minor interest as focus shifted to Bd. Recent studies into the immunocompromising abilities of Bd, however, have opened new questions about its relationship with Ah and their combined effects on a host. In this study, I explore the relationship between infection with these two pathogens, Bd and Ah, in two amphibian species from distinct regions of the United States. I developed a novel qPCR assay to measure the microbial load of Ah on the skin of two anuran species, Lithobates yavapaiensis (N=232) and Pseudacris ornata (N=169), which have confirmed Bd infections. I use a logistic regression model to identify whether significant relationships exist between these two pathogens, disease, and death. I find that even amongst the most severely infected frogs, Ah is not detectable on the skin and only appears post-mortem. I therefore conclude that Ah is an opportunistic bacterial pathogen, scavenging on anurans only after mortality events. This research is the first known study to quantitatively assess Ah in amphibians in conjunction with Bd. While there is no causal relationship between these pathogens, future work will examine potential Ah infections in other organs to more fully understand the relationship between Bd and Ah.
Show less - Date Issued
- 2016
- Identifier
- CFH2000013, ucf:45589
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000013
- Title
- Wetland diversity in a disturbance-maintained landscape: Effects of fire and a fire surrogate on aquatic amphibian survival and species depauperateness.
- Creator
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Klaus, Joyce, Noss, Reed, Quintana-Ascencio, Pedro, Jenkins, David, Dr. L. Katherine Kirkman, University of Central Florida
- Abstract / Description
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Disturbance is one of the central concepts explaining how diversity arises and is perpetuated in ecological time. A good model system for testing hypotheses related to disturbance is the longleaf pine ecosystem in the southeastern U.S. because in this ecosystem frequent, low-severity fires acts as a disturbance that maintains a unique vegetation structure and high species richness. Vegetation structure influences animal distributions; in fire-dependent ecosystems many animals rely on open...
Show moreDisturbance is one of the central concepts explaining how diversity arises and is perpetuated in ecological time. A good model system for testing hypotheses related to disturbance is the longleaf pine ecosystem in the southeastern U.S. because in this ecosystem frequent, low-severity fires acts as a disturbance that maintains a unique vegetation structure and high species richness. Vegetation structure influences animal distributions; in fire-dependent ecosystems many animals rely on open-structured, fire-maintained vegetation but shrubs and trees encroach into fire-dependent ecosystems where fire has been excluded. Prescribed burning and mechanical removal are commonly used as restoration tools to control encroachment. To better assess and compare the restoration potential of these tools, a more thorough understanding of how they change vegetation structure and habitat suitability for animals is necessary.The southeastern U.S. is a diversity hot-spot for amphibians, many of which require ephemeral wetlands embedded in longleaf pine uplands for the aquatic phase of their life cycle. Amphibian diversity has been declining in recent decades and habitat loss/degradation has been cited as one of the leading causes. Although often overlooked in studies of fire ecology, the ephemeral wetlands required by many amphibians are also fire-dependent habitats that have been negatively impacted by lack of fire. To understand how disturbance interacts with wetland vegetation and aquatic-phase amphibians, three disturbance treatments meant to mimic the effects of natural disturbance on vegetation structure were applied randomly to 28 dry ephemeral wetlands in the Lower Coastal Plain of South Carolina, U.S. The treatments consisted of early growing-season prescribed fire, mechanical vegetation removal (a proposed fire surrogate), and a combination of mechanical removal plus fire; some sites were left untreated for reference. Vegetation structure was quantified and amphibian assemblages were monitored before and after treatments. In addition, one species of amphibian was used in a tadpole survival experiment to examine differences in performance among treatments. Other factors that could be affected by treatments and in turn influence amphibians were measured, including water chemistry, wetland depth, quantity and quality of epilithon, and leaf litter composition.Amphibian survival was lowest, and species depauperateness highest in untreated wetlands. Depauperateness of species whose range was restricted to the range of longleaf pine was lowest in sites that had mechanical treatment plus fire. The mechanical plus fire treatment created the most open vegetation structure with lowest leaf litter accumulation, especially of hardwood litter, conditions correlated with high amphibian survival and diversity. When data from this study was combined with data from a previous study of similar nearby wetlands, a pattern emerged in which one suite of species was absent from recently burned sites, while an entirely different suite of species was absent from long-unburned sites. This evidence suggests that disturbance is related to a shift in amphibian assemblage possibly due to changes in vegetation structure and perhaps wetland ecology in general, from an algal-based system maintained by frequent fire to a detrital-based system that develops in the absence of fire.
Show less - Date Issued
- 2013
- Identifier
- CFE0005015, ucf:49994
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005015
- Title
- TREEFROG (HYLA SQUIRELLA) RESPONSES TO RANGELAND MANAGEMENT IN SEMI-TROPICAL FLORIDA, USA.
- Creator
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Windes, Kathryn, Fauth, John, University of Central Florida
- Abstract / Description
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As urban areas expand, agricultural lands become increasingly important habitat for many species. Compared to some types of agricultural land-use, ranchlands provide vast expanses of minimally modified habitat that support many threatened and endangered species. Conservation biologists can promote ecologically sound management approaches by quantifying the effects of agricultural practices on resident species. I examined the effects of pasture management, cattle grazing, and landscape...
Show moreAs urban areas expand, agricultural lands become increasingly important habitat for many species. Compared to some types of agricultural land-use, ranchlands provide vast expanses of minimally modified habitat that support many threatened and endangered species. Conservation biologists can promote ecologically sound management approaches by quantifying the effects of agricultural practices on resident species. I examined the effects of pasture management, cattle grazing, and landscape characteristics on both adult and larval treefrogs in a ranchland in south-central Florida. I experimentally determined optimal deployment of artificial treefrog shelters constructed of polyvinylchloride (PVC) pipe to efficiently sample adult treefrogs (Chapter 1). Seventy-two shelters were hung on oak trees (Quercus virginiana) and cabbage palm trees (Sabal palmetto) with smooth trunks or boots (residual palm fronds), at all possible combinations of three heights (2, 3, and 4 m), four compass directions (N, S, E, and W) and two water levels (with or without 10 cm). Shelter residence was completely dominated by the Squirrel Treefrog, Hyla squirella (N = 65). Significantly fewer H. squirella were found in shelters on palms with boots than on smooth palms or oak trees (0.29 ± 0.21 [mean ± 1 SE hereinafter] versus 1.3 ± 0.21 and 1.1 ± 0.21, respectively), and shelters with water had slightly more H. squirella than those without (1.5 ± 0.19 versus 0.88 ± 0.19, respectively). Orientation and height did not affect the number of treefrogs encountered; thus, the optimal protocol is to deploy shelters on either smooth palms or oak trees, with water, at 2 m height for easy sampling, and in random compass orientations. I used this protocol to sample H. squirella in woodlots surrounding twelve wetlands and examined how time, frog stage and sex, and landscape features influenced treefrog survival, recapture and site fidelity (Chapter 2). I deployed 15 shelters/ha of woodlot within a 100 m buffer around each wetland. I sampled shelters three times during the fall breeding season, removed all shelters to force frogs to overwinter in natural refugia, and replaced shelters for the final spring sampling. During sampling periods, I sexed, measured, and individually marked each frog using visual implant elastomer (VIE) tags. I used Program MARK to build linear models that included either gender group (female, male or juvenile) or life history stage (adult, juvenile) and either time (sampling interval 1, 2, or 3) or season (fall, spring). I used the most informative model as a null model to assess effects of landscape covariates on survival and recapture. Females had higher survival than either males or juveniles, for which estimates were similar (0.867 vs 0.741 and 0.783, respectively). Survival did not vary over time, although there was some support for an effect of season, with lower survival during the final over-wintering period than in the fall intervals (relative variable importance: group = 0.730; stage = 0.134; time = 0.200; season = 0.310). Adults had higher recapture rates than juveniles (average recapture 0.214 vs 0.102), and recapture for both stages varied over time, with highest recapture in sampling interval two (relative variable importance: group = 0.262; stage = 0.514; time = 0.513; season = 0.229). Hyla squirella was extremely site loyal; no individuals moved between sampling sites, and 95% of recaptured individuals were in their original shelter. Strong terrestrial site fidelity calls into question the traditional ÂÂ"ponds as patchesÂÂ" metapopulation view of treefrog population dynamics. Area of woodlot within 250 m was the most important landscape variable in explaining additional variation in both survival and recapture. Frogs had higher survival and lower recapture in larger woodlots, indicating that intact, contiguous woodlots are higher quality habitat than more fragmented woodlots. Neither survival nor recapture varied with wetland grazing treatments or between pasture types. Finally, I experimentally assessed the effects of cattle grazing and pasture management on larval H. squirella. I selected four wetlands: two in semi-natural pastures (SN) and two in intensively managed pastures (IM). One wetland in each pasture type was fenced so that it was released from cattle grazing (R). I collected three clutches of H. squirella eggs (Clutches A, B, and C) and reared tadpoles in the laboratory until Gosner stage 25. In each wetland, I deployed a total of 50 tadpoles from each clutch into 105 L pens constructed of plastic laundry baskets and mesh window screening. Clutch significantly affected tadpole survival, with Clutch A having the highest percent survival, followed by Clutch B and finally Clutch C (41.66, 32.11 – 53.95 [mean, 95% confidence limits hereinafter]; 9.00, 6.76 – 11.88; 2.89, 2.02 – 4.01, respectively). Wetland type also affected survival, with SN wetlands supporting significantly higher survival than IM wetlands (SN-R: 53.95, 32.88 – 88.13; SN-G: 18.95, 11.30 – 31.36 vs IM-R: 7.32, 4.13 – 12.49; IM-G: 1.09, 0.29 – 2.39). Genetic variation in survival confirms the potential for H. squirella to adapt to rangeland management, but extremely low survival of some clutches indicates that few clutches may be able to survive in low quality wetlands, such as IM-G wetlands. Higher survival in SN pasture wetlands suggest this is a superior habitat and future management objectives should conserve semi-natural pastures and limit further modification of intensively managed pastures, including removing woodlots near wetlands.
Show less - Date Issued
- 2010
- Identifier
- CFE0003178, ucf:48592
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003178
- Title
- GENETIC AND PHENOTYPIC EVOLUTION IN THE ORNATE CHORUS FROG (PSEUDACRIS ORNATA): TESTING THE RELATIVE ROLES OF NATURAL SELECTION, MIGRATION, AND GENETIC DRIFT.
- Creator
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Degner, Jacob, Hoffman, Eric, University of Central Florida
- Abstract / Description
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Understanding how migration, genetic drift, and natural selection interact to maintain the genetic and phenotypic variation we observe in natural populations is a central goal of population genetics. Amphibians provide excellent model organisms for investigating the interplay between these evolutionary forces because amphibians are generally characterized by limited dispersal abilities, high philopatry, and are obligately associated with the areas around suitable habitats (e.g. breeding ponds...
Show moreUnderstanding how migration, genetic drift, and natural selection interact to maintain the genetic and phenotypic variation we observe in natural populations is a central goal of population genetics. Amphibians provide excellent model organisms for investigating the interplay between these evolutionary forces because amphibians are generally characterized by limited dispersal abilities, high philopatry, and are obligately associated with the areas around suitable habitats (e.g. breeding ponds). Thus, on relatively small geographic scales, the relative effects of all of these evolutionary forces can be studied together. Here, we study the interaction of migration, genetic drift, natural selection, and historical process in the ornate chorus frog (Pseudacris ornata). We report the development and characterization of 10 polymorphic microsatellite genetic markers. Number of alleles per locus ranged from 2 to 21 averaging 9.2 and expected heterozygosities ranged from 0.10 to 0.97 averaging 0.52. However, in an analysis of two populations, three locus-by-population comparisons exhibited significant heterozygote deficiencies and indicated that null alleles may be present some loci. Furthermore, we characterized genetic structure and historical biogeographic patterns in P. ornata using these microsatellite markers along with mitochondrial DNA sequence data. Our data indicate that in these frogs, migration may play a large role in determining population structure as pairwise estimates of FST were relatively small ranging from 0.04 to 0.12 (global FST = 0.083). Additionally, we observed an overall pattern of isolation-by-distance in neutral genetic markers across the species range. Moreover, our data suggest that the Apalachicola River basin does not impede gene flow in P. ornata as it does in many vertebrate taxa. Interestingly, we identified significant genetic structure between populations separated by only 6 km. However, this fine scale genetic structure was only present in the more urbanized of two widespread sampling localities. Finally, in this study, we demonstrated that there was a significant correlation between the frequency of green frogs and latitude. There was a higher frequency of green frogs in southern samples and a lower frequency of green frogs in northern samples. However, when we interpreted this phenotypic cline in light of the overall pattern of isolation-by-distance, it was apparent that the neutral evolutionary forces of genetic drift and migration could explain the cline, and the invocation of natural selection was not necessary.
Show less - Date Issued
- 2007
- Identifier
- CFE0001721, ucf:47319
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001721
