The Role of Tadpole Predation in the Habitat Distribution of the Green Treefrog (Hyla Cinerea)

• Other Authors: Gunzburger, Margaret Sarah (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Biology
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-3913

Understanding the factors that contribute to the distribution of species across habitats allows predictions of the effects habitat alterations on species distributions. Amphibians are important components of wetland ecosystems and are especially susceptible to changes in aquatic and terrestrial habitats. My research focused on the role of predation in the habitat distribution of tadpoles of the green treefrog, Hyla cinerea. Predation pressure on H. cinerea tadpoles varies across a gradient of 23 localities in northern Florida. The main division in the predator community is between ponds with and without fish; H. cinerea occurs primarily in permanent ponds with fish. The most effective predators are bass (Micropterus salmoides), odonates (Aeshnidae, Libellulidade), and newts (Notophthalmus viridescens). A predation pressure index constructed from predation rates and predator abundances varies strongly across habitats, but odonates are the most important predators in most habitats and fishless habitats generally have higher predation pressure index values than permanent habitats with fish. Combinations of multiple predator species tend to have similar effects on H. cinerea tadpoles. Tadpole survival with combinations of three predators (M. salmoides, aeshnid and libellulid odonates) was similar in five predator treatments, and slightly higher in the libellulid and aeshnid + libellulid treatments. Comparisons of behavior and predation rates revealed that H. cinerea tend to hide more in response to warmouth (Lepomis gulosis) predation than their sister taxon H. gratiosa. There were not strong differences in survival between these species with warmouth or odonate predators. My research demonstrates that H. cinerea tadpoles are subject to strong variation in predation pressure across the range of habitats in which they breed, and an adaptation to cope with this variation may be the ability to have similar survival with various combinations of multiple predator species. Predation probably plays a role in the habitat distribution of H. cinerea tadpoles because tadpole predation pressure tends to be lower in the habitats in which H cinerea typically choose for breeding. Other factors which may result in H. cinerea choosing permanent habitats include adult habitat selection and other factors influencing tadpole survival, such as competition and abiotic effects. === A Dissertation submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. === Fall Semester, 2004. === September 9, 2004. === Predator-Prey Interactions, Hylidae, Community Structure, Hybrid, Habitat Grdient, Multiple Predators === Includes bibliographical references. === Joseph Travis, Professor Directing Dissertation; James Smith, Outside Committee Member; Frances James, Committee Member; Thomas Miller, Committee Member; Thomas Houpt, Committee Member; Bruce Means, Committee Member.