Ecological and Environmental Physiology of Amphibians

Transcription

1 Oxford Scholarship Online You are looking at 1-10 of 22 items for: keywords : Manilius bioaqa bioani Ecological and Environmental Physiology of Amphibians Item type: book acprof:oso/ Amphibians are the descendants of the first vertebrate class to successfully colonize terrestrial environments. They rely on water more than any other terrestrial group and occupy a unique position between fishes and reptiles. This book provides a synthesis of current research on the ecological and environmental physiology of amphibians, with a particular emphasis on metabolic and water balance strategies associated with the range of habitats, aquatic to terrestrial, that are occupied by extant amphibian species. The topics include the suite of morphological, physiological, and behavioral adaptations associated with specific habitats, and the use of systematics in elucidating patterns of evolutionary change. The book includes over one thousand references on basic physiological principles, ecology, phylogeny, and development. Introduction acprof:oso/ This chapter introduces the morphological characters that define the Class Amphibia and its three orders: Gymnophiona (caecilians), Caudata (salamanders), and Anura (frogs and toads). It defines the variety of morphotypes and characteristics that are related to the ecology of species, for each order. The physical principles that determine gas, solute, solvent, and energy exchange are described. Finally, an amphibian phylogeny is presented, and how it can be used to analyze and interpret physiological data. Page 1 of 6

2 General Physiological Principles acprof:oso/ This chapter introduces water and ion budgets along with what is known about their physiological control mechanisms. It delineates both thermal and chemical potential energy budgets for amphibians, and discusses the respiratory cascade for oxygen and carbon dioxide exchange, providing estimates of the variables involved for both diffusive (lungs and tissues) and convective (ventilation and cardiac transport) processes involved in the exchange of these gasses. The chapter concludes with a discussion of blood volume and the variables that control it. Specialized Physiological Characteristics of Amphibia acprof:oso/ This chapter delineates the specialized physiological characteristics of amphibians, including anatomy and physiology of physiological processes of amphibians that have served as unique and powerful model systems for other vertebrates. It first describes how the skin and urinary bladder have been models for water and solute transport, in both water and air, followed by an analysis of the physiological mechanisms involved in the remarkable capacity of amphibians to withstand dehydration. The biology and physiology of thermoregulation is then explored, followed by an analysis of the range and limitations of temperature to activity metabolism, both aerobic and anaerobic. The diverse range of nitrogen excretory products of amphibians, along with their varied kidney physiology, is then described. Finally, the benefits of developmental plasticity are explored as a model. Page 2 of 6

3 Physiological Adaptations to Extreme Environments acprof:oso/ This chapter explores what is known about how amphibians deal with extreme environmental situations, beginning with aquatic environments, both fresh water and marine. It then describes life in extreme terrestrial and underground environments. The next section deals with overwintering in both aquatic and terrestrial environments, and discusses the particular stresses of hypoxia and low temperature. The chapter concludes with a discussion of metabolic depression as an intrinsic metabolic mechanism that extends energy reserves when environmental conditions preclude activity. Approaches and Techniques acprof:oso/ This chapter describes both analytic and measurement techniques used in the study of the environmental physiology of amphibians. The first section explores the benefits and pitfalls of utilizing phylogenetic methods to analyze and interpret physiological and morphological data with respect to phylogeny. The remainder of the chapter describes common techniques used for the measurement of temperature, water and ion exchange, cardiovascular physiology, and metabolism. Conclusions and Future Directions acprof:oso/ Page 3 of 6

4 This concluding chapter summarizes what we know and what future directions will help our understanding. It argues that greater phylogenetic breadth is required in future studies of amphibians, and that physiology is at the heart of any complete understanding of amphibian declines occurring worldwide. It concludes with a plea for collaboration and integration of different levels of biological organization in future studies. Aquatic Entomology Jill Lancaster and Barbara J. Downes Published in print: 2013 Published Online: December 2013 ISBN: eisbn: Item type: book acprof:oso/ Aquatic insects are the dominant invertebrate fauna in most freshwater ecosystems, and these insects figure prominently in the work of researchers, students, and managers, from diverse backgrounds. This broad-based reference text brings together a huge and scattered literature that presents recent advancements in the basic biology of aquatic insects from around the world information that is not available in standard texts on entomology, freshwater ecology, or ecohydrology. Because aquatic insects have complex life cycles, they must master both terrestrial and aquatic environments, and also cross these ecosystem boundaries during different stages of development and reproduction. Consequently, this text presents the essential, relevant basics of entomology, but also topics unique to aquatic species. Life in and on top of the water surface are covered in unusual detail, including the biomechanics of life in water, locomotion on surface films and under water, gas exchange, physico-chemical stressors, feeding underwater, sensory perception and communication, reproduction, egg-laying and development, and the evolution of aquatic habits. Reproduction and mating behaviour Jill Lancaster and Barbara J. Downes in Aquatic Entomology Published in print: 2013 Published Online: December 2013 ISBN: eisbn: acprof:oso/ Reproduction is essential for populations to persist and for species to remain extant. Fertilisation is internal in the insects so females typically retain eggs internally, and sperm must be transferred from the male Page 4 of 6

5 to the female reproductive tract. In aquatic insects, mating typically takes place between adults that are terrestrial in habit. This chapter discusses reproductive events up to, and including mating and egg fertilization, beginning with a brief description of the male and female internal reproductive organs and the formation of eggs and sperm. Some species are ready to mate almost immediately after they emerge as non-feeding adults, whereas others require a period of maturation and may feed during this period. How many offspring each female produces (fecundity) may depend on events during the maturation period and also during the larval stage. Inter-individual communication is very important in finding a suitable mate and this is discussed in the context of the kind of sensory information communicated, including vision, vibrational signalling, and sound and chemical communication. Once a mate has been located, the pair must copulate to transfer sperm; for most species, the male and female separate immediately after copulation, but mating pairs of a few species, especially the Odonata, remain together in post-copulatory mate guarding. Finally, a few species (primarily Ephemeroptera) have done away with males and mating altogether, and the females reproduce parthenogenetically. Oviposition and eggs Jill Lancaster and Barbara J. Downes in Aquatic Entomology Published in print: 2013 Published Online: December 2013 ISBN: eisbn: acprof:oso/ Oviposition is the term used to describe laying of eggs. This is a complex event and the discussion in this chapter is organised around two different sets of behaviours: pre-oviposition and post-oviposition. Pre-oviposition incorporates all the behaviours and factors involved in the selection of, or attraction to, an oviposition site and oviposition itself. Aquatic insects exploit an enormous range of oviposition sites (many aquatic and some terrestrial) and have egg-laying behaviours that include broadcasting eggs while in flight, laying eggs on and inside plant material, and females that enter the water to lay eggs attached to substrates underwater. Locating suitable oviposition sites may involve visual cues, such as using polarized light to locate water bodies, and chemical cues to select sites that are free of predators or that have suitable resources for larvae. Once the eggs have left the female (post-oviposition), they have many different strategies for ensuring that development of the embryo can proceed. Strategies discussed include gas exchange in eggs, coatings that provide eggs with protection from environmental stresses, devices Page 5 of 6

6 for attaching eggs to substrates, and defences from would-be attackers. The eggs of most aquatic insects develop without the benefit of parental care, but there are a few cases of parental care, particularly in the Belostomatidae. Page 6 of 6