American Zoologist articles from April 1999

American Zoologist archives from April 1999

Red Blood Cells: Centerpiece in the Evolution of the Vertebrate Circulatory System(1).
April 1, 1999... INTRODUCTION Hemoglobins were the first of the oxygen carriers (Mangum, 1992). They are the most widely distributed of the respiratory pigments and may be found in cells (the tissue hemoglobins) or circulating in one or more fluid...

Evolution of the Cardiovascular System in Crustacea(1).
April 1, 1999... INTRODUCTION This essay on the evolution of the cardiovascular system (CVS) in the Crustacea is constructed on the recognition that evolutionary change in form must be functional. Functional requirements of the CVS of a crustacean are...

Aquatic Organisms, Terrestrial Eggs: Early Development at the Water's Edge. Introduction to the Symposium(1).
April 1, 1999... Why do some animals live in water yet put their eggs on land? Many aquatic species--from algae to snails, and fish to frogs--use oviposition sites that expose their eggs to air. The duration of emergence ranges from occasional, short-term...

Gamete Release at Low Tide in Fucoid Algae: Maladaptive or Advantageous?(1).
April 1, 1999... Fucoid algae are brown seaweeds that are abundant in temperate rocky intertidal zones of the open-coast and estuaries. For reasons of space, this review is principally about gamete release in representatives of the Fucaceae, one of several...

Adaptations to Physical Stresses in the Intertidal Zone: The Egg Capsules of Neogastropod Molluscs(1).
April 1, 1999... INTRODUCTION To survive within the intertidal zone of marine environments, plants and animals may have to withstand exposure to desiccation, osmotic stress, temperature stress, and UV radiation, as well as cope with problems associated...

Egg-Mass Size and Cell Size: Effects of Temperature on Oxygen Distribution(1).
April 1, 1999... INTRODUCTION Despite vast differences in scale, gelatinous egg masses and ectothermic cells share two simple and fundamental properties. With isometrically increasing size, volume increases more rapidly than does surface area. And with...

Two Designs of Marine Egg Masses and their Divergent Consequences for Oxygen Supply and Desiccation in Air(1).
April 1, 1999... INTRODUCTION Air and water present different hazards and advantages for embryos. Two of these hazards are risk of desiccation in air and a much more limited oxygen supply in water. Many terrestrial eggs have shells or coats that limit...

Respiration of Aquatic and Terrestrial Amphibian Embryos(1).
April 1, 1999... INTRODUCTION Amphibian eggs are elegantly circumscribed structures. The embryo develops inside of a gelatinous capsule that protects and supports it in an essentially gravity-free, water-filled space. Almost all of the requirements for...

Development in the Floating World: Defenses of Eggs and Embryos Against Damage from UV Radiation(1).
April 1, 1999... INTRODUCTION Many organisms deposit their eggs and pass through the first part of their life cycle at the air-water interface (neuston). Examples include embryos of tunicates, amphibians and fish. This emplacement in a floating world...

Ready and Waiting: Delayed Hatching and Extended Incubation of Anamniotic Vertebrate Terrestrial Eggs(1).
April 1, 1999... INTRODUCTION Hatching is a life-history switch point (Sih and Moore, 1993), when an animal changes from an intracapsular egg to a free-living larva (Yamagami, 1988). Eggs are sessile, spherical, and have limited energy, but larvae are...

Water Relations of Chelonian Eggs and Embryos: Is Wetter Better?(1).
April 1, 1999... INTRODUCTION Female turtles usually emerge from water onto land in late spring or early summer to lay their eggs (Ernst et al., 1994). Each female first locates an appropriate site to nest and then uses her hind feet to dig a...

Size and Performance of Juvenile Marine Invertebrates: Potential Contrasts Between Intertidal and Subtidal Benthic Habitats(1).
April 1, 1999... INTRODUCTION The intertidal environment, the zone between high and low water surrounding the world's oceans, supports a rich and unique biota consisting almost entirely of marine organisms. Intertidal organisms are exposed to air on a...

A Suite of Adaptations for Intertidal Spawning(1).
April 1, 1999... High intertidal spawning in fishes involves a complex reproductive strategy requiting adaptations in adults, eggs and larvae. The adults typically display reproductive cyclicity that ensures sexual maturity at the times of most complete...

Introduction to the Symposium: What is Evolutionary Physiology?(1).
April 1, 1999... Organisms in natural populations possess a number of physiological and morphological traits that appear to increase fitness in the natural environment. For example, with regard to cold tolerance these include long fur in Arctic mammals,...

Testing the Adaptive Significance of Acclimation: A Strong Inference Approach(1).
April 1, 1999... INTRODUCTION Acclimation is often defined as a phenotypic alteration in physiology that occurs in response to (or in anticipation of) an environmental change. Studies of acclimation have been central to comparative physiology at least...

Physiological Responses to Selection for Desiccation Resistance in Drosophila melanogaster(1).
April 1, 1999... Stress has been defined by Koehn and Bayne (1989) as "any environmental change that acts to reduce the fitness of an organism". Stress, so defined, can encompass abiotic conditions such as meteorological conditions, biotically-induced...

Experimental Evolution and Its Role in Evolutionary Physiology(1).
April 1, 1999... "Karl Marx seems today a shadowed and limited historical figure, whereas Darwin is entirely contemporary. What he learned may affect everything we desire and everything we forget, what we wish to do and what we do not wish to do." David...

Interaction of Drosophila and Its Endosymbiont Wolbachia: Natural Heat Shock and the Overcoming of Sexual Incompatibility(1).
April 1, 1999... INTRODUCTION A traditional focus of comparative physiology and biochemistry has been on the distinctive mechanisms that enable organisms to overcome the challenges of extreme environments, be they abiotic (e.g., extreme in temperature...

An Introduction to Phylogenetically Based Statistical Methods, with a New Method for Confidence Intervals on Ancestral Values(1).
April 1, 1999... INTRODUCTION Many approaches can and should be used in evolutionary physiology (Feder et al., 1987; Bennett, 1997; Gibbs, 1999; Koteja et al., 1999), and combinations of approaches are often necessary (Garland and Carter, 1994; Leroi et...

Evolutionary Physiology of Closely Related Taxa: Analyses of Enzyme Expression(1).
April 1, 1999... INTRODUCTION What constitutes a biochemical adaptation (a derived biochemical trait that benefits an organism by increasing its longevity, reproductive fitness or probability of survival)? We present an argument that examining variation...

Metabolic Interrelations Underlying the Physiological and Evolutionary Advantages of Genetic Diversity(1).
April 1, 1999... INTRODUCTION Genetic components of fitness are affected by separate interactions with independent environmental variables, whilst selective forces upon each locus vary according life history stage and physiological condition (for review,...

Physiological Variation in Clonal Anemones: Energy Balance and Quantitative Genetics(1).
April 1, 1999... INTRODUCTION "After the Dark Age of Electrophoresis, evolutionary biologists are now experiencing the Renaissance of the Phenotype. During that dark age, researchers observed molecular differences in enzymes often without knowing what...

Sources of Variation in Physiological Phenotypes and Their Evolutionary Significance(1).
April 1, 1999... INTRODUCTION Evolutionary physiology embraces a broad spectrum of ideas, from studies of the phylogenetic diversity of physiological traits to examining the heritability of variation in physiological phenotypes (Garland and Carter,...

The Diving Response Mechanism and its Surprising Evolutionary Path in Seals and Sea Lions(1).
April 1, 1999... LABORATORY DIVING STUDIES AND THE FIRST CONCEPTUAL ASYMPTOTE Intrigued by diving mammals and birds for well over a century, biologists first began to make significant progress in understanding the physiological and metabolic mechanisms...

Genetic Architecture of Physiological Phenotypes: Empirical Evidence for Coadapted Gene Complexes(1).
April 1, 1999... INTRODUCTION Developmental and physiological processes require the complex orchestration of gene expression in space and time. Production of viable phenotypes dictates that deleterious mutations are selected against and that only alleles...

Play Behavior: Evolutionary, Comparative, and Ecological Perspectives.(Review)
April 1, 1999... Play Behavior: Evolutionary, Comparative, and Ecological Perspectives. MARC BEKOFF AND JOHN A. BYERS, eds. Cambridge University Press, Cambridge, 1998. xvi + 274; paperback $32.95 (ISBN 0-521-58656-9); hardback $80.00 (ISBN 0-521-58383-7)....

Pleistocene Amphibians and Reptiles in Britain and Europe.(Review)
April 1, 1999... PleistoCene Amphibians and Reptiles in Britain and Europe. J. ALAN HOLMAN. Oxford Monographs on Geology and Geophysics, no. 38, Oxford University Press Inc., 1998, ISBN 0-19-511232-6. The Pleistocene period (c. 1.9-0.01 Ma) was notable...