A strong foundation of basic and applied research documents that the estuarine fish Fundulus heteroclitus and related species are unique laboratory and field models for understanding how individuals and populations interact with their environment. In this paper we summarize an extensive body of work examining the adaptive responses of Fundulus species to environmental conditions, and describe how this research has contributed importantly to our understanding of physiology, gene regulation, toxicology, and ecological and evolutionary genetics of teleosts and other vertebrates. These explorations have reached a critical juncture at which advancement is hindered by the lack of genomic resources for these species. We suggest that a more complete genomics toolbox for F. heteroclitus and related species will permit researchers to exploit the power of this model organism to rapidly advance our understanding of fundamental biological and pathological mechanisms among vertebrates, as well as ecological strategies and evolutionary processes common to all living organisms.

Oxygen concentrations in gelatinous egg masses of two species of opisthobranch gastropods were examined with microelectrodes. Embryos in central positions are near the limit of the oxygen supply required for development. This limit is approached despite a diffusion constant for oxygen in masses that is close to that in water. Closed-chamber respirometry shows that oxygen is consumed by masses in the dark but generated in the light. Internal oxygen concentrations were greater in bright than in dim light. Thus photosynthesis and respiration of microorganisms associated with the masses affects the supply of oxygen to embryos within the mass. This effect of light was confirmed for egg masses of a polychaete. These observations, together with other published observations on the effects of hypoxia on development, indicate that the developmental rates of embryos in egg masses may depend on algal photosynthesis and metabolism. Flow around the masses also affects delivery of oxygen to embryos, but masses in dim light are at the limit of adequate supply even in a strong flow with a very thin boundary layer. Because the central embryos are near the limit for adequate supply of oxygen by diffusion, their development rate thus depends on light, abundance of photosynthetic and heterotrophic microorganisms, flow, and oxygen concentration in the surrounding water.

Evolutionary developmental biology (evo-devo) has undergone dramatic transformations since its emergence as a distinct discipline. This paper aims to highlight the scope, power, and future promise of evo-devo to transform and unify diverse aspects of biology. We articulate key questions at the core of eleven biological disciplines-from Evolution, Development, Paleontology, and Neurobiology to Cellular and Molecular Biology, Quantitative Genetics, Human Diseases, Ecology, Agriculture and Science Education, and lastly, Evolutionary Developmental Biology itself-and discuss why evo-devo is uniquely situated to substantially improve our ability to find meaningful answers to these fundamental questions. We posit that the tools, concepts, and ways of thinking developed by evo-devo have profound potential to advance, integrate, and unify biological sciences as well as inform policy decisions and illuminate science education. We look to the next generation of evolutionary developmental biologists to help shape this process as we confront the scientific challenges of the 21st century.

Fertilization success was measured in the bluehead wrasse, Thalassoma bifasciatum, a tropical reef fish with external fertilization of pelagic eggs. This species exhibits intraspecific variation in its spawning behavior; females either spawn with single males (pair spawning) or spawn with a group of at least three and often >20 males (group spawning). Fertilization success averaged °75% and did not differ between pair and group spawning, despite an estimated 80—fold increase in sperm release in group spawns. There was also no evidence that pair—spawning males suffered sperm depletion over the course of the spawning period. Thalassoma bifasciatum occurs in a variety of habitats and is exposed to varying levels of water turbulence. Fertilization success varied among days, and decreased with rougher water conditions. Within a reef, the calmer spawning sites behind the reef relative to the current had higher fertilization success than those along the side of the reef. These data suggest that while the type of spawning occurring at the site does not affect selection for fertilization success, females may gain fertilizations by selecting particular locations or periods of calmer water conditions to spawn. This is an alternative hypothesis to explain temporal and spatial patterns of mating. We provide detailed methods on how to accurately obtain data on fertilization success. Our technique can be used to study natural spawning in a wide variety of reef fishes and other marine organisms with pelagic eggs, external fertilization, and predictable spawning.