Reproductive physiology studies in zoological species: Concerns and strategies

A sophisticated understanding of reproductive physiology of domestic animals has evolved over only the past several decades. Related technical advances in this field have permitted propagation through artificial insemination and/or embryo transfer using fresh or frozen-thawed gametic or embryonic material. More recent studies in genetic engineering and embryo micromanipulation have generated additional potential for improved reproductive efficiency in the farm-animal industry. Although these procedures provide incentive for solving management problems and improving the endangered status of many zoological species, achieving these objectives will be neither simple nor immediate. Major obstacles to confront include the poor image of research, unavailability of research stocks, lack of financial support, scarcity of trained personnel, and the idea that new reproductive techniques offer a “quick fix” to the problem of inadequate reproduction in an endangered species. Zoological researchers should now concentrate on establishing basic reproductive relationships in species of interest. Comparative studies in domesticated animals will accelerate progress. The immediate goal should be the production of sound scientific data of publishable quality. Only then can artificial propagation be considered as a viable alternative to preserving wildlife species.     

Ecological and evolutionary physiology of desert birds: a progress report

The adaptive significance of mechanisms of energy and water conservation among species of desert rodents, which avoid temperature extremes by remaining within a burrow during the day, is well established. Conventional wisdom holds that arid-zone birds, diurnal organisms that endure the brunt of their environment, occupy these desert climates because of the possession of physiological design features common to all within the class Aves. We review studies that show that desert birds may have evolved specific features to deal with hot desert conditions including: a reduced basal metabolic rate (BMR) and field metabolic rate (FMR), and lower total evaporative water loss (TEWL) and water turnover (WTO).Previous work on the comparative physiology of desert birds relied primarily on information gathered on species from the deserts of the southwestern U.S., which are semi-arid habitats of recent geologic origin. We include data on species from Old World deserts, which are geologically older than those in the New World, and place physiological responses along an aridity axis that includes mesic, semi-arid, arid, and hyperarid environments.The physiological differences between desert and mesic birds that we have identified using the comparative method could arise as a result of acclimation to different environments, of genetic change mediated by selection, or both. We present data on the flexibility of BMR and TEWL in Hoopoe Larks that suggest that phenotypic adjustments in these variables can be substantial. Finally, we suggest that linkages between the physiology of individual organism and its life-history are fundamental to the understanding of life-history evolution.     

Living history of physiology: Carl Gans

In 2005, The American Physiological Society initiated The Living History of Physiology Project to recognize senior members who have made extraordinary contributions during their career to the advancement of the discipline and profession of physiology. Each Eminent Physiologist will be interviewed for archival purposes, and the video tape will be available from the American Physiological Society Headquarters. In addition, a biographical profile of the recipient will be published in Advances in Physiology Education.     

Living history of physiology: Bodil Schmidt-Nielsen

In 2005, The American Physiological Society initiated The Living History of Physiology Project to recognize senior members who have made extraordinary contributions during their career to the advancement of the discipline and profession of physiology. Each physiologist will be interviewed for archival purposes, and the video tape will be available from the American Physiological Society Headquarters. In addition, a biographical profile of the recipient will be published in Advances in Physiology Education.     

Mineral nutrition of plants: a short history of plant physiology.

The development of the knowledge on the mineral nutrition of plants begins between the 17th and 18th centuries when some European naturalists gave the first experimental evidences of what had been empirically known for about two millennia. The works of Hales and Ingenhousz were of absolute importance in relation to the transport of water and solutes, and assimilation of "fixed air" (carbon dioxide), respectively. The early chemistry introduced by Lavoisier benefited the first physiologists Senebier and De Saussure to reject the "theory of humus", which imposed the soil as the unique source of carbon. During the first half of the 19th century, Sprengel and Liebig investigated on the problems related to some indispensable mineral salts, while Boussingault and Ville attempted to prove the nitrogen fixation from air without giving any convincing evidence. Liebig was the pioneer of the agricultural chemistry: he epitomised the knowledge of that period by imposing the so-called "law of the minima", already acknowledged by Sprengel, and patronised the use of mineral fertilisers in Europe by devising several formulas of mineral manure. He, however, did not recognise the needs of external supplies of nitrogen salts for the crops, in open dispute with the English school of Lawes and Gilbert, who were instead convinced assertors of such needs. At the end of the 19th century Hellriegel showed that leguminous plants presenting peculiar nodules on their roots could really fix the gaseous nitrogen. From these nodules Beijerinck and Prazmowski isolated for the first time some bacteria which were recognised as the real agents fixing nitrogen. This discovery was of fundamental importance for plant nutrition, only second to the discovery of photosynthesis. Another basic contribution came from early research of Sachs on plants grown on aqueous solutions: these techniques allowed to impose the concept of "essential elements", which was fixed as a principle by Arnon and Stout in 1939. This principle benefited further research concerning the effects of states of deficiency on plant growth and development through investigation on the anatomical, histologic and biochemical nutritional disorders of plants.     

Diving physiology and winter foraging behavior of a juvenile leopard seal (Hydrurga leptonyx)

Diving physiology and at-sea behavior of a juvenile leopard seal (Hydrurga leptonyx) were opportunistically measured in the Antarctic Peninsula during winter 2002. Total body oxygen stores were estimated from measures of hematocrit, hemoglobin, myoglobin, and total blood volume and were used to calculate an aerobic dive limit (ADL). Movement patterns and diving behavior were measured by equipping the seal with a Satellite Relay Data Logger that transmitted data from 8–31 August 2002. The seal remained in a focal area, in contrast to crabeater seals tracked simultaneously. The seal displayed short, shallow dives (mean 2.0±1.4 min, 44±48 m) and spent 99.9% of its time within the estimated ADL of 7.4 min. The shallow diving behavior contradicts previous diet research suggesting Antarctic krill (Euphausia superba) is the primary prey of leopard seals during the winter months as krill were found at deeper depths during this period. These measurements of diving and movement of a leopard seal provide valuable preliminary data necessary to develop future research on the at-sea behavior of an apex predator in the Antarctic ecosystem.     

Integrative physiology of fundamental frequency control in birds

One major feature of the remarkable vocal repertoires of birds is the range of fundamental frequencies across species, but also within individual species. This review discusses four variables that determine the oscillation frequency of the vibrating structures within a bird’s syrinx. These are (1) viscoelastic properties of the oscillating tissue, (2) air sac pressure, (3) neuromuscular control of movements and (4) source-filter interactions. Our current understanding of morphology, biomechanics and neural control suggests that a complex interplay of these parameters can lead to multiple combinations for generating a particular fundamental frequency. An increase in the complexity of syringeal morphology from non-passeriform birds to oscines also led to a different interplay for regulating oscillation frequency by enabling control of tension that is partially independent of regulation of airflow. In addition to reviewing the available data for all different contributing variables, we point out open questions and possible approaches.     

Cooperative breeding in birds: a comparative test of the life history hypothesis

In approximately 3.2% of bird species individuals regularly forgo the opportunity to breed independently and instead breed cooperatively with other conspecifics, either as non-reproductive ''helpers'' or as co-breeders. The traditional explanation for cooperative breeding is that the opportunities for breeding independently are limited owing to peculiar features of the species'' breeding ecology. However, it has proved remarkably difficult to find any common ecological correlates of cooperative breeding in birds. This difficulty has led to the ''life history hypothesis'', which suggests that the common feature of cooperatively breeding birds is their great longevity, rather than any particular feature of their breeding ecology. Here, we use a comparative method to test the life history hypothesis by looking for correlations between life history variation and variation in the frequency of cooperative breeding. First, we find that cooperative breeding in birds is not randomly distributed, but concentrated in certain families, thus supporting the idea that there may be a common basis to cooperative breeding in birds. Second, increases in the level of cooperative breeding are strongly associated with decreases in annual adult mortality and modal clutch size. Third, the proportion of cooperatively breeding species per family is correlated with a low family-typical value of annual mortality, suggesting that low mortality predisposes cooperative breeding rather than vice versa. Finally, the low rate of mortality typically found in cooperatively breeding species is associated with increasing sedentariness, lower latitudes, and decreased environmental fluctuation. We suggest that low annual mortality is the key factor that predisposes avian lineages to cooperative breeding, then ecological changes, such as becoming sedentary, further slow population turnover and reduce opportunities for independent breeding. As the traditional explanation suggests, the breeding habitat of cooperatively breeding species is saturated, but this saturation is not owing to any peculiar feature of the breeding ecology of cooperative breeders. Rather, the saturation arises because the local population turnover in these species is unusually slow, as predicted by the life history hypothesis.     

Karyological studies in four species of ardeid birds (Ardeldae,Ciconiiformes)

Karyotypic analyses of 4 species of birds: Ardeola grayii grayii, Bubulcus ibis coromandus, Egretta garzetta, Nycticorax nycticorax nycticorax (Ardeidae, Ciconiiformes) reveal low diploid values (2n=60–68), absence of sharp bimodality and an unusually large W chromosome in A. g. grayii. N-banding studies in two species (B. i. coromandus and N. n. nycticorax) show 6–8 microchromosomes to contain NORs and the G-banded karyotype of A. g. grayil reveals the usual avian pattern.     

Invasive birds in a novel landscape: habitat associations and effects on established species

Studying the relationships among introduced species, their preferred habitats, and native species can be important for predicting the effects of invasions on native populations. Examining the colonization of North America by the Eurasian collared‐dove Streptopelia decaocto, we quantified the habitat characteristics of sites most likely to be occupied by this invasive bird species in the early stages of the invasion. Further, we studied the relationship between collared‐dove abundance and the abundance of other dove species in the study area, anticipating a negative effect on established species following the introduction of a potential competitor. Linking satellite‐derived landcover data with winter bird community data gathered from 444 study sites in Florida, USA from 1999 to 2008, we found that collared‐doves were more likely to occur in landscapes that had been highly‐modified by human activity than in forested landscapes. Collared‐dove abundance increased as the proportion of the landscape characterized as low‐intensity development and medium/high‐intensity development increased. The probability of collared‐doves occurring at a site was also related to the spatial proximity of other sites reporting doves (positive spatial autocorrelation). Contrary to our expectations, the site‐level abundance of four other dove species all increased with collared‐dove abundance throughout the sampling period. Interactions between collared‐doves and native species should be further studied in different environments as this invasive bird rapidly colonizes North America.     

Stress and translocation: alterations in the stress physiology of translocated birds

Translocation and reintroduction have become major conservation actions in attempts to create self-sustaining wild populations of threatened species. However, avian translocations have a high failure rate and causes for failure are poorly understood. While ‘stress’ is often cited as an important factor in translocation failure, empirical evidence of physiological stress is lacking. Here we show that experimental translocation leads to changes in the physiological stress response in chukar partridge, Alectoris chukar. We found that capture alone significantly decreased the acute glucocorticoid (corticosterone, CORT) response, but adding exposure to captivity and transport further altered the stress response axis (the hypothalamic–pituitary–adrenal axis) as evident from a decreased sensitivity of the negative feedback system. Animals that were exposed to the entire translocation procedure, in addition to the reduced acute stress response and disrupted negative feedback, had significantly lower baseline CORT concentrations and significantly reduced body weight. These data indicate that translocation alters stress physiology and that chronic stress is potentially a major factor in translocation failure. Under current practices, the restoration of threatened species through translocation may unwittingly depend on the success of chronically stressed individuals. This conclusion emphasizes the need for understanding and alleviating translocation-induced chronic stress in order to use most effectively this important conservation tool.     

Target species for deep-sea studies in ecology, genetics, and physiology

This paper describes Tharyx luticastellus sp. nov. (Polychaeta: Cirratulidae), an important structural component of the bathyal (approximately 1200 m) macrobenthic community in the San Diego Trough of the North Pacific Ocean. Its robust, distinctive, helically coiled tube permits ready identification and collection or manipulation in relatively un-traumatized condition.
Major problems in applying modern ecological, genetic, and physiological methods in the deep sea include the in situ or shipboard identification of species, the obtaining of sufficient specimens of any single species for adequate statistical treatment, and the manipulation or retrieval of animals without induction of severe trauma. This species satisfies all these criteria.