Integrative and Comparative Biology - recent issues

Integrative & Comparative Biology

Mon, 16 Nov 2009 07:17:52 PST

2009 SICB Membership Application/Dues Renewal

Mon, 16 Nov 2009 07:17:52 PST

Integrative & Comparative Biology - Volume 49 Number 6 December 2009 - Back cover

Mon, 16 Nov 2009 07:17:52 PST

Integrative & Comparative Biology - Volume 49 Number 6 December 2009 - Front cover

Mon, 16 Nov 2009 07:17:52 PST

Subscriptions

Mon, 16 Nov 2009 07:17:52 PST

Integrative & Comparative Biology - Volume 49 Number 6 December 2009

Mon, 16 Nov 2009 07:17:52 PST

Genomics and vertebrate adaptive radiation: A celebration of the first cichlid genome

Hulsey, C. D., Renn, S. C. P. — Mon, 16 Nov 2009 07:17:51 PST

Cichlid genomics and phenotypic diversity in a comparative context

Hulsey, C. D. — Mon, 16 Nov 2009 07:17:51 PST

Cichlid fishes provide an excellent natural system for integrating studies of genomics and adaptive radiation. Cichlids are unique in comprising a substantial fraction of all vertebrate species, possessing unique jaw structures, displaying an exceptional range of breeding systems, and exhibiting rampant phenotypic convergence. The rate of divergence in cichlid jaws, teeth, color patterns, visual systems, reproductive biology, and mating behaviors is unparalleled among vertebrates. I discuss ways rapid divergence in cichlids and other adaptive radiations make understanding the genomic basis of adaptive divergence more tractable. Then, I briefly overview some major findings and insights into vertebrate adaptation that have been gained through cichlid genetic studies. Finally, I discuss the extensive evolutionary replication provided by cichlid adaptive radiations and their potential for studies of genotype-to-phenotype mapping.

Gene duplication and differential gene expression play an important role in the diversification of visual pigments in fish

Hofmann, C. M., Carleton, K. L. — Mon, 16 Nov 2009 07:17:51 PST

Sensory systems provide crucial information about an organism's external environment and, thus, are often subject to strong natural selection. Because of the large variation in the intensity and spectral quality of light in aquatic environments, studies of sensory adaptation have focused on the visual systems of fish for over a half a century. Recently, the molecular genetic mechanisms that determine the spectral sensitivity of visual pigments have been characterized in several fishes including zebrafish, guppies, medaka, killifish, bream, and cichlids. The results of these studies suggest that teleost fish have incredibly diverse visual systems. In this paper, we review the role that opsin duplication and differential gene expression have played in the diversification of visual pigments. We compare our findings in cichlids to five other taxonomic groups and highlight the ways that their similarities and differences may provide new insights into the molecular genetic basis of sensory adaptation and diversification.

Interspecific profiling of gene expression informed by comparative genomic hybridization: A review and a novel approach in African cichlid fishes

Machado, H. E., Pollen, A. A., Hofmann, H. A., Renn, S. C.P. — Mon, 16 Nov 2009 07:17:51 PST

Modern genomic approaches have facilitated great progress in our understanding of the molecular and genetic underpinnings of ecological and evolutionary processes. Analysis of gene expression through heterologous hybridization in particular has enabled genome-scale studies in many ecologically and evolutionarily interesting species. However, these studies have been hampered by the difficulty of comparing—on a common array platform—gene-expression profiles across species due to sequence divergence altering the dynamics of hybridization. All too often, comparisons of expression profiles across species were limited to contrasting lists of gene or even of just functional categories. Here we review these issues and propose a novel solution. Exploiting the diverse cichlid lineages of East Africa as our model-system, we then present results from an experimental case study that compares the neural gene-expression profiles of males and females of two species that differ in mating system. Using a single microarray platform that contains genes from one species, Astatotilapia burtoni, we conducted a total of 16 direct comparisons for neural gene-expression level between individual males and females from a pair of sister species, the polygynous Enantiopus melanogenys and the monogamous Xenotilapia flavipinnis. Next, we conducted a meta-analysis with previously published data from two different intra-specific expression studies to determine whether sex-specific neural gene expression is more closely associated with behavioral phenotype than it is with gonadal sex. Our results indicate that the gene expression profiles are species-specific to a large extent, as relatively few genes show conserved expression patterns associated with either sex. Finally, we describe how competitive genomic DNA hybridizations between the two focal species allow us to assess the degree to which divergence of sequences biases the results. We propose a masking technique that correlates interspecific expression ratios obtained with cDNA with hybridization ratios obtained with genomic DNA for the same set of species and determines threshold sequence divergence to reduce false positives. Our approach should be applicable to a wide range of interesting questions related to the evolution and ecology of gene expression.

Maternal care and altered social phenotype in a recently collected stock of Astatotilapia burtoni cichlid fish

Renn, S. C. P., Carleton, J. B., Magee, H., Nguyen, M. L. T., Tanner, A. C. W. — Mon, 16 Nov 2009 07:17:51 PST

For over 30 years, the African cichlid fish, Astatotilapia burtoni, has been an important model system for studying the mechanisms underlying socially mediated behavioral change, with the focus being the dominance behavior of males. A recently collected wild-stock (WS) of this species invigorates interest in parallel studies of females’ behavior. Here, we describe a robust ‘good-mother’ phenotype, increased maternal affiliation in fry, and subtle differences in males’ behavior that are exhibited by this new stock. While the females of both the laboratory-stock (LS) and the WS brood the developing fry in their buccal cavity, only the WS continues to provide maternal care after initial release of the fry while the LS engage in filial cannibalism. We show that weight loss during starvation, either during brooding or with restriction of food, is greater in the LS than in the WS; thus, the observed behavioral differences may be tied to metabolic differences. The WS also exhibits a robust androgen response to challenge during the maternal care phase. Given the increasing power of genomic tools available for this species, the comparison of these two stocks will offer the opportunity to investigate the genetic and genomic basis of behavioral differences.

Using Drosophila for studying fundamental processes in hearing

Lu, Q., Senthilan, P. R., Effertz, T., Nadrowski, B., Gopfert, M. C. — Mon, 16 Nov 2009 07:17:51 PST

Apart from detecting sounds, vertebrate ears occasionally produce sounds. These spontaneous otoacoustic emissions are the most compelling evidence for the existence of the cochlear amplifier, an active force-generating process within the cochlea that resides in the motility of the hair cells. Insects have neither a cochlea nor hair cells, yet recent studies demonstrate that an active process that is equivalent to the cochlear amplifier occurs in at least some insect ears; like hair cells, the chordotonal sensory neurons that mediate hearing in Drosophila actively generate forces that augment the minute vibrations they transduce. This neuron-based force-generation, its impact on the ear's macroscopic performance, and the underlying molecular mechanism are the topics of this article, which summarizes some of the recent findings on how the Drosophila organ of hearing works. Functional parallels with vertebrate auditory systems are described that recommend the fly for the study of fundamental processes in hearing.

Active touch, exploratory movements, and sensory prediction

Hartmann, M. J. Z. — Mon, 16 Nov 2009 07:17:51 PST

The relation between somatosensory input and motor output is asymmetric. Somatosensation is associated with every movement an animal makes, but movement is not required for somatosensation. This symposium paper proposes a classification scheme for movement, in which movements are placed along a continuum that describes the role that somatosensory information plays during the movement. Fine sensorimotor control—manipulation and exploration—are found to fall to one extreme of the spectrum, and exploratory movements in particular are shown to possess characteristics that clearly distinguish them from other varieties of movement. Specifically, the exploratory process must permit animals to extract an object's features independently of the sequence of movements executed to explore the object. Based in part on our work on the rat vibrissal system, we suggest that exploration of objects may consist of two complementary levels of sensorimotor prediction operating in parallel. At the cognitive level, the animal might move so as to perform hypothesis testing about the identity or nature of the object. The particular hypothesis tests chosen by the animal might be implemented through sequences of control-level predictions that could be generated at the level of the brainstem and cerebellum.

The influence of viscous hydrodynamics on the fish lateral-line system

Windsor, S. P., McHenry, M. J. — Mon, 16 Nov 2009 07:17:51 PST

Fish exhibit many behaviors that involve sensing water flows with their lateral-line system. In many situations, viscosity affects how the flow interacts with the body of the fish and the neuromasts of the lateral line. Here we discuss how viscosity influences the stimulus to the fish lateral-line system. The movement of a fish's body creates flows that can interfere with the detection of external signals, but these flows can also serve as a source of information about nearby obstacles and the fish's own hydrodynamic performance. The viscous boundary layer on the surface of the skin alters external signals by attenuating the low-frequency components of stimuli. The stimulus to each neuromast depends on the interaction of the fluid surrounding the neuromast and the structural properties of that neuromast, including the number of mechanosensory hair cells it contains. A consideration of the influences of viscosity on flow, at both the whole-body and receptor levels, offers the promise of a more comprehensive understanding of the signals involved in behaviors mediated by the lateral-line system.

Environmental influences in the evolution of tetrapod hearing sensitivity and middle ear tuning

Gridi-Papp, M., Narins, P. M. — Mon, 16 Nov 2009 07:17:51 PST

Vertebrates inhabit and communicate acoustically in most natural environments. We review the influence of environmental factors on the hearing sensitivity of terrestrial vertebrates, and on the anatomy and mechanics of the middle ears. Evidence suggests that both biotic and abiotic environmental factors affect the evolution of bandwidth and frequency of peak sensitivity of the hearing spectrum. Relevant abiotic factors include medium type, temperature, and noise produced by nonliving sources. Biotic factors include heterospecific, conspecific, or self-produced sounds that animals are selected to recognize, and acoustic interference by sounds that other animals generate. Within each class of tetrapods, the size of the middle ear structures correlates directly to body size and inversely to frequency of peak sensitivity. Adaptation to the underwater medium in cetaceans involved reorganization of the middle ear for novel acoustic pathways, whereas adaptation to subterranean life in several mammals resulted in hypertrophy of the middle ear ossicles to enhance their inertial mass for detection of seismic vibrations. The comparative approach has revealed a number of generalities about the effect of environmental factors on hearing performance and middle ear structure across species. The current taxonomic sampling of the major tetrapod groups is still highly unbalanced and incomplete. Future expansion of the comparative evidence should continue to reveal general patterns and novel mechanisms.

Animal Osmoregulation. Tim Bradley.

Somero, G. N. — Mon, 16 Nov 2009 07:17:52 PST

The Genial Gene. Deconstructing Darwinian Selfishness. Joan Roughgarden.

Byers, J. — Mon, 16 Nov 2009 07:17:52 PST

Evolution of Communicative Flexibility - Complexity, Creativity, and Adaptability in Human and Animal Communication. D. Kimbrough Oller and Ulrike Griebel editors.

Miller, C. T., Osmanski, M. — Mon, 16 Nov 2009 07:17:52 PST

Evolution, Second Edition. Douglas J. Futuyma.

Mooi, R. — Mon, 16 Nov 2009 07:17:52 PST

Not By Design: Retiring Darwin's Watchmaker. John O. Reiss.

Hodge, A.-M. C. — Mon, 16 Nov 2009 07:17:52 PST

The Rise of Amphibians: 365 Million Years of Evolution. Robert Carroll.

Sues, H.-D. — Mon, 16 Nov 2009 07:17:52 PST

In the Light of Evolution, Volume II: Biodiversity and Extinction. John C. Avise, Stephen P. Hubbell, and Francisco J. Ayala, editors (National Research Council).

Voirin, B. — Mon, 16 Nov 2009 07:17:52 PST

Ecological Developmental Biology: Integrating Epigenetics, Medicine and Evolution. Scott F. Gilbert and David Epel.

Davidowitz, G. — Mon, 16 Nov 2009 07:17:52 PST

Insect Species Conservation. T. R. New.

Haddad, N. — Mon, 16 Nov 2009 07:17:52 PST

Sperm Biology - An Evolutionary Perspective. Tim R. Birkhead, Dave J. Hosken, and Scott Pitnick, editors.

Morrow, E. H. — Mon, 16 Nov 2009 07:17:52 PST

Morphological selection in an extreme flow environment: body shape and waterfall-climbing success in the Hawaiian stream fish Sicyopterus stimpsoni

Mon, 16 Nov 2009 07:17:52 PST

Integrative & Comparative Biology

Mon, 26 Oct 2009 21:38:41 PDT

2009 SICB Membership Application/Dues Renewal

Mon, 26 Oct 2009 21:38:42 PDT

Integrative & Comparative Biology - Volume 49 Number 5 November 2009 - Back cover

Mon, 26 Oct 2009 21:38:42 PDT

Integrative & Comparative Biology - Volume 49 Number 5 November 2009 - Front cover

Mon, 26 Oct 2009 21:38:42 PDT

Subscriptions

Mon, 26 Oct 2009 21:38:42 PDT

Integrative & Comparative Biology - Volume 49 Number 5 November 2009

Mon, 26 Oct 2009 21:38:42 PDT

Grand challenges in organismal biology: The need to develop both theory and resources

Halanych, K. M., Goertzen, L. R. — Mon, 26 Oct 2009 21:38:41 PDT

This contribution is fifth in a series of articles in Integrative and Comparative Biology that was initiated by Schwenk et al. (2009) and followed by Satterlie et al. (2009), Denny and Helmuth (2009), and Denver et al. (2009). Here, our intent is to be provocative and to stimulate further discourse. Like other contributors we have our own biases, and as it should be clear to the readers, we approach this task as evolutionary biologists, specifically systematists.

Food supplementation experiments: A tool to reveal mechanisms that mediate timing of reproduction

Schoech, S. J. — Mon, 26 Oct 2009 21:38:41 PDT

Food supplementation of free-living animals has been used to address the role of availability of resources in the timing of reproduction. A meta-analysis by Schoech and Hahn suggested that responsiveness of the reproductive axis to the supplementary cue of food is lessened at higher latitudes, presumably because the brief time during which conditions are appropriate to rear offspring has led to an evolved resistance to supplementary cues with a primary reliance on photoperiod. Unfortunately, few investigators have examined the potential underlying mechanisms that mediate this differential responsiveness to supplemental food across latitudes. Considerable research, however, links nutritional state and plasma glucocorticoid levels, both of which impinge upon the reproductive axis. Long-term research on Florida scrub-jays (Aphelocoma coerulescens) in my laboratory shows that suburban birds with access to ad libitum supplemental food express early breeding and lower plasma corticosterone (CORT) levels in comparison to jays in nearby natural habitat. Furthermore, supplementation in natural habitat advances laying, with the largest effects occurring in bad years (i.e., years defined by late breeding and poor reproductive output by non-supplemented controls). Similarly, reproductive output of supplemented jays is greater and exhibits considerably less variance than do controls, suggesting fitness benefits of supplementation that are tied to advanced breeding. Generally, CORT levels in early-breeding supplemented jays are lower than are those of controls. Also, regression analysis suggests that clutch-initiation dates of non-supplemented female breeders are predicted by baseline CORT levels. Although these data are not conclusive and trends can be obscured by year-effects, they suggest a role for CORT in timing of breeding. Whether this link might help to explain the above-referenced latitudinal trends remains to be characterized.

Proximate control and adaptive potential of protandrous migration in birds

Coppack, T., Pulido, F. — Mon, 26 Oct 2009 21:38:41 PDT

Migration determines where, when, and in which order males and females converge for reproduction. Protandry, the earlier arrival of males relative to females at the site of reproduction, is a widespread phenomenon found in many migratory organisms. Detailed knowledge of the determinants of protandry is becoming increasingly important for predicting how migratory species and populations will respond to rapid phenological shifts caused by climatic change. Here, we review and discuss the potential mechanisms underlying protandrous migration in birds, focusing on evidence from passerine species. Latitudinal segregation during the non-breeding period and differences in the initiation of spring migration are probably the key determinants of protandrous arrival at the breeding sites, while sexual differences in speed of migration appear to play a minor role. Experimental evidence suggests that differences between the sexes in the onset of spring migratory activity are caused by differences in circannual rhythmicity or by photoperiodic responsiveness. Both of these mechanisms are hardwired and could prevent individuals from responding plastically to chronic changes in temperature at the breeding grounds. As a consequence, adaptive changes in both the timing of arrival in spring and of reproduction will require evolutionary (genetic) changes of the cue-response systems underlying the initiation and extent of migration in both males and females.

Comparative analysis of the molecular basis of photoperiodic signal transduction in vertebrates

Yasuo, S., Yoshimura, T. — Mon, 26 Oct 2009 21:38:41 PDT

In temperate zones, the reproductive physiology of most vertebrates is controlled by changes in photoperiod. Mechanisms for the regulation of photoperiodic gonadal responses are known to differ between mammals and birds: in mammals, melatonin is the photoperiodic signal messenger, whereas in birds, photoperiodic information is received by deep brain photoreceptors. Recently, the molecular mechanism of photoperiodism has been revealed by studies on Japanese quail, which exhibit a most remarkable responsiveness to photoperiod among vertebrates, and molecular cascades involved in photoperiodism have been elucidated. Long-day stimulus induces expression of the β-subunit of thyroid stimulating hormone (TSH-β) in the pars tuberalis (PT) of the pituitary gland, and TSH derived from the PT regulates reciprocal switching of genes encoding types 2 and 3 deiodinases (Dio2 and Dio3, respectively) in the mediobasal hypothalamus (MBH) by retrograde action. Dio2 locally converts prohormone thyroxine (T₄) to bioactive triiodothyronine (T₃) in the MBH, which subsequently stimulates the gonadal axis. These events have been confirmed to occur in mammals with seasonal breeding, such as hamsters and sheep, suggesting that similar mechanisms are involved among various vertebrates. In addition, nonphotoperiodic mice also appeared to possess the same molecular mechanisms at the hypothalamo-hypophysial level. It has been noted that melatonin regulates the above-mentioned key genes (Dio2, Dio3, and TSH-β) in mammals, while photoperiod directly regulates these genes in birds. Thus, the input pathway of photoperiod is different between mammals and birds (i.e., melatonin versus light); however, the essential mechanisms are conserved among these vertebrates.

Proximate mechanisms driving circadian control of neuroendocrine function: Lessons from the young and old

Mon, 26 Oct 2009 21:38:41 PDT

Circadian rhythms impact a variety of behavioral and physiological functions contributing to longevity and successful reproduction. In their natural environments, individuals of a species are faced with a multitude of challenges and the coordination of internal processes and behavior with external pressures has been hypothesized to be an important target of natural selection. Several lines of evidence from cyanobacteria, Drosophila, and plants provide strong support for an important role of the circadian clock in survival and reproductive success. Similarly in mammals, disruptions in circadian function markedly impact reproduction and lifespan. The present review discusses research outlining the proximate and ultimate mechanisms responsible for the central and peripheral control of the reproductive axis. Because precise temporal coordination of the endocrine system is particularly crucial for reproduction by females, the present overview focuses on the role of circadian timing in this sex.

Opportunism, photoperiodism, and puberty: Different mechanisms or variations on a theme?

Perfito, N., Bentley, G. E. — Mon, 26 Oct 2009 21:38:41 PDT

There are many parallels between the neural regulation of seasonal breeding in birds and puberty in primates, but most studies of the regulation of puberty in vertebrates involve the use of rodents. The findings from rodent studies are often perceived as being typical of mammals and therefore pertinent to human reproductive biology and in many cases, rodent models have a great deal to offer in terms of an understanding of the regulation of puberty and reproductive biology. However, knowledge available from comparative work perhaps highlights mechanistic similarities that may not exist between rodent and primate systems. In this short review, we highlight some of the advantages of studying avian reproductive biology in this regard. We discuss disparities between rodent puberty and primate puberty, and similarities between primates and birds. Thus, understanding the mechanisms regulating avian puberty and seasonal breeding might in some cases provide greater insight into the mechanistic control of puberty in nonrodent mammals. We also describe in detail the neuroendocrine regulation of reproduction in birds and aim to provoke discussion of the possible roles of thyroid hormones and multiple forms of gonadotropin-releasing hormone in avian and mammalian reproduction.

Microevolution of neuroendocrine mechanisms regulating reproductive timing in Peromyscus leucopus

Heideman, P. D., Pittman, J. T. — Mon, 26 Oct 2009 21:38:41 PDT

A key question in the evolution of life history and in evolutionary physiology asks how reproductive and other life-history traits evolve. Genetic variation in reproductive control systems may exist in many elements of the complex inputs that can affect the hypothalamic–pituitary–gonadal (HPG) or reproductive axis. Such variation could include numbers and other traits of secretory cells, the amount and pattern of chemical message released, transport and clearance mechanisms, and the number and other traits of receptor cells. Selection lines created from a natural population of white-footed mice (Peromyscus leucopus) that contains substantial genetic variation in reproductive inhibition in response to short winter daylength (SD) have been used to examine neuroendocrine variation in reproductive timing. We hypothesized that natural genetic variation would be most likely to occur in the inputs to GnRH neurons and/or in GnRH neurons themselves, but not in elements of the photoperiodic pathway that would have pleiotropic effects on nonreproductive functions as well as on reproductive functions. Significant genetic variation has been found in the GnRH neuronal system. The number of GnRH neurons immunoreactive to an antibody to mature GnRH peptide under conditions maximizing detection of stained neurons was significantly heritable in an unselected control (C) line. Furthermore, a selection line that suppresses reproduction in SD (photoperiod responsive, R) had fewer IR-GnRH neurons than a selection line that maintains reproduction in SD (photoperiod nonresponsive, NR). This supports the hypothesis that genetic variation in characteristics of GnRH neurons themselves may be responsible for the observed phenotypic variation in reproduction in SD. The R and NR lines differ genetically in food intake and iodo-melatonin receptor binding, as well as in other characteristics. The latter findings are consistent with the hypothesis that genetic variation occurs in the nutritional and hormonal inputs to GnRH neurons. Genetic variation also exists in the phenotypic plasticity of responses to two combinations of treatments, (1) food and photoperiod, and (2) photoperiod and age, indicating genetic variation in individual norms of reaction within this population. Overall, the apparent multiple sources of genetic variation within this population suggest that there may be multiple alternative combinations of alleles for both the R and NR phenotypes. If that interpretation is correct, we suggest that this offers some support for the evolutionary "potential" hypothesis and is inconsistent with the evolutionary "constraint" and "symmorphosis" hypotheses for the evolution of complex neuroendocrine pathways.

Geographically distinct reproductive schedules in a changing world: Costly implications in captive Stonechats

Helm, B. — Mon, 26 Oct 2009 21:38:41 PDT

With progressively faster global change, shifts in phenology, and distributional ranges are reported for an increasing number of species. The success of organisms at coping with novel seasonal conditions depends on the mechanisms that determine their schedules. Species that rely on fixed schedules and those that time their activities by predictive cues may be particularly constrained in their ability to accommodate changes. The present study examines rigid scheduling and its implications for breeding in captivity in an avian model taxon, the Stonechat (Saxicola torquata). Within their extensive breeding range, Stonechats differ geographically in migratory behavior and reproduce and molt under a wide range of daylengths (10–17 h). Stonechats time their activities by programs that involve circannual rhythms and photoperiodism. The study reports reproductive timing of four taxa (central European, Irish, Siberian, and Kenyan), relates it to laydates in the field, and investigates modifying influences of housing conditions and of social context. Reproductive consequences of timing programs were then tested by crossbreeding of taxa with different schedules. The study revealed persistent, population-specific breeding windows in captivity. Resident Stonechats from equatorial Kenya synchronized their reproductive cycles with the European summer, presumably in response to local photoperiod, and bred at similar times as northern migrants. In all other taxa schedules matched those in the field, but were timed slightly earlier in captivity and advanced by indoor keeping conditions. Influences of social context were negligible. In pairs with clutches, testes regressed slightly later than in pairs without clutches, but presence of a mate per se had no influence on breeding cycles. Accordingly, crossbreeding Stonechats were predicted to have limited capacity to adjust schedules to those of their mates. This prediction was tested by crossbreeding of single-clutched Siberian long-distance migrants with multiple-clutched European short-distance migrants. Males and females of both taxa retained their characteristic breeding schedules, regardless of their mate's activities. This led to dramatic loss of reproductive success in the population with the longer breeding season, European Stonechats. Siberian Stonechats were unable to profit from the presence of a sexually active mate, but they suffered no disadvantage from crossbreeding. In a changing world, inherited timing programs may severely constrain responses to novel conditions, impose schedule-dependent, asymmetric costs of hybridization, and contribute to directional gene flow or to reproductive isolation.

The evolution of photoperiod response systems and seasonal GnRH plasticity in birds

Mon, 26 Oct 2009 21:38:41 PDT

Animals’ lives are typically subdivided into distinct stages, some of which (e.g. breeding) contribute to fitness through enhancing current reproductive success, and some of which (e.g. molting and migration in birds; hibernation in mammals) contribute to fitness through enhancing survival and, therefore, future reproductive opportunities. There is often a trade-off between these two kinds of processes, either because they are temporally incompatible with one another (e.g. migration precludes simultaneous nesting in birds) or because they are energetically incompatible with one another (e.g. successful molting appears to be incompatible with simultaneous nesting in many birds). Consequently, adaptations facilitating appropriate timing and coordination of different life-cycle stages are arguably as important to fitness as are more obvious adaptations such as feeding morphologies and predator avoidance. Mechanisms that facilitate coordination of life-cycle events with the annual cycle of changes in the environment are therefore expected to evolve in response to selection imposed by different environmental challenges. This article focuses on how mechanisms affecting the timing of, and transitions between, life-cycle stages, particularly breeding, have evolved in birds. Through comparative analyses, we show that photorefractoriness and one neuroendocrine correlate of it—plasticity of the gonadotropin releasing hormone system—have evolved in ways that facilitate different degrees of flexibility in timing of the transition from breeding to molting in different environments. We argue that the nature of the mechanistic adaptations will affect the capacity for adaptive adjustments to changing environmental conditions both in the short term (plasticity inherent in individuals) and in the long term (evolutionary responses of populations to selection).

Episodes in insect evolution

Mon, 26 Oct 2009 21:38:41 PDT

This article derives from a society-wide symposium organized by Timothy Bradley and Adriana Briscoe and presented at the 2009 annual meeting of the Society for Integrative and Comparative Biology in Boston, Massachusetts. David Grimaldi provided the opening presentation in which he outlined the major evolutionary events in the formation and subsequent diversification of the insect clade. This presentation was followed by speakers who detailed the evolutionary history of specific physiological and/or behavioral traits that have caused insects to be both ecologically successful and fascinating as subjects for biological study. These include a review of the evolutionary history of the insects, the origins of flight, osmoregulation, the evolution of tracheal systems, the evolution of color vision, circadian clocks, and the evolution of eusociality. These topics, as covered by the speakers, provide an overview of the pattern and timing of evolutionary diversification and specialization in the group of animals we know as insects.

Integrated Pest Management: Concepts, Tactics, Strategies and Case Studies. Edward B. Radcliffe, William D. Hutchinson, and Rafael E. Cancelado, editors

Toth, S. J. — Mon, 26 Oct 2009 21:38:41 PDT

Animal Behavior, Ninth edition. John Alcock.

Engell, M. — Mon, 26 Oct 2009 21:38:41 PDT

Clonality: The Genetics, Ecology, and Evolution of Sexual Abstinence in Vertebrate Animals. John C. Avise.

Hammock, E. — Mon, 26 Oct 2009 21:38:41 PDT

Biology of the Reptilia. Volume 20, Morphology H, The Skull of Lepidosauria. Carl Gans, Abbot S. Gaunt, and Kraig Adler, editors.

Heatwole, H. — Mon, 26 Oct 2009 21:38:41 PDT

Integrative & Comparative Biology

Mon, 14 Sep 2009 02:18:10 PDT

2009 SICB Membership Application/Dues Renewal

Mon, 14 Sep 2009 02:18:11 PDT

Integrative & Comparative Biology - Volume 49 Number 4 October 2009 - Back cover

Mon, 14 Sep 2009 02:18:11 PDT

Integrative & Comparative Biology - Volume 49 Number 4 October 2009 - Front cover

Mon, 14 Sep 2009 02:18:11 PDT

Subscriptions

Mon, 14 Sep 2009 02:18:11 PDT

Integrative & Comparative Biology - Volume 49 Number 4 October 2009

Mon, 14 Sep 2009 02:18:11 PDT

Comparative endocrinology in the 21st century

Mon, 14 Sep 2009 02:18:10 PDT

Hormones coordinate developmental, physiological, and behavioral processes within and between all living organisms. They orchestrate and shape organogenesis from early in development, regulate the acquisition, assimilation, and utilization of nutrients to support growth and metabolism, control gamete production and sexual behavior, mediate organismal responses to environmental change, and allow for communication of information between organisms. Genes that code for hormones; the enzymes that synthesize, metabolize, and transport hormones; and hormone receptors are important targets for natural selection, and variation in their expression and function is a major driving force for the evolution of morphology and life history. Hormones coordinate physiology and behavior of populations of organisms, and thus play key roles in determining the structure of populations, communities, and ecosystems. The field of endocrinology is concerned with the study of hormones and their actions. This field is rooted in the comparative study of hormones in diverse species, which has provided the foundation for the modern fields of evolutionary, environmental, and biomedical endocrinology. Comparative endocrinologists work at the cutting edge of the life sciences. They identify new hormones, hormone receptors and mechanisms of hormone action applicable to diverse species, including humans; study the impact of habitat destruction, pollution, and climatic change on populations of organisms; establish novel model systems for studying hormones and their functions; and develop new genetic strains and husbandry practices for efficient production of animal protein. While the model system approach has dominated biomedical research in recent years, and has provided extraordinary insight into many basic cellular and molecular processes, this approach is limited to investigating a small minority of organisms. Animals exhibit tremendous diversity in form and function, life-history strategies, and responses to the environment. A major challenge for life scientists in the 21st century is to understand how a changing environment impacts all life on earth. A full understanding of the capabilities of organisms to respond to environmental variation, and the resilience of organisms challenged by environmental changes and extremes, is necessary for understanding the impact of pollution and climatic change on the viability of populations. Comparative endocrinologists have a key role to play in these efforts.

Hormonal regulation of whole-animal performance: Implications for selection

Husak, J. F., Irschick, D. J., McCormick, S. D., Moore, I. T. — Mon, 14 Sep 2009 02:18:10 PDT

Steroid use and human performance: Lessons for integrative biologists

Husak, J. F., Irschick, D. J. — Mon, 14 Sep 2009 02:18:10 PDT

While recent studies have begun to address how hormones mediate whole-animal performance traits, the field conspicuously lags behind research conducted on humans. Recent studies of human steroid use have revealed that steroid use increases muscle cross-sectional area and mass, largely due to increases in protein synthesis, and muscle fiber hypertrophy attributable to an increased number of satellite cells and myonuclei per unit area. These biochemical and cellular effects on skeletal muscle morphology translate into increased power and work during weight-lifting and enhanced performance in burst, sprinting activities. However, there are no unequivocal data that human steroid use enhances endurance performance or muscle fatigability or recovery. The effects of steroids on human morphology and performance are in general consistent with results found for nonhuman animals, though there are notable discrepancies. However, some of the discrepancies may be due to a paucity of comparative data on how testosterone affects muscle physiology and subsequent performance across different regions of the body and across vertebrate taxa. Therefore, we advocate more research on the basic relationships among hormones, morphology, and performance. Based on results from human studies, we recommend that integrative biologists interested in studying hormone regulation of performance should take into account training, timing of administration, and dosage administered when designing experiments or field studies. We also argue that more information is needed on the long-term effects of hormone manipulation on performance and fitness.

Phenotypic integration and independence: Hormones, performance, and response to environmental change

Ketterson, E. D., Atwell, J. W., McGlothlin, J. W. — Mon, 14 Sep 2009 02:18:10 PDT

Hormones coordinate the co-expression of behavioral, physiological, and morphological traits, giving rise to correlations among traits and organisms whose parts work well together. This article considers the implications of these hormonal correlations with respect to the evolution of hormone-mediated traits. Such traits can evolve owing to changes in hormone secretion, hormonal affinity for carrier proteins, rates of degradation and conversion, and interaction with target tissues to name a few. Critically, however, we know very little about whether these changes occur independently or in tandem, and thus whether hormones promote the evolution of tight phenotypic integration or readily allow the parts of the phenotype to evolve independently. For example, when selection favors a change in expression of hormonally mediated characters, is that alteration likely to come about through changes in hormone secretion (signal strength), changes in response to a fixed level of secretion (sensitivity of target tissues), or both? At one extreme, if the phenotype is tightly integrated and only the signal responds via selection's action on one or more hormonally mediated traits, adaptive modification may be constrained by past selection for phenotypic integration. Alternatively, response to selection may be facilitated if multivariate selection favors new combinations that can be easily achieved by a change in signal strength. On the other hand, if individual target tissues readily "unplug" from a hormone signal in response to selection, then the phenotype may be seen as a loose confederation that responds on a trait-by-trait basis, easily allowing adaptive modification, although perhaps more slowly than if signal variation were the primary mode of evolutionary response. Studies reviewed here and questions for future research address the relative importance of integration and independence by comparing sexes, individuals, and populations. Most attention is devoted to the hormone testosterone (T) and a songbird species, the dark-eyed junco (Junco hyemalis).

Hormonal regulation of energy metabolism in insects as a driving force for performance

Lorenz, M. W., Gade, G. — Mon, 14 Sep 2009 02:18:10 PDT

Since all life processes depend on energy, the endocrine control of energy metabolism is one of the driving forces for the performance of an individual. Here, we review the literature on the key players in the endocrine regulation of energy homeostasis in insects, the adipokinetic hormones. These pleiotropic peptides not only control dynamic performance traits (flight, swimming, walking) but also regulatory performance traits (egg production, larval growth, and molting). Adipokinetic hormone is released into the hemolymph during intense muscular activity (flight) and also during apparently less energy-demanding locomotory activities, such as swimming and even walking, and, finally, activates the catabolic enzymes phosphorylase and/or triacylglycerol lipase that mobilize carbohydrates and/or lipids and proline, respectively. At the same time, anabolic processes such as the synthesis of protein, lipid, and glycogen are inhibited. Furthermore, adipokinetic hormones affect locomotory activity via neuromodulatory mechanisms that apparently employ biogenic amines. During oogenesis, it is thought that adipokinetic hormone performs similar tasks, because energetic substrates have to be mobilized and transported from the fat body to the ovaries in order to support oocyte growth. Inhibition of anabolic processes by exogenous adipokinetic hormone results in females that lay fewer and smaller eggs. Much less is known about the role of adipokinetic hormones during larval development and during molting but in this case energy homeostasis has to be tightly regulated as well: in general, during the early phase of a larval instar intake of food prevails and the energy stores of the fat body are established, whereas, prior to the molt, insects stop feeding and mobilize energy stores in the fat body, thereby fueling energy-demanding processes such as the formation of the new cuticle and the emergence from the old one. From the few data available to date, it is clear that adipokinetic hormones are involved in the regulation of these events in larvae.

Hormones, performance and fitness: Natural history and endocrine experiments on a lizard (Sceloporus undulatus)

John-Alder, H. B., Cox, R. M., Haenel, G. J., Smith, L. C. — Mon, 14 Sep 2009 02:18:10 PDT

We used the "morphology–performance–fitness" paradigm (Arnold, 1983) as our framework to investigate endocrine control of performance and fitness in Sceloporus undulatus (Eastern Fence Lizard). Focusing on males, we used the "natural experiments" of seasonal, sexual, and developmental variation in growth and in exercise endurance to identify testosterone and corticosterone as potential modulators of performance and related traits of interest. We followed with experimental manipulations of testosterone to investigate functional relationships, both in the laboratory and in the field. Further, we used focal observations and demographic studies, coupled with genetic determination of paternity, to test associations between performance and fitness, measured as reproductive success. We found that in males, endurance and plasma concentrations of testosterone and corticosterone are at their peaks in the spring breeding season, when lizards are most actively engaged in patrolling home ranges and in reproductive behavior. At that time, plasma concentrations of testosterone are correlated with body size; plasma concentrations of corticosterone and parameters of home range, including area and the number of overlapped females, are correlated with home-range overlap between males and females. During prereproductive development, males (but not females) experience a maturational increase in plasma testosterone. At about the same time, they become more active, expand their home ranges, and grow less quickly than do females, suggesting a trade-off in the allocation of energy, mediated by testosterone. Experimentally, testosterone has positive effects on fitness by stimulating endurance and reproductive activity and increasing home-range area, but it exacts costs in fitness by increasing ectoparasitism, decreasing growth, and decreasing survivorship. We found evidence of selection on body size, endurance, and home-range size (and thus access to potential mates). Despite having positive effects on performance traits, plasma concentrations of testosterone were not correlated with number of offspring sired by males. However, we found a strong correlation between the level of plasma corticosterone and the number of offspring sired. We also found evidence of size-assortative mating, indicating that for males, both the number and the size (and thus, fecundity) of their mates increase with body size. Our studies exemplify the power of natural history combined with experimental endocrine manipulations to identify hormonal regulators of performance and linkages to fitness. Furthermore, our results illustrate ecological and evolutionary significance of individual variation in endocrine traits.

Evolution of the hormonal control of animal performance: Insights from the seaward migration of salmon

McCormick, S. D. — Mon, 14 Sep 2009 02:18:10 PDT

The endocrine system is the key mediator of environmental and developmental (internal) information, and is likely to be involved in altering the performance of animals when selection has favored phenotypic plasticity. The endocrine control of performance should be especially pronounced in animals that undergo a developmental shift in niche, such as occurs in migratory species. By way of example, I review the developmental and environmental control of the preparatory changes for seawater entry of juvenile salmon (known as smolting) and its hormonal regulation. There is a size threshold for smolt development in juvenile Atlantic salmon that results in greater sensitivity of the growth hormone and cortisol axes to changes in daylength. These hormones, in turn, have broad effects on survival, ion homeostasis, growth and swimming performance during entry into seawater. Migratory niche shifts and metamorphic events are extreme examples of the role of hormones in animal performance and represent one end of a continuum. A framework for predicting when hormones will be involved in performance of animals is presented. Endocrine involvement in performance will be more substantial when (1) selection differentials on traits underlying performance are high and temporally discontinuous over an animal's lifetime, (2) the energetic and fitness costs of maintaining performance plasticity are less than those of constant performance, (3) cues for altering performance are reliable indicators of critical environmental conditions, require neurosensory input, and minimize effects of lag, and (4) the need for coordination of organs, tissues and cells to achieve increased performance is greater. By examining these impacts of selection, endocrinologists have an opportunity to contribute to the understanding of performance, phenotypic plasticity, and the evolution of life-history traits.

Social behavior in context: Hormonal modulation of behavioral plasticity and social competence

Oliveira, R. F. — Mon, 14 Sep 2009 02:18:10 PDT

In social species animals should fine-tune the expression of their social behavior to social environments in order to avoid the costs of engaging in costly social interactions. Therefore, social competence, defined as the ability of an animal to optimize the expression of its social behavior as a function of the available social information, should be considered as a performance trait that impacts on the Darwinian fitness of the animal. Social competence is based on behavioral plasticity which, in turn, can be achieved by different neural mechanisms of plasticity, namely by rewiring or by biochemically switching nodes of a putative neural network underlying social behavior. Since steroid hormones respond to social interactions and have receptors extensively expressed in the social behavioral neural network, it is proposed that steroids play a key role in the hormonal modulation of social plasticity. Here, we propose a reciprocal model for the action of androgens on short-term behavioral plasticity and review a set of studies conducted in our laboratory using an African cichlid fish (Oreochromis mossambicus) that provide support for it. Androgens are shown to be implicated as physiological mediators in a wide range of social phenomena that promote social competence, namely by adjusting the behavioral response to the nature of the intruder and the presence of third parties (dear enemy and audience effects), by anticipating territorial intrusions (bystander effect and conditioning of the territorial response), and by modifying future behavior according to prior experience of winning (winner effect). The rapid behavioral actions of socially induced short-term transient changes in androgens indicate that these effects are most likely mediated by nongenomic mechanisms. The fact that the modulation of rapid changes in behavior is open to the influence of circulating levels of androgens, and is not exclusively achieved by changes in central neuromodulators, suggests functional relevance of integrating body parameters in the behavioral response. Thus, the traditional view of seeing neural circuits as unique causal agents of behavior should be updated to a brain–body–environment perspective, in which these neural circuits are embodied and the behavioral performance (and outcomes as fitness) depends on a dynamic relationship between the different levels. In this view hormones play a major role as behavioral modulators.

Interactions and trade-offs among physiological determinants of performance and reproductive success

Moore, I. T., Hopkins, W. A. — Mon, 14 Sep 2009 02:18:10 PDT

How an animal performs in its natural environment ultimately plays a key role in its reproductive success. While a number of studies have investigated how selection acts on performance-related traits, far fewer studies have examined the mechanisms responsible for variation in performance. Among mechanisms, variable morphology has received the most attention. Although physiological traits have received less attention, they are intrinsically related to performance and ultimately to reproductive success. We present a framework whereby investigators can link some basic physiological functions with organismal performance and ultimately with reproductive success. We propose that performance and ultimately reproductive success are strongly influenced by hormones, immune functions, and energetics. We further argue that no physiological function can be considered in isolation and thus our model emphasizes interactions and trade-offs both within each physiological function as well as among them. Some of the most commonly studied trade-offs are between reproduction and immune functions, with energetics as one of the key common currencies for these trade-offs. From an evolutionary perspective, the largest gaps in our knowledge lie in how these interactions and trade-offs influence reproductive success. We believe that a full understanding of how hormones, immune functions, and energetics influence performance traits related to reproduction and, ultimately, lifetime reproductive success requires recognition of the complex relationships, interactions, and trade-offs among these processes.

Hormones and acoustic communication in anuran amphibians

Leary, C. J. — Mon, 14 Sep 2009 02:18:10 PDT

Circulating hormone levels can mediate changes in the quality of courtship signals by males and/or mate choice by females and may thus play an important role in the evolution of courtship signals. Costs associated with shifts in hormone levels of males, for example, could effectively stabilize directional selection by females on male signals. Alternatively, if hormone levels affect the selection of mates by females, then variation in hormone levels among females could contribute to the maintenance of variability in the quality of males’ signals. Here, I review what is known regarding the effects of hormone levels on the quality of acoustic signals produced by males and on the choice of mates by females in anuran amphibians. Surprisingly, despite the long history of anuran amphibians as model organisms for studying acoustic communication and physiology, we know very little about how variation in circulating hormone levels contributes to variation in the vocal quality of males. Proposed relationships between androgen levels and vocal quality depicted in recent models, for example, are subject to the same criticisms raised for similar models proposed in relation to birds, namely that the evidence for graded effects of androgens on vocal performance is often weak or not rigorously tested and responses seen in one species are often not observed in other species. Although several studies offer intriguing support for graded effects of hormones on calling behavior, additional comparative studies will be required to understand these relationships. Recent studies indicate that hormones may also mediate changes in anuran females’ choice of mates, suggesting that the hormone levels of females can influence the evolution of males’ mating signals. No studies to date have concurrently addressed the potential complexity of hormone–behavior relationships from the perspective of sender as well as receiver, nor have any studies addressed the costs that are potentially associated with changes in circulating hormone levels in anurans (i.e., life-history tradeoffs associated with elevations in circulating androgens in males). The mechanisms involved in hormonally induced changes in signal production and selectivity also require further investigation. Anuran amphibians are, in many ways, conducive to investigating such questions.

Carrots and Sticks: Principles of Animal Training. Paul McGreevy and Robert Boakes.

Frear, L. — Mon, 14 Sep 2009 02:18:10 PDT

Integration of Ecology and Endocrinology in Avian Reproduction: A New Synthesis. John C. Wingfield, Marcel E. Visser and Tony D. Williams, editors.

Gill, S. A. — Mon, 14 Sep 2009 02:18:10 PDT

The Biology of Caves and Other Subterranean Habitats. David C. Culver and Tanja Pipan.

Simon, K. S. — Mon, 14 Sep 2009 02:18:10 PDT