Ontogeny as a whole: Some developmental trends

In many animal groups, rudimentary organs of adult organisms appear at early stages of egg cleavage, when there is no trace of morphological differentiation. More than half a century ago, I. I. Schmalhausen developed a profound concept of integrity of the organism in the course of development. He emphasized that mutual adaptation of organs is based on correlations, involving the so-called nonhereditary modifications, which are transformed into hereditary traits by means of natural selection. There are many exceptions to the biogenetic law, as it was understood by de Beer. In particular, embryo of the pouched tree frog Gastrotheca shows a retarded development and is spread over the yolk surface. As a result, it becomes similar somewhat to embryos of amniotes. After the metamorphosis, Xenopus returns to ammonotelism. The integrity of ontogeny at the molecular level has much in common with the neutrality theory.     

Turtles Are Not Just Walking Stones: Conspicuous Coloration and Sexual Selection in Freshwater Turtles

Turtles are among the most intriguing amniotes but their communication and signaling have rarely been studied. Traditionally, they have been seen as basically just silent armored ‘walking stones’ with complex physiology but no altruism, maternal care, or aesthetic perception. Recently, however, we have witnessed a radical change in the perception of turtle behavioral and cognitive skills. In our study, we start by reviewing some recent findings pertaining to various highly developed behavioral and cognitive patterns with special emphasis on turtles. Then we focus on freshwater turtles and use data about their sexual behavior and size sexual dimorphism (SSD) to test whether conspicuous coloration of the head is in these animals related to sexual processes. We found that absence of aggressive mating behavior is statistically associated with the presence of conspicuous coloration on turtles’ heads. It also seems that while species with female-biased SSD are characterised by conspicuously colored head ornaments, in species with male-biased SSD conspicuous coloration is absent. Unlike large females, males thus seem to be under pressure to develop conspicuous coloration and engage in non-aggressive behavior using signaling to succeed in courtship. And finally, we discuss possible roles of head color patterns in turtle communication during mating.     

The Ontogeny of Sexual Size Dimorphism of a Moth: When Do Males and Females Grow Apart?

Sexual dimorphism in body size (sexual size dimorphism) is common in many species. The sources of selection that generate the independent evolution of adult male and female size have been investigated extensively by evolutionary biologists, but how and when females and males grow apart during ontogeny is poorly understood. Here we use the hawkmoth, Manduca sexta, to examine when sexual size dimorphism arises by measuring body mass every day during development. We further investigated whether environmental variables influence the ontogeny of sexual size dimorphism by raising moths on three different diet qualities (poor, medium and high). We found that size dimorphism arose during early larval development on the highest quality food treatment but it arose late in larval development when raised on the medium quality food. This female-biased dimorphism (females larger) increased substantially from the pupal-to-adult stage in both treatments, a pattern that appears to be common in Lepidopterans. Although dimorphism appeared in a few stages when individuals were raised on the poorest quality diet, it did not persist such that male and female adults were the same size. This demonstrates that the environmental conditions that insects are raised in can affect the growth trajectories of males and females differently and thus when dimorphism arises or disappears during development. We conclude that the development of sexual size dimorphism in M. sexta occurs during larval development and continues to accumulate during the pupal/adult stages, and that environmental variables such as diet quality can influence patterns of dimorphism in adults.     

Sexual Dimorphism in Melanin Pigmentation,Feather Coloration and Its Heritability in the Barn Swallow (Hirundo rustica)

Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex- and age-related variation, and heritability. The concentrations of eu- and pheomelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both melanins whereas coloration of throat feathers was only predicted by pheomelanin in females. In addition, Pheo:Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable.     

The Cannabinoid CB<Subscript>1</Subscript> Receptor Antagonist,Rimonabant, as a Promising Pharmacotherapy for Alcohol Dependence: Preclinical Evidence

Several lines of preclinical evidence indicate the ability of the prototypic cannabinoid CB₁ receptor antagonist, rimonabant, to suppress various alcohol-related behaviors, including alcohol drinking and seeking behavior and alcohol self-administration in rats and mice. Together, these data—synthetically reviewed in the present paper—suggest (a) the involvement of the cannabinoid CB₁ receptor in the neural substrate controlling alcohol intake, alcohol reinforcement, and the motivational properties of alcohol and (b) that rimonabant may constitute a new and potentially effective medication for the treatment of alcohol dependence.     

A Sexual Ornament in Chickens Is Affected by Pleiotropic Alleles at HAO1 and BMP2, Selected during Domestication

Domestication is one of the strongest forms of short-term, directional selection. Although selection is typically only exerted on one or a few target traits, domestication can lead to numerous changes in many seemingly unrelated phenotypes. It is unknown whether such correlated responses are due to pleiotropy or linkage between separate genetic architectures. Using three separate intercrosses between wild and domestic chickens, a locus affecting comb mass (a sexual ornament in the chicken) and several fitness traits (primarily medullary bone allocation and fecundity) was identified. This locus contains two tightly-linked genes, BMP2 and HAO1, which together produce the range of pleiotropic effects seen. This study demonstrates the importance of pleiotropy (or extremely close linkage) in domestication. The nature of this pleiotropy also provides insights into how this sexual ornament could be maintained in wild populations.     

Parasite-induced Host Mortality: Indirect Evidence From a Long-term Study

A long-term field study of a perturbed host–helminth system provides indirect evidence that a long-lived swimbladder nematode, Cystidicola farionis, induces mortality of Arctic charr, Salvelinus alpinus. The prevalence and abundance of this parasite has changed little over the period from 1987 to 1999. The cumulative numbers of L₃-stage larvae steadily increased with increasing host age, indicating a continuous exposure to infection throughout the life of the target fish host. Indirect methods, which used data pooled over years and long-term cohort analyses, indicate that parasite-induced host mortality (PIHM) occurs in hosts older than 10 years. Furthermore, using a short-term cohort method adjusted for worm recruitment, we found indications of PIHM occurrence even in younger age groups. These patterns do not seem to be caused by high parasite mortality rates since dead worms are rarely observed inside the swimbladder. Age-related changes in infection rates or in resistance to infection seem to play only a minor role as there were only slight changes in the preference of charr for feeding on amphipods (which are intermediate hosts) and in the acquisition rate of L₃ larvae in older hosts. Mortality of the most heavily infected hosts is the most probable explanation for the observed patterns.     

Opercular Flaps as Sexual Ornaments for Male Longear Sunfish (Lepomis megalotis): Male Condition and Male-Male Competition

Male longear sunfish, Lepomis megalotis , have longer opercular flaps than females, and females are known to prefer males with longer flaps, suggesting that these exaggerated structures serve as sexual ornaments. We tested the hypothesis that opercular flap length is associated with body condition and is therefore potentially an honest indicator of male quality. Opercular flaps grew significantly faster than pelvic fin spines, a non-sexually selected trait, regardless of diet treatment, suggesting an advantage to having fast-growing opercular flaps. Growth indices (opercular flap growth divided by pelvic fin spine growth) of males fed a larger ration were greater than those of males fed a smaller ration, although the difference was marginally non-significant. We also tested for an effect of opercular flap length on resource holding power by manipulating flap length on pairs of males matched for body length. In an experiment where opercular flaps were clipped to different lengths, only longer original (unmanipulated) flap length was associated with a significantly greater frequency of dominance. In a corollary experiment where opercular flaps were artificially lengthened, the abnormally long-flapped males were dominant significantly more often than the 'normal' males given transparent extensions. These results indicate that the opercular flap length of male longear sunfish may serve as an honest indicator of male quality and may be used to assess the resource holding power of rival males.     

Sexual jealousy as a facultative trait: Evidence from the pattern of sex differences in adults from China and the United States

Across two studies, 716 and 308 undergraduate students from the United States and mainland China, respectively, were administered a series of measures on jealousy, emotional responses to partner infidelity, family background, and personality. Across both studies for the U.S. and Chinese samples, a higher proportion of males than females reported more distress to a partner's imagined sexual infidelity than to emotional infidelity, whereas a higher proportion of females than males reported more distress to a partner's emotional infidelity than to sexual infidelity, consistent with theoretical expectations and previous empirical research. However, a much higher proportion of U.S. males and females reported more distress to sexual infidelity than their same-sex Chinese peers, suggesting that the tendency toward sexual jealousy might be facultatively influenced by sexual permissiveness in the general culture. The overall pattern of results is considered in terms of individual and contextual differences in the expression of jealousy, as well as in terms of the emotional and behavioral responses associated with jealousy reactions.     

Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection,Mate Choice,and Sexual Conflict

Genital coevolution between the sexes is expected to be common because of the direct interaction between male and female genitalia during copulation. Here we review the diverse mechanisms of genital coevolution that include natural selection, female mate choice, male–male competition, and how their interactions generate sexual conflict that can lead to sexually antagonistic coevolution. Natural selection on genital morphology will result in size coevolution to allow for copulation to be mechanically possible, even as other features of genitalia may reflect the action of other mechanisms of selection. Genital coevolution is explicitly predicted by at least three mechanisms of genital evolution: lock and key to prevent hybridization, female choice, and sexual conflict. Although some good examples exist in support of each of these mechanisms, more data on quantitative female genital variation and studies of functional morphology during copulation are needed to understand more general patterns. A combination of different approaches is required to continue to advance our understanding of genital coevolution. Knowledge of the ecology and behavior of the studied species combined with functional morphology, quantitative morphological tools, experimental manipulation, and experimental evolution have been provided in the best-studied species, all of which are invertebrates. Therefore, attention to vertebrates in any of these areas is badly needed.Of all the evolutionary interactions between the sexes, the mechanical interaction of genitalia during copulation in species with internal fertilization is perhaps the most direct. For this reason alone, coevolution between genital morphologies of males and females is expected. Morphological and genetic components of male and female genitalia have been shown to covary in many taxa (Sota and Kubota 1998; Ilango and Lane 2000; Arnqvist and Rowe 2002; Brennan et al. 2007; Rönn et al. 2007; Kuntner et al. 2009; Tatarnic and Cassis 2010; Cayetano et al. 2011; Evans et al. 2011, 2013; Simmons and García-González 2011; Yassin and Orgogozo 2013; and see examples in

Sexual Orientation Disparities in Weight Status in Adolescence: Findings From a Prospective Study

A growing number of studies among adult women have documented disparities in overweight adversely affecting lesbian and bisexual women, but few studies have examined sexual orientation–related patterns in weight status among men or adolescents. We examined sexual orientation group trends in BMI (kg/m²), BMI Z‐scores, and overweight using 56,990 observations from 13,785 adolescent females and males in the Growing Up Today Study (GUTS), a large prospective cohort of US youth. Participants provided self‐reported information from six waves of questionnaire data collection from 1998 to 2005. Gender‐stratified linear regression models were used to estimate BMI and BMI Z‐scores and modified Poisson regression models to estimate risk ratios for overweight, controlling for age and race/ethnicity, with heterosexuals as the referent group. Among females, we observed fairly consistently elevated BMI in all sexual orientation minority groups relative to heterosexual peers. In contrast, among males we documented a sexual‐orientation‐by‐age interaction indicating steeper increases in BMI with age from early‐to‐late adolescence in heterosexuals relative to sexual orientation minorities. Additional prospective research is needed to understand the determinants of observed sexual orientation disparities and to inform appropriate preventive and treatment interventions. The long‐term health consequences of overweight are well‐documented and over time are likely to exact a high toll on populations with elevated rates.     

Ontogeny and phylogeny: a quantitative theory of heterochrony

Developmental variability in organisms underlies the relationship between ontogeny and phylogeny. The concept entropy permits a quantitative characterization of this variability and provides a basis for interpreting the phylogeny of heterochrony in evolution.     

Peroxidase Ontogeny in a Dwarf Pea Stem as Affected by Gibberellin and Decapitation

The ontogeny of peroxidase activity and isoenzyme pattern wasinvestigated in the stem of dwarf pea plants. Peroxidase activityper unit soluble protein was a given internode is highest inthe youngest growth stage, drops during elongation, remainsconstant upon cessation of growth, and increase at senescence.The lower the internode on the stem the higher is its peroxidaseactivity. These developmental differences are already apparentat the youngest growth stage of the internodes adn increaseduring elongation. Several anodic and five cathodic isoperoxidasesare apparent after starch gel electrophoresis. This patternis constant for all internodes at all growth stages, but therelative importance of particular isoenzymes changes with time. Gibberellic acid (GA₃) treatment causes greatly elongated internodes,decreased soluble protein, and inhibition of the rise in peroxidaseactivity within 4–8 h. Application of GA₃ to young internodesleads to a persistent depression in peroxidase activity, whiletreated older internodes suffer only a temporary depression.GA₃ causes no qualitative changes in the isoenzyme pattern butproduces some quantitative alterations in internodes in whichits influence on peroxidase activity is persistent. Decapitation of untreated and GA₃-treated dwarfs has littleinfluence on internode elongation, causes an increase in peroxidaseactivity, especially in the upper internodes, and alters therelative activity of particular isoenzymes. By contrast, decapitationinhibits elongation of young internodes in genetically tallpea plants.     

Sexual Behavior and Condom Use among Gay Men,Female Sex Workers,and Their Customers: Evidence from South Korea

Background

Despite the significance for sexually transmitted diseases (STD) control in East Asia, few studies have examined the relationship between high-risk sexual behavior and condom use. We investigated how three sexually vulnerable groups for STDs show differences in condom use behaviors (CUBs) depending on their STD infection.

Methods

The source of data came from the National Survey for STD Prevalence Rate and Sexual Behavior of the High-Risk Sexual Community. The effects of behavioral determinants on CUBs were estimated by using path analysis models. An 11-item questionnaire assessing subjects’ health risk behaviors, sexual beliefs, sexual risk behaviors, and condom use.

Results

Condom use was higher for men who have sex with men (MSM; n = 108) when they were bisexuals and had high self-efficacy, for Johns (Johns; n = 118) when they had experience of STD infection, and for female sex workers (FSWs; n = 1,083) when they had high self-efficacy, did not engage in drunken sex, and were anxious about infection. Regardless of whether they were infected with STDs, FSWs always used condom when they had high sexual beliefs. On the contrary, Johns exhibited a negative relationship between sexual risk behavior and condom use when they had experience of STD infection. The variable commonly significant to all three groups was the number of sex partners; but it exhibited a positive relationship with MSMs and Johns, and a negative one with FSWs.

Conclusions

CUBs were related to sexual beliefs as well as sexual risk behavior. At the same time, the experience of STD infection mediated the relationship between the two. Therefore, we need to draw social attention to promote safer sex among STD-vulnerable groups.     

From thought to action: the parietal cortex as a bridge between perception, action, and cognition

The lateral intraparietal area (LIP) is a subdivision of the inferior parietal lobe that has been implicated in the guidance of spatial attention. In a variety of tasks, LIP provides a "salience representation" of the external world-a topographic visual representation that encodes the locations of salient or behaviorally relevant objects. Recent neurophysiological experiments show that this salience representation incorporates information about multiple behavioral variables-such as a specific motor response, reward, or category membership-associated with the task-relevant object. This integration occurs in a wide variety of tasks, including those requiring eye or limb movements or goal-directed or nontargeting operant responses. Thus, LIP acts as a multifaceted behavioral integrator that binds visuospatial, motor, and cognitive information into a topographically organized signal of behavioral salience. By specifying attentional priority as a synthesis of multiple task demands, LIP operates at the interface of perception, action, and cognition.     

From Clinging to Digging: The Postembryonic Skeletal Ontogeny of the Indian Purple Frog,Nasikabatrachus sahyadrensis (Anura: Nasikabatrachidae)

The Indian Purple frog, Nasikabatrachus sahyadrensis, occupies a basal phylogenetic position among neobatrachian anurans and has a very unusual life history. Tadpoles have a large ventral oral sucker, which they use to cling to rocks in torrents, whereas metamorphs possess adaptations for life underground. The developmental changes that underlie these shifts in habits and habitats, and especially the internal remodeling of the cranial and postcranial skeleton, are unknown. Using a nearly complete metamorphic series from free-living larva to metamorph, we describe the postembryonic skeletal ontogeny of this ancient and unique monotypic lineage. The torrent-dwelling larva possesses a dorsoventrally flattened body and a head with tiny dorsal eyes, robust lower and upper jaw cartilages, well-developed trabecular horns, and a definable gap between the trabecular horns and the tip of the snout. Unlike tadpoles of many other frogs, those of Nasikabatrachus retain larval mouthparts into late metamorphic stages. This unusual feature enables the larvae to maintain their clinging habit until near the end of metamorphosis. The subsequent ontogenetic shift from clinging to digging is correlated with rapid morphological changes and behavioral modifications. Metamorphs are equipped with a shortened tibiafibula and ossified prehallical elements, which likely facilitate initial digging using the hind limbs. Subsequently, the frogs may shift to headfirst burrowing by using the wedge-shaped skull, anteriorly positioned pectoral girdle, well-developed humeral crests and spatula-shaped forelimbs. The transition from an aquatic life in torrents to a terrestrial life underground entails dramatic changes in skeletal morphology and function that represent an extreme in metamorphic remodeling. Our analysis enhances the scope for detailed comparative studies across anurans, a group renowned for the diversity of its life history strategies.