The hepcidin-binding site on ferroportin is evolutionarily conserved

Mammalian iron homeostasis is regulated by the interaction of the liver-produced peptide hepcidin and its receptor, the iron transporter ferroportin. Hepcidin binds to ferroportin resulting in degradation of ferroportin and decreased cellular iron export. We identify the hepcidin-binding domain (HBD) on ferroportin and show that a synthetic 19 amino acid peptide corresponding to the HBD recapitulates the characteristics and specificity of hepcidin binding to cell-surface ferroportin. The binding of mammalian hepcidin to ferroportin or the HBD shows an unusual temperature dependency with an increased rate of dissociation at temperatures below 15°C. The increased rate of dissociation is due to temperature- dependent changes in hepcidin structure. In contrast, hepcidin from poikilothermic vertebrates, such as fish or frogs, binds the HBD in a temperature-independent fashion. The affinity of hepcidin for the HBD permits a rapid, sensitive assay of hepcidin from all species and yields insights into the evolution of hepcidin.     

Queen-queen competition by precocious male production in multiqueen ant colonies

Arriving earlier in the breeding area than his rivals may be beneficial for a male when females mate only once or during a short time span. The timing of a male's entrance is usually determined by the male himself, e.g., through returning early from his winter quarters or through accelerated larval development . Here, we document a surprisingly simple way of "first come, first served" in a species with local mate competition. In multiqueen colonies of a Cardiocondyla ant, mother queens make sure that their own sons are the first to monopolize mating with a large harem of female sexuals by producing extremely long-lived males early in colony life. Whereas queens in newly founded single-queen colonies started to produce male and female sexuals only several weeks after the eclosion of their first worker offspring, queens in multiqueen colonies precociously reared sons long before the first female sexuals and even before the emergence of their first workers. These early males killed all later emerging males in the nest and mated with all female sexuals subsequently produced. Our data document that the patterns of growth and productivity of insect colonies are surprisingly flexible and can be turned upside down under appropriate selection pressures.     

Duplication of fgfr1 Permits Fgf Signaling to Serve as a Target for Selection during Domestication

The genetic basis of morphological variation both within and between species has been a lasting question in evolutionary biology and one of considerable recent debate [1], [2] and [3]. It is thought that changes in postembryonic development leading to variations in adult form often serve as a basis for selection [4], [5] and [6]. Thus, we investigated the genetic basis of the development of adult structures in the zebrafish via a forward genetic approach and asked whether the genes and mechanisms found could be predictive of changes in other species [7] and [8]. Here we describe the spiegeldanio (spd) zebrafish mutation, which leads to reduced scale formation in the adult. The affected gene is fibroblast growth factor receptor 1 (fgfr1), which is known to have an essential embryonic function in vertebrate development [9] and [10]. We find that the zebrafish has two paralogs encoding Fgfr1 and show that they function redundantly during embryogenesis. However, only one paralog is required for formation of scales during juvenile development. Furthermore, we identify loss-of-function alleles changing the coding sequence of Fgfr1a1 that have been independently selected twice during the domestication of the carp (Cyprinus carpio) [11]. These findings provide evidence for the role for gene duplication in providing the raw material for generation of morphological diversity.     

Orchid Mimics Honey Bee Alarm Pheromone in Order to Attract Hornets for Pollination

Approximately one-third of the world's estimated 30,000 orchid species are deceptive and do not reward their pollinators with nectar or pollen [1]. Most of these deceptive orchids imitate the scent of rewarding flowers or potential mates [2] and [3]. In this study, we investigated the floral scent involved in pollinator attraction to the rewardless orchid Dendrobium sinense, a species endemic to the Chinese island Hainan that is pollinated by the hornet Vespa bicolor. Via chemical analyses and electrophysiological methods, we demonstrate that the flowers of D. sinense produce (Z)-11-eicosen-1-ol and that the pollinator can smell this compound. This is a major compound in the alarm pheromones of both Asian (Apis cerana) and European (Apis mellifera) honey bees [4] and [5] and is also exploited by the European beewolf (Philanthus triangulum) to locate its prey [6]. This is the first time that (Z)-11-eicosen-1-ol has been identified as a floral volatile. In behavioral experiments, we demonstrate that the floral scent of D. sinense and synthetic (Z)-11-eicosen-1-ol are both attractive to hornets. Because hornets frequently capture honey bees to feed to their larvae, we suggest that the flowers of D. sinense mimic the alarm pheromone of honey bees in order to attract prey-hunting hornets for pollination.     

Aging and fertility patterns in wild chimpanzees provide insights into the evolution of menopause

Human menopause is remarkable in that reproductive senescence is markedly accelerated relative to somatic aging, leaving an extended postreproductive period for a large proportion of women. Functional explanations for this are debated, in part because comparative data from closely related species are inadequate. Existing studies of chimpanzees are based on very small samples and have not provided clear conclusions about the reproductive function of aging females. These studies have not examined whether reproductive senescence in chimpanzees exceeds the pace of general aging, as in humans, or occurs in parallel with declines in overall health, as in many other animals. In order to remedy these problems, we examined fertility and mortality patterns in six free-living chimpanzee populations. Chimpanzee and human birth rates show similar patterns of decline beginning in the fourth decade, suggesting that the physiology of reproductive senescence was relatively conserved in human evolution. However, in contrast to humans, chimpanzee fertility declines are consistent with declines in survivorship, and healthy females maintain high birth rates late into life. Thus, in contrast to recent claims, we find no evidence that menopause is a typical characteristic of chimpanzee life histories.     

Reversed sexual conflict in a promiscuous antelope

A general tenet of sexual conflict theory is that males have higher optimum mating rates than do females and therefore should be more persistent when it comes to mating. However, in promiscuous species, females might benefit from high mating rates as a result of increased conception probability with favored males, whereas favored males benefit from mating selectively because of sperm depletion. When this results in higher optimum mating rates for females than for males, there is potential for reversed sexual conflicts between persistent females and resistant males. Here I report evidence of such a reversed sexual conflict in a promiscuous antelope, the African topi. Rather than mating randomly, favored males prefer to balance mating investment equally between females as predicted by strategic sperm allocation theory. Females, however, enhance their probability of mating with favored males through aggression toward mating pairs. Supporting the idea that aggressive females thereby harass males to mate at a rate that is suboptimal from the males' perspective, males become increasingly likely to counterattack aggressive females with whom they have already mated disproportionately, and such male counterattacks are associated with refusal to mate with the aggressive females. This study points to reversed sexual conflict as a more significant evolutionary force in promiscuous mammals than previously thought; however, such conflicts probably often go unnoticed because males, in contrast to females, can avoid mating without conspicuous resistance.     

Evidence for a genetic basis of aging in two wild vertebrate populations

Aging, or senescence, defined as a decline in physiological function with age, has long been a focus of research interest for evolutionary biologists. How has natural selection failed to remove genetic effects responsible for such reduced fitness among older individuals? Current evolutionary theory explains this phenomenon by showing that, as a result of the risk of death from environmental causes that individuals experience, the force of selection inevitably weakens with age. This in turn means that genetic mutations having detrimental effects that are only felt late in life might persist in a population. Although widely accepted, this theory rests on the assumption that there is genetic variation for aging in natural systems, or (equivalently), that genotype-by-age interactions (GxA) occur for fitness. To date, empirical support for this assumption has come almost entirely from laboratory studies on invertebrate systems, most notably Drosophila and C. elegans, whereas tests of genetic variation for aging are largely lacking from natural populations. By using data from two wild mammal populations, we perform quantitative genetic analyses of fitness and provide the first evidence for a genetic basis of senescence to come from a study in the natural environment. We find evidence that genetic differences among individuals cause variation in their rates of aging and that additive genetic variance for fitness increases with age, as predicted by the evolutionary theory of senescence.     

Competing selfish genetic elements in the butterfly Hypolimnas bolina

Maternally inherited selfish genetic elements are common in animals . Whereas host genetics and ecology are recognized as factors that may limit the incidence of these parasites , theory suggests one further factor-interference with other selfish elements-that could affect their prevalence . In this paper, we show that spatial heterogeneity in the occurrence of the male-killing Wolbachia wBol1 in the tropical butterfly Hypolimnas bolina is caused by a second infection that can exclude the male-killer. We first provide evidence of a second Wolbachia strain, wBol2, present in most populations that do not carry the male-killer but rare or absent when the male-killer is present. Crossing data indicate that wBol2 in males induces cytoplasmic incompatibility to both uninfected and wBol1-infected females. The wBol2 infection can therefore not only spread through uninfected populations but also resist invasion by wBol1. Thus, we provide empirical support for the hypothesis that the incidence of particular selfish genetic elements can limit the presence of competing types.     

Noise Pollution Changes Avian Communities and Species Interactions

Humans have drastically changed much of the world's acoustic background with anthropogenic sounds that are markedly different in pitch and amplitude than sounds in most natural habitats [1], [2], [3] and [4]. This novel acoustic background may be detrimental for many species, particularly birds [1]. We evaluated conservation concerns that noise limits bird distributions and reduces nesting success via a natural experiment to isolate the effects of noise from confounding stimuli and to control for the effect of noise on observer detection biases [5]. We show that noise alone reduces nesting species richness and leads to different avian communities. Contrary to expectations, noise indirectly facilitates reproductive success of individuals nesting in noisy areas as a result of the disruption of predator-prey interactions. The higher reproductive success for birds within noisy habitats may be a previously unrecognized factor contributing to the success of urban-adapted species and the loss of birds less tolerant of noise. Additionally, our findings suggest that noise can have cascading consequences for communities through altered species interactions. Given that noise pollution is becoming ubiquitous throughout much of the world, knowledge of species-specific responses to noise and the cumulative effects of these novel acoustics may be crucial to understanding and managing human-altered landscapes.