Multiple sexual advertisements honestly reflect health status in peacocks (Pavo cristatus)

The evolution of multiple sexual traits remains controversial and poorly understood in evolutionary biology. In many bird species, males exhibit complex courtships involving feather ornaments and behavioral display. Multiple traits may convey information on the genetic and phenotypic quality of males. In particular, fixed characters, such as feather ornaments (produced once a year during the annual molt in many bird species) might convey information about past male condition (at the time of trait development); whereas flexible traits such as behavioral displays should be sensitive to present condition. Here we show that both flexible behavioral displays and fixed feather ornaments of peacocks, used by females to choose a mate, honestly reflect health status. Correlative data showed that peacocks with high display rate (the number of behavioral displays per hour) and a large number of tail eyespots had low levels of circulating heterophils, suggesting better health status. Experimental activation of the immune system, through LPS injection, significantly reduced display rate compared to a control group. However, the sensitivity of a male display rate to the immune challenge was dependent on the number of tail eyespots: males with higher number of tail eyespots were better able to cope with the experimental immune challenge, and maintained their display rate at levels closer to the levels performed before the immune activation. These results are consistent with the idea that multiple signaling might enhance information reliability.     

Savviness of prey to introduced predators

The prey naivety hypothesis posits that prey are vulnerable to introduced predators because many generations in slow gradual coevolution are needed for appropriate avoidance responses to develop. It predicts that prey will be more responsive to native than introduced predators and less responsive to introduced predators that differ substantially from native predators and from those newly established. To test these predictions, we conducted a global meta-analysis of studies that measured the wariness responses of small mammals to the scent of sympatric mammalian mesopredators. We identified 26 studies that met our selection criteria. These studies comprised 134 experiments reporting on the responses of 36 small mammal species to the scent of six introduced mesopredators and 12 native mesopredators. For each introduced mesopredator, we measured their phylogenetic and functional distance to local native mesopredators and the number of years sympatric with their prey. We used predator and prey body mass as a measure of predation risk. Globally, small mammals were similarly wary of the scent of native and introduced mesopredators; phylogenetic and functional distance between introduced mesopredators and closest native mesopredators had no effect on wariness; and wariness was unrelated to the number of prey generations, or years, since first contact with introduced mesopredators. Small mammal wariness was associated with predator-prey body mass ratio, regardless of the nativity. The one thing animals do not seem to recognize is whether their predators are native.     

COSMOS,a spatially explicit model to simulate the epidemiology of Cosmopolites sordidus in banana fields

A stochastic individual-based model called COSMOS was developed to simulate the epidemiology of banana weevil Cosmopolites sordidus, a major pest of banana fields. The model is based on simple rules of local movement of adults, egg laying of females, development and mortality, and infestation of larvae inside the banana plants. The biological parameters were estimated from the literature, and the model was validated at the small-plot scale. Simulated and observed distributions of attacks were similar except for five plots out of 18, using a Kolmogorov–Smirnov test. These exceptions may be explained by variation in predation of eggs and measurement error. An exhaustive sensitivity analysis using the Morris method showed that predation rate of eggs, demographic parameters of adults and mortality rate of larvae were the most influential parameters. COSMOS was therefore used to test different spatial arrangements of banana plants on the epidemiology of C. sordidus. Planting bananas in groups increased the time required to colonise plots but also the percentage of banana plants with severe attacks. Spatial heterogeneity of banana stages had no effect on time required to colonise plots but increased the mean level of attacks. Our model helps explain key factors of population dynamics and the epidemiology of this tropical pest.     

Insights from life history theory for an explicit treatment of trade‐offs in conservation biology

As economic and social contexts become more embedded within biodiversity conservation, it becomes obvious that resources are a limiting factor in conservation. This recognition is leading conservation scientists and practitioners to increasingly frame conservation decisions as trade‐offs between conflicting societal objectives. However, this framing is all too often done in an intuitive way, rather than by addressing trade‐offs explicitly. In contrast, the concept of trade‐off is a keystone in evolutionary biology, where it has been investigated extensively. I argue that insights from evolutionary theory can provide methodological and theoretical support to evaluating and quantifying trade‐offs in biodiversity conservation. I reviewed the diverse ways in which trade‐offs have emerged within the context of conservation and how advances from evolutionary theory can help avoid the main pitfalls of an implicit approach. When studying both evolutionary trade‐offs (e.g., reproduction vs. survival) and conservation trade‐offs (e.g., biodiversity conservation vs. agriculture), it is crucial to correctly identify the limiting resource, hold constant the amount of this resource when comparing different scenarios, and choose appropriate metrics to quantify the extent to which the objectives have been achieved. Insights from studies in evolutionary theory also reveal how an inadequate selection of conservation solutions may result from considering suboptimal rather than optional solutions when examining whether a trade‐off exits between 2 objectives. Furthermore, the shape of a trade‐off curve (i.e., whether the relationship between 2 objectives follows a concave, convex, or linear form) is known to affect crucially the definition of optimal solutions in evolutionary biology and very likely affects decisions in biodiversity conservation planning too. This interface between evolutionary biology and biodiversity conservation can therefore provide methodological guidance to support decision makers in the difficult task of choosing among conservation solutions. Percepciones de la Teoría de Historia de Vida para una Tratamiento Explícito de las Compensaciones en la Biología de la Conservación     

Sexual dimorphism in amphipods: the role of male posterior gnathopods revealed in Gammarus pulex

In the mate-guarding amphipod, Gammarus pulex, the enlarged male posterior gnathopods have been variously suggested to function to grasp and subdue the female, to be used as weapons in fights between males, to signal to the female the male presence and stimulate moult accelaration, egg development or egg extrusion. These hypotheses were tested in a series of experiments, the results of which reveal an unexpected function. Ablation of the posterior gnathopods of males showed that they were neither necessary for, nor advantageous in, establishment and/or maintenance of precopula mate guarding, with or without competition with intact males. Furthermore, these appendages do not function to advance female moult, or stimulate egg development or extrusion. However, only males with intact posterior gnathopods were able to copulate. We also show that females require a full copulation of several bouts to extrude eggs. We conclude that the function of the posterior gnathopods is to facilitate copulation and suggest future studies focus on the selective pressures acting on copulating males.     

Factors Associated with Alien Plants Transitioning from Casual, to Naturalized, to Invasive

Abstract:  To explain current plant invasions, or predict future ones, more knowledge on which factors increase the probability of alien species becoming naturalized and subsequently invasive is needed. We created a database of the alien plants in seminatural habitats in Ireland that included data on taxonomy, invasive status, invasion history, distribution, and biological and ecological plant characteristics. We used information from this database to determine the importance of these factors in increasing the ability of species to become naturalized and invasive. More specifically, we used two multiple logistic regressions to identify factors that distinguish naturalized from casual alien plant species and invasive from noninvasive, naturalized alien species. Clonal growth, moisture-indicator value, nitrogen-indicator value, native range, and date of first record affected (in order of decreasing importance) the probability of naturalization. Factors that distinguished invasive from noninvasive species were ornamental introduction, hermaphrodite flowers, pollination mode, being invasive elsewhere, onset of flowering season, moisture-indicator value, native range, and date of first record. Incorporation of phylogenetic information had little influence on the results, suggesting that the capacity of alien species to naturalize and become invasive evolved largely independently in several phylogenetic lineages. Whereas some of the variables were important for both transitions, others were only important for naturalization or for invasion. This emphasizes the importance of studying different stages of the invasion process when looking for mechanisms of becoming a successful invasive plant, instead of simply comparing invasive with noninvasive alien species. Our results also suggest that a combination of species traits and other variables is likely to produce the most accurate prediction of invasions.     

黔中木本植物叶功能性状对退化喀斯特土壤特性的响应

研究不同退化背景下优势木本植物功能性状的适应机制,有助于从功能生态学的角度来解释喀斯特山区的群落演替过程。本研究以贵州普定不同退化背景样地优势木本为研究对象,测定LT、LA、SLA、LDMC、LTD、Chlc6个叶片功能性状指标,分析土壤特性对区域内植被叶片功能性状的作用及影响,揭示喀斯特山区植物对不同环境的适应策略及其演替过程。结果表明:①喀斯特区退化环境下植被叶片向增大化趋势发展,以退耕地经济林最显著;火烧、火烧砍伐、退耕下植被性状差异显著,以LA、LTD、SLA变化范围最大,在相应样地可分别高达121.9%、118.08%、86.00%。②退化样地内叶片性状在乔木、灌木和藤本物种间差异显著,总体上灌木与藤本物种种间变异高于乔木物种,群落处于演替前中期阶段。③不同退化背景下土壤特性差异较大,与植被叶功能性状间具有显著相关性,其中土层深度、土壤养分与土壤含水率是植被叶功能性状的关键土壤特性因子。④退化区域植被叶性状表现出LA大、LT较小、SLA和LTD低、LDMC高、Chlc较低,趋向于发展贫瘠干旱性状组合。揭示了黔中退化喀斯特次生林内在差异性的演替规律,为喀斯特次生林的管理和生物多样性保护提供科学依据。     

Plant polyphenols – implications of different sampling,storage and sample processing in biodiversity-ecosystem functioning experiments

Plant polyphenols are involved in important ecosystem processes and may affect nutrient cycling. Previous investigations have demonstrated detrimental effects of suboptimal sample treatment on the quantity of extractable plant polyphenols. We compared leaf polyphenol concentrations of 20 tree species from East China in two sample sets collected under different conditions: (a) according to established protocols and stored more than three years, (b) under conditions optimised for leaf polyphenols. We investigated the variance brought about by suboptimal sample handling as compared to the variance caused by the taxonomic range of species. Family-affiliation explained the largest proportion of variance, whereas sample handling had only minor effects. Reducing the taxonomic range increased the impact of differences in sample handling. Additionally, we showed that the concentrations of leaf polyphenols were phylogenetically more conserved than other leaf traits. Non-metric-multi-dimensional scaling revealed similar ordination patterns for leaf polyphenol concentrations in both sample sets with both ordinations being closely correlated. Finally, we computed separate ordinations including an extended set of leaf traits and found that both analyses led to similar ecological conclusions. Consequently, in studies comprising a wide taxonomic range, the adverse effects of suboptimal sample handling may be overridden by the variation brought about by phylogeny.     

Spotted bowerbirds<Emphasis Type="Italic"> Chlamydera maculata</Emphasis> do not prefer rare or costly bower decorations

Females target elaborate secondary sexual traits to acquire either direct benefits, represented or provided by the trait, or indirect benefits usually in the form of genetic components. The link between a males trait and his potential genetic contribution is often unclear. Bowers are extreme examples of secondary sexual traits, built and decorated by males and targeted by females. However, why females should base their mate choice on such structures is unclear. One of the simplest suggestions is that bowers are sites where males exhibit collections of objects that are inherently highly costly, indicating male quality to the choosy female. Such costs can be imposed in two ways, acquisition from the local area, and maintenance in the face of degradation. We studied bowers of spotted bowerbirds Chlamydera maculata at three sites in central Queensland and tested whether components of the bowers that best predict mating success were some of the most costly in the local environment by measuring their abundance, physical dimensions and rate of decay. We also tested whether rare objects per se found on the bowers, were relatively good predictors of mating success. Finally, we experimentally tested whether males preferentially chose rare, and hence costly, objects to use as decorations. We found that objects used on bowers were not unusually costly. Specific objects identified as good predictors of mating success were also some of the more common objects found in the area. They were not the largest objects used on bowers and decayed slowly relative to other objects available for use as decorations. Rare objects in general were not good predictors of mating success and males did not prefer to use rare objects when offered choices. In conclusion, we found no support for the theory that by simply inspecting numbers of decorations and assessing their costs of acquisition and maintenance females can easily obtain information regarding the owners quality. This is due to the fact that decorations used by spotted bowerbirds are not inherently costly.Communicated by J. Graves