Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology.

Although variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different fields and has found substantial variability among results despite analysts having the same data and research question.

Sickness behaviour and the effect of sex, age, and immune status on individual behavioural variation in Tenebrio molitor.

Sick animals generally behave differently than healthy individuals by, for example, being less active and exploratory. How an individual responds to illness is also likely to be mediated by the individual's age because age will dictate the individual's ability to fight a challenge. To date, empirical research on sickness behaviour has focused on the population-level average effect of ill health on behaviour.

Passive plasticity and a sex difference in the predictability of mobility.

Behavioural predictability describes the behavioural variability of an individual. Unpredictability can arise from many sources including non-adaptive passive plasticity in which an environmental factor acts directly on the individual to create non-adaptive phenotypic variation. In this study, I use radiotelemetry to field test the hypothesis that Cook Strait giant weta (Orthoptera: Anostostomatidae) exhibit a sex difference in the predictability of their nightly travel distance due to passive behavioural plasticity.

Alternative mating strategies in the Wellington tree weta expressed via genetic polymorphism for precocial male maturation.

The expression of alternative mating strategies is generally hypothesized to be a plastic response of the genome to the environment or a genetic polymorphism. The Wellington tree weta () is an orthopteran insect in which males express three alternative mating morphotypes related to the size of mandibular weaponry. My common garden experiment in the laboratory shows that male weapon size at maturity in this species is nether condition- nor environment-dependent; therefore, supporting the hypothesis that it is genetically polymorphic.

The complex ecology of genitalia: Gonopodium length and allometry in the Trinidadian guppy.

Male genitalia present an extraordinary pattern of rapid divergence in animals with internal fertilization, which is usually attributed to sexual selection. However, the effect of ecological factors on genitalia divergence could also be important, especially so in animals with nonretractable genitalia because of their stronger interaction with the surrounding environment in comparison with animals with retractable genitalia. Here, we examine the potential of a pervasive ecological factor (predation) to influence the length and allometry of the male genitalia in guppies.

Towards open, reliable, and transparent ecology and evolutionary biology.

Unreliable research programmes waste funds, time, and even the lives of the organisms we seek to help and understand. Reducing this waste and increasing the value of scientific evidence require changing the actions of both individual researchers and the institutions they depend on for employment and promotion. While ecologists and evolutionary biologists have somewhat improved research transparency over the past decade (e.

Equal fitness among alternative mating strategies in a harem polygynous insect.

Alternative mating strategies are widespread among animal taxa, with strategies controlled by a genetic polymorphism (Mendelian strategy) being rarer in nature than condition-dependent developmental strategies. Mendelian strategies are predicted to have equal average fitnesses and the proportion of offspring produced by a strategy should equal the equilibrium proportion of individuals representing the strategy in a population. Developmental strategies are not expected to produce offspring in equilibrium proportions; however, whether the alternative phenotypes should have equal average fitness is debated.

No evidence of sickness behavior in immune-challenged field crickets.

Sickness behavior is a taxonomically widespread coordinated set of behavioral changes that increases shelter-seeking while reducing levels of general activity, as well as food (anorexia) and water (adipsia) consumption, when fighting infection by pathogens and disease. The leading hypothesis explaining such sickness-related shifts in behavior is the energy conservation hypothesis. This hypothesis argues that sick (i.

Rate and success of study replication in ecology and evolution.

The recent replication crisis has caused several scientific disciplines to self-reflect on the frequency with which they replicate previously published studies and to assess their success in such endeavours. The rate of replication, however, has yet to be assessed for ecology and evolution. Here, I survey the open-access ecology and evolution literature to determine how often ecologists and evolutionary biologists replicate, or at least claim to replicate, previously published studies.

Refuge size variation and potential for sperm competition in Wellington tree weta.

Ecological variation in resources can influence the distribution and encounter rates of potential mates and competitors and, consequently, the opportunity for sexual selection. Factors that influence the likelihood that females mate multiply could also affect the potential for sperm competition. In Wellington tree weta (, plural "weta"), the size of tree cavities (called galleries) used as refuges affects weta distribution and thus the opportunity for sexual selection and selection on male weaponry size.

Developmental and genetic effects on behavioral and life-history traits in a field cricket.

A fundamental goal of evolutionary ecology is to identify the sources underlying trait variation on which selection can act. Phenotypic variation will be determined by both genetic and environmental factors, and adaptive phenotypic plasticity is expected when organisms can adjust their phenotypes to match environmental cues. Much recent research interest has focused on the relative importance of environmental and genetic factors on the expression of behavioral traits, in particular, and how they compare with morphological and life-history traits.

Sexual dimorphism in immunity across animals: a meta-analysis.

In animals, sex differences in immunity are proposed to shape variation in infection prevalence and intensity among individuals in a population, with females typically expected to exhibit superior immunity due to life-history trade-offs. We performed a systematic meta-analysis to investigate the magnitude and direction of sex differences in immunity and to identify factors that shape sex-biased immunocompetence. In addition to considering taxonomic and methodological effects as moderators, we assessed age-related effects, which are predicted to occur if sex differences in immunity are due to sex-specific resource allocation trade-offs with reproduction.

The causes and evolutionary consequences of variation in female mate choice in insects: the effects of individual state, genotypes and environments.

Sexual selection generally involves males evolving secondary sexual characters that satisfy the mating preferences of females. Behavioral ecologists have spent considerable research effort on identifying how variation in sexually-selected traits in insects is maintained among males at the expense of investigating the proximate and ultimate causes of variation in female mating preferences for those male traits. The past decade has witnessed improved effort in redressing this bias in insects with researchers identifying a host of factors intrinsic and extrinsic to the female as mediating flexibility in female mating behavior.

Transparency in Ecology and Evolution: Real Problems, Real Solutions.

To make progress scientists need to know what other researchers have found and how they found it. However, transparency is often insufficient across much of ecology and evolution. Researchers often fail to report results and methods in detail sufficient to permit interpretation and meta-analysis, and many results go entirely unreported.

Females gain survival benefits from immune-boosting ejaculates.

Females in many animal taxa incur significant costs from mating in the form of injury or infection, which can drastically reduce survival. Therefore, immune function during reproduction can be important in determining lifetime fitness. Trade-offs between reproduction and immunity have been extensively studied, yet a growing number of studies demonstrate that mated females have a stronger immune response than virgins.

Direct costs and benefits of multiple mating: Are high female mating rates due to ejaculate replenishment?

Females often mate more than is necessary to ensure reproductive success even when they incur significant costs from doing so. Direct benefits are hypothesized to be the driving force of high female mating rates, yet species in which females only receive an ejaculate from their mate still realize increased fitness from multiple mating. Using the Texas field cricket, Gryllus texensis, we experimentally test the hypothesis that multiple mating via monandry or polyandry increases female fitness by replenishing ejaculates, thereby allowing females to produce more offspring for a longer period of time.

Are attractive male crickets better able to pay the costs of an immune challenge?

Reproduction and immunity are fitness-related traits that trade-off with each other. Parasite-mediated theories of sexual selection suggest, however, that higher-quality males should suffer smaller costs to reproduction-related traits and behaviours (e.g.

Mating for male-derived prostaglandin: a functional explanation for the increased fecundity of mated female crickets?

Direct benefits are considered to be the driving force of high female mating rates, yet species in which females do not receive material resources from males still experience increased fitness from mating frequently. One hypothesis suggests that substances within the ejaculate may boost survival or offspring production. If these materials are limiting to females, they will require continual renewal via mating and could provide a functional understanding of how high mating rates lead to increased female fitness.

Sexual size and shape dimorphism and allometric scaling patterns in head traits in the New Zealand common gecko Woodworthia maculatus.

Sexual dimorphism in shape and size is widespread across animal taxa and arises when natural or sexual selection operates differently on the sexes. Male and female common geckos (Woodworthia maculatus; formerly Hoplodactylus maculatus) in New Zealand do not appear to experience different viability selection pressure, nor do males appear to be under intense pre-copulatory sexual selection. It was therefore predicted that this species would be sexually monomorphic with regard to body size and the size and shape of the head.

Evaluating indices of body condition in two cricket species.

Body mass components (dry mass, lean dry mass, water mass, fat mass) in each sex correlate strongly with body mass and pronotum length in Gryllus texensis and Acheta domesticus. Ordinary least squares (OLS) regression underestimates the scaling relationship between body mass and structural size (i.e.

Effect of an immune challenge on the functional performance of male weaponry.

Theories of parasite-mediated sexual selection predict a positive association between immune function and the expression of sexually selected ornaments. Few studies, however, have investigated how an immune challenge affects the performance of sexually selected weaponry. Male Wellington tree weta (Hemideina crassidens) (Orthoptera: Anostostomatidae) possess enlarged mandibles that are used as weapons in fights for access to females residing in tree galleries.

Sex-specific effect of juvenile diet on adult disease resistance in a field cricket.

Food limitation is expected to reduce an individual's body condition (body mass scaled to body size) and cause a trade-off between growth and other fitness-related traits, such as immunity. We tested the condition-dependence of growth and disease resistance in male and female Gryllus texensis field crickets by manipulating diet quality via nutrient content for their entire life and then subjecting individuals to a host resistance test using the live bacterium Serratia marcescens. As predicted, crickets on a high-quality diet eclosed more quickly, and at a larger body size and mass.

Sexual selection and sperm quantity: meta-analyses of strategic ejaculation.

Multiple mating or group spawning leads to post-copulatory sexual selection, which generally favours ejaculates that are more competitive under sperm competition. In four meta-analyses we quantify the evidence that sperm competition (SC) favours greater sperm number using data from studies of strategic ejaculation. Differential investment into each ejaculate emerges at the individual level if males exhibit phenotypic plasticity in ejaculate properties in response to the likely risk and/or intensity of sperm competition after a given mating.

Evidence for male allocation in pipefish?

Sexual differences in the extent and type of parental care lie at the heart of sexual selection theory, and evolution resulting from parental conflict has produced some striking behavioural and morphological adaptations. In a study of male pregnancy in Gulf pipefish, Paczolt and Jones showed that more eggs were transferred to the male's brood pouch and more offspring survived following mating with large females (preferred by males) than with small (less preferred) females. Although the authors conclude that the lower survival of embryos from small females is most consistent with males actively removing resources from these offspring, no data are presented to directly support this hypothesis (ref.