Chemosensory enrichment as a simple and effective way to improve the welfare of captive lizards

Ageing via perception costs of reproduction magnifies sexual selection.

Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series …

Language ruling stymies brain gain

Sexual selection drives asymmetric introgression in wall lizards.

Hybridisation is increasingly recognised as an important cause of diversification and adaptation. Here, we show how divergence in male secondary sexual characters between two lineages of the common wall lizard (Podarcis muralis) gives rise to strong asymmetries in male competitive ability and mating success, resulting in asymmetric hybridisation upon secondary contact. Combined with no negative effects of hybridisation on survival or reproductive characters in F1-hybrids, these results suggest that introgression should be asymmetric, resulting in the displacement of sexual characters of the sub-dominant lineage. This prediction was confirmed in two types of secondary contact, across a natur…

Ageing via sexual perception is a by-product of male adaptive plasticity inDrosophila melanogaster

ABSTRACTSensory perception of environmental cues can dramatically modulate ageing across distant taxa. For example, maleDrosophila melanogasterage faster if they perceive female cues but fail to mate (ageing via sexual perception). This finding has been a breakthrough for our understanding of the mechanisms of ageing, yet we ignore how and why such responses have evolved. Here, we usedD. melanogasterto ask whether ageing via sexual perception may be a by-product of plastic adaptive responses to female cues, and found that while long-term sexual perception leads to reproductive costs, short-term perception increases male lifetime reproductive success in a competitive environment. Simulations…

The ecology of sexual conflict: Temperature variation in the social environment can drastically modulate male harm to females

Sexual conflict is a fundamental driver of male/female adaptations, an engine of biodiversity and a crucial determinant of population viability. Sexual conflict frequently leads to behavioural adaptations that allow males to displace their rivals, but in doing so harm those same females they are competing to access, which can decrease population viability and facilitate extinction. We are far from understanding what factors modulate the intensity of sexual conflict and particularly the role of ecology in mediating underlying behavioural adaptations. In this study, we show that, in Drosophila melanogaster, variations in environmental temperature of ±4°C decrease male harm impact on female fi…

Electronic Supplementary File from Ageing via perception costs of reproduction magnifies sexual selection

Contains supplementary figures and tables referred to in the manuscript.

Recognition of familiarity on the basis of howls: a playback experiment in a captive group of wolves

Playback experiments were conducted with a pack of captive Iberian wolves. We used a habituation–discrimination paradigm to test wolves’ ability to discriminate howls based on: (1) artificial manipulation of acoustic parameters of howls and (2) the identity of howling individuals. Manipulations in fundamental frequency and frequency modulation within the natural range of intra-individual howl variation did not elicit dishabituation, while manipulation of modulation pattern did produce dishabituation. With respect to identity, across trials wolves habituated to unfamiliar howls by a familiar wolf (i.e., no direct contact, but previous exposure to howls by this wolf), but not to unfamiliar ho…

Animals in translation: why there is meaning (but probably no message) in animal communication

Supplementary Tables 1-5 and Supplementary Figures 1-2 from Male relatedness and familiarity are required to modulate male-induced harm to females in Drosophila.

All electronic supplementary material.

Aggressive mimicry coexists with mutualism in an aphid

Understanding the evolutionary transition from interspecific exploitation to cooperation is a major challenge in evolutionary biology. Ant-aphid relationships represent an ideal system to this end because they encompass a coevolutionary continuum of interactions ranging from mutualism to antagonism. In this study, we report an unprecedented interaction along this continuum: aggressive mimicry in aphids. We show that two morphs clonally produced by the aphid Paracletus cimiciformis during its root-dwelling phase establish relationships with ants at opposite sides of the mutualism-antagonism continuum. Although one of these morphs exhibits the conventional trophobiotic (mutualistic) relations…

Social behavior, chemical communication, and adult neurogenesis: Studies of scent mark function in Podarcis wall lizards

Lacertid lizards have been hailed as a model system for the study of reptilian chemical communication. However, results obtained with the genus Podarcis, a diverse group of wall lizards with complex systematics, challenge emerging paradigms and caution against hasty generalizations. Here we review the available evidence on the role of chemical stimuli in male-female and male-male interactions in Iberian Podarcis. Males of several species can discriminate between chemicals left on substrates by females of their own or a different species, suggesting that differences in female chemical cues may underlie species recognition in this group. Females, on the other hand, do not respond differential…

AGONISTIC INTERACTIONS IN A LIOLAEMUS LIZARD: STRUCTURE OF HEAD BOB DISPLAYS

Males from different iguanian lizard species engage in frequent visual signaling during agonistic interactions, mainly by displaying head bobs. We conducted a detailed study of the structure of head bob displays mediating male agonistic interactions in Liolaemus lemniscatus lizards. We staged pair-wise encounters where one male, the intruder, was placed in the terrarium of a conspecific male, the resident. During these interactions, males exhibited only one type of head bob display made up of three distinct units: a low amplitude bob (unit 1), a brief pause (unit 2), and two consecutive high-amplitude bobs (unit 3). Head bob displays occurred singly or as a part of a bout, with a mean numbe…

Putting information back into biological communication.

At the heart of many debates on communication is the concept of information. There is an intuitive sense in which communication implies the transfer of some kind of information, probably the reason why information is an essential ingredient in most definitions of communication. However, information has also been an endless source of misunderstandings, and recent accounts have proposed that information should be dropped from a formal definition of communication. In this article, we re-evaluate the merits and the internal logic of information-based vs. information-free approaches and conclude that information-free approaches are conceptually incomplete and operationally hindered. Instead, we …

Condition‐dependent mortality exacerbates male (but not female) reproductive senescence and the potential for sexual conflict

Disentangling the relationship between age and reproduction is central to understand life-history evolution, and recent evidence shows that considering condition-dependent mortality is a crucial piece of this puzzle. For example, nonrandom mortality of 'low-condition' individuals can lead to an increase in average lifespan. However, selective disappearance of such low-condition individuals may also affect reproductive senescence at the population level due to trade-offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition-dependent extrinsic mortality (i.e. simulated predation) may increase the a…

"Predator-elicited foot shakes in wall lizards (Podarcis muralis): Evidence for a pursuit-deterrent function": Correction to Font, Carazo, Pérez i de Lanuza, and Kramer (2012).

Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

False dichotomies and human sexual size dimorphism: A comment of Dunsworth (2020)

Experimental contact zones reveal causes and targets of sexual selection in hybridizing lizards

Divergence in sexually selected traits in allopatry should affect the degree and direction of hybridization. However, few studies have established the causes and targets of sexual selection during secondary contact. Common wall lizards (Podarcis muralis) from north-central Italy have highly exaggerated male sexual traits compared to populations in Western Europe. Using experimental populations, we show that this creates asymmetries in male dominance, spatial habitat use and reproductive success upon secondary contact. Hybridization occurred almost exclusively between males of the Italian lineage and females of the Western European lineage. We provide evidence to suggest stronger ongoing sel…

Beyond ‘nasty neighbours’ and ‘dear enemies’? Individual recognition by scent marks in a lizard (Podarcis hispanica)

True individual recognition (TIR), the ability to recognize conspecific individuals on the basis of identity cues, is required for the evolution of several social traits (e.g. the maintenance of dominance hierarchies). However, knowledge about the distribution and functional significance of TIR is scant in some vertebrate groups, such as reptiles. In this study we used a functional modification of a habituation-dishabituation paradigm to investigate the existence and adaptive significance of TIR in a territorial lizard (Podarcis hispanica, Lacertidae). Males discriminated between individual rivals of similar characteristics (e.g. size, weight, familiarity) solely on the basis of their scent…

Insulin signalling mediates the response to male-induced harm in female Drosophila melanogaster.

Genetic manipulations in nutrient-sensing pathways are known to both extend lifespan and modify responses to environmental stressors (e.g., starvation, oxidative and thermal stresses), suggesting that similar mechanisms regulate lifespan and stress resistance. However, despite being a key factor reducing female lifespan and affecting female fitness, male-induced harm has rarely been considered as a stressor mediated by nutrient sensing pathways. We explored whether a lifespan-extending manipulation also modifies female resistance to male-induced harm. To do so, we used long-lived female Drosophila melanogaster that had their insulin signalling pathway downregulated by genetically ablating t…

‘Communication breakdown’: the evolution of signal unreliability and deception

For a signalling system to be stable, signals must confer net fitness benefits to senders and receivers, which means that some aspect of their design must correlate with a quality that receivers benefit from knowing about. However, examples abound where this correlation is complicated by phenomena commonly referred to as deception and/or signal unreliability. We argue here that unreliability and deception are notions marred with conceptual ambiguities, often used as equivalent or as catch-all terms for qualitatively different processes. Signal unreliability refers to a pattern of design–information dissociation that can arise through different processes, some deceptive and some not, with di…

Color-assortative mating in a color-polymorphic lacertid lizard

Color polymorphisms are common in lizards, which provide an excellent model system to study their evolution and adaptive function. The lacertid genus Podarcis is particularly interesting because it comprises several polymorphic species. Previous studies with lacertid lizards have tried to explain the maintenance of color polymorphisms by correlational selection between color morphs and several phenotypic traits. Particular attention has been paid to their putative role as signals reflecting alternative reproductive strategies under frequency-dependent selection, but the relationship between mating patterns and color polymorphism has not been previously considered. In this study, we use long…

Impact of human disturbance and beliefs on the tree agama Acanthocercus atricollis atricollis in a South African communal settlement

We investigated the effects of human disturbance and attitudes on the density of the tree agama Acanthocercus atricollis atricollis in a densely populated rural settlement in South Africa. In this environment agamas live on trees that are harvested for firewood or maintained for fruit production. We conducted visual encounter surveys of A. a. atricollis and interviewed local households to establish whether human attitudes and actions could affect tree agama populations. Although local residents viewed tree agamas negatively (50% of interviewees claimed to have killed an agama) and acted to exclude them from their environment, tree agama density in villages was higher than that of adjacent c…

Learning outdoors: male lizards show flexible spatial learning under semi-natural conditions.

Spatial cognition is predicted to be a fundamental component of fitness in many lizard species, and yet some studies suggest that it is relatively slow and inflexible. However, such claims are based on work conducted using experimental designs or in artificial contexts that may underestimate their cognitive abilities. We used a biologically realistic experimental procedure (using simulated predatory attacks) to study spatial learning and its flexibility in the lizard Eulamprus quoyii in semi-natural outdoor enclosures under similar conditions to those experienced by lizards in the wild. To evaluate the flexibility of spatial learning, we conducted a reversal spatial-learning task in which …

Quantity Estimation Based on Numerical Cues in the Mealworm Beetle (Tenebrio molitor)

In this study, we used a biologically relevant experimental procedure to ask whether mealworm beetles (Tenebrio molitor) are spontaneously capable of assessing quantities based on numerical cues. Like other insect species, mealworm beetles adjust their reproductive behavior (i.e., investment in mate guarding) according to the perceived risk of sperm competition (i.e., probability that a female will mate with another male). To test whether males have the ability to estimate numerosity based on numerical cues, we staged matings between virgin females and virgin males in which we varied the number of rival males the experimental male had access to immediately preceding mating as a cue to sperm…

No evidence that relatedness or familiarity modulate male harm in wild Drosophila melanogaster

Sexual selection frequently promotes the evolution of aggressive behaviours that help males compete against their rivals, but which may harm females and hamper their fitness. Kin selection theory predicts that optimal male-male competition levels can be reduced when competitors are more genetically related to each other than to the population average, contributing to resolve this sexual conflict. Work in Drosophila melanogaster has spearheaded empirical tests of this idea, but studies so far have been conducted in lab-adapted populations in homogeneous rearing environments that may hamper kin recognition, and used highly skewed sex ratios that may fail to reflect average natural conditions.…

Inclusive fitness and sexual conflict: How population structure can modulate the battle of the sexes

Competition over reproductive opportunities among members of one sex often harms the opposite sex, creating a conflict of interest between individual males and females. Recently, this battle of the sexes has become a paradigm in the study of intersexual coevolution. Here, we review recent theoretical and empirical advances suggesting that – as in any scenario of intraspecific competition – selfishness (competitiveness) can be influenced by the genetic relatedness of competitors. When competitors are positively related (e.g. siblings), an individual may refrain from harming its competitor(s) and their mate(s) because this can improve the focal individual's inclusive fitness. These findings r…

Colour patch size and measurement error using reflectance spectrophotometry

1 - Over the past twenty years, portable and relatively affordable spectrophotometers have greatly advanced the study of animal coloration. However, the small size of many colour patches poses methodological challenges that have not, to date, been assessed in the literature. Here, we tackle this issue for a reflectance spectrophotometry set-up widely used in ecology and evolution (the beam method). 2 - We reviewed the literature on animal coloration reporting the use of reflectance spectrophotometry to explore how the minimum measurable size of a colour patch is determined. We then used coloured plastic sheets to create artificial colour patches, and quantify the relationship between colour…

Digest: Chemical communication and sexual selection in lizards*

Re-thinking the effects of body size on the study of brain size evolution

Body size correlates with most structural and functional components of an organism’s phenotype – brain size being a prime example of allometric scaling with animal size. Therefore, comparative studies of brain evolution in vertebrates rely on controlling for the scaling effects of body size variation on brain size variation by calculating brain weight/body weight ratios. Differences in the brain size-body size relationship between taxa are usually interpreted as differences in selection acting on the brain or its components, while selection pressures acting on body size, which are among the most prevalent in nature, are rarely acknowledged, leading to conflicting and confusing conclusions. …

Sex ratio at mating does not modulate age fitness effects in Drosophila melanogaster

Abstract Understanding the effects of male and female age on reproductive success is vital to explain the evolution of life history traits and sex‐specific aging. A general prediction is that pre‐/postmeiotic aging processes will lead to a decline in the pre‐ and postcopulatory abilities of both males and females. However, in as much the sexes have different strategies to optimize their fitness, the decline of reproductive success late in life can be modulated by social context, such as sex ratio, in a sex‐specific manner. In this study, we used Drosophila melanogaster to investigate whether sex ratio at mating modulates age effects on male and female reproductive success. As expected, male…

Endless forms. Evolutionary scenarios to unravel biodiversity

In this monograph we set out to explore this complex relationship through a series of singular evolutionary scenarios. Some of these scenarios will shed light into phenomena that may at first glance appear inscrutable through the lens of evolution. Our aim is to illustrate the power harnessed by evolutionary biology to tackle some of the most pressing challenges we face as a species, from the diseases that threaten our survival to the recent anthropogenic changes that endanger the only planet we inhabit.

Chemosensory assessment of rival competitive ability and scent-mark function in a lizard, Podarcis hispanica

Recent studies have stressed the role of scent marks as signals potentially mediating competitor assessment. According to this view, receivers may use scent marks to derive information about the costs of exploiting a given area, but few studies have directly addressed this hypothesis. One of its main predictions is that scent marks should reflect a signaller's competitive ability. We simulated the situation faced by an intruding male when entering the scent-marked territories of rival males of varying competitive ability to test predictions about the role of scent marks in a lizard, Podarcis hispanica. We report that males were attracted to areas marked by males of similar or higher competi…

Male reproductive senescence as a potential source of sexual conflict in a beetle

The link between senescence and reproductive success is a contentious yet crucial issue to our understanding of mate choice, sexual conflict, and the evolution of ageing. By imposing direct (i.e., male fertility) or indirect (i.e., zygote viability) reproductive costs to females, male senescence may lead to sexual conflict at different levels. For example, ageing may affect male ability to deliver sperm, thus setting the scene for sexual conflict over mating, and/or may affect the quality of individual sperm cells, generating the potential for sexual conflict over fertilizing strategies. We addressed these issues by studying the mating behavior, reproductive fitness, and fertilization patte…

Supplementary Figures from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Supplementary figures which compare the behaviour and lifespan profiles of male and female fly control strains. As outlined in the main text, different control strains were not deemed to differ in lifespan or behaviour in a significant way in either sex and were pooled during analyses in to single 'control' groups.

No evidence for differential sociosexual behavior and space use in the color morphs of the European common wall lizard (Podarcis muralis)

Abstract Explaining the evolutionary origin and maintenance of color polymorphisms is a major challenge in evolutionary biology. Such polymorphisms are commonly thought to reflect the existence of alternative behavioral or life‐history strategies under negative frequency‐dependent selection. The European common wall lizard Podarcis muralis exhibits a striking ventral color polymorphism that has been intensely studied and is often assumed to reflect alternative reproductive strategies, similar to the iconic “rock–paper–scissors” system described in the North American lizard Uta stansburiana. However, available studies so far have ignored central aspects in the behavioral ecology of this spec…

Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

ABSTRACTSex-specific lifespans are ubiquitous across the tree of life and exhibit broad taxonomic patterns that remain a puzzle, such as males living longer than females in birds and vice versa in mammals. The prevailing “unguarded-X” hypothesis (UXh) explains this by differential expression of recessive mutations in the X/Z chromosome of the heterogametic sex (e.g., females in birds and males in mammals), but has only received indirect support to date. An alternative hypothesis is that the accumulation of deleterious mutations and repetitive elements on the Y/W chromosome might lower the survival of the heterogametic sex (“toxic Y” hypothesis). Here, we report lower survival of the heterog…

The “unguarded-X” and the genetic architecture of lifespan: Inbreeding results in a potentially maladaptive sex-specific reduction of female lifespan inDrosophila melanogaster

Sex differences in ageing and lifespan are ubiquitous in nature. The "unguarded-X" hypothesis (UXh) suggests they may be partly due to the expression of recessive mutations in the hemizygous sex chromosomes of the heterogametic sex, which could help explain sex-specific ageing in a broad array of taxa. A prediction central to the UX hypothesis is that inbreeding will decrease the lifespan of the homogametic sex more than the heterogametic sex, because only in the former does inbreeding increase the expression of recessive deleterious mutations. In this study, we test this prediction by examining the effects of inbreeding on the lifespan and fitness of male and female Drosophila melanogaster…

Chemosensory cues allow male Tenebrio molitor beetles to assess the reproductive status of potential mates

Males of many insect species, including beetles, choose their mates according to their reproductive status. However, the ways in which male beetles evaluate female reproductive status have received little attention. We tested the existence of male mate choice in the mealworm beetle, Tenebrio molitor, by observing mating and courtship behaviour of males given simultaneous access to pairs of females differing in their reproductive status: (1) mature versus immature; (2) virgin versus previously mated; (3) familiar (mated with the experimental male) versus unfamiliar (mated with a different male). Males courted and mated preferentially with mature and virgin females. To determine whether chemi…

Colours of quality: structural (but not pigment) coloration informs about male quality in a polychromatic lizard

Chromatic signals result from the differential absorption of light by chemical compounds (pigment-based colours) and/or from differential scattering of light by integument nanostructures (structural colours). Both structural and pigment-based colours can be costly to produce, maintain and display, and have been shown to convey information about a variety of individual quality traits. Male wall lizards, Podarcis muralis, display conspicuously coloured ventral and lateral patches during ritualized inter- and intrasexual displays: ventral colours (perceived as orange, yellow or white by humans) are pigment based, while the ultraviolet (UV)-blue of the outer ventral scales (OVS), located along …

Chemosensory assessment of sperm competition levels and the evolution of internal spermatophore guarding

Males of many species adjust their reproductive behaviour according to the perceived risk of sperm competition. Although this phenomenon is widespread in insects and other animals, the mechanisms that allow mates to assess sperm competition levels remain largely unexplored. In this study, we analysed the mating behaviour of pairs ofTenebrio molitorbeetles under three odour treatments representing increasing levels of sperm competition risk (SCR) and sperm competition intensity (SCI). Copula duration and male and female post-copulatory behaviour varied significantly with odour treatment. Both copula duration and post-copulatory associations (PCAs) increased significantly in odour treatments …

Temperature as a modulator of sexual selection

A central question in ecology and evolution is to understand why sexual selection varies so much in strength across taxa; it has long been known that ecological factors are crucial to this. Temperature is a particularly salient abiotic ecological factor that modulates a wide range of physiological, morphological and behavioural traits, impacting individuals and populations at a global taxonomic scale. Furthermore, temperature exhibits substantial temporal variation (e.g. daily, seasonally and inter-seasonally), and hence for most species in the wild sexual selection will regularly unfold in a dynamic thermal environment. Unfortunately, studies have so far almost completely neglected the rol…

The role of male coloration in the outcome of staged contests in the European common wall lizard (Podarcis muralis)

Colour signals play a key role in regulating the intensity and outcome of animal contests. Males of the common wall lizard (Podarcis muralis) show conspicuous ventrolateral ultraviolet (UV)-blue and black patches. In addition, some populations express a striking ventral colour polymorphism (i.e., discrete orange, white and yellow morphs). In this study, we set out to evaluate the potential signalling function of these colour patches by staging pairwise combats between 60 size-matched adult lizards (20 per morph). Combats were held in a neutral arena, with each lizard facing rivals from the three morphs in a tournament with a balanced design. We then calculated a fighting ability ranking usi…

Lifespan data for experiment 2 from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Experiment 1 Behaviour - Females.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster.

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Data from: Rethinking the effects of body size on the study of brain size evolution

Body size correlates with most structural and functional components of an organism’s phenotype – brain size being a prime example of allometric scaling with animal size. Therefore, comparative studies of brain evolution in vertebrates rely on controlling for the scaling effects of body size variation on brain size variation by calculating brain weight/body weight ratios. Differences in the brain size-body size relationship between taxa are usually interpreted as differences in selection acting on the brain or its components, while selection pressures acting on body size, which are among the most prevalent in nature, are rarely acknowledged, leading to conflicting and confusing conclusions. …

Data from: Learning outdoors: Male lizards show flexible spatial learning under semi-natural conditions

Spatial cognition is predicted to be a fundamental component of fitness in many lizard species, and yet some studies suggest that it is relatively slow and inflexible. However, such claims are based on work conducted using experimental designs or in artificial contexts that may underestimate their cognitive abilities. We used a biologically realistic experimental procedure (using simulated predatory attacks) to study spatial learning and its flexibility in the lizard Eulamprus quoyii in semi-natural outdoor enclosures under similar conditions to those experienced by lizards in the wild. To evaluate the flexibility of spatial learning, we conducted a reversal spatial-learning task in which p…

Behaviour data for experiment 2 from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

List of papers selected in bibliographic search from Ageing via perception costs of reproduction magnifies sexual selection

Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series o…

Lifespan data for experiment 1 from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Experiment 1 Behaviour - Males.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster.

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Data from: The "unguarded-X" and the genetic architecture of lifespan: Inbreeding results in a potentially maladaptive sex-specific reduction of female lifespan in Drosophila melanogaster

Sex differences in ageing and lifespan are ubiquitous in nature. The "unguarded-X” hypothesis (UXh) suggests they may be partly due to the expression of recessive mutations in the hemizygous sex chromosomes of the heterogametic sex, which could help explain sex-specific ageing in a broad array of taxa. A prediction central to the UX hypothesis is that inbreeding will decrease the lifespan of the homogametic sex more than the heterogametic sex, because only in the former does inbreeding increase the expression of recessive deleterious mutations. In this study, we test this prediction by examining the effects of inbreeding on the lifespan and fitness of male and female Drosophila melanogaster…

Data from: Experimental contact zones reveal causes and targets of sexual selection in hybridizing lizards

Divergence in sexually selected traits in allopatry should affect the degree and direction of hybridization. However, few studies have established the causes and targets of sexual selection during secondary contact. Common wall lizards (Podarcis muralis) from north-central Italy have highly exaggerated male sexual traits compared to populations in Western Europe. Using experimental populations, we show that this creates asymmetries in male dominance, spatial habitat use and reproductive success upon secondary contact. Hybridization occurred almost exclusively between males of the Italian lineage and females of the Western European lineage. We provide evidence to suggest stronger ongoing sel…

Behaviour data for experiment 1 from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Data from: Sex ratio at mating does not modulate age fitness effects in D. melanogaster

Understanding the effects of male and female age on reproductive success is vital to explain the evolution of life history traits and sex-specific ageing. A general prediction is that pre/post-meiotic ageing processes will lead to a decline in the pre- and post-copulatory abilities of both males and females. However, inasmuch as sexes have different strategies to optimize their fitness, the decline of reproductive success late in life can be modulated by social context, such as sex ratio, in a sex-specific manner. In this study, we used Drosophila melanogaster to investigate whether sex ratio at mating modulates age effects on male and female reproductive success. As expected, male and fema…

Experiment 1 Survival.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster.

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Data from: The ecology of sexual conflict: temperature variation in the social environment can drastically modulate male harm to females

1. Sexual conflict is a fundamental driver of male/female adaptations, an engine of biodiversity, and a crucial determinant of population viability. Sexual conflict frequently leads to behavioural adaptations that allow males to displace their rivals, but in doing so harm those same females they are competing to access, which can decrease population viability and facilitate extinction. 2. We are far from understanding what factors modulate the intensity of sexual conflict, and particularly the role of ecology in mediating underlying behavioural adaptations. 3. In this study we show that, in Drosophila melanogaster, variations in environmental temperature of ±4ºC decrease male harm impact on…

Data from: Inbreeding removes sex differences in lifespan in a population of Drosophila melanogaster

Sex differences in ageing rates and lifespan are common in nature, and an enduring puzzle for evolutionary biology. One possibility is that sex-specific mortality rates may result from recessive deleterious alleles in ‘unguarded’ heterogametic X or Z sex chromosomes (the unguarded X hypothesis). Empirical evidence for this is, however, limited. Here, we test a fundamental prediction of the unguarded X hypothesis in Drosophila melanogaster, namely that inbreeding shortens lifespan more in females (the homogametic sex in Drosophila) than in males. To test for additional sex-specific social effects, we studied the lifespan of males and females kept in isolation, in related same-sex groups, and…

Data from: Ageing via perception costs of reproduction magnifies sexual selection

Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series o…

Experiment 2 Survival.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…

Data from: Colour patch size and measurement error using reflectance spectrometry

1. Over the past twenty years, portable and relatively affordable spectrophotometers have greatly advanced the study of animal coloration. However, the small size of many colour patches poses methodological challenges that have not, to date, been assessed in the literature. Here, we tackle this issue for a reflectance spectrophotometry set-up widely used in ecology and evolution (the beam method). 2. We reviewed the literature on animal coloration reporting the use of reflectance spectrophotometry to explore how the minimum measurable size of a colour patch is determined. We then used coloured plastic sheets to create artificial colour patches, and quantify the relationship between colour p…

Experiment 2 Behaviour.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster.

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system f…