Andrea Pilastro

University of Padova | UNIPD · Department of Biology

Life‐history theory suggests that ageing is one of the costs of reproduction. Accordingly, a higher reproductive allocation is expected to increase the deterioration of both the somatic and the germinal lines through enhanced telomere attrition. In most species, males' reproductive allocation mainly regards traits that increase mating and fertiliza...

Sperm size is highly variable across species and is influenced by various factors including fertilization mode, female reproductive traits and sperm competition. Despite considerable efforts, many questions about sperm size variation remain open. Variation in body size may affect sperm size evolution through its influence on these factors, but the...

Amidst the current biodiversity crisis, the availability of genomic resources for declining species can provide important insights into the factors driving population decline. In the early 1990s, the black-legged kittiwake (Rissa tridactyla), a pelagic gull widely distributed across the arctic, subarctic and temperate zones, suffered a steep popula...

Postcopulatory sexual selection (PCSS), namely sperm competition and cryptic female choice, is typically investigated in benign environments, with a fixed number of partners, which mate at the same time intervals; all conditions that are rarely met in natural populations. Although there is increasing evidence that environmental fluctuations affect...

Future climatic scenarios forecast increases in average temperatures as well as in the frequency, duration, and intensity of extreme events, such as heatwaves. Whereas behavioral adjustments can buffer direct physiological and fitness costs of exposure to excessive temperature in wild animals, these may prove more difficult during specific life sta...

Theoretical models indicate that the evolution of biparental care depends on how parents behaviourally negotiate their level of care in response to those of their partner and whether sexes and individuals consistently vary in their response (compensatory response). While the compensatory response has been widely investigated empirically, its repeat...

Life history theory suggests that aging is one of the costs of reproduction. Accordingly, a higher reproductive allocation is expected to increase the deterioration of both the somatic and the germinal lines through enhanced telomere attrition. In most species, male's reproductive allocation mainly regards traits that increase mating and fertilizat...

Kin selection theory predicts that individual progeny members, in species where offspring share depreciable parental care, should increasingly attempt to monopolize resources provided by the parents as their relatedness to brood competitors declines. Although the level of relatedness among broodmates is often variable in vertebrates, whether it aff...

Endotherms need to respond properly to temperature changes in their environment to avoid loss of their physiological functions. Whereas evaporative cooling favours rapid heat dissipation, it requires big energy investments and can lead to dehydration if prolonged. Another mechanism endotherms rely on is heat dissipation through dry heat exchange, b...

In order to maximize their fitness, individuals have evolved to match the requirements of predictable environmental variation in their habitats. An increment in the frequency and intensity of unpredictable extreme weather events associated with climate change (e.g. heatwaves) can have major impacts on bird reproduction, especially during early deve...

Imminent predation risk affects mating behaviours in prey individuals in a multitude of ways that can theoretically impact the strength of sexual selection, as well as its operation on traits. However, empirical studies of the effects of imminent predation risk on sexual selection dynamics are still scarce. Here we explore how perceived predation a...

Urbanization transforms natural and agricultural areas into built landscapes. Such profound habitat alteration imposes strong pressure on phenotypic trait changes through processes related to natural and/or sexual selection. Evidence of how natural selection drives changes to traits in urban biota is increasing, but little is known about the role o...

We conducted a temperature manipulation experiment during a heatwave (5 days at 38 oC) to study the effect of high nest temperatures during nestling development. We paired nestboxes and shaded one of them. Shaded nestboxes were 4 oC cooler than control ones (left with their normal level of insulation) (F 1,46 = 53.91; p < 0.001). Future climatic sc...

Predation risk perception can alter mating behaviours in males and females, but the consequences for sexual selection remain underexplored. We have previously shown that in experimental populations of Trinidadian guppies Poecilia reticulata the opportunity for sexual selection (i.e. the variance in male reproductive fitness) was higher following ex...

Extra-pair paternity (EPP) has been broadly reported in socially monogamous bird species and it has been hypothesized that females engage in extra-pair copulations to increase the genetic variability of the offspring and to reduce the risk of inbreeding and genetic incompatibilities. This hypothesis makes two predictions: within populations, female...

In many species, males can rapidly adjust their ejaculate performance in response to changing levels of sperm competition, an ability that is probably mediated by seminal fluid adaptive plasticity. In the black goby, Gobius niger , territorial males attach viscous ejaculate trails to the nest roof, from which sperm are slowly released into the wate...

This study considered possible sexual dimorphism in the relative lengths of the third, fourth and fifth digits (digit ratio), in calves. Furthermore, a different length of the bone structures of the third (3D) and of the fourth (4D) digits has been examined as an evolutionary adaptation to locomotion on soft ground. The length of the digital bones...

The role of non-gametic components of the ejaculate (seminal fluid) in fertility and sperm competitiveness is now well established. Surprisingly, however, we know far less about female reproductive fluid (FRF) in the context of sexual selection, and insights into male–FRF interactions in the context of sperm competition have only recently emerged....

Fifty years of research on sperm competition has led to a very good understanding of the interspecific variation in sperm production traits. The reasons why this variation is often very large within populations have been less investigated. We suggest that the interaction between fluctuating environmental conditions and polyandry is a key phenomenon...

The environment that parents experience can influence their reproductive output and their offspring’s fitness via parental effects. Perceived predation risk can affect both parent and offspring phenotype, but it remains unclear to what extent offspring behavioral traits are affected when the mother is exposed to predation risk. This is particularly...

In polyandrous species males invest significant resources in producing large and high-quality ejaculates. As ejaculates are costly, males are expected to modulate their investment in response to social cues associated with the expected level of sperm competition or mating opportunity, to anticipate future mating conditions. Another consequence of e...

Males of many species evolved the capability of adjusting their ejaculate phenotype in response to social cues to match the expected mating conditions. When females store sperm for a prolonged time, the expected fitness return of plastic adjustments of ejaculate phenotype may depend on the interval between mating and fertilization. While prolonged...

In many species, males show anticipatory plasticity for sperm production, which they adjust to match perceived mating opportunities. While the strategic adjustment of sperm production is likely to be beneficial, it may be also associated with costs, including those arising from the expression of a phenotype that is poorly matched to the conditions...

The tight connection between immunity and reproduction has been studied for decades. However, basic knowledge at the molecular level of the effect of mating on immune function is still lacking in many taxa. Determining whether and how the immune system is engaged after mating is a crucial step in understanding post‐mating mechanisms of reproduction...

In species where females mate with more than one male during the same reproductive event, males typically increase the number of sperm produced to boost their fertilization share. Sperm is not limitless, however, and theory predicts that their production will come at the cost of other fitness-related traits, such as body growth or immunocompetence,...

Abstract The perception of predation risk could affect prey phenotype both within and between generations (via parental effects). The response to predation risk could involve modifications in physiology, morphology, and behavior and can ultimately affect long‐term fitness. Among the possible modifications mediated by the exposure to predation risk,...

Although it is often expected that adverse environmental conditions depress the expression of condition‐dependent sexually selected traits, the full consequences of environmental change for the action of sexual selection, in terms of the opportunity for total sexual selection and patterns of phenotypic selection, are unknown. Here we show that diet...

Many animals, from humans to invertebrates, exhibit sexual preference for unfamiliar partners. This may reduce the risk of inbreeding and increase offspring heterozygosity. An alternative less tested hypothesis is that selection for neophilia in other contexts (e.g. exploration of unfamiliar environments) may promote mate preference for unfamiliar...

Despite serving the primary objective of ensuring that at least one sperm cell reaches and fertilizes an ovum, the male ejaculate (i.e. spermatozoa and seminal fluid) is a compositionally complex ‘trait’ that can respond phenotypically to subtle changes in conditions. In particular, recent research has shown that environmentally and genetically ind...

Traits associated with mating and fertilization success are expected to senesce with age, but limited information is available on their relative rates of senescence. In polyandrous species, male reproductive fitness depends on both mating and fertilization success. Because successful mating is a prerequisite for post-copulatory sexual selection, ej...

In 1695 the Italian anatomist and physician Lorenzo Bellini published an account of the ‘airways’ in birds’ eggs. Bellini suggested that these structures — that appear as dark channels running between the inner surface of the eggshell and the shell membranes, from the pointed to the blunt end of the egg — were connected to the eggshell pores and tr...

Several fish species are characterized by social systems in which individuals prefer to interact with specific group mates. However, there is no clear evidence that such associations are equitable, that is, they are mutual between individuals. We addressed this issue in the guppy (Poecilia reticulata), a species in which social network analyses hav...

Sexually selected traits involved in mate acquisition and fertilization success are usually costly and males often plastically adjust their reproductive investment in response to social conditions. Phenotypic plasticity in male sexual traits is generally assumed to be adap-tive, yet its costs are rarely investigated. Male guppies (Poecilia reticula...

Male and female gametes are often embedded in fluids that are produced by gonads and other reproductive tissues. Female reproductive fluids, usually called ovarian fluid (OF), which often constitute a relevant volumetric component of the egg mass, are rich in ions, sugars and proteins, and are involved in several functions, from protecting gametes...

Phenotypic plasticity, i.e. the ability of an organism to produce different phenotypes in response to environmental conditions, in male sexual traits is nearly universal and generally assumed to be adaptive. For example, socio-sexual conditions are often variable in natural populations, and males adjust accordingly their reproductive investment in...

According to theory, in species in which male variance in reproductive success exceeds that of the females, sons are more costly to produce; females mated with high quality males or those in better condition should produce more sons. In monogamous species, however, the variance in the reproductive success of the two sexes is often similar and mate...

Producing sperm is costly and males have been selected to strategically adjust their sperm production and/or expenditure according to the fitness return associated with a specific mating. For example, males respond to fluctuations in the mating opportunities by adjusting the number of ‘ready’ sperm. This phenomenon is known as ‘sperm priming’ and i...

Sperm competition is taxonomically widespread in animals and is usually associated with large sperm production, being the number of sperm in the competing pool the prime predictor of fertilization success. Despite the strong postcopulatory selection acting directionally on sperm production, its genetic variance is often very high. This can be expla...

The three earliest – all eighteenth-century – illustrated accounts of birds’ eggs were by Luigi Marsili (or Marsigli): Danubius Pannonico-Mysicus, Giuseppe Zinanni (or Ginanni): Delle Uova e dei Nidi degli Uccelli, and Jacob Theodor Klein: Ova avium plurimarum ad naturalem magnitudinem delineata et genuinis coloribus picta. Marsili’s account descri...

Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm-female interactions (postmating-prezygotic barriers) are arguably the hardest to identify, not least because these are likely to operate at the cellular or molecular level. Yet sperm-female inte...

Several factors are involved in determining the outcome of sperm competition. In addition to sperm number, sperm quality and male phenotype, insemination order is often associated with skewed paternity share. Patterns of sperm precedence can be produced by the mechanics of sperm storage and fertilization, or by active processes under male or female...

Presentation regarding a study on the costs of phenotypic plasticity of male reproductive traits. The study was conducted with the guppy (Poecilia reticulata).

Keywords: fish behaviour mirror test Poecilia reticulata shoaling sociability Many fish species are social, and individuals spend most of their lives in shoals, but sociability can vary greatly between species, populations and individuals. Sociability has been largely studied by measuring the time spent by a focal fish in proximity to one or more c...

Parents are expected to strategically partition their limited resources among the current and future progeny in order to maximize their fitness. Since an equal investment in offspring of different reproductive value entails fitness costs, natural selection has promoted the evolution of reliable signals of offspring condition, allowing parents to in...

In animals, events occurring early in life can have profound effects on subsequent life-history events. Early developmental stresses often produce negative long-lasting impacts, although positive effects of mild stressors have also been documented. Most studies of birds have investigated the effects of events occurring at early developmental stages...

Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for no...

The function and maintenance of the immune system impose costs that can take the form of energy consumption and/or physiological side effects. These, in turn, can affect the expression of several traits, including traits closely related to fitness. The interaction of the immune system with other life-history traits (e.g. growth and survival) and wi...

While it is well established that females prefer to mate with well-ornamented males, the influence of perceptive and cognitive processes on the expression of female mate choice is still poorly known. It has been suggested that the female perception of a male's attractiveness is not absolute, but depends on the other males with which he is compared...

Theory predicts that in polyandrous species males that invest more in traits enhancing postcopulatory success should have less energy to invest in mating acquisition, leading to trade-offs between pre- and post-copulatory episodes of sexual selection. Although such trade-offs are well studied, the potential constraints that postcopulatory sexual se...

Males of several species have been shown to alter their mate preference in the presence of an eavesdropping rival. This evasive tactic has been interpreted as an attempt by the courting male to drive the attention of the rival away from the preferred female. The fitness return of this deceptive strategy will depend on the costs of cheating for the...

In many species, females mate with multiple partners, meaning that sexual selection on male traits operates across a spectrum that encompasses the competition for mates (that is, before mating) and fertilizations (after mating). Despite being inextricably linked, pre-and postcopulatory sexual selection are typically studied independently, and we kn...

In several species, males increase their mating and sperm investment in the presence of unfamiliar females, the so-called Coolidge effect. Such an elevated reproductive effort is expected to be associated with a decreased investment in other costly traits, such as somatic growth and maintenance. How precopulatory, postcopulatory, and somatic invest...

Females that mate multiply have the possibility to exert postcopulatory choice and select more compatible sperm to fertilize eggs. Prior work suggests that dissimilarity in Major Histocompatibility Complex (MHC) plays an important role in determining genetic compatibility between partners. Favouring a partner with dissimilar MHC alleles would resul...

Nest-dwelling ectoparasites represent an early stressor for birds as they impair the development of nestlings, which can adaptively respond by adjusting their growth rate to current conditions. While nest ectoparasites have long-term effects on nesting adults, no study has examined if they also have an impact on the moult patterns of juveniles. Her...

In polyandrous species, a male's reproductive success depends on his fertilization capability and traits enhancing competitive fertilization success will be under strong, directional selection. This leads to the prediction that these traits should show stronger condition dependence and larger genetic variance than other traits subject to weaker or...

Recent theory predicts that in species where females tend to mate with the relatively most ornamented males, males may increase their attractiveness to females, and hence mating success, by preferentially associating with females that are surrounded by less ornamented competitors. Despite this prediction, we still lack explicit experimental evidenc...

In seasonally fluctuating environments, timing of reproduction is a crucial determinant of fitness. Studies of birds show that late breeding attempts generally result in offspring of lower reproductive value, with lower recruit-ment and long-term survival prospects. Several proximate mechanisms, including a seasonal decline of immune sys-tem functi...

Sexual selection can operate both before and after mating. For males, selection will favor a suite of traits involved in mate acquisition (precopulatory) and in the competition among ejaculates to fertilize eggs (postcopulatory). Sperm competition theory predicts a trade-off between investment in pre- and postcopulatory traits, thus generating nega...

The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females' receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an i...

Sexual harassment is a common outcome of sexual conflict over mating rate. A large number of studies have identified several direct costs to females of sexual harassment including energy expenditure and reduced foraging ability. However, the fitness consequences of sexual harassment for descendants have rarely been investigated. Here, we manipulate...

Understanding how local environmental factors lead to temporal variability of vital rates and to plasticity of life history tactics is one of the central questions in population ecology. We used long-term capture-recapture data from five populations of a small hibernating rodent, the edible dormouse Glis glis, collected over a large geographical ra...

In internally fertilizing species male genitalia often show a higher degree of elaboration than required for simply transferring sperm to females. Among the hypotheses proposed to explain such diversity, sexual selection has received the most empirical support, with studies revealing that genital morphology can be targeted by both pre-and postcopul...

While both sperm number and quality are now recognized to be important in determining the outcome of sperm competition, very few studies have experimentally assessed the influence of these two parameters simultaneously. We studied the effect of sperm quality and number on competitive fertilization success in an internal-fertilizing fish, the guppy...

Colourful feathers are important traits in female mate choice in birds because the colour properties of the feathers are often correlated with individual condition during moult. Feather colour can change after moult, and dirt accumulation has been suggested to contribute to this variation. However, we still know little about the influence of dirt o...

The role of sexual selection in fuelling genital evolution is becoming increasingly apparent from comparative studies revealing interspecific divergence in male genitalia and evolutionary associations between male and female genital traits. Despite this, we know little about intraspecific variance in male genital morphology, or how male and female...

As inbreeding is costly, it has been suggested that polyandry may evolve as a means to reduce the negative fitness consequences of mating with genetically related males. While several studies provide support for this hypothesis, evidence of pure post-copulatory mechanisms capable of biasing paternity towards genetically unrelated males is still lac...

Background/Question/Methods Within their distribution range animals are often confronted with different environmental conditions which can result in diverse vital rates in populations of the same species. Therefore, investigations on different local populations are necessary to reveal general insights into the biology of a species. Edible dormic...

Elaborate or colourful feathers are important traits in female-mate choice in birds but little attention has been given to the potential costs of maintaining these traits in good condition via preening behaviour. While preening is known to be an important component of plumage maintenance, it has received little attention with respect to colouration...

There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently, differences in moult strategies between the sexes can be expected. The aim of this study was to assess whether, u...

Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the o...

Albeit there is growing evidence that males prefer to mate with ornamented females, it has been suggested that the production of costly ornaments may reduce female fecundity, hence favoring males with a preference for females with average ornamentation. In the rock sparrow, Petronia petronia, males and females possess a sexually selected patch of y...

In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may vary more among than within broods, parents may use this information to adjust their parental allocation to the...

As sperm production is costly, males are expected to strategically allocate resources to sperm production according to mating opportunities. While sperm number adjustments have been reported in several taxa, only a few studies investigated whether sperm quality shows adaptive plasticity as well. We tested this prediction in the guppy, Poecilia reti...

Growing evidence suggests that structural feather colours honestly reflect individual quality or body condition but, contrary to pigment-based colours, it is not clear what mechanism links condition to reflectance in structural feather colours. We experimentally accelerated the moult speed of a group of blue tits (Cyanistes caeruleus) by exposing t...

Secondary sexual characters may provide information about individual quality to a partner, which may use it during parental care to strategically allocate resources to the current breeding attempt (Differential Allocation Hypothesis). Differential allocation by females has been demonstrated for a number of species, while male differential allocatio...