The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients

Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e. inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on (i) mean fitness of a population (relative to that of an outbred control population), (ii) within‐population inbreeding depression (reduction in fitness of offspring fro…

THE EFFECTS OF MATING SYSTEM AND GENETIC VARIABILITY ON SUSCEPTIBILITY TO TREMATODE PARASITES IN A FRESHWATER SNAIL, LYMNAEA STAGNALIS

The amount and distribution of genetic variability in host populations can have significant effects on the outcome of host-parasite interactions. We studied the effect of mating system and genetic variability on susceptibility of Lymnaea stagnalis snails to trematode parasites. Mating system of snails from eight populations differing in the amount of genetic variability was manipulated, and self- and cross-fertilized offspring were exposed to naturally occurring trematode parasites in a controlled lake experiment. Susceptibility of snails varied between populations, but mating-system treatment did not have a significant effect. Heterozygosity of snails was negatively correlated with the pro…

Planetary well-being : Ontology and ethics

This chapter elaborates the ontological and ethical underpinnings and implications of the concept of planetary well-being. We illustrate how planetary well-being can contribute conceptually to transformative thinking and discussing well-being, and to organizing human societies in more life-considerate ways. The chapter focuses on two themes: First, the ontological grounding and implications of planetary well-being, and second, the central ethical underpinnings and ramifications of planetary well-being. We demonstrate how planetary well-being is positioned in the broader ontological and ethical-theoretical landscape, owing to its process-oriented perspective and morally inclusive (non-anthro…

Primers for nine microsatellite loci in the hermaphroditic snailLymnaea stagnalis

Variation in and amplification conditions for nine polymorphic microsatellite loci identified from Lymnaea stagnalis , a hermaphroditic pulmonate snail, are described. Eight populations from central Finland were studied, which varied in terms of both observed polymorphism and heterozygosity. The number of alleles at each locus is moderate (two to seven), except for one exceptional locus having 16 alleles, and for which null alleles are possible. There is no evidence for genotypic disequilibrium in the populations for all pairs of loci. Heterozygosity levels are indicative of outcrossing in L. stagnalis , whose mating system will be characterized further using these markers.

The joint emergence of group competition and within-group cooperation

Abstract Between-group conflict and within-group cooperation can be seen as two sides of the same coin, coevolving in a group-structured population. There is strong support for between-group competition facilitating the evolution of human cooperative tendencies, yet our understanding of how competition arises is less clear. We show that groups of randomly assembled individuals spontaneously engage in costly group competition, and that decisions promoting between-group conflict are associated with high levels of within-group cooperation. Remarkably, when groups were given the possibility to compete against other groups, net earnings for individuals were higher than when groups were not allow…

Assortment, but not knowledge of assortment, affects cooperation and individual success in human groups

The success or failure of human collective action often depends on the cooperation tendencies of individuals in groups, and on the information that individuals have about each other's cooperativeness. However, it is unclear whether these two factors have an interactive effect on cooperation dynamics. Using a decision-making experiment, we confirm that groups comprising individuals with higher cooperation tendencies cooperate at a higher level than groups comprising individuals with low cooperation tendencies. Moreover, assorting individuals with similar cooperation tendency together affected behaviour so that the most cooperative individuals tended to cooperate more and the least cooperativ…

Mate choice for optimal (k)inbreeding.

Mating between related individuals results in inbreeding depression, and this has been thought to select against incestuous matings. However, theory predicts that inbreeding can also be adaptive if it increases the representation of genes identical by descent in future generations. Here, I recapitulate the theory of inclusive fitness benefits of incest, and extend the existing theory by deriving the stable level of inbreeding in populations practicing mate choice for optimal inbreeding. The parsimonious assumptions of the model are that selection maximizes inclusive fitness, and that inbreeding depression is a linear function of homozygosity of offspring. The stable level of inbreeding that…

The evolutionary dynamics of adaptive virginity, sex-allocation and altruistic helping in haplodiploid animals

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. H…

High cooperation and welfare despite — and because of — the threat of antisocial punishments and feuds

Cooperation can be difficult to sustain when there is a temptation to free-ride on the efforts of others. In experiments, peer punishment often stabilizes cooperation but fails to improve earnings because of the costs associated with punishment. In addition, antisocial use of punishment—punishing cooperators, counterpunishing, and feuding—often leads to lower cooperation and earnings. The current study investigated if powerful individuals—individuals who can punish without cost or who are immune from punishment—police the antisocial use of punishment, thus reducing the undesirable effects of punishment. In order to create ample opportunities for antisocial punishment and identify the motive…

The evolutionary dynamics of adaptive virginity, sex-allocation, and altruistic helping in haplodiploid animals

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. H…

Mate‐Search Efficiency Can Determine the Evolution of Separate Sexes and the Stability of Hermaphroditism in Animals

Limited availability of mating partners has been proposed as an explanation for the occurrence of simultaneous hermaphroditism in animals with pair mating. When low population density or low mobility of a species limits the number of potential mates, simultaneous hermaphrodites may have a selective advantage because, first, they are able to adjust the allocation of resources between male and female functions in order to maximize fitness; second, in a hermaphroditic population the likelihood of meeting a partner is higher because all individuals are potential mates; and, third, in the absence of mating partners, many simultaneously hermaphroditic animals have the option of reproducing throug…

Extinction risk indices for measuring and promoting planetary well-being

The concept of planetary well-being, which stresses the persistence of lineages in ecosystems, is intimately linked to species extinction risk. Avoiding extinctions is a moral issue, as wiping out the outcomes of eons of evolutionary history and their future potential is clearly unconscionable. The concept of planetary well-being is also systemic: It is understood that species, as integral parts of ecosystems, are vital for the well-being of all systems on Earth. Yet, despite international agreements to protect biodiversity, global biodiversity loss and ecosystem degradation has continued unimpeded over the past decades. We review the role of goals and targets in the UN Convention on Biolog…

The Good-Genes and Compatible-Genes Benefits of Mate Choice

Genetic benefits from mate choice could be attained by choosing mates with high heritable quality (“good genes”) and that are genetically compatible (“compatible genes”). We clarify the conceptual and empirical framework for estimating genetic benefits of mate choice, stressing that benefits must be measured from offspring fitness because there are no unequivocal surrogates for genetic quality of individuals or for compatibility of parents. We detail the relationship between genetic benefits and additive and nonadditive genetic variance in fitness, showing that the benefits have been overestimated in previous verbal treatments. We point out that additive benefits readily arise from nonaddit…

Introduction to interdisciplinary perspectives on planetary well-being

This chapter gives an overview of the objectives of the book, presents its structure, and summarizes the content of each section and chapter. It introduces planetary well-being as a novel cross-disciplinary concept coined to foster global transformation to a more inclusive and equal expression of well-being for all. The chapter describes how researchers from different human, social, and natural sciences apply and reflect on the concept of planetary well-being in this book, demonstrating its value as an interdisciplinary and cross-cutting driver of change. The Introduction concludes that sustainability science and policy need a concept of well-being that is built on systemic and non-anthropo…

Temperature-dependent mutational robustness can explain faster molecular evolution at warm temperatures, affecting speciation rate and global patterns of species diversity

Distribution of species across the Earth shows strong latitudinal and altitudinal gradients with the number of species decreasing with declining temperatures. While these patterns have been recognized for well over a century, the mechanisms generating and maintaining them have remained elusive. Here, we propose a mechanistic explanation for temperature-dependent rates of molecular evolution that can influence speciation rates and global biodiversity gradients. Our hypothesis is based on the effects of temperature and temperature-adaptation on stability of proteins and other catalytic biomolecules. First, due to the nature of physical forces between biomolecules and water, stability of biomo…

The benefits of interpopulation hybridization diminish with increasing divergence of small populations.

Interpopulation hybridization can increase the viability of small populations suffering from inbreeding and genetic drift, but it can also result in outbreeding depression. The outcome of hybridization can depend on various factors, including the level of genetic divergence between the populations, and the number of source populations. Furthermore, the effects of hybridization can change between generations following the hybridization. We studied the effects of population divergence (low vs. high level of divergence) and the number of source populations (two vs. four source populations) on the viability of hybrid populations using experimental Drosophila littoralis populations. Population v…

Unmatedness promotes the evolution of helping more in diplodiploids than in haplodiploids

The predominance of haplodiploidy (where males develop from unfertilized haploid eggs and females from fertilized diploid eggs) among eusocial species has inspired a body of research that focuses on the possible role of relatedness asymmetries in the evolution of helping and eusociality. Previous theory has shown that in order for relatedness asymmetries to favor the evolution of helping, there needs to be variation in sex ratios among nests in the population (i.e., split sex ratios). In haplodiploid species, unmated females can produce a brood of all males, and this is considered the most likely mechanism for split sex ratios at the origin of helping. In contrast, in diploidiploids unmated…

The good-genes and compatible-genes benefits of mate choice.

Genetic benefits from mate choice could be attained by choosing mates with high heritable quality ("good genes") and that are genetically compatible ("compatible genes"). We clarify the conceptual and empirical framework for estimating genetic benefits of mate choice, stressing that benefits must be measured from offspring fitness because there are no unequivocal surrogates for genetic quality of individuals or for compatibility of parents. We detail the relationship between genetic benefits and additive and nonadditive genetic variance in fitness, showing that the benefits have been overestimated in previous verbal treatments. We point out that additive benefits readily arise from nonaddit…

Supplementary results from Evolution of male and female choice in polyandrous systems

Model results for high population density, expensive mate choice, and fixed male mating costs

Evolution of hermaphroditic mating systems in animals

Miksi jotkin eläinlajit ovat kaksineuvoisia ja toisissa lajeissa koiras- ja naarasominaisuudet ovat eri yksilöissä? Kaksineuvoiset eläimet pystyvät lisääntymään itsesiitoksella ilman kumppania tai ristisiitoksella kumppanin kanssa. Kumpi lisääntymistapa on parempi? Muun muassa näitä kysymyksiä väitöskirjassaan pohtinut Mikael Puurtinen loi tutkimuksessaan teoriaa lisääntymistapojen evoluutiosta, sekä selvitti vedessä elävän isolimakotilon (Lymnaea stagnalis) lisääntymisbiologiaa. Suomen Akatemian nimittämässä evoluutioekologian huippuyksikössä tehty tutkimus toi arvokasta tietoa populaation geneettisen monimuotoisuuden vaikutuksista populaation elinkykyyn sekä kykyyn vastustaa loistauteja. …

Inbreeding depression in intraspecific metabolic scaling

Metabolic scaling (i.e., the relationship between the size and metabolic rate of organisms) has been suggested to explain a large variety of biological patterns from individual growth to species diversity. However, considerable disagreement remains regarding the underlying causes of metabolic scaling patterns, and what these patterns are. As in all biology, understanding metabolic scaling will require understanding its evolution by natural selection. We searched for evidence of natural selection on metabolic scaling indirectly by manipulating the genetic quality of male and female Drosophila montana flies with induced mutations and inbreeding, building on the notion that mutations and inbre…

Extended haplodiploidy hypothesis

P.R., M.P., and H.H. were supported by Academy of Finland (grant 258385 to M.P., grant 135970 to H.H., and 252411 to the Centre of Excellence in Biological Interactions), P.R. also by the Royal Society Newton International Fellowship, and H.H. also by the Kone Foundation. Evolution of altruistic behavior was a hurdle for the logic of Darwinian evolution. Soon after Hamilton formalized the concept of inclusive fitness, which explains how altruism can evolve, he suggested that the high sororal relatedness brought by haplodiploidy could be why Hymenopterans have a high prevalence in eusocial species, and why helpers in Hymenoptera are always female. Later it was noted that in order to capitali…

Males Benefit from Mating with Outbred Females in Drosophila littoralis: Male Choice for Female Genetic Quality?

The evolution and expression of mate choice behaviour in either sex depends on the sex-specific combination of mating costs, benefits of choice and constraints on choice. If the benefits of choice are larger for one sex, we would expect that sex to be choosier, assuming that the mating costs and constraints on choice are equal between sexes. Because deliberate inbreeding is a powerful genetic method for experimental manipulation of the quality of study organisms, we tested the effects of both male and female inbreeding on egg and offspring production in Drosophila littoralis. Female inbreeding significantly reduced offspring production (mostly due to lower egg-to-adult viability), whereas m…

Sexual selection for genetic quality: disentangling the roles of male and female behaviour

According to the good genes model of sexual selection, females choose males of good heritable genetic quality to obtain offspring with high fitness. However, better mating success of high-quality males can also be brought about by direct interference competition between males, or simply through elevated activity of high-quality males. We examined the roles of different processes leading to sexual selection for genetic quality in Drosophila montana. We manipulated genetic quality of male flies by inducing mutations with ionizing radiation. We then recorded the effects of inherited heterozygous mutations on several aspects of mating behaviour of males and females in two experiments. We found …

Conditions for the spread of conspicuous warning signals: A numerical model with novel insights

The initial evolution of conspicuous warning signals presents an evolutionary problem because selection against rare conspicuous signals is presumed to be strong, and new signals are rare when they first arise. Several possible solutions have been offered to solve this apparent evolutionary paradox, but disagreement persists over the plausibility of some of the proposed mechanisms. In this paper, we construct a deterministic numerical simulation model that allows us to derive the strength of selection on novel warning signals in a wide range of biologically relevant situations. We study the effects of predator psychology (learning, rate of mistaken attacks, and neophobia) on selection. We a…

Temperature-dependent mutational robustness can explain faster molecular evolution at warm temperatures, affecting speciation rate and global patterns of species diversity

Distribution of species across the Earth shows strong latitudinal and altitudinal gradients with the number of species decreasing with declining temperatures. While these patterns have been recognized for well over a century, the mechanisms generating and maintaining them have remained elusive. Here, we propose a mechanistic explanation for temperature-dependent rates of molecular evolution that can influence speciation rates and global biodiversity gradients. Our hypothesis is based on the effects of temperature and temperature-adaptation on stability of proteins and other catalytic biomolecules. First, due to the nature of physical forces between biomolecules and water, stability of biomo…

Mate choice for indirect genetic benefits: scrutiny of the current paradigm

Summary 1Sexual selection through mate choice, and in particular female choice for indirect fitness benefits for their offspring, is a major paradigm that currently seems to enjoy almost unequivocal acceptance. A large body of theoretical work has been built to explain the evolution of mate choice in the absence of direct benefits, and the empiricists have enthusiastically verified the various assumptions and predictions of the theory. 2However, the relative importance of mate choice for indirect benefits in comparison to choice for direct benefits or to other mechanisms of sexual selection such as male–male competition or sensory exploitation remains a controversial issue, and this seems t…

Genetic compatibility and sexual selection

In a recent review in TREE [1], Mays and Hill discuss the interface between sexual selection for good genes (i.e. female choice based on traits indicating heritable fitness) and sexual selection for genetic compatibility (i.e. how well the genes of the parents function together in their offspring). We feel that the scope of their contribution is somewhat limited, primarily because they implicitly equate genetic compatibility with genetic dissimilarity. Compatibility does, however, not equal dissimilarity.

Evolution of male and female choice in polyandrous systems

We study the evolution of male and female mating strategies and mate choice for female fecundity and male fertilization ability in a system where both sexes can mate with multiple partners, and where there is variation in individual quality (i.e. in the availability of resources individuals can allocate to matings, mate choice and production of gametes). We find that when the cost of mating differs between sexes, the sex with higher cost of mating is reluctant to accept matings and is often also choosy, while the other sex accepts all matings. With equal mating costs, the evolution of mating strategies depends on the strength of female sperm limitation, so that when sperm limitation is stro…

Laboratory relationships between adult lifetime reproductive success and fitness surrogates in a Drosophila littoralis population.

The difficulties in measuring total fitness of individuals necessitate the use of fitness surrogates in ecological and evolutionary studies. These surrogates can be different components of fitness (e.g. survival or fecundity), or proxies more uncertainly related to fitness (e.g. body size or growth rate). Ideally, fitness would be measured over the lifetime of individuals; however, more convenient short-time measures are often used. Adult lifetime reproductive success (adult LRS) is closely related to the total fitness of individuals, but it is difficult to measure and rarely included in fitness estimation in experimental studies. We explored phenotypic correlations between female adult LRS…

Mate Choice for Genetic Benefits: Time to Put the Pieces Together

It is thought that mate choice allows individuals to obtain genetic benefits for their offspring, and although many studies have found some support for this hypothesis, several critical questions remain unresolved. One main problem is that empirical studies on mate choice and genetic benefits have been rather piecemeal. Some studies (1) aimed to test how mate choice affects offspring fitness, but have not examined whether the benefits are because of genetic effects. Other studies tested whether mate choice provides (2) additive or (3) non-additive genetic benefits and only a few studies (4) considered these genetic effects together. Finally, some studies (5) examined whether the potential b…

Conservation implications of species–genetic diversity correlations

Despite its importance for the long-term viability of populations and functioning of ecosystems, the genetic diversity of populations is seldom given explicit consideration in conservation prioritization. Research on the species–genetic diversity correlation (SGDC) suggests that species diversity within a community and intrapopulation genetic diversity are positively correlated, due to the parallel influences of environmental characteristics (area, connectivity, and environmental heterogeneity) on both levels of diversity. A positive locality scale SGDC (i.e. α-SGDC) thus provides potential for simultaneous conservation of both species diversity within a locality and intrapopulation genetic…

GENETIC VARIABILITY AND DRIFT LOAD IN POPULATIONS OF AN AQUATIC SNAIL

Population genetic theory predicts that in small populations, random genetic drift will fix and accumulate slightly deleterious mutations, resulting in reduced reproductive output. This genetic load due to random drift (i.e., drift load) can increase the extinction risk of small populations. We studied the relationship between genetic variability (indicator of past population size) and reproductive output in eight isolated, natural populations of the hermaphroditic snail Lymnaea stagnalis. In a common laboratory environment, snails from populations with the lowest genetic variability mature slower and have lower fecundity than snails from genetically more variable populations. This result s…

Predominance of outcrossing in Lymnaea stagnalis despite low apparent fitness costs of self-fertilization.

We have quantified the natural mating system in eight populations of the simultaneously hermaphroditic aquatic snail Lymnaea stagnalis, and studied the ecological and genetic forces that may be directing mating system evolution in this species. We investigated whether the natural mating system can be explained by the availability of mates, by the differential survival of self- and cross-fertilized snails in nature, and by the effects of mating system on parental fecundity and early survival. The natural mating system of L. stagnalis was found to be predominantly cross-fertilizing. Density of snails in the populations had no relationship with the mating system, suggesting that outcrossing ra…

Between-group competition and human cooperation.

A distinctive feature of human behaviour is the widespread occurrence of cooperation among unrelated individuals. Explaining the maintenance of costly within-group cooperation is a challenge because the incentive to free ride on the efforts of other group members is expected to lead to decay of cooperation. However, the costs of cooperation can be diminished or overcome when there is competition at a higher level of organizational hierarchy. Here we show that competition between groups resolves the paradigmatic ‘public goods’ social dilemma and increases within-group cooperation and overall productivity. Further, group competition intensifies the moral emotions of anger and guilt associated…

Planetary well-being

Tensions between the well-being of present humans, future humans, and nonhuman nature manifest in social protests and political and academic debates over the future of Earth. The increasing consumption of natural resources no longer increases, let alone equalizes, human well-being, but has led to the current ecological crisis and harms both human and nonhuman well-being. While the crisis has been acknowledged, the existing conceptual frameworks are in some respects ill-equipped to address the crisis in a way that would link the resolving of the crisis with the pivotal aim of promoting equal well-being. The shortcomings of the existing concepts in this respect relate to anthropocentric norma…

Planetary well-being

Tensions between the well-being of present humans, future humans, and nonhuman nature manifest in social protests and political and academic debates over the future of Earth. The increasing consumption of natural resources no longer increases, let alone equalises, human well-being, but has led to the current ecological crisis and harms both human and nonhuman well-being. While the crisis has been acknowledged, the existing conceptual frameworks are in some respects ill-equipped to address the crisis in a way that would link the resolving of the crisis with the pivotal aim of promoting equal well-being. The shortcomings of the existing concepts in this respect relate to anthropocentric norma…

Inbreeding rate modifies the dynamics of genetic load in small populations

The negative fitness consequences of close inbreeding are widely recognized, but predicting the long-term effects of inbreeding and genetic drift due to limited population size is not straightforward. As the frequency and homozygosity of recessive deleterious alleles increase, selection can remove (purge) them from a population, reducing the genetic load. At the same time, small population size relaxes selection against mildly harmful mutations, which may lead to accumulation of genetic load. The efficiency of purging and the accumulation of mutations both depend on the rate of inbreeding (i.e., population size) and on the nature of mutations. We studied how increasing levels of inbreeding …

On the resolution of the lek paradox.

Directional female mate choice is expected to deplete additive genetic variation in male traits. This should preclude such trait-based choice from resulting in genetic benefits to offspring, and yet genetic benefits are the explanation for the choice. This evolutionary conundrum is known as the lek paradox. Newly proposed resolutions to this paradox aim to unravel mechanisms that contribute to the persistence of genetic variance in traits under directional female mate choice.

Content, cost, and context: A framework for understanding human signaling systems

Humans frequently perform extravagant and seemingly costly behaviors, such as widely sharing hunted resources, erecting conspicuous monumental structures, and performing dramatic acts of religious devotion. Evolutionary anthropologists and archeologists have used signaling theory to explain the function of such displays, drawing inspiration from behavioral ecology, economics, and the social sciences. While signaling theory is broadly aimed at explaining honest communication, it has come to be strongly associated with the handicap principle, which proposes that such costly extravagance is in fact an adaptation for signal reliability. Most empirical studies of signaling theory have focused on…

On female choice, heterozygosity and the lek paradox

Human cooperation in groups: variation begets variation

Open Access Published: 04 November 2015 Human cooperation in groups: variation begets variation Pieter van den Berg, Lucas Molleman, Jaakko Junikka, Mikael Puurtinen & Franz J. Weissing Scientific Reports volume 5, Article number: 16144 (2015) Cite this article 383 Accesses 4 Citations 6 Altmetric Metricsdetails Abstract Many experiments on human cooperation have revealed that individuals differ systematically in their tendency to cooperate with others. It has also been shown that individuals condition their behaviour on the overall cooperation level of their peers. Yet, little is known about how individuals respond to heterogeneity in cooperativeness in their neighbourhood. Here, we presen…

Costly punishment prevails in intergroup conflict.

Understanding how societies resolve conflicts between individual and common interests remains one of the most fundamental issues across disciplines. The observation that humans readily incur costs to sanction uncooperative individuals without tangible individual benefits has attracted considerable attention as a proximate cause as to why cooperative behaviours might evolve. However, the proliferation of individually costly punishment has been difficult to explain. Several studies over the last decade employing experimental designs with isolated groups have found clear evidence that the costs of punishment often nullify the benefits of increased cooperation, rendering the strong human tenden…

Data from: Evolution of male and female choice in polyandrous systems

We study the evolution of male and female mating strategies and mate choice for female fecundity and male fertilization ability in a system where both sexes can mate with multiple partners, and where there is variation in individual quality (i.e. in the availability of resources individuals can allocate to matings, mate choice and production of gametes). We find that when the cost of mating differs between sexes, the sex with higher cost of mating is reluctant to accept matings and is often also choosy, while the other sex accepts all matings. With equal mating costs, the evolution of mating strategies depends on the strength of female sperm limitation, so that when sperm limitation is stro…

Data from: The evolutionary dynamics of adaptive virginity, sex-allocation and altruistic helping in haplodiploid animals

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g. when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests (‘split sex ratios’), which promotes the evolution of altruistic helping by daughters in mated queen nests. How…

Data from: The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients

Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e., inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on 1) mean fitness of a population (relative to that of an outbred control population), 2) within-population inbreeding depression (reduction in fitness of offspring from …

Data from: Extended haplodiploidy hypothesis

Evolution of altruistic behaviour was a hurdle for the logic of Darwinian evolution. Soon after Hamilton formalised the concept of inclusive fitness, which explains how altruism can evolve, he suggested that the high sororal relatedness brought by haplodiploidy could be why Hymenopterans have a high prevalence in eusocial species, and why helpers in Hymenoptera are always female. Later it was noted that in order to capitalize on the high sororal relatedness, helpers would need to direct help towards sisters, and this would bias the population sex ratio. Under a 1:3 males:females sex ratio, the inclusive fitness valuation a female places on her sister, brother and an own offspring are equal …