Abstract Natural selection operates both directly, via the impact of a trait upon individual’s own fitness, and indirectly, fitness genetically related social partners. These effects are often framed in terms Hamilton’s rule, rb − c > 0, which provides central result social‐evolution theory. However, number studies have questioned generality suggesting that it requires restrictive assumptions. Here, we use Fisher’s genetical paradigm to demonstrate rule clarify links between different...

Two standard mathematical formulations of kin-selection models can be found. Inclusive fitness is an actor-centred approach, which calculates the effect on a number recipients behaviour single actor. Direct recipient-centred recipient actors. offers us powerful heuristic, choosing to maximize fitness, but direct mathematically easier work with and has recently emerged as preferred approach theoreticians. In this paper, we explore fundamental connection between these two approaches in both...

Tests of sex allocation theory in vertebrates are usually based on verbal arguments. However, the operation multiple selective forces can complicate arguments, possibly making them misleading. We construct an inclusive fitness model for evolution condition-dependent brood ratio adjustment response to two leading explanations vertebrates: effect maternal quality male and female offspring (the Trivers-Willard hypothesis [TWH]) local resource competition (LRC) between females. show (1)...

Empirical data suggest that low levels of promiscuity have played a key role in the evolution cooperative breeding and eusociality. However, from theoretical perspective, can favour dispersal away natal patch, been argued to select against cooperation way cannot be explained by inclusive fitness theory. Here, we use an approach model selection stay help simple patch-structured population, with strict density dependence, where helping increases survival breeder on patch. Our predicts level...

Most animals and many plants make use of specialized chromosomes (sex chromosomes) to determine an individual's sex. Best known are the XY ZW sex-determination systems. Despite having evolved numerous times, sex present something evolutionary puzzle. At their origin, alleles that dictate development as one or other (primitive face a selective penalty, they will be found more often in abundant How is it possible primitive overcome this disadvantage? Any theory for origin must identify benefit...

Abstract Kin selection theory predicts that individuals should evolve to help relatives, either by helping indiscriminately in a population where they do not move very far from their or discriminating kin and conditionally them. It has been argued that, because discrimination enables reduce how helpful are with some social partners as well increase others, this could lead an decrease the overall level of helping. Specifically, it was would if function relating optimal genetic relatedness is...

Vertical transmission is widely predicted to select for reduced virulence of pathogens. Recent theory cast doubt on this prediction by showing that the evolutionary response host vertical can lead severe disease outcomes. That theory, however, takes a simplified view population dynamics assuming pathogen-induced mortality alone inhibits growth. The assumption limits our ability uncover benign co-evolutionary outcomes characterized low levels mortality. Here, we revisit role using model...

We investigate two methods of measuring fitness in evolutionary games played among members a finite population. Classical notions stability account for the action selection only, and use immediate reproductive gains as measure fitness. This classical interpretation is what we call (RF), found early studies populations. More recent work has incorporated influence random genetic drift by applying fixation probability (FP) When defined this way, represents ultimate success. Our main result...

In multipartite viruses, the genome is split into multiple segments, each of which transmitted via a separate capsid. The existence viruses poses problem, because replication only possible when all segments are present within same host. Given this clear cost, why multipartitism so common in viruses? Most previous hypotheses try to explain how could provide an advantage. doing, they require scenarios that unrealistic and cannot with more than 2 segments. We show theoretically selection for...

Genomic imprinting allows maternally and paternally derived alleles to have different patterns of expression (one allele is often silent). Kin selection provides an explanation genomic because conflicts interest can arise between inherited when they probabilities being present in other individuals. Our aim here examine the extent which could over allocation resources male female reproduction (sex allocation), for example, conflict offspring sex ratio. We situations influenced by competitive...

Abstract With any theoretical model, the modeler must decide what kinds of detail to include and which simplifying assumptions make. It could be assumed that models more are better, or correct. However, no model is a perfect description reality relative advantage different levels depends on model's empirical purpose. We consider specific case how relatedness modeled in field social evolution. Different types either leave as an independent parameter (open models), for demography life cycle...

Social behaviours are typically modelled using neighbour-modulated fitness, which focuses on individuals having their fitness altered by neighbours. However, these models either interpreted inclusive altering the of neighbours, or not at all. This disconnect leads to interpretational mistakes and obscures adaptive significance behaviour. We bridge this gap presenting a systematic methodology for constructing inclusive-fitness models. find behaviour's 'inclusive-fitness effect' summing...

Abstract Medical research reports that women often exhibit stronger immune responses than men, while pathogens tend to be more virulent in men. Current explanations cannot account for this pattern, creating an obstacle our understanding of infectious-disease outcomes and the incidence autoimmune diseases. We offer alternative explanation relies on a fundamental difference between sexes: maternity opportunities it creates transmission from mother child (vertical transmission). Our...

Small numbers of fetal cells cross the placenta during pregnancy turning mothers into microchimeras. Fetal from all previous pregnancies accumulate forming mother's microchiome. What is significant about microchimeric that they have been linked to health problems including reproductive and autoimmune diseases. Three decades after discovery microchimerism, function these remains a mystery. Here, we contend role inform fetus likelihood its genes are present in future pregnancies. We argue...

This study investigates the evolution of sex ratio (parental investment in sons) when breeding adults are supported by help provided nonbreeding individuals one sex. The also assumes that helping remains on its natal site to compete for opportunity breed, whereas nonhelping disperses. Two kin-selection models presented, both which incorporate age structure found many natural populations where such occurs. first model helpers increase survival their parents. second indiscriminant: a helper...

It has been hypothesized that horizontal gene transfer on plasmids can facilitate the evolution of cooperation, by allowing genes to jump between bacteria, and hence increase genetic relatedness at cooperative loci. However, we show theoretically only appreciably increases when are rare, where there many plasmid-free cells available infect (many opportunities for transfer). In contrast, common, few transfer, meaning is not increased, so cooperation favored. Plasmids, therefore, evolve be...