scholarly journals The evolution of infanticide by females in mammals

2018 ◽  
Author(s):  
Dieter Lukas ◽  
Elise Huchard
Keyword(s):  
Reproductive Output ◽  
Mammalian Species ◽  
Female Aggression ◽  
Fitness Costs ◽  
Qualitative Synthesis ◽  
Female Infanticide ◽  
Taxonomic Distribution ◽  
Competitive Behaviour ◽  
Indirect Fitness ◽  
Critical Resources

AbstractIn most mammalian species, females regularly interact with kin, and it may thus be difficult to understand the evolution of some aggressive and harmful competitive behaviour among females, such as infanticide. Here, we investigate the evolutionary determinants of infanticide by females by combining a quantitative analysis of the taxonomic distribution of infanticide with a qualitative synthesis of the circumstances of infanticidal attacks in published reports. Our results show that female infanticide is widespread across mammals and varies in relation to social organization and life-history, being more frequent where females breed in groups and have intense bouts of high reproductive output. Specifically, female infanticide occurs where the proximity of conspecific offspring directly threatens the killer’s reproductive success by limiting access to critical resources for her dependent progeny, including food, shelters, care or a social position. In contrast, infanticide is not immediately modulated by the degree of kinship among females, and females occasionally sacrifice closely related juveniles. Our findings suggest that the potential direct fitness rewards of gaining access to reproductive resources have a stronger influence on the expression of female aggression than the indirect fitness costs of competing against kin.

scholarly journals The evolution of infanticide by females in mammals

2019 ◽  
Vol 374 (1780) ◽  
pp. 20180075 ◽  
Author(s):  
Dieter Lukas ◽  
Elise Huchard
Keyword(s):  
Reproductive Output ◽  
Mammalian Species ◽  
Female Aggression ◽  
Fitness Costs ◽  
Qualitative Synthesis ◽  
Theme Issue ◽  
Female Infanticide ◽  
Competitive Behaviour ◽  
Indirect Fitness ◽  
Critical Resources

In most mammalian species, females regularly interact with kin, which is expected to reduce aggressive competitive behaviour among females. It may thus be difficult to understand why infanticide by females has been reported in numerous species and is sometimes perpetrated by groupmates. Here, we investigate the evolutionary determinants of infanticide by females by combining a quantitative analysis of the taxonomic distribution of infanticide with a qualitative synthesis of the circumstances of infanticidal attacks in published reports. Our results show that female infanticide is widespread across mammals and varies in relation to social organization and life history, being more frequent where females breed in groups and have intense bouts of high reproductive output. Specifically, female infanticide occurs where the proximity of conspecific offspring directly threatens the killer's reproductive success by limiting access to critical resources for her dependent progeny, including food, shelters, care or a social position. By contrast, infanticide is not immediately modulated by the degree of kinship among females, and females occasionally sacrifice closely related infants. Our findings suggest that the potential direct fitness rewards of gaining access to reproductive resources have a stronger influence on the expression of female aggression than the indirect fitness costs of competing against kin. This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals’.

Annual Reproductive Yield in the Cooperative Pygmy Nuthatch (Sitta pygmaea)

The Auk ◽  
1988 ◽  
Vol 105 (1) ◽  
pp. 70-77 ◽  
Author(s):  
William J. Sydeman ◽  
Marcel Güntert ◽  
Russell P. Balda
Keyword(s):  
Reproductive Success ◽  
Cooperative Breeding ◽  
Reproductive Output ◽  
Breeding Birds ◽  
Overwinter Survival ◽  
Northern Arizona ◽  
Floral Diversity ◽  
Indirect Fitness ◽  
The Difference ◽  
The Relationship

Abstract We studied cooperative-breeding Pygmy Nuthatches (Sitta pygmaea) for 4 yr in northern Arizona. Breeding units contained 2-5 birds. Helpers were found at about 30% of all nests. All helpers that later bred on the study area were male. Helpers were mostly yearlings, and offspring or siblings of the birds that they aided, but often aided at least one unrelated breeder. Breeding units with helpers produced significantly more young than those without helpers. Breeding units in habitats with the greatest floral diversity and structural maturity fledged significantly more young than those in other habitats. Habitat did not influence the effect of helpers. Year effects increased the strength of the relationship between helpers and annual reproductive output. Previous breeding experience and pair-bond duration were not related to reproductive success. Total brood loss, although rare, was responsible for the difference in reproductive output among pairs with and without helpers and between habitats. Breeding birds with helpers benefit by an increase in direct fitness. The advantage to the helpers is not clear but may be an increase in indirect fitness associated with aiding relatives. Helpers may benefit directly, however, by sharing roosting cavities on a group territory thereby enhancing overwinter survival.

scholarly journals Males harm females less when competing with familiar relatives

2017 ◽  
Vol 284 (1867) ◽  
pp. 20171984 ◽  
Author(s):  
Samuel J. Lymbery ◽  
Leigh W. Simmons
Keyword(s):  
Egg Production ◽  
Callosobruchus Maculatus ◽  
Genetic Relatedness ◽  
Inclusive Fitness ◽  
Fitness Costs ◽  
Offspring Production ◽  
Social Familiarity ◽  
Indirect Fitness ◽  
Opposite Sex ◽  
Female Lifespan

Sexual conflict occurs when reproductive partners have different fitness optima, and can lead to the evolution of traits in one sex that inflict fitness costs on the opposite sex. Recently, it has been proposed that antagonism by males towards females should be reduced when they compete with relatives, because reducing the future productivity of a female would result in an indirect fitness cost for a harmful male. We tested this prediction in the seed beetle Callosobruchus maculatus , the males of which harm females with genital spines and pre-copulatory harassment. We compared lifespan, lifetime egg production and lifetime offspring production among females housed with groups of males that varied in their familiarity and relatedness. Females produced significantly more eggs and offspring when grouped with males who were both related and familiar to each other. There was no effect of male relatedness or familiarity on female lifespan. Our results suggest that males plastically adjust their harmfulness towards females in response to changes in inclusive fitness payoffs, and that in this species both genetic relatedness and social familiarity mediate this effect.

scholarly journals First- and second-order sociality determine survival and reproduction in cooperative cichlids

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151971 ◽  
Author(s):  
Arne Jungwirth ◽  
Michael Taborsky
Keyword(s):  
Social Organization ◽  
Group Size ◽  
Reproductive Output ◽  
Local Population ◽  
Cichlid Fish ◽  
Evolution Of Cooperation ◽  
Large Group ◽  
Indirect Fitness ◽  
Fitness Benefits ◽  
Different Levels

Cooperative breeders serve as a model to study the evolution of cooperation, where costs and benefits of helping are typically scrutinized at the level of group membership. However, cooperation is often observed in multi-level social organizations involving interactions among individuals at various levels. Here, we argue that a full understanding of the adaptive value of cooperation and the evolution of complex social organization requires identifying the effect of different levels of social organization on direct and indirect fitness components. Our long-term field data show that in the cooperatively breeding, colonial cichlid fish Neolamprologus pulcher , both large group size and high colony density significantly raised group persistence. Neither group size nor density affected survival at the individual level, but they had interactive effects on reproductive output; large group size raised productivity when local population density was low, whereas in contrast, small groups were more productive at high densities. Fitness estimates of individually marked fish revealed indirect fitness benefits associated with staying in large groups. Inclusive fitness, however, was not significantly affected by group size, because the direct fitness component was not increased in larger groups. Together, our findings highlight that the reproductive output of groups may be affected in opposite directions by different levels of sociality, and that complex forms of sociality and costly cooperation may evolve in the absence of large indirect fitness benefits and the influence of kin selection.

Male Sexual Orientation and Avuncularity in Canada: Implications for the Kin Selection Hypothesis

2011 ◽  
Vol 11 (3-4) ◽  
pp. 339-352 ◽  
Author(s):  
Deanna L. Forrester ◽  
Doug P. VanderLaan ◽  
Paul L. Vasey ◽  
Jessica L. Parker
Keyword(s):  
Kin Selection ◽  
Sexual Attraction ◽  
Altruistic Behavior ◽  
Adult Males ◽  
Social Tolerance ◽  
Fitness Costs ◽  
Future Directions ◽  
Selection Hypothesis ◽  
Indirect Fitness ◽  
Male Sexual Orientation

AbstractAndrophilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The Kin Selection Hypothesis (KSH) posits that genes for male androphilia can persist if androphilic males offset the fitness costs of not reproducing directly by enhancing indirect fitness. In theory, by directing altruistic behavior toward kin, androphilic males can increase the reproduction of kin, thereby enhancing indirect fitness. Evidence supporting the KSH has been documented in Samoa. Samoan transgendered, androphilic males, known locally as fa’afafine, are socially accepted by the majority of Samoans. In contrast, no supportive evidence has been garnered from other cultures (i.e., USA, UK, Japan) that are characterized by less social tolerance toward male androphiles. Tests of the KSH in Canada might be more likely to yield findings consistent with Samoa because Canadian social and political attitudes toward male androphiles are markedly more tolerant and accepting. Here, we compared the willingness of Canadian androphilic men, gynephilic men, and androphilic women to invest in nieces and nephews as well as in non-kin children. Consistent with the KSH and findings from Samoa, androphilic men exhibited a significantly greater cognitive dissociation between altruistic tendencies directed toward kin versus non-kin children relative to gynephilic men and androphilic women. The present study, therefore, provides some tentative support for the KSH from a culture other than Samoa. Findings and future directions for research are considered within the context of the existing cross-cultural literature.

scholarly journals Competition Drives Group Formation and Reduces Within Nest Relatedness in a Facultatively Social Carpenter Bee

2021 ◽  
Vol 9 ◽  
Author(s):  
Jess L. Vickruck ◽  
Miriam H. Richards
Keyword(s):  
Resource Sharing ◽  
Resource Competition ◽  
Group Formation ◽  
Social Groups ◽  
Fitness Costs ◽  
Short Supply ◽  
Carpenter Bee ◽  
Direct Fitness ◽  
Indirect Fitness ◽  
Almost All

Animals respond to competition among kin for critical breeding resources in two ways: avoidance of direct fitness costs via dispersal of siblings to breed separately, and formation of kin-based societies in which subordinates offset direct fitness costs of breeding competition via altruism and increased indirect fitness. In the facultatively social eastern carpenter bee, nests are a critical breeding resource in perpetually short supply, leading to strong competition among females. Observations of individually marked and genotyped females in conditions of high and low resource competition demonstrate that competition leads to resource sharing and group nesting. However, in contrast to almost all known animal societies, females avoid nesting with relatives, and disperse from their natal nests to join social groups of non-relatives. This is the first example of a structured insect society with cooperation nestmates, the majority of which are unrelated; thus cooperation is more likely based on selection for direct, rather than indirect fitness. By forming social groups of non-kin, females avoid the indirect fitness costs of kin competition among sisters, yet increase their chances of successful reproduction, and thus direct fitness, when forming colonies of non-relatives.

scholarly journals Costs and benefits of sub-lethal Drosophila C virus infection

2017 ◽  
Author(s):  
Pedro F. Vale ◽  
Vanika Gupta ◽  
Charlotte Stewart ◽  
Samuel S.C. Rund ◽  
Katy Monteith
Keyword(s):  
Immune Responses ◽  
Reproductive Output ◽  
Fruit Fly ◽  
Insect Immunity ◽  
Costs And Benefits ◽  
Fitness Costs ◽  
Host Genotype ◽  
In The Wild ◽  
Host Genetic ◽  
Digestive Health

AbstractViruses are major evolutionary drivers of insect immune systems. Much of our knowledge of insect immune responses derives from experimental infections using the fruit fly Drosophila melanogaster. Most experiments, however, employ lethal pathogen doses through septic injury, frequently overwhelming host physiology. While this approach has revealed a number of immune mechanisms, it is less informative about the fitness costs hosts may experience during infection in the wild. Using both systemic and oral infection routes we find that even apparently benign, sub-lethal infections with the horizontally transmitted Drosophila C Virus (DCV) can cause significant physiological and behavioral morbidity that is relevant for host fitness. We describe DCV-induced effects on fly reproductive output, digestive health, and locomotor activity, and we find that viral morbidity varies according to the concentration of pathogen inoculum, host genetic background and sex. Notably, sub-lethal DCV infection resulted in a significant increase in fly reproduction, but this effect depended on host genotype. We discuss the relevance of sub-lethal morbidity for Drosophila ecology and evolution, and more broadly, we remark on the implications of deleterious and beneficial infections for the evolution of insect immunity.

scholarly journals A Life-History Perspective On Sexual Selection in a Polygamous Species

2020 ◽  
Author(s):  
Ke Gao ◽  
Michiel van Wijk ◽  
Zoe Clement ◽  
Martijn Egas ◽  
Astrid Groot
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sperm Competition ◽  
Reproductive Output ◽  
Relative Fitness ◽  
Costs And Benefits ◽  
Fitness Costs ◽  
Bateman Gradient ◽  
Multiple Matings ◽  
Males And Females

Abstract Background: Ever since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we hypothesize that in polygamous species these roles change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis by assessing fitness costs and benefits of multiple matings in both males and females in a polygamous moth species, as in moths not males but females are the signalers and males are the responders. Results: We found that multiple matings confer fitness costs and benefits for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but only 67 % of the males and 14 % of the females mated successfully in all five nights. In addition, the female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, more than 3 matings decreased her reproductive output, so that the Bateman gradient for females fit a quadratic model better than a linear model. The male’s reproductive success was positively affected by the number of matings and a linear regression line best fit the data. Simulations of the effect of sperm competition showed that increasing last-male paternity increases the steepness of the male Bateman gradient and thus the male’s relative fitness gain from additional mating. Irrespective of last-male paternity value, the female Bateman gradient is steeper than the male one for up to three matings. Conclusion: Our results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.

scholarly journals An animal society based on kin competition, not kin cooperation

2019 ◽  
Author(s):  
Jessica L. Vickruck ◽  
Miriam H. Richards
Keyword(s):  
Social Groups ◽  
Fitness Costs ◽  
Short Supply ◽  
Animal Society ◽  
Kin Competition ◽  
Direct Fitness ◽  
Carpenter Bees ◽  
Indirect Fitness ◽  
Strong Competition ◽  
Breeding Resources

AbstractAnimals respond to competition among kin for critical breeding resources in two ways: avoidance of direct fitness costs via dispersal of siblings to breed separately, and formation of kin-based societies in which subordinates offset direct fitness costs of breeding competition via altruism and increased indirect fitness. Here we provide the first evidence that kin competition can promote the evolution of societies based on non-kin cooperation. For eastern carpenter bees, nests are a critical breeding resource in perpetually short supply, leading to strong competition among females. Observations of individually marked and genotyped females demonstrate that sisters disperse from their natal nests to join social groups of nonrelatives. By forming social groups of non-kin, females increase their chances of successful reproduction, while avoiding the indirect fitness cost of competition among sisters.One Sentence SummaryWe describe the first known example of an animal society based on avoidance of kin competition rather than on promotion of kin cooperation.

scholarly journals A Life-History Perspective on Sexual Selection in a Polygamous Species

2020 ◽  
Author(s):  
Ke Gao ◽  
Michiel van Wijk ◽  
Zoe Clement ◽  
Martijn Egas ◽  
Astrid Groot
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sperm Competition ◽  
Reproductive Output ◽  
Relative Fitness ◽  
Costs And Benefits ◽  
Fitness Costs ◽  
Bateman Gradient ◽  
Multiple Matings ◽  
Males And Females

Abstract Background: Ever since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we hypothesize that in polygamous species these roles change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis by assessing fitness costs and benefits of multiple matings in both males and females in a polygamous moth species, as in moths not males but females are the signalers and males are the responders. Results: We found that multiple matings confer fitness costs and benefits for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but only 67 % of the males and 14 % of the females mated successfully in all five nights. In addition, the female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, more than 3 matings decreased her reproductive output, so that the Bateman gradient for females fit a quadratic model better than a linear model. The male’s reproductive success was positively affected by the number of matings and a linear regression line best fit the data. Simulations of the effect of sperm competition showed that increasing last-male paternity increases the steepness of the male Bateman gradient and thus the male’s relative fitness gain from additional mating. Irrespective of last-male paternity value, the female Bateman gradient is steeper than the male one for up to three matings. Conclusion: Our results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.

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