Kinship effects in quasi-social parasitoids I: co-foundress number and relatedness affect suppression of dangerous hosts

Abstract Explanations for the highest levels of sociality typically invoke the concept of inclusive fitness. Sclerodermus, a genus of parasitoid hymenopterans, is quasi-social, exhibiting cooperative brood care without generational overlap or apparent division of labour. Foundress females successfully co-exploit hosts that are too large to suppress when acting alone and the direct fitness benefits of collective action may explain their cooperation, irrespective of kinship. However, cooperation in animal societies is seldom free of conflicts of interest between social partners, especially when their relatedness, and thus their degree of shared evolutionary interests, is low. We screened components of the life-history of Sclerodermus brevicornis for effects of varying co-foundress number and relatedness on cooperative reproduction. We found that the time taken to paralyse standard-sized hosts is shorter when co-foundress number and/or relatedness is higher. This suggests that, while females must access a paralysed host in order to reproduce, individuals are reluctant to take the risk of host attack unless the benefits will be shared with their kin. We used Hamilton’s rule and prior data from studies that experimentally varied the sizes of hosts presented to congeners to explore how the greater risks and greater benefits of attacking larger hosts could combine with relatedness to determine the sizes of hosts that individuals are selected to attack as a public good. From this, we predict that host size and relatedness will interact to affect the timing of host paralysis; we test this prediction in the accompanying study.

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Why inclusive fitness can make it adaptive to produce less fit extra-pair offspring

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.2716 ◽

2015 ◽

Vol 282 (1801) ◽

pp. 20142716 ◽

Cited By ~ 15

Author(s):

Jussi Lehtonen ◽

Hanna Kokko

Keyword(s):

Inclusive Fitness ◽

Empirical Work ◽

Reproductive Season ◽

Breeding Systems ◽

Social Partner ◽

Social Monogamy ◽

Monogamous Species ◽

Social Partners ◽

Socially Monogamous ◽

Fitness Benefits

Social monogamy predominates in avian breeding systems, but most socially monogamous species engage in promiscuous extra-pair copulations (EPCs). The reasons behind this remain debated, and recent empirical work has uncovered patterns that do not seem to fit existing hypotheses. In particular, some results seem to contradict the inbreeding avoidance hypothesis: females can prefer extra-pair partners that are more closely related to them than their social partners, and extra-pair young can have lower fitness than within-pair young. Motivated by these studies, we show that such results can become explicable when an asymmetry in inbreeding tolerance between monogamy and polygamy is extended to species that combine both strategies within a single reproductive season. Under fairly general conditions, it can be adaptive for a female to choose an unrelated social partner, but inbreed with an extra-pair partner. Inbreeding depression is compensated for by inclusive fitness benefits, which are only fully realized in EPCs. We also show that if a female has already formed a suboptimal social bond, there are scenarios where it is beneficial to engage in EPCs with less related males, and others where EPCs with more related males increase her inclusive fitness. This has implications for detecting general relatedness or fitness trends when averaged over several species.

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Life History of Normal Human Lymphocytes Revealed By Somatic Mutations

Blood ◽

10.1182/blood-2019-128188 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1045-1045 ◽

Cited By ~ 1

Author(s):

Heather E Machado ◽

Nina Friesgaard Øbro ◽

Emily Mitchell ◽

Megan Davies ◽

Anthony R Green ◽

...

Keyword(s):

T Cells ◽

Life History ◽

Somatic Mutations ◽

Lymphocyte Subsets ◽

Conflicts Of Interest ◽

Human Lymphocytes ◽

Hematopoietic Stem ◽

Mutation Burden ◽

History Of ◽

Mutational Processes

Introduction: Mature blood cells harbor a mixture of mutations inherited from ancestral hematopoietic stem cells (HSCs) and mutations accumulated after maturation. The landscape of these somatic mutations in normal blood is poorly mapped, with questions as simple as "how many mutations does a memory T cell accumulate throughout life?" remaining unanswered. This gap in our knowledge is particularly relevant for hematopoietic malignancy- while we know that lymphomas derive from lymphocytes of particular stages of differentiation, we do not know if the patterns we see are reflected in their normal counterparts. Results: In order to characterize normal somatic mutation in lymphocytes, we performed single-cell expansion and whole genome sequencing of over 600 T and B lymphocytes and 200 HSC and progenitor cells across 5 individuals (ages 0-85). All lymphocyte subsets show increased mutation burden with respect to HSCs across all classes of variants (Figure 1). Some of this increase can explained by lymphocyte-specific mutational processes, such as the activity of RAG, accounting for at least 20% of observed structural variants. We also find a striking variation in mutation burden within and between lymphocyte subsets. Microenvironment specific mutational processes dominate the observed differences. Examples of this include germinal center ("non-canonical AID") mutations in memory B cells and UV-like mutations in memory T cells (putatively skin resident cells). Naive B and T cells show a lack of variation in discrete mutational patterns relative to their memory counterparts, and have mutational profiles and mutation burdens more similar to that of HSCs. We also observe differences in the mutational patterns between B and T cells that are indicative of the increased divergence of T lymphocytes from the HSC pool. In general, the mutation burden we observe in normal lymphocytes approach those seen in lymphoma. Conclusions: Our work highlights the substantial genetic diversity in normal lymphocytes, with some cells accumulating thousands of mutations on top of those inherited from the HSC compartment. These mutations can be used to describe the life history of each individual lymphocyte including their exposure to specific microenvironments. Our findings shed light on the biology of these cells and will help differentiate between normal and disease processes. Figure 1 Disclosures No relevant conflicts of interest to declare.

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Postreproductive killer whale grandmothers improve the survival of their grandoffspring

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1903844116 ◽

2019 ◽

Vol 116 (52) ◽

pp. 26669-26673 ◽

Cited By ~ 6

Author(s):

Stuart Nattrass ◽

Darren P. Croft ◽

Samuel Ellis ◽

Michael A. Cant ◽

Michael N. Weiss ◽

...

Keyword(s):

Life History ◽

Inclusive Fitness ◽

Killer Whale ◽

Mammalian Species ◽

Life History Trait ◽

Killer Whales ◽

Reproductive Conflict ◽

Significant Survival ◽

Fitness Benefits ◽

Difficult Times

Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after stopping reproduction. This unusual life history trait is thought to have evolved, in part, due to the inclusive fitness benefits that postreproductive females gain by helping kin. In humans, grandmothers gain inclusive fitness benefits by increasing their number of surviving grandoffspring, referred to as the grandmother effect. Among toothed whales, the grandmother effect has not been rigorously tested. Here, we test for the grandmother effect in killer whales, by quantifying grandoffspring survival with living or recently deceased reproductive and postreproductive grandmothers, and show that postreproductive grandmothers provide significant survival benefits to their grandoffspring above that provided by reproductive grandmothers. This provides evidence of the grandmother effect in a nonhuman menopausal species. By stopping reproduction, grandmothers avoid reproductive conflict with their daughters, and offer increased benefits to their grandoffspring. The benefits postreproductive grandmothers provide to their grandoffspring are shown to be most important in difficult times where the salmon abundance is low to moderate. The postreproductive grandmother effect we report, together with the known costs of late-life reproduction in killer whales, can help explain the long postreproductive life spans of resident killer whales.

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Genetic relatedness in two-tiered plains zebra societies suggests that females choose to associate with kin

Behaviour ◽

10.1163/1568539x-00003314 ◽

2015 ◽

Vol 152 (15) ◽

pp. 2059-2078 ◽

Cited By ~ 5

Author(s):

Wenfei Tong ◽

Beth Shapiro ◽

Daniel I. Rubenstein

Keyword(s):

Sex Differences ◽

Positive Relationship ◽

Genetic Relatedness ◽

Inclusive Fitness ◽

Lactating Females ◽

Female Dispersal ◽

Fitness Benefits ◽

Dispersal Distances ◽

Plains Zebra ◽

Animal Societies

How kinship structures alter inclusive fitness benefits or competition costs to members of a group can explain variation in animal societies. We present rare data combining behavioural associations and genetic relatedness to determine the influence of sex differences and kinship in structuring a two-tiered zebra society. We found a significantly positive relationship between the strength of behavioural association and relatedness. Female relatedness within herds was higher than chance, suggesting that female kin drive herd formation, and consistent with evidence that lactating females preferentially group into herds to dilute predation risk. In contrast, male relatedness across harems in a herd was no different from relatedness across herds, suggesting that although stallions benefit from associating to fend off bachelors, they do not preferentially form kin coalitions. Although both sexes disperse, we found that most harems contained adult relatives, implying limited female dispersal distances and inbreeding in this population, with potential conservation consequences.

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Resolving social conflict among females without overt aggression

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0076 ◽

2013 ◽

Vol 368 (1631) ◽

pp. 20130076 ◽

Cited By ~ 20

Author(s):

Michael A. Cant ◽

Andrew J. Young

Keyword(s):

Social Conflict ◽

Conflicts Of Interest ◽

Empirical Work ◽

Overt Aggression ◽

Reproductive Conflict ◽

Biological Reality ◽

Social Partners ◽

Behavioural Conflict ◽

Time Changes ◽

Animal Societies

Members of animal societies compete over resources and reproduction, but the extent to which such conflicts of interest are resolved peacefully (without recourse to costly or wasteful acts of aggression) varies widely. Here, we describe two theoretical mechanisms that can help to understand variation in the incidence of overt behavioural conflict: (i) destruction competition and (ii) the use of threats. The two mechanisms make different assumptions about the degree to which competitors are socially sensitive (responsive to real-time changes in the behaviour of their social partners). In each case, we discuss how the model assumptions relate to biological reality and highlight the genetic, ecological and informational factors that are likely to promote peaceful conflict resolution, drawing on empirical examples. We suggest that, relative to males, reproductive conflict among females may be more frequently resolved peacefully through threats of punishment, rather than overt acts of punishment, because (i) offspring are more costly to produce for females and (ii) reproduction is more difficult to conceal. The main need now is for empirical work to test whether the mechanisms described here can indeed explain how social conflict can be resolved without overt aggression.

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