Facultative Helping Does Not Influence Reproductive Success or Survival in Cooperatively Breeding White-Browed Scrubwrens

10.2307/5919 ◽  
1997 ◽  
Vol 66 (5) ◽  
pp. 658 ◽  
Author(s):  
Robert D. Magrath ◽  
Stephen M. Yezerinac
Keyword(s):  
Reproductive Success ◽  
Cooperatively Breeding

scholarly journals Live long and prosper: durable benefits of early-life care in banded mongooses

2019 ◽  
Vol 374 (1770) ◽  
pp. 20180114 ◽  
Author(s):  
Emma I. K. Vitikainen ◽  
Faye J. Thompson ◽  
Harry H. Marshall ◽  
Michael A. Cant
Keyword(s):  
Reproductive Success ◽  
Early Life ◽  
Female Offspring ◽  
Evolutionary Medicine ◽  
Laboratory Animals ◽  
Lifetime Reproductive Success ◽  
Life Care ◽  
Developmental Effects ◽  
Cooperatively Breeding ◽  
Fitness Benefits

Kin selection theory defines the conditions for which altruism or ‘helping’ can be favoured by natural selection. Tests of this theory in cooperatively breeding animals have focused on the short-term benefits to the recipients of help, such as improved growth or survival to adulthood. However, research on early-life effects suggests that there may be more durable, lifelong fitness impacts to the recipients of help, which in theory should strengthen selection for helping. Here, we show in cooperatively breeding banded mongooses ( Mungos mungo ) that care received in the first 3 months of life has lifelong fitness benefits for both male and female recipients. In this species, adult helpers called ‘escorts’ form exclusive one-to-one caring relationships with specific pups (not their own offspring), allowing us to isolate the effects of being escorted on later reproduction and survival. Pups that were more closely escorted were heavier at sexual maturity, which was associated with higher lifetime reproductive success for both sexes. Moreover, for female offspring, lifetime reproductive success increased with the level of escorting received per se , over and above any effect on body mass. Our results suggest that early-life social care has durable benefits to offspring of both sexes in this species. Given the well-established developmental effects of early-life care in laboratory animals and humans, we suggest that similar effects are likely to be widespread in social animals more generally. We discuss some of the implications of durable fitness benefits for the evolution of intergenerational helping in cooperative animal societies, including humans. This article is part of the theme issue ‘Developing differences: early-life effects and evolutionary medicine’.

scholarly journals The determinants of dominance relationships among subordinate females in the cooperatively breeding meerkat

Behaviour ◽  
2014 ◽  
Vol 151 (1) ◽  
pp. 89-102 ◽  
Author(s):  
N.K. Thavarajah ◽  
M. Fenkes ◽  
T.H. Clutton-Brock
Keyword(s):  
Reproductive Success ◽  
Competitive Advantage ◽  
Reproductive Skew ◽  
Breeding Female ◽  
Suricata Suricatta ◽  
Dominance Relationships ◽  
Dominance Structure ◽  
Starting Point ◽  
Cooperatively Breeding ◽  
Group Members

In cooperatively breeding species with high reproductive skew, a single breeding female is dominant to all other group members, but it is not yet known if there are consistent dominance relationships among subordinates. In this study on meerkats (Suricata suricatta), we used naturally observed dominance assertions and submissive interactions within dyads of subordinate females to investigate: (i) whether or not a dominance structure exists among them and what factors influence dominance relationships; and (ii) how dominance may influence the future reproductive success of subordinate females. Our study indicates that superiority in age and weight provide a competitive advantage during conflicts among subordinate females and that females who consistently dominate in these contests are subsequently more likely to attain a dominant breeding position. This provides a starting point for further investigations into dominance structure among subordinates in meerkat societies and other cooperative breeders.

scholarly journals Hamilton's inclusive fitness maintains heritable altruism polymorphism through rb = c

2018 ◽  
Vol 115 (8) ◽  
pp. 1860-1864 ◽  
Author(s):  
Changcao Wang ◽  
Xin Lu
Keyword(s):  
Reproductive Success ◽  
Inclusive Fitness ◽  
Lifetime Reproductive Success ◽  
Adult Males ◽  
Breeding Bird ◽  
Annual Fluctuation ◽  
The Social ◽  
Cooperatively Breeding ◽  
Social Partners ◽  
Indirect Fitness

How can altruism evolve or be maintained in a selfish world? Hamilton’s rule shows that the former process will occur when rb > c—the benefits to the recipients of an altruistic act b, weighted by the relatedness between the social partners r, exceed the costs to the altruists c—drives altruistic genotypes spreading against nonaltruistic ones. From this rule, we infer that altruistic genotypes will persist in a population by forming a stable heritable polymorphism with nonaltruistic genotypes if rb = c makes inclusive fitness of the two morphs equal. We test this prediction using the data of 12 years of study on a cooperatively breeding bird, the Tibetan ground tit Pseudopodoces humilis, where helping is performed by males only and kin-directed. Individual variation in ever acting as a helper was heritable (h2 = 0.47), and the resultant altruism polymorphism remained stable as indicated by low-level annual fluctuation of the percentage of helpers among all adult males (24–28%). Helpers’ indirect fitness gains from increased lifetime reproductive success of related breeders statistically fully compensated for their lifetime direct fitness losses, suggesting that rb = c holds. While our work provides a fundamental support for Hamilton’s idea, it highlights the equivalent inclusive fitness returns to altruists and nonaltruists mediated by rb = c as a theoretically and realistically important mechanism to maintain social polymorphism.

Group Structure, Nest Size and Reproductive Success in the Cooperatively Breeding CichlidJulidochromis ornatus: A Correlation Study

Ethology ◽  
2010 ◽  
Vol 116 (4) ◽  
pp. 316-328 ◽  
Author(s):  
Satoshi Awata ◽  
Masanori Kohda ◽  
Jun-Ya Shibata ◽  
Michio Hori ◽  
Dik Heg
Keyword(s):  
Reproductive Success ◽  
Group Structure ◽  
Correlation Study ◽  
Nest Size ◽  
Cooperatively Breeding

scholarly journals Elevated glucocorticoid concentrations during gestation predict reduced reproductive success in subordinate female banded mongooses

2015 ◽  
Vol 11 (10) ◽  
pp. 20150620 ◽  
Author(s):  
J. L. Sanderson ◽  
H. J. Nichols ◽  
H. H. Marshall ◽  
E. I. K. Vitikainen ◽  
F. J. Thompson ◽  
...  
Keyword(s):  
Reproductive Success ◽  
First Trimester ◽  
Reproductive Skew ◽  
Third Trimester ◽  
Communal Breeding ◽  
Social Species ◽  
Cooperatively Breeding ◽  
Banded Mongoose ◽  
Breeding Attempt ◽  
Related Stress

Dominant females in social species have been hypothesized to reduce the reproductive success of their subordinates by inducing elevated circulating glucocorticoid (GC) concentrations. However, this ‘stress-related suppression' hypothesis has received little support in cooperatively breeding species, despite evident reproductive skews among females. We tested this hypothesis in the banded mongoose ( Mungos mungo ), a cooperative mammal in which multiple females conceive and carry to term in each communal breeding attempt. As predicted, lower ranked females had lower reproductive success, even among females that carried to term. While there were no rank-related differences in faecal glucocorticoid (fGC) concentrations prior to gestation or in the first trimester, lower ranked females had significantly higher fGC concentrations than higher ranked females in the second and third trimesters. Finally, females with higher fGC concentrations during the third trimester lost a greater proportion of their gestated young prior to their emergence from the burrow. Together, our results are consistent with a role for rank-related maternal stress in generating reproductive skew among females in this cooperative breeder. While studies of reproductive skew frequently consider the possibility that rank-related stress reduces the conception rates of subordinates, our findings highlight the possibility of detrimental effects on reproductive outcomes even after pregnancies have become established.

Top males gain high reproductive success by guarding more successful females in a cooperatively breeding mongoose

2010 ◽  
Vol 80 (4) ◽  
pp. 649-657 ◽  
Author(s):  
Hazel J. Nichols ◽  
William Amos ◽  
Michael A. Cant ◽  
Matthew B.V. Bell ◽  
Sarah J. Hodge
Keyword(s):  
Reproductive Success ◽  
Cooperatively Breeding

scholarly journals Subordinate male meerkats prospect for extra-group paternity: alternative reproductive tactics in a cooperative mammal

2007 ◽  
Vol 274 (1618) ◽  
pp. 1603-1609 ◽  
Author(s):  
Andrew J Young ◽  
Goran Spong ◽  
Tim Clutton-Brock
Keyword(s):  
Reproductive Success ◽  
Alternative Reproductive Tactics ◽  
Substantial Proportion ◽  
Reproductive Tactics ◽  
Age At First Reproduction ◽  
Suricata Suricatta ◽  
Cooperatively Breeding ◽  
First Reproduction ◽  
Fitness Benefits ◽  
Animal Societies

In cooperatively breeding species, subordinates typically suffer strong constraints on within-group reproduction. While numerous studies have highlighted the additional fitness benefits that subordinates might accrue through helping, few have considered the possibility that subordinates may also seek extra-group matings to improve their chances of actually breeding. Here, we show that subordinate males in cooperative meerkat, Suricata suricatta , societies conduct frequent extraterritorial forays, during periods of peak female fertility, which give rise to matings with females in other groups. Genetic analyses reveal that extra-group paternity (EGP) accrued while prospecting contributes substantially to the reproductive success of subordinates: yielding the majority of their offspring (approx. 70%); significantly reducing their age at first reproduction and allowing them to breed without dispersing. We estimate that prospecting subordinates sire 20–25% of all young in the population. While recent studies on cooperative birds indicate that dominant males accrue the majority of EGP, our findings reveal that EGP can also arise from alternative reproductive tactics employed exclusively by subordinates. It is important, therefore, that future attempts to estimate the fitness of subordinate males in animal societies quantify the distribution of extra-group as well as within-group paternity, because a substantial proportion of the reproductive success of subordinates may otherwise go undetected.

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