Can incest within cooperative breeding groups be detected using DNA fingerprinting?

Abstract A biased adult sex ratio (ASR) can influence cooperative breeding behavior if the bias limits mating opportunities for the more abundant sex. We tested predictions associated with the ASR-cooperation hypothesis in the brown-headed nuthatch (Sitta pusilla). We manipulated ASR by cross-fostering known-sex nestlings within 2 large (≥100 ha) experimental plots for 5 years using a crossover design where each plot received an opposing male- or female-biased treatment for 2 consecutive years. A year with no manipulations followed before the bias was reversed on each plot for 2 additional years. Variation in ASR (adult males/total adults) was pronounced compared to background proportions (0.55) and ranged from a female bias in female-biased plots (0.47) to a strong male bias in male-biased plots (0.71). Sex ratios during the postbreeding period ranged more broadly (0.33 in female-biased plots vs. 0.74 in male-biased plots). Territory densities did not change significantly and allowed 6 predictions to be assessed. Consistent with predictions, the prevalence of cooperative breeding groups doubled under male-biased treatments and large cooperative groups appeared (≥2 male helpers vs. the single male helper most common prior to the experiment). These changes occurred despite increased dispersal of cross-fostered males in male-biased plots. Most juvenile females dispersed, but, consistent with predictions, the prevalence of female helpers increased under female-biased treatments. Manipulations did not alter the sex of nestlings produced nor extend the time that males served as helpers. Taken collectively, results support the ASR-cooperation hypothesis and the role that mate limitations play in cooperative breeding behavior.

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Workers influence royal reproduction

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2010.1774 ◽

2010 ◽

Vol 278 (1711) ◽

pp. 1524-1531 ◽

Cited By ~ 8

Author(s):

Richard J. Gill ◽

Robert L. Hammond

Keyword(s):

Sex Ratio ◽

Social Insects ◽

Cooperative Breeding ◽

Parentage Analysis ◽

Egg Laying ◽

Male Production ◽

Leptothorax Acervorum ◽

Worker Brood ◽

Breeding Groups ◽

Animal Societies

Understanding which parties regulate reproduction is fundamental to understanding conflict resolution in animal societies. In social insects, workers can influence male production and sex ratio. Surprisingly, few studies have investigated worker influence over which queen(s) reproduce(s) in multiple queen (MQ) colonies (skew), despite skew determining worker-brood relatedness and so worker fitness. We provide evidence for worker influence over skew in a functionally monogynous population of the ant Leptothorax acervorum . Observations of MQ colonies leading up to egg laying showed worker aggressive and non-aggressive behaviour towards queens and predicted which queen monopolized reproduction. In contrast, among-queen interactions were rare and did not predict queen reproduction. Furthermore, parentage analysis showed workers favoured their mother when present, ensuring closely related fullsibs (average r = 0.5) were reared instead of less related offspring of other resident queens ( r ≤ 0.375). Discrimination among queens using relatedness-based cues, however, seems unlikely as workers also biased their behaviour in colonies without a mother queen. In other polygynous populations of this species, workers are not aggressive towards queens and MQs reproduce, showing the outcome of social conflicts varies within species. In conclusion, this study supports non-reproductive parties having the power and information to influence skew within cooperative breeding groups.

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Helpers increase daily survival rate of Southern Lapwing (Vanellus chilensis) nests during the incubation stage

10.1101/179606 ◽

2017 ◽

Cited By ~ 1

Author(s):

Eduardo S. A. Santos ◽

Regina H. Macedo

Keyword(s):

Survival Rate ◽

Cooperative Breeding ◽

Null Model ◽

Daily Survival Rate ◽

Egg Survival ◽

Incubation Stage ◽

Daily Survival ◽

Group Members ◽

Breeding Groups ◽

Model Weight

AbstractCooperative breeding is characterized by reproduction in the presence of helpers. What impact these helpers have on the reproductive success of group members is one of the long-standing questions in the cooperative breeding literature. In cooperative species, helpers are known to provide benefits during multiple stages or at a particular stage of the reproductive cycle. The aim of this study was to investigate whether helpers increased the daily survival rate of nests during the incubation stage in the Southern Lapwing (Vanellus chilensis), a crested plover with a cooperative breeding system. Southern Lapwings have a variable mating system, with some breeding groups composed of unassisted pairs, and others that breed in the presence of helpers. Our best supported model indicated a positive effect of the presence of helpers on the daily survival rate of nests, leading to a probability of nest success (i.e., survival until hatching) of 83%, compared to 51% for nests of unassisted pairs. But a null model had a similar model weight as the best supported model and was the second-best model. Our study provides evidence that helpers influence egg survival during the egg-incubation stage, which could influence the fitness of breeders.

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Winter is coming: harsh environments limit independent reproduction of cooperative-breeding queens in a socially polymorphic ant

Biology Letters ◽

10.1098/rsbl.2019.0730 ◽

2020 ◽

Vol 16 (1) ◽

pp. 20190730

Author(s):

Ornela De Gasperin ◽

Pierre Blacher ◽

Guglielmo Grasso ◽

Michel Chapuisat

Keyword(s):

Cooperative Breeding ◽

Harsh Environments ◽

Brood Production ◽

Winter Condition ◽

Mild Winter ◽

Ecological Conditions ◽

Formica Selysi ◽

Single Queen ◽

Breeding Groups ◽

Family Groups

Cooperative breeding animals frequently inhabit harsh environments. It is widely accepted that harsh environments hinder independent reproduction, and this constraint maintains individuals in family groups. Yet the assumption that harsh ecological conditions reduce the success of members of cooperative breeding groups when breeding independently has not been experimentally tested. We addressed this shortcoming using the socially polymorphic Alpine silver ant, Formica selysi . This species has single-queen (independent breeders) and multiple-queen (cooperative breeders) colonies coexisting within populations. We placed newly mated queens emerging from each type of colony to breed alone in either a harsh or mild winter condition and recorded their brood production and survival. Queens emerging from single-queen colonies were unaffected by the winter condition and were more successful at founding a nest independently than queens from multiple-queen colonies. By contrast, queens from multiple-queen colonies had higher mortality after a harsh than after a mild winter. These results support the long-held assumption that harsh environments constrain independent reproduction of members of cooperative breeding groups.

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Cooperatively Breeding Groups of Carrion Crow(Corvus Corone Corone) in Northern Spain

The Auk ◽

10.1093/auk/119.3.790 ◽

2002 ◽

Vol 119 (3) ◽

pp. 790-799 ◽

Cited By ~ 11

Author(s):

Vittorio Baglione ◽

José M. Marcos ◽

Daniela Canestrari

Keyword(s):

Cooperative Breeding ◽

Northern Spain ◽

Juvenile Dispersal ◽

Carrion Crow ◽

Cooperatively Breeding ◽

Corvus Corone ◽

Group Members ◽

Breeding Groups ◽

Mode 3 ◽

One Year

AbstractThe Carrion Crow (Corvus corone) is almost invariably reported as a species breeding as unassisted pairs, but a population of Carrion Crows (Corvus c. corone) from northern Spain that we have been studying since 1995 regularly exhibits cooperative breeding. The Spanish population thus demonstrates that cooperative breeding can vary greatly across populations. Most of the breeding territories (73.3%) in Spain were held by cohesive groups, which consisted of up to nine birds (mode = 3 birds). The proportion of fledglings that delayed dispersal for one year varied between 12.2 and 47.5% for different cohorts. The corresponding values for juveniles postponing dispersal for two years were 4.9 and 19.2%. Philopatry was skewed toward males. Some social groups contained immigrants. Therefore, delayed juvenile dispersal was not the only route towards sociality. Up to three helpers provided food to the nestling and at least one helper was found in all the groups surveyed. However, some group members refrained from visiting nests and thus the contribution to nestling care was highly variable among individuals.

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