Fitness consequences of within-brood dominance in the cooperatively breeding acorn woodpecker

Abstract Natal dispersal is a key life-history component that may be influenced by the fitness consequences of inbreeding. We studied natal dispersal and inbreeding within a large population of cooperatively breeding, endangered Red-cockaded Woodpeckers (Picoides borealis). We assessed the costs of close inbreeding, the spatial distribution of related males and its relationship to dispersal distance of females, and the change in dispersal behavior of females in the presence of closely related males. Close inbreeding resulted in a significant loss of fitness, through two separate effects: closely related pairs (kinship coefficient ≥ 0.125) exhibited lowered hatching rates and lowered survival and recruitment of fledglings relative to unrelated pairs. Despite a highly predictable spatial clustering of closely related males near the female's natal territory, natal dispersal distance of females was not sufficient to avoid these males as mates. Females changed dispersal behavior in the presence of closely related males on the natal territory: female fledglings were significantly more likely to disperse from natal territories if there were closely related males breeding there in the following year. Females did not change dispersal behavior in the presence of related males that were not on the natal territory. We suggest that dispersal behavior is a trade-off between benefits of short-distance dispersal, e.g., an advantage in competing for scarce breeding vacancies, and the substantial cost of close inbreeding.

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Intergroup aggression in meerkats

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.1993 ◽

2019 ◽

Vol 286 (1917) ◽

pp. 20191993 ◽

Cited By ~ 1

Author(s):

Mark Dyble ◽

Thomas M. Houslay ◽

Marta B. Manser ◽

Tim Clutton-Brock

Keyword(s):

Genetic Relatedness ◽

Group Living ◽

Lethal Violence ◽

Suricata Suricatta ◽

Group Cooperation ◽

Fitness Consequences ◽

Cooperatively Breeding ◽

Adult Sex Ratio ◽

Violent Conflicts ◽

Large Groups

Violent conflicts between groups have been observed among many species of group living mammals and can have important fitness consequences, with individuals being injured or killed and with losing groups surrendering territory. Here, we explore between-group conflict among meerkats ( Suricata suricatta ), a highly social and cooperatively breeding mongoose. We show that interactions between meerkat groups are frequently aggressive and sometimes escalate to fighting and lethal violence and that these interactions have consequences for group territories, with losing groups moving to sleeping burrows closer to the centre of their territories following an intergroup interaction and with winning groups moving further away. We find that larger groups and groups with pups are significantly more likely to win contests, but that the location of the contest, adult sex ratio, and mean within-group genetic relatedness do not predict contest outcome. Our results suggest that intergroup competition may be a major selective force among meerkats, reinforcing the success of large groups and increasing the vulnerability of small groups to extinction. The presence of both within-group cooperation and between-group hostility in meerkats make them a valuable point of comparison in attempts to understand the ecological and evolutionary roots of human warfare.

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Extended and cumulative effects of experimentally induced intergroup conflict in a cooperatively breeding mammal

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.1743 ◽

2021 ◽

Vol 288 (1964) ◽

Author(s):

Amy Morris-Drake ◽

Jennifer F. Linden ◽

Julie M. Kern ◽

Andrew N. Radford

Keyword(s):

Selective Pressure ◽

Scent Marking ◽

Cumulative Effects ◽

Intergroup Conflict ◽

Fitness Consequences ◽

Cooperatively Breeding ◽

Single Presentation ◽

Herbivore Faeces ◽

Territorial Intrusion ◽

Experimental Findings

Conflict between rival groups is rife in nature. While recent work has begun exploring the behavioural consequences of this intergroup conflict, studies have primarily considered just the 1–2 h immediately after single interactions with rivals or their cues. Using a habituated population of wild dwarf mongooses ( Helogale parvula ), we conducted week-long manipulations to investigate longer-term impacts of intergroup conflict. Compared to a single presentation of control herbivore faeces, one rival-group faecal presentation (simulating a territorial intrusion) resulted in more within-group grooming the following day, beyond the likely period of conflict-induced stress. Repeated presentations of outsider cues led to further changes in baseline behaviour by the end of the week: compared to control weeks, mongooses spent less time foraging and foraged closer to their groupmates, even when there had been no recent simulated intrusion. Moreover, there was more baseline territorial scent-marking and a higher likelihood of group fissioning in intrusion weeks. Consequently, individuals gained less body mass at the end of weeks with repeated simulated intrusions. Our experimental findings provide evidence for longer-term, extended and cumulative, effects of an elevated intergroup threat, which may lead to fitness consequences and underpin this powerful selective pressure.

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Mothers front-load their investment to the egg stage when helped in a wild cooperative bird

10.1101/2021.11.11.468195 ◽

2021 ◽

Author(s):

Pablo Capilla-Lasheras ◽

Alastair J Wilson ◽

Andrew J Young

Keyword(s):

Maternal Investment ◽

Reaction Norm ◽

Beneficial Effects ◽

Fitness Consequences ◽

Cooperatively Breeding ◽

Post Natal Care ◽

Per Se ◽

Nestling Feeding ◽

Maternal Responses ◽

Maternal Strategy

In many cooperative societies, including our own, helpers assist with the post-natal care of breeders' young, and may thereby benefit the post-natal development of offspring. Here we present evidence of a novel mechanism by which such post-natal helping could also have hitherto unexplored beneficial effects on pre-natal development: by lightening post-natal maternal workloads, helpers may allow mothers to increase their pre-natal investment per offspring. We present the findings of a decade-long study of cooperatively breeding white-browed sparrow weaver, Plocepasser mahali, societies. Within each social group, reproduction is monopolized by a dominant breeding pair, and non-breeding helpers assist with nestling feeding. Using a within-mother reaction norm approach to formally identify maternal plasticity, we demonstrate that when mothers have more female helpers they decrease their own post-natal investment per offspring (feed their nestlings at lower rates) but increase their pre-natal investment per offspring (lay larger eggs, which yield heavier hatchlings). That these plastic maternal responses are predicted by female helper number, and not male helper number, implicates the availability of post-natal helping per se as the likely driver (rather than correlated effects of group size), because female helpers feed nestlings at substantially higher rates than males. We term this novel maternal strategy 'maternal front-loading' and hypothesize that the expected availability of post-natal help allows helped mothers to focus maternal investment on the pre-natal phase, to which helpers cannot contribute directly. Such cryptic maternally mediated helper effects on pre-natal development may markedly complicate attempts to identify and quantify the fitness consequences of helping.

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The fitness consequences of kin-biased dispersal in a cooperatively breeding bird

Biology Letters ◽

10.1098/rsbl.2015.0336 ◽

2015 ◽

Vol 11 (7) ◽

pp. 20150336 ◽

Cited By ~ 7

Author(s):

Lea Pollack ◽

Dustin R. Rubenstein

Keyword(s):

Social Rank ◽

Group Living ◽

Breeding Bird ◽

Direct Benefits ◽

Fitness Consequences ◽

Cooperatively Breeding ◽

Potential Benefits ◽

Indirect Fitness ◽

Living Species

Cooperative alliances among kin may not only lead to indirect fitness benefits for group-living species, but can also provide direct benefits through access to mates or higher social rank. However, the immigrant sex in most species loses any potential benefits of living with kin unless immigrants disperse together or recruit relatives into the group in subsequent years. To look for evidence of small subgroups of related immigrants within social groups (kin substructure), we used microsatellites to assess relatedness between immigrant females of the cooperatively breeding superb starling, Lamprotornis superbus. We determined how timing of immigration led to kin subgroup formation and if being part of one influenced female fitness. Although mean relatedness in groups was higher for males than females, 26% of immigrant females were part of a kin subgroup with a sister. These immigrant sibships formed through kin recruitment across years more often than through coalitions immigrating together in the same year. Furthermore, females were more likely to breed when part of a kin subgroup than when alone, suggesting that female siblings form alliances that may positively influence their fitness. Ultimately, kin substructure should be considered when determining the role of relatedness in the evolution of animal societies.

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Dealing with hot rocky environments: Critical thermal maxima and locomotor performance in Leptodactylus lithonaetes (Anura: Leptodactylidae)

Herpetological Journal ◽

10.33256/hj29.3.155161 ◽

2019 ◽

pp. 155-161 ◽

Cited By ~ 1

Author(s):

Ivan Beltran

Keyword(s):

Environmental Temperature ◽

Extreme Temperature ◽

Effect Of Temperature ◽

Maximum Speed ◽

Locomotor Performance ◽

Extreme Temperatures ◽

Physiological Limits ◽

Fitness Consequences ◽

Thermal Maximum ◽

Environmental Temperatures

Environmental temperature has fitness consequences on ectotherm development, ecology and behaviour. Amphibians are especially vulnerable because thermoregulation often trades with appropriate water balance. Although substantial research has evaluated the effect of temperature in amphibian locomotion and physiological limits, there is little information about amphibians living under extreme temperature conditions. Leptodactylus lithonaetes is a frog allegedly specialised to forage and breed on dark granitic outcrops and associated puddles, which reach environmental temperatures well above 40 ˚C. Adults can select thermally favourable microhabitats during the day while tadpoles are constrained to rock puddles and associated temperature fluctuations; we thus established microhabitat temperatures and tested whether the critical thermal maximum (CTmax) of L. lithonaetes is higher in tadpoles compared to adults. In addition, we evaluated the effect of water temperature on locomotor performance of tadpoles. Contrary to our expectations, puddle temperatures were comparable and even lower than those temperatures measured in the microhabitats used by adults in the daytime. Nonetheless, the CTmax was 42.3 ˚C for tadpoles and 39.7 ˚C for adults. Regarding locomotor performance, maximum speed and maximum distance travelled by tadpoles peaked around 34 ˚C, approximately 1 ˚C below the maximum puddle temperatures registered in the puddles. In conclusion, L. lithonaetes tadpoles have a higher CTmax compared to adults, suggesting a longer exposure to extreme temperatures that lead to maintain their physiological performance at high temperatures. We suggest that these conditions are adaptations to face the strong selection forces driven by this granitic habitat.

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