Helpers benefit offspring in both the short and long-term in the cooperatively breeding banded mongoose

Abstract

Helpers in cooperative and communal breeding species are thought to accrue fitness benefits through improving the condition and survival of the offspring that they care for, yet few studies have shown conclusively that helpers benefit the offspring they rear. Using a novel approach to control for potentially confounding group-specific variables, I compare banded mongoose (Mungos mungo) offspring within the same litter that differ in the amount of time they spend with a helper, and hence the amount of care they receive. I show that pups that spend more time in close proximity to a helper are fed more, grow faster and have a higher probability of survival to independence than their littermates. Moreover, high growth rates during development reduce the age at which females breed for the first time, suggesting that helpers can improve the future fecundity of the offspring for which they care. These results provide strong evidence that it is the amount of investment per se that benefits offspring, rather than some correlate such as territory quality, and validate the assumption that helpers improve the reproductive success of breeders, and hence may gain fitness benefits from their actions. Furthermore, the finding that helpers may benefit offspring in the long-term suggests that current studies underestimate the fitness benefits that helpers gain from rearing the offspring of others.

Road Effects on Food Availability and Energetic Intake in Florida Scrub-Jays (Aphelocoma coerulescens)

“…Jays that achieved 4 postfledging developmental milestones (surviving to day 30, day 90, day 300, and becoming a breeder) were larger as nestlings than jays that failed to achieve these milestones ( Figure 5). This result corroborates evidence from other avian and mammalian species that variation in natal body condition can have far-reaching fitness consequences (Magrath 1991, Hatchwell et al 2004, Hodge 2005, Ridley 2007, Rödel et al 2009, Sparkman et al 2010, Tilgar et al 2010, Brouwer et al 2012.…”

“…Strong evidence exists that the presence of helpers during the natal rearing period can enhance the growth, development, and condition of young, leading to higher juvenile survival (Hatchwell et al 2004, Hodge 2005, Ridley 2007, Sparkman et al 2010, earlier age at first breeding (Hodge 2005, Russell et al 2007, and higher adult survival later in life (Sparkman et al 2010, Brouwer et al 2012. Collectively, these studies suggest that variation in the early social environment of cooperative breeders can influence the lifetime reproductive fitness of individuals.…”

Strategic adjustment of begging effort by banded mongoose pups

“…Escorts are generally young, non-breeding males (1-3 years old) or breeding females who contributed to the current litter (Gilchrist 2004;Hodge 2005). Associations are initiated and maintained by the pups, with escorts following a relatively passive 'feed the nearest begging pup' rule (Gilchrist 2004;Hodge 2005), and escorts do not preferentially associate with close relatives (S. J.…”

The Right Tools for the Job: Cooperative Breeding Theory and an Evaluation of the Methodological Approaches to Understanding the Evolution and Maintenance of Sociality

“…While there is some support for this hypothesis (Burda, 1990), several observational studies of growth rates in mammals tend to view this life-history trait as a consequence of sociality rather than a potential cause (Oli and Armitage, 2003;Hodge, 2005). Nevertheless, these studies show the usefulness of observational methodology in informing discussions surrounding the role that life-history traits may or may not have played in the evolution of sociality.…”