Many studies have been dedicated to the phenomena of alloparenting and cooperative breeding.
Not always the benefits are so apparent or immediate.
Many studies have not found pronounced effects of alloparenting on, e.g., individual’s lifetime reproductive success which is a typically applied estimate or individual’s short-term survival (pup recruitment).
For example, alloparenting (subordinate helpers and allosuckling of the dominant female’s pups by subordinate females) in Ethiopian wolves (i.e., Marino, J. et al., 2012) have not found profound effects on pup survival.
However, it would appear that alloparenting may benefit individuals during a time of crisis (e.g., during a disease outbreak or food deficiency) which might result in many years when alloparenting brings little immediate profit to the group vs. few years when it is crucial to the survival not only of the group but, indeed, of the entire population.
Also, with regard to allosuckling in Ethiopian wolves (see, i.a., Sillero-Zubini, C. et al., 2004), it appeared that while allosuckling did not benefit the group’s reproductive success (litter size, pup recruitment), it could have benefited the allosuckled individuals because several of these either became breeders or survived fatal rabies outbreaks in the population.
While survival and reproductive success are valid and important measures applied to determine the effects of alloparenting in social species, I have been wondering about other types of benefits that perhaps do not necessarily carry over into the adult individual’s breeding success (and are thereby difficult to quantify) but that could nevertheless be of importance.
Usually, the input by helpers is estimated as food delivery input or offspring defense input (e.g., babysitting in order to protect from potential predator attacks or active defense upon agonistic invasions by other groups).
And the outcome is measured as litter size, pup survival at infancy/juvenile level or reproductive success at adult level.
However, I believe that helpers – the presence of invested non-breeders – might also benefit the pups from a physical and cognitive development perspective.
And this might manifest – on an adult level – as, for example, general health status even with the exclusion of reproductive fitness (i.e., the individuals remain healthier and more resilient even if they do not become breeders and do not manifest these accrued benefits in the production of progeny).
Several individuals who are closely related but who also have different personalities, different experience and skill sets etc. can provide the opportunity to acquire a more diverse array of strategies on both physical and cognitive level that later translate into improved foraging and defense and a greater group cohesion which further enhances foraging and defense (and possibly other crucial life functions).
If the juvenile is exposed to a diversity of skills and traits represented by the helpers and communicated through play or everyday interactions, it might be important in developing a varied set of potential responses to life situations.
This could be profitable for the individual even if the individual does not become a breeder as an adult and it could also be profitable for the group outside of the pup recruitment rates.
Perhaps it would be interesting to study the possible effects of helpers on:
- group persistence;
- group or local population general health rates;
- the stability of the group’s territory and size through years;
- group’s tenancy duration;
- individual’s life expectancy in adult life stage;
- group’s foraging performance (e.g., whether group is better at providing for itself during periods when juveniles that have had a greater number of helpers are the group’s active provisioning force);
- individual’s foraging performance (also with respect to, for example, senescence and the individual’s ability to perform after the performance rates are expected to drop) etc.
Physical fitness that is achieved through improved nutrition and the number of recruits are very important in population demographics which is also why the helper impact on reproductive rates should be studied.
However, helpers might bear less notable effects that tend to stabilize the social units and the local populations but that do not necessarily manifest on a demographic level.
Or if they do – they manifest on social group’s or local populations long-term trends in demographic dynamics.
Perhaps the value of helpers is rooted in well-rounded development and varied experience of the individuals raised in larger, cooperative groups and it is later expressed as a stabilizing factor yielding not individual excellence or substantial increases in some aspects of individual’s or group’s success but rather on the endurance and daily performance that results in improved health, long-term tenancy, improved cooperation etc.
Notes by Ieva 