What are the benefits of parental care? The importance of parental effects on developmental rate

Abstract

The evolution of parental care is beneficial if it facilitates offspring performance traits that are ultimately tied to offspring fitness. While this may seem self-evident, the benefits of parental care have received relatively little theoretical exploration. Here, we develop a theoretical model that elucidates how parental care can affect offspring performance and which aspects of offspring performance (e.g., survival, development) are likely to be influenced by care. We begin by summarizing four general types of parental care benefits. Care can be beneficial if parents (1) increase offspring survival during the stage in which parents and offspring are associated, (2) improve offspring quality in a way that leads to increased offspring survival and/or reproduction in the future when parents are no longer associated with offspring, and/or (3) directly increase offspring reproductive success when parents and offspring remain associated into adulthood. We additionally suggest that parental control over offspring developmental rate might represent a substantial, yet underappreciated, benefit of care. We hypothesize that parents adjust the amount of time offspring spend in life-history stages in response to expected offspring mortality, which in turn might increase overall offspring survival, and ultimately, fitness of parents and offspring. Using a theoretical evolutionary framework, we show that parental control over offspring developmental rate can represent a significant, or even the sole, benefit of care. Considering this benefit influences our general understanding of the evolution of care, as parental control over offspring developmental rate can increase the range of life-history conditions (e.g., egg and juvenile mortalities) under which care can evolve.

Short-term benefits, but transgenerational costs of maternal loss in an insect with facultative maternal care

“…In line with this prediction, short-term costs of parental loss have been reported in a large set of taxonomically diverse species, in which it is typically associated with a reduction in growth and/or survival rates of juveniles [1,[4][5][6]. Importantly, other studies also showed that parental loss can entail long-term and transgenerational costs by hampering the mating success of adult offspring and diminishing the level of care they express towards their own descendants [1,7,8]. For instance in rats, females that had experienced long periods of maternal loss as pups exhibited low levels of care towards their own offspring, which in turn also exhibited lower levels of care as F 2 adults [9,10].…”

“…These benefits mostly derive from the expression of parenting behaviours [1,2] such as nest construction, brood/ juvenile attendance or food provisioning [2,3], and are thus contingent on the parental presence. Consequently, parental loss, e.g.…”

Are sexually selected traits affected by a poor environment early in life?

“…For example, in a dung beetle, developing larvae depend on nutrients provided by their parents which affects male body and horn size and thereby their mating success [93]. In some cases the diet or conditions that parents’ experience is transmitted to their own offspring (i.e., transgenerational effects: [1, 96, 97]), and can thereby affect their mating success. For example, in birds the amount of carotenoids available to mothers influences what they can deposit into egg yolks, which can then affect their sons’ adult ornamental coloration [98].…”

Unbalanced biparental care during colony foundation in two subterranean termites

“…to insects, parental care can take multiple forms, such as egg and offspring attendance, nest building and burrowing and food provisioning (Smiseth et al, 2012). All these forms typically provide benefits to offspring by enhancing offspring survival, growth, and/or quality, as well as by improving their lifetime reproductive success (Klug & Bonsall, 2014; but see Kramer et al, 2017). However, investing into parental care may also go along with costs for parents.…”