Browsing by Subject "parental care"

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  • Raulo, Aura; Dantzer, Ben (2018)
    The causes and consequences of individual differences in animal behavior and stress physiology are increasingly studied in wild animals, yet the possibility that stress physiology underlies individual variation in social behavior has received less attention. In this review, we bring together these study areas and focus on understanding how the activity of the vertebrate neuroendocrine stress axis (HPA-axis) may underlie individual differences in social behavior in wild animals. We first describe a continuum of vertebrate social behaviors spanning from initial social tendencies (proactive behavior) to social behavior occurring in reproductive contexts (parental care, sexual pair-bonding) and lastly to social behavior occurring in nonreproductive contexts (nonsexual bonding, group-level cooperation). We then perform a qualitative review of existing literature to address the correlative and causal association between measures of HPA-axis activity (glucocorticoid levels or GCs) and each of these types of social behavior. As expected, elevated HPA-axis activity can inhibit social behavior associated with initial social tendencies (approaching conspecifics) and reproduction. However, elevated HPA-axis activity may also enhance more elaborate social behavior outside of reproductive contexts, such as alloparental care behavior. In addition, the effect of GCs on social behavior can depend upon the sociality of the stressor (cause of increase in GCs) and the severity of stress (extent of increase in GCs). Our review shows that the while the associations between stress responses and sociality are diverse, the role of HPA-axis activity behind social behavior may shift toward more facilitating and less inhibiting in more social species, providing insight into how stress physiology and social systems may co-evolve.
  • Heubel, Katja (2018)
    Mating decisions can be affected by intrasexual competition and sensitive to operational sex-ratio (OSR) changes in the population. Conceptually, it is assumed that both male and female mate-competition may interfere with female reproductive decisions. Experimentally, however, the focus has been on the effect of male competition on mate choice. In many species with paternal care as in the common goby Pomatoschistus microps, the OSR is often female-biased and female mate-competition for access to available nesting males occurs. Using the same protocol for 3 experiments testing the effect of a perceived risk of female mate-competition, I studied female preferences for nest-holding males differing in its nest size (large/small), body size (large/small), and nest status (with/without eggs already in nest) and measured mating decisions, spawning latencies, and clutch size. Regardless of the social context, females preferred males with larger nests. A preference for large males was only expressed in presence of additional females. For nest status, there was a tendency for females to prefer mating with males with an empty nest. Here, female-female competition increased the propensity to mate. The results of this study show that females are sensitive to a female competitive social environment and suggest that in choice situations, females respond to the social context mainly by mating decisions per se rather than by adjusting the clutch size or spawning latency. Females base their mating decisions not only on a male's nest size but also on male size as an additional cue of mate quality in the presence of additional females.
  • Gravolin, Isaac; Lehtonen, Topi Kasperi; Deal, Nicholas D. S.; Candolin, Ulrika; Wong, Bob (2021)
    Nest predation has a large impact on reproductive success in many taxa. Defending offspring from would-be predators can also be energetically and physiologically costly for parents. Thus, to maximize their reproductive payoffs, individuals should adjust their reproductive behaviors in relation to the presence of nest predators. However, effects of nest predator presence on parental behaviors across multiple reproductive contexts remain poorly understood, particularly in non-avian taxa. We ran a series of experiments to test how the presence of an egg predator, the invasive rockpool shrimp, Palaemon elegans, influences male reproductive decisions and egg survival in a species of fish with exclusive paternal care, the three-spined stickleback, Gasterosteus aculeatus. We found that, in the presence of shrimp, male sticklebacks were less likely to build a nest, invested less in territory defense against an intruder, and tended to fan eggs in their nest less and in shorter bouts, but did not alter their investment in courtship behavior. The predator's presence also did not affect egg survival rates, suggesting that males effectively defended their brood from the shrimp. These results show that reproducing individuals can be highly responsive to the presence of nest predators and adjust their behavioral decisions accordingly across a suite of reproductive contexts.
  • Isotalo, Teija (Helsingin yliopisto, 2020)
    Anthropogenic activity has enhanced global warming at alarming rates, causing temperatures to increase and heat waves to occur more frequently. The effects of global warming are prominent in aquatic ecosystems, particularly in the Baltic Sea. Temperature increases and fluctuations in the Baltic Sea create a changing environment and this can affect inhabiting species’ behaviors, specifically behaviors during reproduction. Reproductive behavior influences both the number and quality of offspring born into a population therefore making behavior changes during reproduction important to study. The three-spined stickleback (Gasterosteus aculeatus), an ectothermic animal, inhabits the Baltic Sea and is an ideal species to study reproductive behavioral changes. Although previous studies have researched three-spined sticklebacks in changing environments, none had specifically looked into the effects of rising temperatures and temperature fluctuations on male three-spined stickleback reproductive behavior. The three-spined stickleback is of particular interest because it reproduces in shallow waters which tend to be more affected by temperature changes. In this study, I aimed to investigate behavioral responses of stickleback males to higher temperatures and to temperature fluctuations during reproduction, as well as the consequences the responses have for reproductive success and the viability of offspring. In order to see how this species would cope with rising temperatures and heat waves during reproduction, a comparative climate chamber experiment was executed in Southern Finland at Tvärminne Zoological Station. Males were housed in either 19°C or 14°C for two breeding cycles, and for the second breeding cycle eight males switched temperatures to experience a temperature fluctuation. Results show that during reproduction, three-spined sticklebacks respond to higher temperatures with increased courtship activity, increased parental activity, quicker breeding cycles, and more weight lost. Parental care activity in constant high temperature decreases from the first to the second breeding cycle, while parental activity in constant low temperature increases. During temperature fluctuations, males experiencing a rise in temperature increase their parental care activity, while males experiencing a drop in temperature demonstrate the opposite. However, no significant consequences of temperature and temperature changes for reproductive success and the viability of offspring were detected during the two breeding cycles. Overall, the results of this study would indicate that the three-spined stickleback will prove to be a resilient species, and maintain population growth in the face of increased temperatures and temperature fluctuations in the Baltic Sea.
  • Vallon, Martin; Anthes, Nils; Heubel, Katja U. (2016)
    Many animals heavily invest in parental care but still reject at least some of their offspring. Although seemingly paradoxical, selection can favor parents to neglect offspring of particularly low reproductive value, for example, because of small survival chances. We here assess whether filial cannibalism (FC), where parents routinely eat some of their own young, is selective in response to individual offspring reproductive value. We performed two independent laboratory experiments in the common goby (Pomatoschistus microps) to test whether caring fathers preferentially cannibalize eggs of a given infection history and paternity. While males did not discriminate kin from nonkin eggs, they consumed significantly more eggs previously exposed to water mold compared to uninfected eggs. Our findings clearly show that parents differentiate between eggs based on differences in egg condition, and thus complement the prevailing view that FC arises for energetic reasons. By preventing the spread of microbial infections, the removal of molded eggs can constitute an important component of parental care and may represent a key driver of selective FC in a wide array of parental fish.
  • Vallon, Martin; Grom, Christina; Kalb, Nadine; Sprenger, Dennis; Anthes, Nils; Lindström, Kai; Heubel, Katja U. (2016)
    Many animal parents invest heavily to ensure offspring survival, yet some eventually consume some or all of their very own young. This so-called filial cannibalism is known from a wide range of taxa, but its adaptive benefit remains largely unclear. The extent to which parents cannibalize their broods varies substantially not only between species, but also between individuals, indicating that intrinsic behavioral differences, or animal personalities, might constitute a relevant proximate trigger for filial cannibalism. Using a marine fish with extensive paternal care, the common goby (Pomatoschistus microps), we investigated the influence of animal personality on filial cannibalism by assessing (1) behavioral consistency across a breeding and a nonbreeding context; (2) correlations between different breeding (egg fanning; filial cannibalism) and nonbreeding (activity) behaviors, and, in a separate experiment; (3) whether previously established personality scores affect filial cannibalism levels. We found consistent individual differences in activity across contexts. Partial filial cannibalism was independent of egg fanning but correlated strongly with activity, where active males cannibalized more eggs than less active males. This pattern was strong initially but vanished as the breeding season progressed. The incidence of whole clutch filial cannibalism increased with activity and clutch size. Our findings indicate that filial cannibalism cannot generally be adjusted independently of male personality and is thus phenotypically less plastic than typically assumed. The present work stresses the multidimensional interaction between animal personality, individual plasticity and the environment in shaping filial cannibalism.