Consistent individual differences in paternal behavior: a field study of three-spined stickleback

Abstract

Consistent individual differences in parenting are widespread; however, we know little about why there is variation in parenting behavior among individuals within species. One possible explanation for consistent individual differences in parenting is that individuals invest in different aspects of parental care, such as provisioning or defense. In this field study we measured consistent individual differences in parenting behavior and evaluated correlations between parenting and other behaviors in threespine stickleback (Gasterosteus aculeatus). We repeatedly measured male parenting behavior and male behavior in the presence of three different types of live intruders: a female, a conspecific male, and a predator, meant to provoke courtship, aggressive and antipredator behavior, respectively. While males plastically adjusted their reactions to different types of intruders, we found consistent individual differences in behavior (behavioral types) both within and across contexts, even after accounting for variation in body size and nest characteristics. Males that performed more parenting behavior responded faster to all types of intruders. These results suggest that in nature, individual male stickleback exhibit robust parental behavioral types, and highly parental males are more attentive to their surroundings. Future studies are needed to examine the potential causes of individual variation in parental behavior in the field.

The role of variation and plasticity in parental care during the adaptive radiation of three‐spine sticklebacks

“…Across all freshwater populations, males exposed to the dragonfly naiad on average showed reduced parental care for 1 day before converging on similar fanning behavior to control individuals that did not experience predation risk (Figs. & ), similar to previous studies in stickleback with piscivorous predators (Stein & Bell ; Stein & Bell ).…”

“…Males from well‐established populations, which experienced many generations of selection in freshwater, dramatically decreased parenting when the predator was present. This result is consistent with previous studies, which have shown that male sticklebacks from populations that experience high levels of predation by piscivorous fishes decrease parenting both in the presence of an immediately after predation risk (Stein & Bell ; Stein & Bell ; Stein & Bell ). It is likely that the reason why males (on average) from marine populations did not change their behavior in response to the predator was because they did necessarily perceive the dragonfly—a novel predator to marine sticklebacks—as a threat.…”

“…). Alternatively, if the variation among reaction norms results from nongenetic mechanisms, then when marine males move into freshwater, those males that reduce fanning in response to dragonfly naiad could have higher fitness in freshwater because males spend more time guarding their nests (Stein & Bell ), resulting in higher survival rates of offspring. Another intriguing possibility is that the reduction in fanning might provide a cue to offspring about predation risk in their environment, resulting in offspring with predator‐adapted phenotypes (Stein & Bell ; Stein et al.…”

“…We investigate plasticity in paternal care, a behavior essential for offspring survival that could be important during the early stages of establishment in a new environment. Previous studies in this system showed that male sticklebacks that were exposed to predation risk while they were providing care changed their paternal behavior (Stein & Bell ; Stein & Bell ) and produced offspring that had phenotypes associated with high predation pressure (Stein & Bell ). In this study, we induced behavioral plasticity in fathers by exposing them to a live Odonate naiad, an important predator on stickleback eggs and fry that exists only in freshwater, while they were providing care (Reimchen ; Reimchen ; Marchinko ).…”

“…Specifically, we measured the total amount of time the male spent fanning the eggs. Fanning is a paternal behavior that oxygenates the eggs (Wootton ), is important for offspring development (Wootton ), and consistently varies among fathers (Stein & Bell ; Stein & Bell ). We posit that behavioral plasticity in response to immediate predation threat has allowed populations to adapt to novel conditions, such as the presence of a novel predator (Levis & Pfennig ; West‐Eberhard ).…”