Substantial plasticity of reproduction and parental care in response to local resource availability in a wild clownfish population

Abstract

Plasticity, the capacity of individuals to respond to changing environments by modifying traits, may be critically important for population persistence by allowing for adaptive responses on shorter timescales than genetic change. Here, we use the clown anemonefish Amphiprion percula, whose access to resources is constrained by their anemones, to test the role of plasticity in generating variation in reproductive success among groups. We surveyed a wild clownfish population and found positive correlations between anemone area, fish size, reproduction and parental care. We used structural equation modeling to test the hypothesis that these correlations emanate from variation in anemone area and found support for a pathway linking anemone area to female investment, female investment to male investment and male investment to embryo survival. Next, we experimentally tested whether plasticity in response to resource availability can result in variation in parental traits using a feeding manipulation and found substantial plasticity in reproduction and parental care in response to changes in the availability of food resources. The results of this study reveal the role of plasticity in response to local resource availability in generating variation among individuals in reproductive strategies, linking studies of behavior and demography in this model species, and ultimately contributing to our ability to predict how populations might cope with environmental changes.

Vertebrate growth plasticity in response to variation in a mutualistic interaction

“…Growth plasticity in response to the size of their mutualistic hosts is likely adaptive for anemonefishes, though more research is necessary. On the one hand, selection will favor fish that grow large, since larger size is correlated with lower predation rate and higher reproductive output 43 , 49 , 50 . On the other hand, selection will favor fish that do not become too large for the available resources, since being too large may expose them to predators 15 and/or mean that they cannot sustain themselves on available resources 51 .…”

Habitat size, health and saturation do not alter movement decisions or the preference for familiarity in a social coral-reef fish

“…For other social reef fishes, previous studies have demonstrated that habitat factors influence the movement decisions of individuals, thereby promoting sociality [12,14]. Numerous studies found positive correlations between habitat size and group size [16,24,33–36], demonstrating the important role of habitat in determining levels of sociality. In addition, habitat saturation influences dispersal and grouping decisions in the coral goby Paragobiodon xanthosoma [14] whereby individuals preferentially move to adjacent corals of low saturation (low risk of movement).…”

The Next Frontier in Understanding the Evolution of Coral Reef Fish Societies

“…There are positive correlations between the length of the dominant, the number of individuals in the group, and the size of the cnidarian host in A. percula and P. xanthosoma (Figure 4; Fautin, 1992;Elliott and Mariscal, 2001;Buston, 2003a;Wong, 2011;Chausson et al, 2018;Barbasch et al, 2020). These correlates could be caused by extrinsic factors, e.g., dominants, groups, and cnidarians may all flourish at good sites on the reef (the null hypothesis), or they could be caused by intrinsic factors, e.g., the number of fish in a group influencing host size.…”

“…These correlates could be caused by extrinsic factors, e.g., dominants, groups, and cnidarians may all flourish at good sites on the reef (the null hypothesis), or they could be caused by intrinsic factors, e.g., the number of fish in a group influencing host size. Indeed, the causality of some of these relationships has been determined: female size influences the number of fish in a group, due to the rules of the size hierarchy in both species (A. percula -Heteractis magnifica, Buston, 2003b;Buston and Cant, 2006;Branconi et al, 2020; P. xanthosoma -Seriatopora hystrix, Wong et al, 2007;Wong, 2011); and, at least in A. percula, anemone size is positively correlated with the growth of the fish, explaining why larger anemones are associated with larger females (Buston, 2002), and larger females lay more eggs, resulting in more parental care and higher embryo survival (Buston and Elith, 2011;Barbasch et al, 2020). Thereby larger anemones might have a positive influence on fish reproductive output.…”

“…Thereby larger anemones might have a positive influence on fish reproductive output. The latter results are likely explained by larger anemones providing greater foraging area, because foraging is confined to the anemone (Barbasch et al, 2020), and/or larger anemones providing more egesta, which may provide important nutrition (Verde et al, 2015). The critical experiment, manipulating cnidarian size and examining the effect on the breeders remains to be done.…”