Asymmetries in body condition and order of arrival influence competitive ability and survival in a coral reef fish

Abstract

Trade-offs between traits that influence an individual's competitive ability are important in determining community assembly and coexistence of individuals sharing the same resources. Populations of coral reef fish are structurally complex, so it is important to understand how these populations are shaped as a result of an individual's suite of traits and those of its competitors. We conducted a 2 × 2 factorial field experiment that manipulated body condition (high or low, manipulated through a feeding regime) and residency (resident or intruder, where the resident arrived at the habitat 3 h before the intruder) to evaluate effects on competitive ability and survival. Prior residency alleviated the disadvantage of a low body condition with respect to aggression, which was similar between low-condition residents and high-condition intruders. However, high-condition residents displayed a significantly greater level of aggression than intruders, regardless of whether intruders were from high- or low-condition treatments. For intruders to have a high probability of becoming dominant, they needed to have a large body condition advantage. Mortality trajectories suggested that body condition modified the effect of prior residency, and intruders were more likely to suffer mortality if they had a low body condition because residents pushed them away from shelter. Our results highlight that the negative effects of some traits may be compensated for by the positive effects of other traits, and that the specific ecological context an individual faces (such as the characteristics of its competitors) can have a major influence on successful establishment and persistence.

Developmental effects of heatwave conditions on the early life stages of a coral reef fish

“…Fish that developed entirely at elevated temperatures were smaller than fish from all other exposure duration treatments and the control group. Smaller body size is ecologically important in juvenile fish as it typically increases the risk of predation and reduces competitive ability (Poulos and McCormick, 2015;Goatley and Bellwood, 2016;Sogard, 1997). Reduced body size is likely due to increased energy costs for maintenance activities at higher temperatures (Munday et al, 2008;Pörtner and Knust, 2007).…”

“…plasticity) could be disentangled from the effect of the final temperature of each treatment at 108 days (Schulte et al, 2011). We also measured body size, which is a key fitness-related trait in juvenile fishes that links to competitive ability and predation risk (Sogard, 1997;Poulos and McCormick, 2015;Goatley and Bellwood, 2016). Reduced growth rates and smaller body size with increased warming is a commonly observed trend in fishes (Cheung et al, 2013;Munday et al, 2008).…”

Higher rates of prebreeding condition gain positively impacts clutch size: A mechanistic test of the condition‐dependent individual optimization model

“…Studies across multiple taxa have demonstrated that individuals face a decline in the survival probability of offspring as the breeding season progresses (mammals: e.g., Morris, ; insects: e.g., Johansson & Rowe, , reptiles: e.g., Doody, Gorges, & Young, , fish: e.g., Poulos & McCormick, , and birds: e.g., Rowe et al., ; Bêty, Gauthier, & Giroux, ). For many species breeding in seasonal environments, a critical trade‐off occurs between the delay in timing of reproduction in favour of increased body condition and the ability to increase investment in reproduction, against this declining survival probability of the resulting offspring (Bêty et al., ; Drent & Daan, ; Lepage, Gauthier, & Menu, ; Morris, ; Rowe & Ludwig, ; Rowe et al., ).…”

Energetic Physiology Mediates Individual Optimization of Breeding Phenology in a Migratory Arctic Seabird

“…The model predicts that individuals arriving from migration to the breeding grounds earlier and in better body condition (i.e., higher body mass or size-corrected body mass) have the potential to acquire the local resources they need to fuel re-production earlier and therefore initiate reproduction earlier, a key fitness-related parameter in many avian species (Drent and Daan 1980;Rowe et al 1994;Lepage et al 2000;Bêty et al 2003;Descamps et al 2011). Although applied in insect (Johansson and Rowe 1999), mammal (Dobson and Michner 1995;Marrow et al 1996;Morris 1998), reptile (Doughty 1996;Doody et al 2003), and fish (Cargnelli and Neff 2006;Poulos and McCormick 2015) systems, the model's ultimate goal is to examine the mechanisms behind the well-known seasonal decline in clutch size in many avian species, where earlier laying dates should be associated with greater investment in reproduction (i.e., clutch size; Drent and Daan 1980;Rowe et al 1994;Bêty et al 2003;Descamps et al 2011). Independent of arrival date and condition, Rowe et al (1994) also made a second set of important predictions that, to date, have received far less attention in the literature.…”