Many animals exhibit size-assortative mating, and matching theory predicts this occurs because both males females prefer bigger mates. Monogamy pairing have been described for coral reef fishes, but the underlying behavioral mechanism has not tested. Here, we took a long-term observational experimental study to resolve causes of size-based in paternal mouthbrooding cardinalfish Sphaeramia nematoptera. For 65 pairs observed over 23-month period, there was strong size-correlation between...

Plasticity, the capacity of individuals to respond changing environments by modifying traits, may be critically important for population persistence allowing adaptive responses on shorter timescales than genetic change. Here, we use clown anemonefish Amphiprion percula , whose access resources is constrained their anemones, test role plasticity in generating variation reproductive success among groups. We surveyed a wild clownfish and found positive correlations between anemone area, fish...

In social groups, high reproductive skew is predicted to arise when the output of a group limited, and dominant individuals can suppress subordinate efforts. Reproductive suppression often assumed occur via overt aggression or threat eviction. It unclear, however, whether eviction alone sufficient induce restraint by subordinates. Here, we test two assumptions model investigating resource limitation generates competition leads in clown anemonefish Amphiprion percula . First, use feeding...

Animal social groups can be organized in hierarchies where individual status determines privileges within the group, and stability is maintained through conflict (aggression–submission) cooperation. Aggression, submission cooperation are not homogeneous among group members influenced by context associated trade-offs. However, studies of rank-specific behaviours rare which limits our understanding these patterns. Here, we performed rank ascension experiments using 15 Amphiprion clarkii, a...

Research on sociality in marine fishes is a vibrant field that providing new insights into social evolution more generally. Here, we review the past two decades of research, identifying knowledge gaps and directions. Two coral reef fishes, with systems similar to other cooperative breeders, have emerged as models: clown anemonefish Amphiprion percula emerald goby Paragobiodon xanthosoma . In these systems, non-breeders do not forgo their own reproduction gain indirect genetic benefits....

Many animal groups consist of dominance hierarchies. Theoretical models suggest that higher-ranked individuals should increase aggression but decrease helping unless the cost decreases with higher rank. Most empirical tests focus on systems kin selection, whereas for in which are unrelated rare. Here we used two anemonefish species to test hypotheses variation and respect social We assessed behavioural frequencies each rank Amphiprion percula A. perideraion performed a removal experiment...

AbstractThe strength and direction of sexual selection can vary among populations. However, spatial variability is rarely explored at the level social group. Here we investigate sex roles in paternally mouthbrooding, socially monogamous, site-attached pajama cardinalfish, Sphaeramia nematoptera. Females were larger more aggressive had a longer dorsal fin filament, indicating reversed roles. At scale groups, show that Bateman gradient reproductive variance depend on ratio size groups. In...

A central issue in evolutionary ecology is how patterns of dispersal influence relatedness populations. In terrestrial organisms, limited offspring leads to groups related individuals. By contrast, for most marine larval open waters thought minimize kin associations within However, recent molecular evidence and theoretical approaches have shown that dispersal, sibling cohesion and/or differential reproductive success can lead association elevated relatedness. Here, we tested the hypothesis...

It was tested whether the pajama cardinalfish Sphaeramia nematoptera (Apogonidae) could home by displacing individuals up to 250 m within and among isolated reefs. Contrary expectations, only two of 37 (5·4%) displaced S. returned another 16 (43·2%) were found have joined other social groups did not after 26 months observations; while over same period, 94% control remained associated with corals, demonstrating strong site attachment. Hence, this species has potential return home, being able...

Many vertebrates form monogamous pairs to mate and care for their offspring. However, genetic tools have increasingly shown that offspring often arise from matings outside of the pair bond. Social monogamy is relatively common in coral reef fishes, but there been few studies confirmed or extra-pair reproduction, either males females. Here, long-term observations were applied examine parentage embryos a paternally mouth-brooding cardinalfish, Sphaeramia nematoptera. Paternal such as...

Animals forming social groups that include breeders and nonbreeders present evolutionary paradoxes; why do tolerate nonbreeders? And their situation? Both paradoxes are often explained with kin selection. Kin selection is, however, assumed to play little or no role in group formation of marine organisms dispersive larval phases. Yet, some organisms, recent evidence suggests small-scale patterns relatedness, meaning this assumption must always be tested. Here, we investigated the genetic...

Vertebrate growth can be phenotypically plastic in response to predator-prey and competitive interactions. It is unknown however, if it mutualistic Here we investigate plasticity of vertebrate variation interactions, using clown anemonefish their anemone hosts. In the wild, there a positive correlation between size fish anemone, but cause this unknown. Plausible hypotheses are that exhibit food or space provided by host. lab, pair individuals with real anemones various sizes show on larger...

Abstract Many animal groups consist of individuals organised in dominance hierarchies, based on age, size or fighting ability. Lower ranked often do not reproduce themselves but perform cooperative behaviours to help the reproductive output dominant group as a whole. Theoretical models suggest that higher rank should show increased amounts aggressive behaviours, such aggressions towards other members, decrease amount brood care territory maintenance. Most empirical tests these focus insect...

Abstract Understanding drivers of species co-existence on coral reefs is important to predict community responses environmental change. Here, we present, for the first time, observations takeovers anemones occupied by one species, Amphiprion percula , another A. perideraion and ask if habitat characteristics, fish or conditions these occurrences. Comparing survey data from multiple years, find that occur at a frequency 0.48–6.84 per 100 groups/year this does not depend disturbances (anemone...