20880023
not annotated - annotated - LINNAEUS only
Predation is associated with variation in colour pattern, but not body shape or colour reflectance, in a rainbowfish (Melanotaenia australis).
1. In freshwater fishes, inter-population variation in male phenotype is often associated with differences in predation intensity, but these effects can be difficult to disentangle from environmental influences. 2. The western rainbowfish Melanotaenia australis exhibits marked sexual dimorphism - females are plain with a slender body, while males have striking coloration and are deeper in the body. Male traits differ in expression among populations, but this has not been described or explored in the literature. 3. This paper describes a study designed to test for geographic structuring of male phenotype in M. australis and to determine whether between-population variation in male phenotype is attributable to variation in predation regime, after accounting for environment. 4. We collected data describing habitat, and the size, activity and abundance of predators at sites containing M. australis populations. We then used photography, spectrometry and geometric morphometrics to describe colour pattern, spectral reflectance and body shape in males from these populations. Finally, we used permutation-based multivariate statistics to partition variance in these traits according to environment and predation regime. 5. Downstream environments posed higher predation risk to M. australis. Furthermore, males from these sites consistently exhibited larger cheek spots and fewer coloured lateral stripes than those from upstream sites. Variation in predation regime accounted for a significant proportion of the total variance in these traits (30*9%), after controlling for the effects of environment. 6. Variation in predation regime did not explain variation in reflectance or shape. Environmental variation, however, explained a significant portion of the total variance in reflectance (74*9%), and there was a strong trend towards it explaining a portion of the total variance in body shape (34*9%). 7. We conclude that natural selection by predators may be an important determinant of the evolution of colour pattern variation in M. australis, but not of that of body shape or colour reflectance. 8. Further study of M. australis will complement existing models, which show complex relationships between predation regime, environment and phenotype. Understanding these relationships is prerequisite to predicting the evolution of phenotypic variation in natural systems.
Ann file
T1 Species 105 116 rainbowfish
N1 Reference T1 Taxonomy:588576
T2 Species 118 140 Melanotaenia australis
N2 Reference T2 Taxonomy:588576
T3 Species 364 383 western rainbowfish
N3 Reference T3 Taxonomy:588576
T4 Species 384 406 Melanotaenia australis
N4 Reference T4 Taxonomy:588576
T5 Species 759 771 M. australis
N5 Reference T5 Taxonomy:588576
T6 Species 1039 1051 M. australis
N6 Reference T6 Taxonomy:588576
T7 Species 1431 1443 M. australis
N7 Reference T7 Taxonomy:588576
T8 Species 2189 2201 M. australis
N8 Reference T8 Taxonomy:588576
T9 Species 2276 2288 M. australis
N9 Reference T9 Taxonomy:588576
#1 AnnotatorNotes T1 TODO check