10.5061/DRYAD.3XSJ3TXBR
Luehrmann, Martin
University of Queensland
Cortesi, Fabio
University of Queensland
Cheney, Karen
University of Queensland
de Busserolles, Fanny
University of Queensland
Marshall, Justin
University of Queensland
Microhabitat partitioning correlates with opsin gene expression in coral
reef cardinalfishes (Apogonidae)
Dryad
dataset
2020
sensory adaptation
vertebrate
Colour Vision
aquatic environment
Ecological niche
light environment
2020-01-08T00:00:00Z
2020-01-08T00:00:00Z
en
3313628 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Fish are the most diverse vertebrate group, and they have evolved equally
diverse visual systems, varying in terms of eye morphology, number and
distribution of spectrally distinct photoreceptor types, visual opsin
genes and opsin gene expression levels. This variation is mainly due to
adaptations driven by two factors: differences in the light environments
and behavioural tasks. However, while the effects of large-scale habitat
differences are well described, it is less clear whether visual systems
also adapt to differences in environmental light at the microhabitat
level. To address this, we assessed the relationship between microhabitat
use and visual system features in fishes inhabiting coral reefs, where
habitat partitioning is particularly common. We suggest that differences
in microhabitat use by cardinalfishes (Apogonidae) drive morphological and
molecular adaptations in their visual systems. To test this, we
investigated diurnal microhabitat use in 17 cardinalfish species and
assessed whether this correlated with differences in visual opsin gene
expression and eye morphology. We found that cardinalfishes display six
types of microhabitat partitioning behaviours during the day, ranging from
specialists found exclusively in the water column to species that are
always hidden inside the reef matrix. Species predominantly found in
exposed microhabitats had higher expression of the short-wavelength
sensitive violet opsin (SWS2B) and lower expression of the dim-light
active rod opsin (RH1). Species of intermediate exposure, on the other
hand, expressed opsins that are mostly sensitive to the blue-green central
part of the light spectrum (SWS2As and RH2s), while fishes entirely hidden
in the reef substrate had a higher expression of the long-wavelength
sensitive red opsin (LWS). We also found that eye size relative to body
size differed between cardinalfish species, and relative eye size
decreased with an increase in habitat exposure. Retinal topography did not
show co-adaptation with microhabitat use, but data suggested co-adaptation
with feeding mode. We suggest that, although most cardinalfishes are
nocturnal foragers, their visual systems – and possibly those of other
(reef) fishes – have also adapted to the light intensity and the light
spectrum of their preferred diurnal microhabitats.