Functional diversity of the lateral line system among populations of a native Australian freshwater fish

Abstract

Fishes use their mechanoreceptive lateral line system to sense nearby objects by detecting slight fluctuations in hydrodynamic motion within their immediate environment. Species of fish from different habitats often display specialisations of the lateral line system, in particular the distribution and abundance of neuromasts, but the lateral line can also exhibit considerable diversity within a species. Here, we provide the first investigation of the lateral line system of the Australian western rainbowfish (Melanotaenia australis), a species that occupies a diversity of freshwater habitats across semi-arid northwest Australia. We collected 155 individuals from eight populations and surveyed each habitat for environmental factors that may contribute to lateral line specialisation, including water flow, predation risk, habitat structure and prey availability. Scanning electron microscopy and fluorescent dye labelling were used to describe the lateral line system in M. australis, and to examine whether the abundance and arrangement of superficial neuromasts (SNs) varied within and among populations. We found that the SNs of M. australis were present in distinct body regions rather than lines. The abundance of SNs within each body region was highly variable, and also differed among populations and individuals. Variation in SN abundance among populations was best explained by habitat structure and the availability of invertebrate prey. Our finding that specific environmental factors explain among-population variation in a key sensory system suggests that the ability to acquire sensory information is specialised for the particular behavioural needs of the animal.

The Role of Vision and Lateral Line Sensing for Schooling in Giant Danios (Devario Aequipinnatus)

“…Turbid water can change the escape behaviours of schooling species, which adjust their strategies to account for a lack of vision (Kimbell & Morrell, 2015a). Previous studies have also show that environmental factors can change the number of neuromasts for subpopulations within a species (Fischer et al, 2013;Kelley et al, 2017;Spiller et al, 2017). It is therefore not unreasonable to consider that fish living in clearer water may depend more on vision than the lateral line, and those that live in turbid water or that school at night may adapt to depend more on the lateral line.…”

Habitat disruption and the identification and management of functional trait changes

“…Surprisingly, few studies have investigated intraspecific variation in the sensory system, yet such variability is likely linked with behavioural function, fitness and population ecology. For example, a recent study of an Australian dryland fish, the western rainbowfish ( Melanotaenia australis , Melanotaeniidae) revealed that within‐species variation in the lateral line system is associated with environmental variables such as habitat structure and invertebrate prey availability, revealing that populations exhibit habitat‐specific sensory specializations (Spiller, Grierson, Davies, Collin, & Kelley, ). Furthermore, while some studies have demonstrated that this intraspecific sensory variation has a genetic basis (Wark et al., ), senses such as vision (Fuller, Noa, & Strellner, ) and the lateral line (Fischer, Soares, Archer, Ghalambor, & Hoke, ; Kelley, Grierson, Davies, & Collin, ) can exhibit developmental plasticity.…”

The effect of ecological factors on eye morphology in the western rainbowfish, Melanotaenia australis

“…We chose this species because it occupies a large variety of freshwater habitats across northwest Western Australia, including isolated springs and billabongs ( pools), ephemeral creeks, gorges and lakes (Allen et al, 2002). Previous studies have shown that this species shows extensive variation in morphological characteristics, such as body shape and lateral line morphology, in relation to environmental parameters (Young et al, 2011a,b;Kelley et al, 2017;Spiller et al, 2017). However, no previous study has specifically investigated variation in eye morphology, even though these fish are considered to rely heavily on vision for feeding, communication, sexual selection and predator detection (Brown and Warburton, 1997;Arnold, 2000;Brown, 2002Brown, , 2003Hancox et al, 2010;Kelley et al, 2012).…”