Habitat-Specific Morphological Variation among Threespine Sticklebacks (Gasterosteus aculeatus) within a Drainage Basin

Abstract

Habitat-specific morphological variation, often corresponding to resource specialization, is well documented in freshwater fishes. In this study we used landmark based morphometric analyses to investigate morphological variation among threespine sticklebacks (Gasterosteus aculeatus L.) from four interconnected habitat types within a single lowland drainage basin in eastern England. These included the upper and lower reaches of the river, the estuary, a connected ditch network and a coastal salt marsh. We found significant habitat-specific differences in morphology, with three axes of variation describing differences in orbit diameter, body depth, caudal peduncle shape and pectoral fin positioning as well as variation in relative dorsal and pelvic spine size. Interestingly, the ditch system, an artificial and heavily managed habitat, is populated by sticklebacks with a characteristic morphology, suggesting that human management of habitats can in some circumstances lead to morphological variation among the animals that inhabit them. We discuss the mechanisms that conceivably underlie the observed morphological variation and the further work necessary to identify them. Finally, we consider the implications of habitat-specific body shape variation for the behavioural ecology of this ecologically generalist species.

The mechanisms of intertidal fish coexistence: a model

“…The morphological mechanism of coexistence, as found in the thesis, appears similar to the 288 threespine stickleback (Gasterosteus aculeatus) study of Webster et al (2011). They found that 289 where coexistence was occurring between the sticklebacks and piscivorous, gape-limited fish, the 290 sticklebacks had developed deeper bodies, to reduce the likelihood of being eaten.…”

Objectively measuring subjectively described traits: geographic variation in body shape and caudal coloration pattern within Vieja melanura (Teleostei: Cichlidae)

“…Morphological variation in fishes from different habitats is routinely reported in the literature (Mittelbach, Osenberg, Wainwright, 1999;Webster, Atton, Hart, & Ward, 2011); yet this variation is rarely taken into account in taxonomic and morphological phylogenetic studies. In many studies few individuals are used to represent a species, and in fishes, as per convention, generally only the left side is described and used for data collection.…”

Consistency of fish‐shoal social network structure under laboratory conditions

“…Animals may associate through active preference; shoaling fishes have been shown to form associations based upon a range of factors including body size (Ward & Krause, ; Croft et al, ), relatedness (Frommen & Bakker, ; Frommen et al, ; Piyapong et al, ), familiarity (Griffiths & Magurran, ; Croft et al ., ; Frommen & Bakker, ; Ward et al, ), chemical cues derived from similar diet or habitat use patterns (Ward et al, , , , ; Webster et al, , , b; Kleinhappel et al, , ) and competitive ability (Metcalfe & Thomson, ). Assortment may also arise passively through shared habitat preference or site fidelity (Croft et al, ; Webster et al, ; Ward et al, ), similar swimming speeds (Krause et al, ) or similar patterns of activity, risk aversion or cover use linked to personality traits (Pike et al, ; Croft et al, ). The processes or mechanisms behind the positively correlated association patterns seen in this study are not clear; many of the above factors known to affect group composition, such as size, familiarity and habitat and diet use background were held constant as far as possible in our study and are therefore unlikely to be responsible.…”