Structural manipulations of a shelter resource reveal underlying preference functions in a shell-dwelling cichlid fish

Abstract

Many animals can modify the environments in which they live, thereby changing the selection pressures they experience. A common example of such niche construction is the use, creation or modification of environmental resources for use as nests or shelters. Because these resources often have correlated structural elements, it can be difficult to disentangle the relative contribution of these elements to resource choice, and the preference functions underlying niche-construction behaviour remain hidden. Here, we present an experimental paradigm that uses 3D scanning, modelling and printing to create replicas of structures that differ with respect to key structural attributes. We show that a niche-constructing, shell-dwelling cichlid fish, Neolamprologus multifasciatus , has strong open-ended preference functions for exaggerated shell replicas. Fish preferred shells that were fully intact and either enlarged, lengthened or had widened apertures. Shell intactness was the most important structural attribute, followed by shell length, then aperture width. We disentangle the relative roles of different shell attributes, which are tightly correlated in the wild, but nevertheless differentially influence shelter choice and therefore niche construction in this species. We highlight the broad utility of our approach when compared with more traditional methods (e.g. two-choice tasks) for studying animal decision-making in a range of contexts.

Physical enrichment research for captive fish: Time to focus on the DETAILS

“…The first is from a study of a small ‘shell dweller’ cichlid species from Lake Tanganyika, Neolamprologus multifasciatus (Boulenger, 1906), that uses empty shells to shelter from predators and also as brood chambers for their eggs. The cichlids show preferences for specific shell attributes, including size and level of intactness (Bose et al ., 2020). Similarly, sand gobies, Pomatoschistus minutus (Pallas, 1770), show preferences for certain sizes of clay pots that are used for nesting sites (Lehtonen & Wong, 2020).…”

“…When providing PE that is intended to be used as shelter, what are the fine‐scale characteristics of physical structures that fish respond to? Recent studies, as with the previously discussed preferences for specific colours of PVC pipes (de Oliveira et al ., 2019) or shelter dimensions (Bose et al ., 2020), suggest that aspects of physical structure can be important to fish seeking shelter, and fish may pay attention and respond to relatively subtle differences in shape, colour and contrast to the surrounds of the captive environment and sizes of shelter.…”

Brood care in shell-dwelling cichlids is timed by independent maternal and larval clocks

“…1a,b,c,d) (Bills, 1996; Jordan et al, 2021; Sato & Gashagaza, 1997). We devised an artificial shell, modeled after an existing 3D model of the snail species Neothauma tanganyicense (Bose et al, 2020), and removed the back of the shell, opposite to the aperture, just behind the columella (inner spiral), and then extruded the cut walls outwards (Fig. 1e).…”

Patterns of sex-biased dispersal are consistent with social and ecological constraints in a group-living cichlid fish

“…This raises the possibility that large body sizes impose higher dispersal handicaps than small body sizes in this system. For example, larger bodied fish may find it more difficult to seek shelter when venturing away from their own shells, perhaps due to the relative scarcity of large gastropod shells [ 54 ] into which they fit. This remains an open question for future research in N. multifasciatus and other shell-dwelling cichlids.…”