Article

The benefit to some minnows of spawning in the nests of other species

Illinois Natural History Survey
Environmental Biology of Fishes (Impact Factor: 1.57). 05/1994; 40(2):213-218. DOI: 10.1007/BF00002547

ABSTRACT

Fishes that act as nest associates spawn simultaneously with nest-building hosts and then abandon their eggs. The proposed benefit for this behavior is increased brood survivorship, arising from the physical environment provided by the nest or the parental care provided by the host. Field and enclosure experiments indicated that associates benefit from the parental care provided by the host, and not from the physical environment provided by the nests of hosts. This information, along with the effect of nest association on host reproductive success, is necessary before the nature of this nesting symbiosis can be characterized.

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Available from: Carol E. Johnston, Aug 13, 2014
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    • "Contrary to our hypothesis, we observed no effect of egg predator density on the reproductive success of either N. leptocephalus or C. oreas. This is surprising, given the strong effects of predation at determining the outcomes of nest associations in other systems (Baba et al. 1990;Fletcher 1993;Johnston 1994a). The most likely explanation for this is that egg predator density between high and low factor levels was not sufficiently different to generate a meaningful effect. "
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    ABSTRACT: The development of encompassing general models of ecology is precluded by underrepresentation of certain taxa and systems. Models predicting context-dependent outcomes of biotic interactions have been tested using plants and bacteria, but their applicability to higher taxa is largely unknown. We examined context dependency in a reproductive mutualism between two stream fish species: mound nest-building bluehead chub Nocomis leptocephalus and mountain redbelly dace Chrosomus oreas, which often uses N. leptocephalus nests for spawning. We hypothesized that increased predator density and decreased substrate availability would increase the propensity of C. oreas to associate with N. leptocephalus and decrease reproductive success of both species. In a large-scale in situ experiment, we manipulated egg predator density and presence of both symbionts (biotic context), and replicated the experiment in habitats containing high- and low-quality spawning substrate (abiotic context). Contradictory to our first hypothesis, we observed that C. oreas did not spawn without its host. The interaction outcome switched from commensalistic to mutualistic with changing abiotic and biotic contexts, although the net outcome was mutualistic. The results of this study yielded novel insight into how context dependency operates in vertebrate mutualisms. Although the dilution effect provided by C. oreas positively influenced reproductive success of N. leptocephalus, it was not enough to overcome both egg predation and poor spawning habitat quality. Outcomes of the interaction may be ultimately determined by associate density. Studies of context dependency in vertebrate systems require detailed knowledge of species life-history traits.
    Full-text · Article · Jan 2016 · Ecology and Evolution
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    • "Nest-building male Nocomis select a narrow range of substrate sizes and water velocities (Wisenden et al., 2009), creating what are often the only sources of appropriate spawning habitat for associates, which require unsilted gravel substrate to spawn. Tending male Nocomis also provide parental care through egg guarding, cleaning and burying that associates would not achieve by spawning without a host (Johnston, 1994a). "
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    ABSTRACT: Aim The role of biotic interactions in determining species distributions is difficult to decouple from abiotic factors. Most research to date has focused on negative biotic interactions, but the importance of positive interactions such as mutualism and facilitation at large scales is less understood. We used a two-species occupancy modelling approach to decouple the relative effects of abiotic factors and biotic interactions between a habitat-modifying North American stream fish (Nocomis leptocephalus) and two of its nearly-obligate beneficiary species (Chrosomus oreas and Clinostomus funduloides). Location Sixty-one sites on tributaries to the New River basin in the Appalachian mountains of the eastern United States. Methods We sampled fishes using backpack electrofishing in the summers of 2012–2014. We gathered 10 habitat covariates from the National Hydrography Dataset and from instream measurements. We reduced dimensionality in habitat variables, corrected them for spatial autocorrelation and selected two eigenvectors as habitat covariates. We then used an information-theoretic approach to compare two-species occupancy models representing hypotheses specifying the importance of only habitat, only biotic interactions, or combinations of both. Results The best model for each species combination specified the importance of biotic interactions. For both associate species, probabilities that associates would occur in the absence of their host were considerably lower than probabilities of co-occurrence. Species interaction factors indicated positive patterns of co-occurrence between hosts and associates. Models suggested that habitat variables mediated host-associate interactions for C. oreas but not for C. funduloides. Main conclusions This study provides some of the first large-scale quantitative evidence of positive co-occurrence among vertebrates, and demonstrates the importance of abiotic context for mediating interspecific interactions. Two-species occupancy modelling may be superior to traditional co-occurrence analyses for parsing out the relative importance of biotic interactions and habitat variables for determining species distributions. However, experiments and small-scale behavioural observations will also be necessary to confirm mechanisms.
    Full-text · Article · Dec 2015 · Journal of Biogeography
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    • "Furthermore, we only consider physical characteristics of nests as a potential driver of host switching. Behavioral mechanisms may also be at work in this system, particularly the important effect of parental care (Johnston 1994a). For example, tending male Bluehead chubs cover eggs with gravel after spawning, while stonerollers abandon their broods relatively quickly (Sabaj et al. 2000). "
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    ABSTRACT: Several nest-building North American minnows (Cyprinidae) function as reproductive hosts to nest associates–species that require nests of other species for spawning. Understanding the microhabitat preferences of hosts can yield insight into the reproductive ecology of many species, especially of nest associates that can utilize nests of two or more hosts. We observed nests of Central stoneroller Campostoma anomalum in which several associate species were actively spawning. Bluehead chubs Nocomis leptocephalus began constructing nests two days later in the same stream, at which time associates abandoned stoneroller nests and continued on to spawn on chub nests. This presented a unique opportunity for accomplishing two objectives: (1) quantifying stoneroller nesting microhabitat preference and (2) comparing stoneroller and chub habitat preference to gain insight into the mechanisms that may drive host switching by nest associates. We measured substrate size, current velocity, water depth, and egg depth on seven paired stoneroller and chub nests, and compared these measurements to paired microhabitat measurements at a randomly selected point near each nest. Repeated measures analysis of variance with post hoc Tukey tests revealed that stonerollers exhibited distinct nesting microhabitat preferences from chubs. Gravel on stoneroller nests was considerably smaller than on chub nests and stonerollers nested in shallower depths than chubs. However, both species nested at similar current velocities. If nest associates switch partners based on the physical characteristics of nests, then substrate size is likely the most important factor. The larger gravel sizes on chub nests likely provide better egg aeration than stoneroller nests. Chub nests may also be safer for associate broods because male Bluehead chubs cover eggs with gravel after spawning; stonerollers do not. Future work should take an experimental approach to elucidate these mechanisms.
    Full-text · Article · Oct 2015 · Journal of Freshwater Ecology
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