Get access

Input matching and patch use by native and invasive minnows

Authors

  • C. Michael Wagner,

    1. Daniel B. Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA, USA
    Current affiliation:
    1. Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA
    Search for more papers by this author
  • Gary D. Grossman

    Corresponding author
    • Daniel B. Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA, USA
    Search for more papers by this author

Correspondence: G. D. Grossman, Daniel B. Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA 30602, USA. E-mail: grossman@uga.edu

Abstract

When members of a population choose patches that maximise individual net energy gain without interference, they are input matching, a strategy derived from the ideal free distribution (IFD) that results in equal rewards across all patches. We investigated the input matching abilities of yellowfin shiner, a recent invader, and rosyside dace, a common native minnow, found in Coweeta Creek, North Carolina, USA. To test the species' relative input matching abilities, we varied food abundance within the range found in the natural habitat in a two-patch laboratory stream to document the distribution of foragers when food densities differed in the ratio of 2:1. We then applied simple IFD model predictions to determine whether the observed distribution of foragers was best described by (i) the IFD, (ii) differing competitive abilities or (iii) the ideal despotic distribution and/or other unequal competitor models, and to ascertain whether the invader demonstrated a superior ability to track resource distributions. Yellowfin shiner was more likely to move between patches, which resulted in increased ability to match the distribution of food when prey abundance increased. The distribution of rosyside dace between patches did not change in response to increased food abundance. Despite a considerable range of competitive abilities within intraspecific groups, the ‘equal competitors’ IFD was as good at predicting fish distributions as ‘unequal competitor’ models. The ability to track local resource availability in highly variable environments facilitates maximising energy intake and likely promoted the establishment of yellowfin shiner in a southern Appalachian stream.

Get access to the full text of this article

Ancillary