Evidence for Ecological Character Displacement in Western American Catostomid Fishes

Abstract

Much of recent ecological theory rests petition with individuals of another popon the assumption that the primary factor ulation in the same environment. The responsible for the organization of natural characters may be morphological, ecologcommunities, particularly of animals, is ical, behavioral, or physiological and the interspecific competition (e.g., Mac-change may be either divergent or con- Arthur, 1972; Schoener, 1975). The valid-vergent. By divergent competitive charity of this assumption depends almost ex-acter displacement we mean that a charelusively on inference drawn from acter state of a population in ecological observational evidence of two types. Mor-sympatry (= syntopy, Rivas, 1964) exphological changes in the form of ecolog-hibits greater difference than is the case ical character displacement (Brown and when allopatric populations are contrast- Wilson, 1959;Grant, 1972) and niche ed, and that this effect can be attributed shifts correlated with geographic variation to sympatry. If the contrast of allopatric in the number or density of closely related and sympatric populations reveals that the species are generally considered the character states of the two populations are strongest available evidence for the im-more similar in areas of sympatry than in portance of interspecific competition areas of allopatry and if this effect can be (MacArthur, 1972;Cody, 1974; Schoener, attributed to competition, then the situa-1974 Schoener, attributed to competition, then the situa- , 1975

Community-wide character displacement in the presence of clines: A test of Holarctic weasel guilds

“…While geographic size clines are common (Rosenzweig 1968;Ralls & Harvey 1985;Meiri & Dayan 2003;Meiri, Dayan & Simberloff 2005a;Meiri, Yom-Tov & Geffen 2007b;Haba et al 2008;Gu¨r 2010), few studies have tried to correct for their presence while studying character displacement. Dunham, Smith & Taylor (1979) examined character displacement in Catostomus fishes, controlling for geographic clines tracking several variables (e.g. latitude, elevation).…”

How Fluctuating Competition and Phenotypic Plasticity Mediate Species Divergence

“…The role of resource competition in promoting phenotypic divergence between interacting species is difficult to demonstrate empirically, however (Conner and Simberloff 1979;Dunham et al 1979;Schluter and McPhail 1992;Grant 1994;Schluter 1994Schluter , 2000Losos 2000). Experimental tests are generally not feasible because it often takes a long time to observe an evolutionary response to selection imposed by competitors.…”

Convergence, Divergence, and the Effect of Congeners on Body Size Ratios in Stream Fishes

“…If the characters associated with resource partitioning have a genetic basis, character displacement is said to have occurred (Brown and Wilson 1956). Although divergence between sympatric species is the most commonly identified form of character displacement, convergence of traits, presumably to enhance competitive ability in a particular environment, is also included in the theory of character displacement (Grant 1972;Dunham et al 1979).…”

“…It is commonly accepted that community structure can affect the niche and morphological characteristics of an or-ganism. Correspondingly, several studies of character displacement in vertebrates have investigated the phenomenon of character change in relation to community composition (review in Grant 1972;Dunham et al 1979;Strong et al 1979;Hendrickson 1981;Dayan et al 1990;Werdelin 1996). Although some of the initial and best-known studies of community-wide character displacement have considered island biota (Lack 1947;Schoener 1969;Williams 1972), recent studies have shown that this phenomenon is also likely to occur in continental communities (Dayan et al 1990;Werdelin 1996;Ben-Moshe et al 2001).…”

“…Since proposed by Brown and Wilson (1956), the theory of character displacement has been tested on a wide variety of taxa (e.g., Grant 1972;Schluter et al 1985;Schluter 1988;Dayan et al 1989;Losos 1990;Schluter and McPhail 1992;Radtkey et al 1997;Saetre et al 1997;Adams and Rohlf 2000;Pfennig and Murphy 2000). However, a relatively small amount of work has been completed on freshwater fishes (Dunham et al 1979;Crowder 1984;Robinson and Wilson 1994;Schluter and McPhail 1992). Freshwater systems, lakes and small streams in particular, allow a relatively limited amount of dispersal, which may facilitate isolation and adaptation to localized conditions (Robinson and Wilson 1994).…”