ECOLOGICAL PROCESSES DRIVING BIOTIC HOMOGENIZATION: TESTING A MECHANISTIC MODEL USING FISH FAUNAS

Biotic homogenization, the process of gradual replacement of native biotas by nonindigeous and locally expanding nonnative species, is rapidly diminishing the re- gional distinctiveness of global terrestrial and aquatic ecosystems. Although the empirical study of biotic homogenization is substantial and growing, the mechanisms underlying its dynamics remain poorly understood. We recently developed a theoretical model that predicts levels of biotic homogenization or differentiation (i.e., decreased community similarity) according to a series of distinct mechanisms that describe the outcomes of various inter- actions between native species, nonnative species, and the environment. Here, we test this model using empirical data for freshwater fish faunas in the United States at three spatial scales: the entire continent, zoogeographic provinces in California, and watersheds within these provinces. Our analysis reveals that, in general, mechanisms depicting widespread introductions of cosmopolitan species and either no or differential spatial patterns of native- species extirpations explain fish-community homogenization across multiple spatial scales. Our results also highlight the potential effect of spatial grain on the perceived importance of different invasion-extinction scenarios shaping patterns of homogenization and differ- entiation. Next, we discuss the utility of the model for providing insight into the dominant ecological processes likely driving the homogenization of other major taxonomic groups that currently lack quantitative estimates of community change. Our study is the first to quantitatively examine the relative importance of different ecological mechanisms that can generate observed patterns of biotic homogenization. Using this model may allow advance prediction of future patterns of homogenization by explicitly considering underlying eco- logical processes and mechanisms.

[1]  D. Waller,et al.  Biotic Impoverishment and Homogenization in Unfragmented Forest Understory Communities , 2004 .

[2]  Julian D Olden,et al.  Toward a Mechanistic Understanding and Prediction of Biotic Homogenization , 2003, The American Naturalist.

[3]  Jukka Jokimäki,et al.  Spatial similarity of urban bird communities: a multiscale approach , 2003 .

[4]  S. Carpenter,et al.  The effects of an exotic fish invasion on the prey communities of two lakes , 2003 .

[5]  James H Brown,et al.  Species Invasions Exceed Extinctions on Islands Worldwide: A Comparative Study of Plants and Birds , 2002, The American Naturalist.

[6]  F. Rahel.  Homogenization of Freshwater Faunas , 2002 .

[7]  David M. Stoms,et al.  Extinction rates under nonrandom patterns of habitat loss , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[8]  Susan L. Williams,et al.  Aquaculture--A Gateway for Exotic Species , 2001, Science.

[9]  J. Lockwood,et al.  Extinction in a field of bullets: a search for causes in the decline of the world's freshwater fishes , 2001 .

[10]  G. Helfman,et al.  Native Invasions, Homogenization, and the Mismeasure of Integrity of Fish Assemblages , 2001 .

[11]  M. Mckinney.  Effects of human population, area, and time on non-native plant and fish diversity in the United States , 2001 .

[12]  R. Cowie.  Decline and homogenization of Pacific faunas: the land snails of American Samoa ? ? Contribution num , 2001 .

[13]  M. Mckinney.  Role of human population size in raising bird and mammal threat among nations , 2001 .

[14]  P. White,et al.  Horticulture as a Pathway of Invasive Plant Introductions in the United States , 2001 .

[15]  F. Rahel.  Homogenization of fish faunas across the United States. , 2000, Science.

[16]  T. Brooks,et al.  Taxonomic homogenization of the global avifauna , 2000 .

[17]  J. Lockwood,et al.  Biotic homogenization: a few winners replacing many losers in the next mass extinction. , 1999, Trends in ecology & evolution.

[18]  James H. Brown,et al.  Invasion of North American drainages by alien fish species , 1999 .

[19]  W. M. Lonsdale,et al.  GLOBAL PATTERNS OF PLANT INVASIONS AND THE CONCEPT OF INVASIBILITY , 1999 .

[20]  Brian D. Richter,et al.  Threats to Imperiled Freshwater Fauna , 1997 .

[21]  H. Mooney,et al.  Human Domination of Earth’s Ecosystems , 1997, Renewable Energy.

[22]  James T. Carlton,et al.  Pattern, process, and prediction in marine invasion ecology , 1996 .

[23]  T. Case.  Global patterns in the establishment and distribution of exotic birds , 1996 .

[24]  Bryan A. Miller-Hicks.  California Rivers and Streams , 1996 .

[25]  A. Magurran,et al.  Biological diversity : the coexistence of species on changing landscapes , 1994 .

[26]  Paul Radomski,et al.  The Homogenizing of Minnesota Lake Fish Assemblages , 1995 .

[27]  Paul L. Angermeier,et al.  Ecological Attributes of Extinction‐Prone Species: Loss of Freshwater Fishes of Virginia , 1995 .

[28]  N. Mandrak,et al.  Ecology of Freshwater Baitfish Use in Canada and the United States , 1993 .

[29]  J. Geller,et al.  Ecological Roulette: The Global Transport of Nonindigenous Marine Organisms , 1993, Science.

[30]  G. Vermeij.  When Biotas Meet: Understanding Biotic Interchange , 1991, Science.

[31]  J. R. Stauffer,et al.  The Introduced Fish Problem and the Aquarium Fish Industry , 1990 .

[32]  C. Elton.  The Ecology of Invasions by Animals and Plants , 1960, Springer US.

[33]  Charles C. Elton,et al.  The Ecology of Invasions by Animals and Plants , 2004, Biodiversity & Conservation.

[34]  J. Olden,et al.  Ecological and evolutionary consequences of biotic homogenization. , 2004, Trends in ecology & evolution.

[35]  Diego P. Vázquez,et al.  Species-area curves, homogenization and the loss of global diversity , 2002 .

[36]  J. Viers,et al.  Homogenization of California’s Fish Fauna Through Abiotic Change , 2001 .

[37]  R. Blair.  Birds and Butterflies Along Urban Gradients in Two Ecoregions of the United States: Is Urbanization Creating a Homogeneous Fauna? , 2001 .

[38]  J. Lockwood,et al.  Spatial Homogenization of the Aquatic Fauna of Tennessee: Extinction and Invasion Following Land Use Change and Habitat Alteration , 2001 .

[39]  K. Wilson.  Extinct and introduced vertebrate species in New Zealand: a loss of biodistinctiveness and gain in biodiversity , 1997 .

[40]  P. Moyle.  Fish Introductions into North America: Patterns and Ecological Impact , 1986 .

[41]  Harold A. Mooney,et al.  Ecology of Biological Invasions of North America and Hawaii , 1986, Ecological Studies.

[42]  P. Moyle.  Inland Fishes of California , 1976 .