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PALEOREFUGIA AND NEOREFUGIA: THE INFLUENCE OF COLONIZATION HISTORY ON COMMUNITY PATTERN AND PROCESS
Author(s) -
Nekola Jeffrey C.
Publication year - 1999
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(1999)080[2459:pantio]2.0.co;2
Subject(s) - species richness , ecology , habitat , biota , refugium (fishkeeping) , extinction debt , geography , abundance (ecology) , extinction (optical mineralogy) , relative species abundance , biology , habitat destruction , paleontology
Two types of biological refugia (habitats that support populations not able to live elsewhere in a landscape) can be defined from relative refugium age as compared to surrounding matrix age; paleorefugia are now‐fragmented relicts of a formerly widespread matrix community, whereas neorefugia have formed more recently than the matrix. This difference should make extinction a relatively more important process in determining species occurrence in paleorefugia, whereas immigration should be relatively more important in neorefugia. Based on these differences, a series of eight a priori predictions relating to the diversity and distribution patterns for the biota of such sites can be generated: (1) the slope of the species–area relationship, and amount of variance explained by it, should be greater in paleorefugia as compared to neorefugia; (2) the negative relationship between habitat isolation and species richness should be stronger in neorefugia as compared to paleorefugia; (3) species richness should be expected to decrease over time in paleorefugia, but to increase over time in neorefugia; (4) the inverse correlation between site distance and community similarity (distance decay) should be stronger in neorefugia as compared to paleorefugia; (5) neorefugia should be enriched in highly vagile species relative to paleorefugia, whereas paleorefugia should be rich in less vagile species relative to neorefugia; (6) geographic factors should be more important predictors of species occurrence for neorefugia than for paleorefugia; (7) paleorefuge sites should possess more and stronger correlations between community composition and environmental covariables (such as soil chemistry, climate, etc.) as compared to neorefuge sites; and (8) the number of competitive co‐equivalents held within a system of neorefugia should be greater then the number held within a series of paleorefugia. The most readily testable predictions (numbers 1, 2, 4, and 5) were evaluated by comparing species‐richness and community‐composition patterns within two northeastern Iowa refugia: algific talus slopes (paleorefugia) and fens (neorefugia). Results from these tests were consistent with predictions. These results illustrate that colonization history may influence contemporaneous species diversity and community‐composition patterns. They also suggest that (1) equilibrium has yet to be achieved in the example systems after 5000–10000 yr, (2) the ecological‐biogeographic debate centered around the mutual exclusivity of vicariance and dispersal is intrinsically flawed, and (3) optimum reserve‐design strategies for biodiversity protection within paleorefuge and neorefuge systems will differ.