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ARE GENERALISTS PRESSED FOR TIME? AN INTERSPECIFIC TEST OF THE TIME‐LIMITED DISPERSER MODEL
Author(s) -
Prinzing Andreas
Publication year - 2003
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(2003)084[1744:agpfta]2.0.co;2
Subject(s) - generalist and specialist species , ecology , biology , interspecific competition , arboreal locomotion , abiotic component , foraging , biological dispersal , habitat , population , demography , sociology
Optimal‐foraging theory, specifically the “Time‐Limited Disperser Model,” predicts that animals that can search for resources for a long period will be specialists, whereas animals that have limited search times will be generalists. So far, this model has only been tested within individual species, i.e., among animals of similar physiology and life history. I tested the model across multiple species, using a taxonomically diverse community of arthropods found on exposed tree trunks in northern Germany. I sampled 14 arthropod species from different microhabitat types (various cryptogam species and crevice types) and quantified the microhabitat‐niche breadths of species by Simpson index. Then, I used multiple regression analysis across phylogenetically independent contrasts to examine the relationship between microhabitat‐niche breadth and traits that can control search time (degree of residence on the trunks, tolerance of abiotic stress, speed of movement, generation time). I found that microhabitat specialists had longer generation times, spent more of their life on the trunks and could move faster than generalists. This allowed specialists to search the trunk for a longer period of time than generalists and to require less time to traverse a given search distance. These three findings supported the Time‐Limited Disperser Model. However, specialists were no more tolerant of abiotic stress (i.e., desiccation) than were generalists. That is, specialists could not search the trunk during more adverse climatic conditions than could generalists, contradicting the Time‐Limited Disperser Model. Overall, the results supported three out of four predictions of the Time‐Limited Disperser Model at an interspecific level. Specialists can search for a long time; generalists are pressed for time.