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Experimental evidence that competition between stickleback species favours adaptive character divergence
Author(s) -
Gray Suzanne M.,
Robinson Beren W.
Publication year - 2002
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.2002.00313.x
Subject(s) - character displacement , sympatric speciation , allopatric speciation , interspecific competition , biology , sympatry , ecology , competition (biology) , adaptive radiation , stickleback , fishery , phylogenetics , fish <actinopterygii> , population , biochemistry , demography , sociology , gene
The ecological character displacement hypothesis assumes that the effects of interspecific resource competition cause divergent selection to favour phenotypes that exploit non‐shared resources. This model predicts that interspecific competition declines with increased divergence. Direct tests of this decline are rare despite much comparative evidence for character displacement. We tested this prediction using a pair of divergent brook sticklebacks. Brook sticklebacks sympatric with ninespine sticklebacks have diverged from local allopatric brook populations, and so the two types of brook sticklebacks potentially represent pre‐ and post‐displacement forms. We used enclosures placed in a lake to compare short‐term fitness (growth) of sympatric (post‐displacement) and allopatric (pre‐displacement) brook forms in the presence and absence of ninespine sticklebacks. Brook sticklebacks grew less in the presence vs. absence of ninespine sticklebacks, indicating that interspecific competition occurred. As expected, allopatric brook forms had lower growth than sympatric forms when ninespine sticklebacks were present. This result suggests that ecological character displacement has occurred.