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REWINDING THE TAPE: SELECTION OF ALGAE ADAPTED TO HIGH CO 2 AT CURRENT AND PLEISTOCENE LEVELS OF CO 2
Author(s) -
Collins Sinéd,
Sültemeyer Dieter,
Bell Graham
Publication year - 2006
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2006.tb01218.x
Subject(s) - biology , adaptation (eye) , pleistocene , glacial period , selection (genetic algorithm) , limiting , evolutionary biology , range (aeronautics) , replicate , algae , ecology , paleontology , statistics , neuroscience , computer science , engineering , composite material , mechanical engineering , materials science , artificial intelligence , mathematics
Selective history is thought to constrain the extent and direction of future adaptation by limiting access to genotypes that are advantageous in a novel environment. Populations of Chlamydomonas previously selected at high CO 2 were either backselected at ambient levels of CO 2 , or selected at levels of CO 2 that last occurred during glaciation in the Pleistocene. There was no effect of selective history on adaptation to either level of CO 2 , and the high CO 2 phenotypes were evolutionarily reversible such that fitness in ambient CO 2 returned to values seen in controls. CO 2 uptake affinity improved relative to the ancestor in both ambient and glacial CO 2 , although wild‐type regulation of CO 2 uptake, which deteriorated during previous selection at high CO 2 , was not restored by selection at lower levels of CO 2 . Trade‐offs in both CO 2 uptake affinity and growth were seen after selection at any given level of CO 2 . Adaptation to ambient and glacial‐era levels of CO 2 produced a range of phenotypes, suggesting that chance rather than selective history contributes to the divergence of replicate populations in this system.