Predation, herbivory and kelp evolution

摘要: We propose that the kelps (Laminariales) radiated in North Pacific following onset of late Cenozoic polar cooling. The evidence is (1) extant occur exclusively cold-water habitats; (2) all but one 27 kelp genera Pacific, 19 these exclusively; and (3) limpets herbivorous marine mammals obligately associated with or other stipitate brown algae appeared Cenozoic, even though more generalized forms both groups are much older. propose, further, sea otters perhaps benthic-feeding predatory mammals, whose distributions were limited to created an environment for evolution which intensity herbivory was unusually low. hypothesize this interaction predictable differences among habitats on several spatial scales, resulting trade-offs between anti-herbivore defenses plant competitive abilities their respective floras. Sea incur time energy costs diving, depth-related reductions foraging efficiency thus increased sizes densities urchins. Thus, deep-water flora well defended, competitively subordinate, compared shallow-water flora. Similarly, we argue during same period earth history, predation had less a limiting influence invertebrates temperate southwestern Pacific. consequent biogeographical may have selected phenolic-rich algal Australia/New Zealand; tightly coevolved plant/herbivore interactions explain why Australian New Zealand herbivores undeterred by phenolics classes secondary compounds Australian/New significantly deter herbivores.