Charles Darwin: Evolution by Natural Selection

able adaptation already animals appearance areas argument Asa Gray atolls Beagle become believe birds called causes Chapter characters collections common considered containing continued coral Darwin deposits direct discovered edition effects elevation environment evidence evolution existence experiments explain expressed extinct fact feet FitzRoy flowers forms fossil further genes geological groups Hooker important improvement included individuals inheritance insects interest islands known land later less letter living Lyell means method mind mutation natural selection never object observations occurred oceanic offspring organisms Origin parents period plants population possible present principle problem produced published question reason reefs regarded remains result returned rocks seeds shown similar South America species stages structure taken theory thought tion transmutation trees variation varieties voyage whole wrote