Towards a Theory of Speciation in Beroe

摘要: Evolutionary processes in ctenophores cannot be investigated on the basis of fossils. Circumstantial evidence only can provide us with an insight into history this phylum. Such may presence or absence true larvae; they are missing orders Cydippida, and Beroida while other three Lobata, Cestida, Platyctenida have cydippid larvae at least as embryonic stage (Dunlap Pianka, 1974). Therefore Cydippida assumed to more primitive. Other circumstantial is tentacles order Beroida, which combination above mentioned direct development, suggests that taxon originates from common ancestors early forms. From these were derived larvae.