Reproductive Compatibility of European Populations of Two Species of Ulnaria (Bacillariophyta)

Clones of two morphotypes corresponding to species pennate araphid diatoms, Ulnaria ulna and U. acus, were isolated from samples taken in Europe. Clonal cultures entered heterothallic sexual reproduction combinations appropriate their mating types. Following the concept biological species, we tested reproductive compatibility between all representatives geographically distant populations. Isolated clones proved be reproductively compatible within limits each species; progeny (generation F1) viable fertile freely into backcrossing. No cases interspecies hybridization found. The absence intraspecific isolation populations these suggests that both acus are conspecific.