Temperature responses of tropical to warm-temperate atlantic seaweeds. i. absence of ecotypic differentiation in amphi-atlantic tropical-canary islands species

Abstract

Thirty-two isolates of four amphi-Atlantic seaweed species with a tropical to subtropical distribution (Dictyopteris delicatula, Ceratodictyon intricatum, Ernodesmis verticillata and Lophocladia trichoclados) have been investigated for their temperature responses. Long (8 week) incubation times at 15–18°C caused damage or death in all isolates. Lower temperatures were tolerated only for shorter incubation times or caused severe damage. High temperatures in the range 30–35°C were tolerated. For L. trichoclados growth response curves were also determined which showed growth at temperatures ranging from 18/20 to 30°C, with optimum growth rates at 25–30°C. Crossing experiments with isolates of L..