Heteromorphic phases of Leathesia marina (Ectocarpales, Ochrophyta) over time from northern Patagonia, Argentina

POZA, AILEN M.; ESCOBAR, JUAN F.; PARODI, ELISA R.; GAUNA, M. CECILIA

PHYCOLOGIA

INT PHYCOLOGICAL SOC

Año: 2017 vol. 56 p. 579 - 589

0031-8884

ABSTRACT: The emergence and evolution of the heteromorphic life history in algae has been considered as a response tothe selective pressures of changing environments. The brown alga Leathesia marina has a typical heteromorphic lifehistory, alternating between microscopic branched filaments (gametophytic phase) and a macroscopic erect stage(sporophytic phase). The first aim of this study was to describe vegetative and reproductive morphologies of sporophytes(macrothalli and diploid phase) of L. marina and their relationship with environmental factors in an annual cycle. Thesecond aim was to report the discovery of gametophytes (microthalli and haploid phase) in the natural environment onnorthern Patagonian coasts, and to describe their morphology, abundance and reproductive output. The macroscopicphase was observed over 8 months, from September to April during the warm season. The microscopic phase wasobserved in two periods, March?April and September?October. A temporal overlap was observed between themicroscopic and macroscopic phases. The population of macrothalli had a type III survivorship curve. The cover, densityand size of macrothalli were associated with warmer months, but the abundance of microthalli and reproductive outputof both phases were higher in temperate periods. Demographic parameters, including mortality rate, survivorship,reproductive output and the morphological characteristics of L. marina are used to evaluate the adaptation of this speciesto a changing environment, typical of the temperate coasts of northern Patagonia in Argentina.