Temperature responses of tropical to warm-temperate Atlantic seaweeds. II. Evidence for ecotypic differentiation in amphi-Atlantic tropical-Mediterranean species

Abstract

Nineteen isolates of four amphi-Atlantic seaweed species with a tropical to warm-temperate/Mediterranean distribution (Microdictyon boergesenii, M. tenuis, Wurdemannia miniata and Valonia utricularis) and one eastern Atlantic endemic (Mr. calodictyon) have been investigated for their temperature responses (tolerance limits and growth response curves). In all species, isolates survived undamaged at 30°C but died at 33 or 35°C. Growth occurred up to 30°C in most isolates but no growth was observed at higher (33°C) temperatures. Tolerance to low temperatures showed marked differences between and within species. In tropical isolates, damage generally occurred between I5 and 18°C and plants grew at temperatures down to 18-20°C. Isolates from warm-temperate localities (Canary Islands and Mediterranean) tolerated much lower temperatures (0-12°C), and showed substantial growth at temperatures as low as I5-18°C, which indicates ecotypic differentiation. It is hypothesized that these cold-adapted populations are descendants of populations which were isolated in the eastern Mediterranean during the last glacial episode and recolonized the western Mediterranean and Canary Islands at the onset of the interglacial.

Algal Bioremediation of Waste Waters from Land-Based Aquaculture Using Ulva: Selecting Target Species and Strains

“…Studies of local adaptation in macroalgal species are relatively rare. Over large spatial scales (e.g., ocean wide) there is evidence both for [19], [21] and against [25] local adaptation of macroalgae. Likewise, over small spatial scales results are mixed with evidence for local adaptation over 100 s of kilometres [26] and two out of three populations showing evidence of local adaptation across intertidal zones [20].…”

“…If there is a strong genotype × environment (G × E) interaction, local strains may possess traits that provide an advantage under local conditions leading to superior performance under these conditions compared to strains originating from other habitats [15]. Adaptation of populations to local environments has been demonstrated across a range of phototropic organisms including terrestrial plants [16], [17], aquatic plants [18] and algae [19]–[21]. Based on these results, we would expect local strains of algae to have higher growth, and therefore bioremediation capability, in their local habitats compared to non-local strains.…”

THE INVASIVE GENUS ASPARAGOPSIS (BONNEMAISONIACEAE, RHODOPHYTA): MOLECULAR SYSTEMATICS, MORPHOLOGY, AND ECOPHYSIOLOGY OF FALKENBERGIA ISOLATES1

“…Ecotypic differentiation in temperature responses of seaweeds is relatively rare (Breeman 1988), with most reports occurring in seaweed populations that have disjunct distributions, wide latitudinal ranges (Novaczek and Breeman 1990, Novaczek et al 1990), or both. Temperature ecotypes in species with tropical Atlantic/Mediterranean distributions have been linked to their survival in refugia during the last glacial maximum (Pakker and Breeman 1996).…”

PHYLOGEOGRAPHIC STUDIES IN THE TROPICAL SEAWEED CLADOPHOROPSIS MEMBRANACEA (CHLOROPHYTA, ULVOPHYCEAE) REVEAL A CRYPTIC SPECIES COMPLEX1

“…Phylogeographic studies (Avise 2000) provide a way to link larger scale patterns observed today to vicariant events (Ronquist 1997), such as plate tectonics, the closure of the Tethys Sea (Por 1989), or paleoclimatic effects associated with the last glacial maximum (LGM) some 20 to 18,000 years ago (Dawson 1992). Sea surface temperatures, in particular, strongly govern the distribution of seaweeds (Breeman 1988, Pakker and Breeman 1996).…”