Genetic and morphological identification of Fucus radicans sp Nov (Fucales, Phaeophyceae) in the brackish Baltic Sea

• Brown seaweeds of the genus Fucus occupy a wide variety of temperate coastal habitats. The genus is evolutionary dynamic with recent radiations to form morphologically distinct taxa. In the brackish Baltic Sea, fucoids are the only perennial canopy-forming macroalgae. The most northern populations of Fucus occur permanently submerged in extremely low salinity (3-5 psu). These are currently referred to as Fucus vesiculosus L. but are morphologically distinct with a narrow frond without bladders. We report here that a population of this unique morphotype is reproductively isolated from a truly sympatric population of common F. vesiculosus and conclude that the northern morphotype represents a previously undescribed species. We describe Fucus radicans sp. nov., which is attached and dioecious with broadly elliptic receptacles, characterized by a richly branched narrow flat frond (2-5 mm), short thallus (< 26 cm), and a high capacity for vegetative recruitment of attached plants. Analysis of five highly polymorphic microsatellite DNA loci showed genetic differentiation between sympatric populations of F. radicans and F. vesiculosus, whereas allopatric populations of the same species revealed a coherent pattern of genetic variation. Sequences of the RUBISCO region in F. radicans were identical to or differing at only one to two dinucleotide positions from those of F. vesiculosus, indicating a recent common origin of the two species.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

asexual reproduction

brackish water

clonality

Fucaceae

marginal

environment

microsatellite DNA

morphology

RUBISCO sequence

species

description

SEAGRASS ZOSTERA-MARINA

NORTH-SEA

VESICULOSUS L

SALINITY GRADIENT

POPULATION DIFFERENTIATION

CERAMIUM-TENUICORNE

SERRATUS L.

DIVERSITY

FUCACEAE

HYBRIDIZATION

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)