Biology Reference
In-Depth Information
Fig. 12.2
(
a
)
Sargassum muticum
(photo by Stefan Kraan); (
b
)
Undaria pinnatifida
(Harvey)
Suringar (Algaebase, image Ref. 15830, photo by Mike Guiry)
12.3.2 Case Study:
Sargassum Muticum
The large brown Japanese seaweed
Sargassum muticum
(Yendo) Fensholt
(Fig.
12.2a
) is one of the most invasive and widely established algae in Europe and
North America (Monteiro et al.
2009
;Kraan
2008
). Contrary to other brown
macroalgae (such as
Undaria pinnatifida
and
Fucus serratus
) no evidence for genetic
differentiation has been detected between native Asian and introduced populations in
this species. This indicated a number of recent invasion events supported mainly by
the transport of Pacific oysters introduced for farming in Canada, UK, and France.
Nuclear (ITS2; internal transcribed spacer 2) mitochondrial (
Trn
W-
Trn
I spacer) and
plastid (RUBISCO spacer) markers failed to uncover significant levels of DNA
polymorphisms in
S. muticum
individuals collected globally, which would be
required for the reconstruction of the genetic identity of invasive and native
populations in this species. The low levels of genetic variability encountered in the
native and introduced range of
S. muticum
together with previous morphological
confusions with closely related species prohibited the identification of the source
populations and the direction of the introduction episodes along the invasion pathway
of this important invasive seaweed (Cheang et al.
2010
).
