3 Populations and Pathways
93
3.3.2 Marine Bio-Invasions: Using Genomic Resources to Study
Invasive Species
Biological invasions, tightly linked to human activities, are one of the major threats
to marine biodiversity and ecosystem stability. Although one of the main properties
of biological invasions is the unpredictable nature of their appearance, introductions
of non-indigeneous species have been shown to be highly correlated with commercial shipping routes (Ricciardi and MacIsaac 2000) and aquaculture (Wolff and
Reise 2002). For instance, shipping between the USA and Great Britain may have
caused the introduction of 20% of the foreign species in British waters. Foreign
species may also be capable of taking advantage of coastal water pollution (e.g., the
introduced alga Ulva fascicata has supplanted the autochthonous species Ulva pertusa in polluted environments in Japan; Morand and Briand 1996) or climate change
(Stachowicz et al. 2002). In this context, several authors have underlined the usefulness and lack of molecular and genomic data for the study of biological invasions
(Holland 2000, Roman and Darling 2007, Sax et al. 2007, Caroll 2008, Darling
and Blum 2008). Population genomics and DNA-based approaches may provide
important information about biological invasion processes in several ways. For
example, using the completely sequenced mitochondrial genome of Laminaria digitata (AJ344328; Oudot et al. 2002) and Pylaiella littoralis (AJ277126; Oudot-Le
Secq et al. 2001), Engel et al. (2008) identified seven polymorphic intergenic regions
which were conserved over a range of brown algae species from the Laminariale
(sensu lato) and to a lesser extent Fucaceae. The sequences of two of these genomic
regions were used in a worldwide population survey of circa 500 individuals of the
invasive brown alga Undaria pinnatifida, which showed that different introduction
processes were responsible for the successful introduction of this Japanese kelp in
different parts of the world (Voisin et al. 2005).
Darling and Blum (2008) recently advocated the use of genomic resources such
as microarrays and quantitative PCR as potentially powerful tools for examining
microbial or planktonic diversity. The extent of biological invasions involving these
organisms is certainly neglected due to their small size and difficulties with identification. Another important and unresolved question in invasion biology studies is the
tempo and mode of evolution of invasive species in their new range. Genome scan
approaches based on AFLPs, SNPs or full genome studies can potentially provide
tools for analyzing on-going adaptation processes. In the specific case of introduced species, such analyses may be used to examine the possibility for selection
on standing genetic variation (Barrett and Schluter 2008).
3.3.3 Uncovering the Genetic Basis of Hybrid Vigour
in Aquaculture Populations
Oysters are a highly prized commercial species. Investment into understanding
their genetics is of paramount importance for their maintenance as a cash-rich
93
3.3.2 Marine Bio-Invasions: Using Genomic Resources to Study
Invasive Species
Biological invasions, tightly linked to human activities, are one of the major threats
to marine biodiversity and ecosystem stability. Although one of the main properties
of biological invasions is the unpredictable nature of their appearance, introductions
of non-indigeneous species have been shown to be highly correlated with commercial shipping routes (Ricciardi and MacIsaac 2000) and aquaculture (Wolff and
Reise 2002). For instance, shipping between the USA and Great Britain may have
caused the introduction of 20% of the foreign species in British waters. Foreign
species may also be capable of taking advantage of coastal water pollution (e.g., the
introduced alga Ulva fascicata has supplanted the autochthonous species Ulva pertusa in polluted environments in Japan; Morand and Briand 1996) or climate change
(Stachowicz et al. 2002). In this context, several authors have underlined the usefulness and lack of molecular and genomic data for the study of biological invasions
(Holland 2000, Roman and Darling 2007, Sax et al. 2007, Caroll 2008, Darling
and Blum 2008). Population genomics and DNA-based approaches may provide
important information about biological invasion processes in several ways. For
example, using the completely sequenced mitochondrial genome of Laminaria digitata (AJ344328; Oudot et al. 2002) and Pylaiella littoralis (AJ277126; Oudot-Le
Secq et al. 2001), Engel et al. (2008) identified seven polymorphic intergenic regions
which were conserved over a range of brown algae species from the Laminariale
(sensu lato) and to a lesser extent Fucaceae. The sequences of two of these genomic
regions were used in a worldwide population survey of circa 500 individuals of the
invasive brown alga Undaria pinnatifida, which showed that different introduction
processes were responsible for the successful introduction of this Japanese kelp in
different parts of the world (Voisin et al. 2005).
Darling and Blum (2008) recently advocated the use of genomic resources such
as microarrays and quantitative PCR as potentially powerful tools for examining
microbial or planktonic diversity. The extent of biological invasions involving these
organisms is certainly neglected due to their small size and difficulties with identification. Another important and unresolved question in invasion biology studies is the
tempo and mode of evolution of invasive species in their new range. Genome scan
approaches based on AFLPs, SNPs or full genome studies can potentially provide
tools for analyzing on-going adaptation processes. In the specific case of introduced species, such analyses may be used to examine the possibility for selection
on standing genetic variation (Barrett and Schluter 2008).
3.3.3 Uncovering the Genetic Basis of Hybrid Vigour
in Aquaculture Populations
Oysters are a highly prized commercial species. Investment into understanding
their genetics is of paramount importance for their maintenance as a cash-rich