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Phylogeography and invasive history of Codium fragile ssp. tomentosoides
The clonal, siphonous green alga Codium fragile ssp. tomentosoides, a native species of the Indo-Pacific, was first introduced to
European waters in the 1900s. Since then, it has spread throughout Europe and in many instances has replaced the indigenous
C. tomentosum. It is currently unknown whether the alien populations that inhabit European shores are a result of multiple introductions from
different populations in the Indo-Pacific or serial introductions from a single source. We are currently using a combination of high-resolution
plastid microsatellites and sequencing regions of the plastid genome using
universal primers (see below) to elucidate the invasive history of introduced populations of
C. fragile ssp. tomentosoides. [PDF]
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Postglacial history of Palmaria palmata
The present day distribution of the flora and fauna of Europe has been primarily shaped by climatic changes during the Quaternary period.
Fossil and palynological data have to an extent facilitated the analysis of glacial refugia and postglacial recolonisation routes in many plant and
animal species but, to date, it has generally not been possible to study the biogeographic history of organisms with a limited or non-existent fossil
record. Because of this, we have used a phylogeographic approach to analyse samples of the red seaweed Palmaria palmata from its
entire range through a combination of PCR-RFLP and sequencing analysis of three regions of the plastid genome. [PDF]
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Phylogeography of Rhodochorton purpureum and cryptic speciation
The red alga Rhodochorton purpureum has a circumpolar distribution in both hemispheres but is absent from tropical and subtropical areas.
It is an abundant, filamentous, turf-forming species which occupies an exceptionally wide range of habitats and was originally described as a lichen
growing on the walls of a cathedral! We have utilised a combination of nuclear and plastid genetic markers to study the phylogeography of
R. purpureum to gain new insights into the historical biogeography of the species. As well as observing recent trans-arctic and trans-
equatorial migrations of the species, we have also discovered evidence of cryptic speciation within the genus Rhodochorton.
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Phylogeography of Ahnfeltiopsis sp.
Ahnfeltiopsis sp., formerly known as Gymnogongrus sp., is endemic to Northern Ireland within both the British Isles and Europe
as a whole: all known European populations of the species are found in Strangford and Belfast Loughs and adjacent coasts. The species was
originally considered to have been introduced to Northern Ireland anthropogenically from North America, but recent findings have been unable to
rule out the opposite scenario (i.e. that it was introduced into North America from Europe). We are currently using a combination of molecular markers
to clarify the introduction history of the species and to trace the source populations in either Northern Ireland or North America.
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Clonal structure of maerl beds
Several species of calcified red seaweed form extensive deposits, known as maerl beds, that provide an important habitat for a wide variety of
marine animals and plants. These habitats are threatened by various impacts, from which they may be unable to recover. There are no data on
population genetics of any maerl species and population dynamics are very poorly known. It is believed that beds may be entirely clonal,
reproducing by fragmentation only, and thus may be particularly susceptible to impacts. We are using a range of molecular markers (primarily
AFLPs and microsatellites) to test the hypothesis that maerl reproduces entirely clonally and hence has very low genetic variation.
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Universal primers for Chlorophyta and Rhodophyta
To date, the majority of molecular genetic studies in algae have utilized a fairly limited range of markers such as the plastid rbcL gene and
spacer, the mitochondrial cox2-3 spacer or the nuclear ribosomal DNA and spacers. The lack of available markers has been particularly
problematic in studies of within-species variation. The increasing availability of complete plastid genome sequences for several algae has
allowed us to develop two sets of universal primers, similar to those available in higher plants, for the amplification of coding and non-coding
regions of the plastid genome in red and green algae. These markers have already proved useful in a broad range of algal population genetic and
phylogenetic studies. [PDF]
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