Life history variation between species of the relictual genus Borderea (Dioscoreaceae): phylogeography, genetic diversity, and population genetic structure assessed by RAPD markers.
Segarra-Moragues, J.G.; Catalán, P.. Life history variation between species of the relictual genus Borderea (Dioscoreaceae): phylogeography, genetic diversity, and population genetic structure assessed by RAPD markers.. Biological Journal of the Linnean Society. 2003, Vol. 80(3), p. 483-2003.
The genus
Borderea
consists of two species,
B. pyrenaica
and
B. chouardii
, taxa which have been previously considered
as conspecific due to their overall close morphology. These two sole species of the rare genus of Dioscoreaceae
are endemic to the Pyrenees (Spain, France). This mountain range likely operated as a refugium for these plants during
the last glaciations.
B. chouardii
is only known from a single population in the Spanish Prepyrenees and has been
classified as at risk of extinction in the Red List of Endangered Species (IUCN);
B. pyrenaica
shows a narrow distribution
range in the central Pyrenees and Prepyrenees. We analysed genetic variation, population structure and
differentiation in these two taxa using RAPD markers. Our study was conducted on the same seven populations for
which very low levels of genetic differentiation were detected previously through allozyme analysis. By contrast, high
levels of genetic variability were detected through the RAPD hypervariable markers. Twelve RAPD primers produced
112 distinct bands in the 397 surveyed individuals, totalling 395 different RAPD phenotypes. Only four bands
were monomorphic across all samples of
Borderea
, whereas 21 of the polymorphic bands were species-specific (20 for
B. chouardii
, and one for
B. pyrenaica
). The largest genetic distances were those between the
B. chouardii
and the
B. pyrenaica
phenotypes. An analysis of molecular variance showed greater variance between groups (
B. chouardii
vs.
B. pyrenaica
, 76.08%) than within groups (3.60%). RAPD band specificity, phenotypic distances, and the partitioning
of variance all support the taxonomic separation of the two species. Statistical evaluation of within- and
among-population RAPD genetic variability in
B. pyrenaica
showed that genetic variability was higher within populations
(
>
80%) than among them. No clear pattern of RAPD differentiation could be observed among the six studied
populations of this taxon though slight differences in genetic diversity could be observed in the more isolated
Prepyrenean populations compared with the more widespread Pyrenean ones. These results suggest a recent postglacial
origin of the present
B. pyrenaica
populations.
The genus
Borderea
consists of two species,
B. pyrenaica
and
B. chouardii
, taxa which have been previously considered
as conspecific due to their overall close morphology. These two sole species of the rare genus of Dioscoreaceae
are endemic to the Pyrenees (Spain, France). This mountain range likely operated as a refugium for these plants during
the last glaciations.
B. chouardii
is only known from a single population in the Spanish Prepyrenees and has been
classified as at risk of extinction in the Red List of Endangered Species (IUCN);
B. pyrenaica
shows a narrow distribution
range in the central Pyrenees and Prepyrenees. We analysed genetic variation, population structure and
differentiation in these two taxa using RAPD markers. Our study was conducted on the same seven populations for
which very low levels of genetic differentiation were detected previously through allozyme analysis. By contrast, high
levels of genetic variability were detected through the RAPD hypervariable markers. Twelve RAPD primers produced
112 distinct bands in the 397 surveyed individuals, totalling 395 different RAPD phenotypes. Only four bands
were monomorphic across all samples of
Borderea
, whereas 21 of the polymorphic bands were species-specific (20 for
B. chouardii
, and one for
B. pyrenaica
). The largest genetic distances were those between the
B. chouardii
and the
B. pyrenaica
phenotypes. An analysis of molecular variance showed greater variance between groups (
B. chouardii
vs.
B. pyrenaica
, 76.08%) than within groups (3.60%). RAPD band specificity, phenotypic distances, and the partitioning
of variance all support the taxonomic separation of the two species. Statistical evaluation of within- and
among-population RAPD genetic variability in
B. pyrenaica
showed that genetic variability was higher within populations
(
>
80%) than among them. No clear pattern of RAPD differentiation could be observed among the six studied
populations of this taxon though slight differences in genetic diversity could be observed in the more isolated
Prepyrenean populations compared with the more widespread Pyrenean ones. These results suggest a recent postglacial
origin of the present
B. pyrenaica
populations.