Swertia Abyssinica Species - Complex Differences in Afroalpine Mountain Systems as Inferred From AFLP
No Thumbnail Available
Date
2006-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Swertia abyssinica (Hochst.) S. lugardae (Bullock) and S. pumila (Hochst.)
(Gentianaceae) are closely related taxa occurring in the high mountains of North East
Africa. Amplified Fragment Length Polymorphism (AFLP) markers were used to assess
the genetic variation between the higher and the lower altitude populations of the taxa
within and between different mountain regions. In a principal coordinate analysis
(PCoA), the resulted grouping of accessions of the first two taxa corresponds with their
geographical locations rather than taxonomic classifications while S. pumila was far and
distinct. Such groupings were inconsistent with previous study based on morphology.
The PCoA result was supported by the AMOVA with higher variations among mountains
(21.4 %) than variations within mountain among taxa (14.5 %). The considerable
reduction in variation among taxa (7.03 %) in the AMOVA excluding S. pumila and its
distinct position in the PCoA implies S. pumila as a different taxon. The evolutionary
distance tree based on AFLP characters supported the results from AMOVA and PCoA.
These results are in contradiction with the acceptance of three distinct species, but rather
suggest as two distinct species. Thus the results suggest clinal morphological differences
between the two, S. abyssinica and S. lugardae. Thus it is likely that the clinal variation is
caused by primary cline than hybridization. Although there was non - significant
variation between altitudes and weak correlation between them, it is difficult to conclude
for the absence of genetic base for the clinal morphological variation.
Key words: Swertia, ecoclinal evolution, genetic diversity, glacial refugia, AFLP
Description
Keywords
Swertia, ecoclinal evolution, genetic diversity, glacial refugia, AFLP