Phylogenetic and genetic variation analyses in cucurbit species (Cucurbitaceae) from West Africa: definition of conservation strategies (eBook, PDF)

• Format: PDF

Produktbeschreibung

The conservation of the genetic resources of crops and their wild relatives has become a crucial task for mankind as soon as it has been realized that the gene pools of those resources drastically erode. This problem is particularly exacerbated for the gourd family Cucurbitaceae, a worldwide economically important plant group, which contains many overlooked and barely known useful species. Different classification approaches in the family resulted in controversies about phylogenetic relationships of species, genera, and tribes. Moreover, knowledge of genetic patterns and ecological demands of species has been scarce, particularly in West Africa. This dissertation aims at contributing to halt loss of cucurbit resources by shedding light onto relationships among cucurbit species occurring in the phytoregions of West Africa, and to investigate the structure of the genetic variation of two particularly important species of this region, Lagenaria siceraria and Momordica charantia. I use phylogenetic, cytological and population genetic approaches to resolve longstanding ambiguities regarding West African cucurbits. My results indicate that all species of Benincaseae (mostly from Africa) fall within their traditional tribal group. However, the subdivision of the tribe into subtribes Cucumerinae and Benincasinea is not supported, as most species of Cucumerinae are dispersed throughout the Benincaseae. In addition Cucumis melo subsp. melo (watermelon) shows pronounced differences to subsp. agrestis, what is congruent with morphological data. Detailed analyses on cytological and genetic variation in Lagenaria siceraria (calabash) revealed a clear correlation of genome size with two different seed or fruit usage types and with growing elevations in West Africa. The genome size differences in seed types of L. siceraria might indicate differences in their evolutionary history. AFLP polymorphism in the species was in general low, but principal co-ordinate analysis, Bayesian assignment tests, and phylogenetic analyses revealed three significantly differentiated groups. In addition to the already known subsp. siceraria and asiatica, a third taxon, described as subsp. egusi was inferred based on these analyses. Morphometric analyses clarified also the long-standing ambiguity for the identification of Momordica charantia observed in Benin by clearly discriminating two groups characterized by leaf shape differences: the common subsp. charantia and the newly described subsp. macroloba, endemic to the Dahomey gap and the Sudano-Guinean phytoregion of Benin and Togo. Phylogenetic analyses using AFLP indicated the existence of a paraphyletic macroloba group, which clusters within subsp. charantia, and indicated some gene flow between both types. Within subsp. charantia all populations collected in the dry Sudanian zone were monophyletic. Although not formally described I refer to this group as sudanica clade. Ecoclimatic niche modelling revealed different preferential distribution areas for the three entities, and showed a good fit between potential and realised ecoclimatic niches. Apart from the clear structuring of the species, our data show that genetic diversity within peripheral and centre populations of M. charantia are similar. Adequate conservation strategies could therefore be suggested for the promotion and the sustainable use of these valuable resources.

---

Dieser Download kann aus rechtlichen Gründen nur mit Rechnungsadresse in A, B, BG, CY, CZ, D, DK, EW, E, FIN, F, GR, HR, H, IRL, I, LT, L, LR, M, NL, PL, P, R, S, SLO, SK ausgeliefert werden.

Produktdetails

• Verlag: Cuvillier Verlag
• Seitenzahl: 156
• Erscheinungstermin: 16. Oktober 2008
• Englisch
• ISBN-13: 9783736927858
• Artikelnr.: 49150543