Evidence for important genetic differentiation between provenances of Parkia biglobosa from the Sudano-Sahelian zone of West Africa

摘要

Parkia biglobosa is a traditional economic tree legume of considerable multipurpose importance in the sudano-sahelian region in Africa. The species grows in multiple climatic zones with precipitation ranging from 600 to 2,500 mm a year and its natural distribution extends from Senegal and Guinea in West Africa to Uganda in Central Africa. In the present paper, a range wide sample of 25 provenances of P. biglobosa was tested in Burkina Faso, West Africa at two sites; Gonse (latitude 12°25′N; longitude 1°20′W; altitude 280 m) in the north-sudanian zone and at Dinderesso (latitude 11°18′N; longitude 4°35′W; altitude 425 m) in the south-sudanian zone. Based on analysis of survival and growth traits, we provide evidence of substantial genetic differentiation between P. biglobosa populations within West Africa. Height growth was best at Gonse, while the survival rate was higher at Dinderesso (61%) compared to Gonse (35%). Links between geographical parameters and the provenances performance were significant, and interesting geographic patterns were observed. Our results point towards superior fitness of the local Burkina Faso populations, and we speculate that presence of a continuum of locally adapted populations can be a part of the explanation for the species’ ability to thrive under quite different climatic conditions across West Africa. Based on the findings, we suggest recommendations for seed deployment and conservation strategies of the species in the West African Sahel. This is particularly important when considering the on-going climate change.