Impact of Anthropogenic Activities on Genetic Diversity of Celtis zenkeri Engl in South-West Nigeria

Abstract

Celtis zenkeri is a valuable tropical tree species for industrial and domestic purposes. For several years, exploitation of this species has not been sustainable and no reforestation or cultivation effort has been put in place both by governmental and non-governmental agencies. Anthropogenic activities have resulted in deforestation and subsequent reduction in the population size of important timber species. The research aim was to determine the impact of anthropogenic activities on genetic diversity of Celtis zenkeri in South-West Nigeria. Extensive sampling of Celtis zenkeri was carried out in four natural forest ecosystems. Two pristine forests (SNR, Akure forest and Osun Osogbo sacred grove) and two degraded forests (OA3 and Eda forest reserve). Young leaves were collected from each tree found in each site and preserved with silica gel for molecular analysis. In all, 130 accessions were sampled and were analyzed with five chloroplast microsatellite markers. In the result, allelic richness, which is a measure of genetic diversity and an indicator of a population s long-term potential for adaptability and persistence, was significantly higher in the two pristine forests than the two degraded forests. Statistically, a significant difference was not recorded for the observed heterozygosities (Ho) in the population of Celtis zenkeri in the pristine forests (Queen’s plot and Osun-Osogbo Sacred Grove) and a degraded forest (OA3). The formal indicates the possibility of conserving genetic diversity using traditional conservation approaches such as taboos and restrictions. Though OA3 is a degraded forest, the impact of the anthropogenic activities may not have been severe when compared with Eda forest reserve. At present, the scale of human activities in Eda forest reserve and OA3 could pose a serious threat to the future viability of the species if unchecked. Therefore, ex-situ conservation and sustainable harvesting of Celtis zenkeri are recommended.