Estimation and management of genetic diversity in small populations of plains zebra (Equus quagga) in KwaZulu-Natal, South Africa

Plains zebras (Equus quagga antiquorum) occur in few large, but many small, isolated populations in KwaZulu-Natal. Problems identified in small popula tions include reduced striping patterns on hind quarters, smaller size, ele vated mortality rates and high number of still-births. Inbreeding may be im plicated. Population viability analysis (PVA) was conducted with a computer model (VORTEX), and DNA and allozyme analyses were conducted to test the f indings of the model. Using standard methods, DNA (PCR-RAPD) and allozyme d iversity was assessed in blood samples from 72 plains zebra from four KwaZu lu-Natal Nature Conservation Services (KZN-NCS) protected areas: Umfolozi G ame Reserve (UCR), Albert Falls (AFNR), Vernon Crookes (VCNR) and Harold Jo hnson (HJNR) Nature Reserves. Populations of the latter three, small-sized (9-110 individuals) populations were seeded from the same source population (UGR: current population of 2000) during the past 25 years. Information fr om PCR-RAPD and allozyme analysts were compared with each other as well as to that predicted by population genetic modelling (using VORTEX). Allozyme heterozygosities were consistently high in all populations (12.1-12.9%), wi th no observable losses associated with reduced population size. On the oth er hand, percentage loss of polymorphism (20-39%) calculated from the PCR-R APD study appeared to be positively correlated with the loss of heterozygos ity predicted by population viability analysis (PVA), and negatively correl ated with population size. On the basis of the above results, a policy of t ranslocation was advocated for small, intensely managed populations of zebr as. whereby a harem should be translocated every five years for a populatio n size of nine (HJNR). while for a population size of 110 (VCNR) translocat ions should take place every 15 years if heterozygosity is to be maintained at more than 90% within each population over 100 years. (C) 2001 Elsevier Science Ltd. All rights reserved.