Abstract:
Earlier studies investigated the genetic structure of fragmented or isolated elephant populations
by comparing the genetic characteristics of pre-defined populations. This study aimed to
determine if there was genetic evidence for spatial structuring in a continuous elephant
population in the Kavango-Zambezi Transfrontier Conservation Area (KAZA-TFCA).
I sequenced one mtDNA gene region for 88 individuals and genotyped 100 individuals for 10
nuclear microsatellite loci. Bayesian Clustering Algorithms incorporated in the program
Geneland were used to identify groups of genetically similar individuals. An Analysis of
Molecular Variance (AMOVA) determined if these groups (henceforth referred to as subpopulations)
were significantly differentiated. I used a Geographic Information System (GIS) landscape genetic toolbox to identify areas in the landscape with high genetic divergence
between individual samples to determine if there were identifiable genetic barriers in the
landscape.
There were three significantly differentiated mtDNA sub-populations (Fst = 0.787), and two
nDNA sub-populations that were not significantly differentiated (Fst = -0.02; Rst = -0.045),
implying obstructed mtDNA, but high nDNA gene flow across the study region. Also, gene flow
was apparent between Chobe and Kafue National Parks, where telemetry data has as of yet not
recorded inter-population movements between these parks.
The three mtDNA sub-populations were geographically differentiated and followed political
boundaries as apparent sub-populations in Botswana, Zambia and Zimbabwe. The differences
between mtDNA and nDNA genetic structuring may be explained by i) historical events that
shaped the current genetic structure (e.g. through founder-effects and persistent poaching
hotspots) and ii) intrinsic variables that influence genetic structure at a local scale (e.g. through
resource dependencies and social behaviour). The KAZA elephant population has a genetic
diversity (mtDNA diversity as the pairwise number of differences (π) = 2.59; nDNA diversity as
the mean alleles/locus and He = 7.5, 0.71) higher than other southern African populations, and
inter-population movements may be responsible for maintaining this genetic diversity.
I recommend continued support for conservation initiatives that aim at maintaining and restoring
connectivity between populations through landscape linkages, which in so doing may ensure
inter-population gene flow and uphold the current genetic state of the KAZA-TFCA elephant population.
