Abstract:
Earlier studies on savannah elephants (Loxodonta
africana) investigated the genetic structure of
fragmented or isolated populations. Contrastingly, 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). We sequenced one mtDNA gene region
for 88 individuals and genotyped 100 individuals for ten
nuclear microsatellite loci. Bayesian Clustering Algorithms
in Geneland identified groups of genetically similar individuals.
An analysis of molecular variance determined if
these groups (sub-populations) were significantly differentiated.
We identified geographic areas with high genetic
divergence (genetic barriers) between samples using a GIS
landscape genetic toolbox. 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. The KAZA-TFCA population has a genetic
diversity (mtDNA pairwise number of differences
(p) = 2.59; nDNA mean alleles/locus and He = 7.5, 0.71)
higher than other southern African populations, and interpopulation
movements may be responsible for maintaining
this genetic diversity. We discount anthropogenic and
geographic barriers as the primary drivers of genetic
structuring in the KAZA-TFCA population and suggest
that future studies should consider the influence of intrinsic
factors (resource dependencies and social variables that
limit movement) when investigating the genetic structure
of elephant populations. We recommend continued support
for conservation initiatives that aim at maintaining and
restoring connectivity between populations, which in so
doing may ensure inter-population gene flow and uphold
the current genetic state of the KAZA-TFCA population.
