Comparison of genetic structure of native and commercial Bombus
terrestris populations in the Mediterranean region
Abstract
B. terrestris dalmatinus is native and the most widespread Bombus
terrestris subspecies which occurs at different altitudes and habitats
in the Mediterranean region where commercial B. terrestris colonies have
been used for pollination in greenhouses crops for more than two
decades. In this study, we sampled B. terrestris from greenhouses
(commercial populations, CP1-CP7), within the five km areas surrounding
the greenhouses (AK, KM, DM and GB) and more distant native populations
(TM, BB and FS) in the Mediterranean region to determine the genetic
structure of native and commercial B. terrestris populations and to
better understand genetic introgression of commercial greenhouse B.
terrestris populations into the native B. t. dalmatinus populations
using twenty microsatellite markers and two mitochondrial genes (COI and
cyt b). Microsatellite analysis showed adequate levels of genetic
diversity in both commercial and native populations. However,
populations could not been clearly separated from each other (FST =
0.014-0.045; p>0.05). All populations deviated from
Hardy-Weinberg equilibrium due to high inbreeding (mean Fis: 0.234). In
the mitochondrial analyses, we found two haplotypes for COI and six
haplotypes for cyt b gene. Genotypes belonging to the subspecies B. t.
dalmatinus were determined in all populations, while genotypes belonging
to the subspecies B. terrestris terrestris were determined in some
commercial populations and nearby greenhouses populations. Our results
thus indicate that native populations are threatened by gene flow from
non native B. t. terrestris subspecies. Our data also suggest that
aestivated native FS population should be primarily conserved to avoid
extinction.