pollen pool heterogeneity in natural stands of upland and lowland black spruce (picea marinana (mill.) b.s.p.)
abstract
one of the basic assumptions of the mixed-mating model is that
the pollen pool of a population is homogeneous. however mounting
evidence would suggest that a homogeneous pollen pool is not the
norm in populations of forest tree species. such a phenomenon may
have major implications upon the mating systems and genetic
structure of forest tree species. the present study was conducted
in order to develop a better understanding of the nature and
implications of pollen pool heterogeneity in natural populations of
black spruce. four natural stands of black spruce within 100
kilometers of thunder bay, ontario were studied using isozyme
markers from eight polymorphic loci. the stands studied represent
the two basic ecological conditions under which black spruce is
found, i.e. upland and lowland stands. both log-likelihood g tests
and multiple group discriminant analysis indicated the presence of
heterogeneous pollen pools for all four sites. however, as
indicated by the canonical for the first discriminant function
of each site, the separation power of data from three of the four
sites was quite small (r2 of 0.063 to 0.127) . only for raith 2 was
the seperation power strong (r2 of 0.379). overall the
heterogeneity tended to be random in nature. due to the apparent
random nature of the heterogeneity it was not possible to associate
the examined site characteristics with the relative degree of
pollen pool heterogeneity observed in the four sites. possible
agents which may have produced a heterogeneous pollen pool are
considered as are potential implications of this phenomenon on the
genetics of black spruce.
collections
- retrospective theses [1604]