Levels of allozyme diversity in closely related toadflaxes (Linaria, Plantaginaceae) and their correspondence with the breeding systems of the species.

Toadflaxes (Linaria Miller) represent the
largest genus of the tribe Antirrhineae (formerly included
in the Scrophulariaceae) of the Plantaginaceae
family. These taxa vary according to their ranges
(narrow-regional–widespread), biological traits (duration,
flower morphology, breeding system) and ecological
preferences. No comparative genetic studies
have been performed up to the moment and the levels
and distribution of genetic diversity within this genus
remain undocumented. We have conducted an allozyme
study in 8 taxa of Section Supinae. Five of them
are narrow endemic, self-incompatible, insect-pollinated
outcrossers that inhabit relatively unaltered
habitats. The other three taxa are widespread, smallflowered
selfers that inhabit crops subjected to high
levels of recurrent disturbance. Linaria taxa showed
moderate to high levels of genetic diversity. Parameters
of genetic diversity were directly addressed to
differences in breeding systems. Mean number of alleles
per locus, total genetic diversity and genetic
diversity within populations were higher among the
outcrossers than among the selfers, (Ae = 2.28 vs. 1.23;
HT = 0.24 vs. 0.13; HS = 93.99% vs. 54.2%) while genetic
diversity among populations and population differentiation
were lower for the outcrossers than for the
selfers (DST = 0.02% vs. 45.98%; GST = 0.03 vs. 0.52).
Gene flow within and among populations produced a
higher number of different genotypes (mean NG = 16
for outcrossers vs. 5.4 for selfers) and migrants (mean
Nm = 4.58 for outcrossers vs. 0.84 for selfers) that were
attributed to an effective pollinator service in outcrossing
populations. Differences in the levels and
distribution of the genetic diversity are discussed in
relation to biological and autoecological constraints of
each group of taxa.