Patterns of genetic diversity in related taxa of Antirrhinum L. assessed using allozymes.

Mateu-Andrés, I.; Segarra-Moragues, J.G.. Patterns of genetic diversity in related taxa of Antirrhinum L. assessed using allozymes.. Biological Journal of the Linnean Society . 2003, Vol. 79(2), p. 299-2003.

Allozyme diversity was studied within and among populations of five related taxa of Antirrhinum L. endemic to the
Iberian Peninsula (A. graniticum Rothm. ssp. graniticum, ssp. brachycalyx Sutton and ssp. ambiguum (Lange)
Mateu & Segarra, A. boissieri Rothm. and A. onubensis (Fdez. Casas) Fdez. Casas). All of the studied taxa are obligate
outcrossing endemic perennial herbs which form isolated populations. However, the taxa vary in range and population
sizes, and are found on different soil types. The level and distribution of allozyme diversity differed widely
between taxa: A. graniticum ssp. brachycalyx had the lowest level of allozyme diversity (HT = 0.09), whilst the highest
level was detected in A. boissieri (HT = 0.25). Total variation was partitioned into within- and among-population
variation. The proportion attributable to variation within populations varied from about 67% up to 84.3% and 89.5%
in A. graniticum ssp. brachycalyx and A. graniticum ssp. ambiguum, respectively. Both these subspecies also showed
little population divergence (GST = 0.10 and 0.09, respectively) and had high levels of estimated gene flow (Nm = 2.18
and 2.62, respectively). These results are discussed in relation to geographical proximity of populations and habitat
continuity. Isolation by distance was not detected in any of the studied taxa. This result suggests that divergence
among populations is due to random genetic drift.