PATTERNS OF ISOZYME VARIATION IN THE LEUCAENA-SHANNONII ALLIANCE (LEGUMINOSAE, MIMOSOIDEAE)

Genetic variation within, and the relationships between, 4 taxa that c omprise the Leucaena shannonii alliance were analysed with isozymes. S ix enzyme systems were used to analyse 2 natural populations of L. sal vadorensis STANDLEY ex. B. and R., 2 of L. shannonii DONN. SMITH subsp . magnifica C. E. HUGHES, 4 of L. shannonii DONN. SMITH subsp. shannon ii and 2 populations of an undescribed taxon, L. sp. nov.. Cluster ana lysis of NEI's genetic distances (NEI, 1978) and Population Aggregatio n Analysis (PAA) (DAVIS and NIXON, 1992) were used to delimit species. L. sp. nov. was found to be most closely related to L. salvadorensis, however, isozyme variation did not support a close relationship betwe en the 2 subspecies of L. shannonii. The level and structure of geneti c variation within species of the alliance was also assessed. L. shann onii subsp. shannonii was found to be the most diverse taxon, and subs p. magnifica the least diverse. It is Postulated that this may contrib ute to the apparent dissimilarity of the 2 taxa in the cluster analysi s. The use of PAA to delimit species in the L. shannonii alliance is a lso discussed.