Km. Aradhya et al., GENETIC-STRUCTURE AND DIFFERENTIATION IN METROSIDEROS-POLYMORPHA (MYRTACEAE) ALONG ALTITUDINAL GRADIENTS IN MAUI, HAWAII, Genetical Research, 61(3), 1993, pp. 159-170
The level and distribution of genetic variability within and among Met
rosideros polymorpha populations along altitudinal gradients on the is
land of Maui, Hawaii were examined to assess the extent of genetic dif
ferentiation. Sixteen loci encoding 11 enzymes were scored in 17 popul
ations along the NE wet slope of Mt. Haleakala and Kipahulu Valley in
East Maui and six populations along the Puu Kukui trail in West Maui.
On average, 50 % of the loci were polymorphic within populations with
an overall mean of 2.15 alleles per locus. The observed heterozygositi
es for different populations were moderate (0.108-0.220) and conformed
to panmixia except for one of the mid-elevation populations. The dist
ribution of allozyme variation indicates that very little differentiat
ion has occurred along altitudinal gradients. Approximately 90 % of th
e total variation resides within populations in East Maui while 95 % w
as found within West Maui populations. The mean populational pair-wise
genetic identities (Nei's I) ranged from 0.909 to 0.998. The UPGMA cl
uster analysis on genetic identity matrices and PCA on allele frequenc
ies revealed marginal altitudinal differentiation. Twenty one alleles
out of a total 63 showed statistically significant correlations with e
nvironmental variables.