Premium
GENETIC STRUCTURE AND EVOLUTION OF SPECIES IN THE MANGROVE GENUS AVICENNIA (AVICENNIACEAE) IN THE INDO‐WEST PACIFIC
Author(s) -
Duke Norman C.,
Benzie John A. H.,
Goodall John A.,
Ballment Elizabeth R.
Publication year - 1998
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1998.tb02242.x
Subject(s) - biology , avicennia marina , mangrove , biological dispersal , genus , ecology , gene flow , genetic structure , range (aeronautics) , genetic variation , botany , zoology , population , gene , biochemistry , materials science , demography , sociology , composite material
Allozyme variation in species of the mangrove genus Avicennia was screened in 25 populations collected from 22 locations in the Indo‐West Pacific and eastern North America using 11 loci. Several fixed gene differences supported the specific status of Avicennia alba, A. integra, A. marina , and A. rumphiana from the Indo‐West Pacific, and A. germinans from the Atlantic‐East Pacific. The three varieties of A. marina , var. marina , var. eucalyptifolia , and van australasica , had higher genetic similarities (Nei's I ) and no fixed gene differences, confirming their conspecific status. Strong genetic structuring was observed in A. marina , with sharp changes in gene frequencies at the geographical margins of varietal distributions. The occurrence of alleles found otherwise in only one variety, in only immediately adjacent populations of another variety, provided evidence of introgession between varieties. The varieties appear to have diverged recently in the Pleistocene and are apparently not of ancient Cretaceous origin, as suggested earlier. Despite evidence of high degrees of outcrossing, gene flow among populations was relatively low ( N e m < 1–2), except where populations were geographically continuous, questioning assumptions that these widespread mangrove species achieve high levels of long‐distance dispersal.