Systematics and biogeography of Myricaceae
Abstract
Two molecular phylogenetic studies were undertaken to examine relationships within
Myricaceae. Analyses of DNA sequences of the plastid rbcL gene, trnL-Fregion and
nuclear ITS region showed the family to be monophyletic. In all analyses
Canacomyrica, a monotypic genus endemic to New Caledonian that bears several
distinctive features such as staminodes in the female flowers, fell into a well-
supported clade sister to the rest of Myricaceae. Phylogenetic analyses of ITS and
trnL-F sequence data, representing all genera and subgeneric groups, were undertaken
using maximum parsimony and Bayesian methods. The following relationships were
strongly supported: (Canacomyrica (Comptonia (Myrica, Morella))). The clade
containing all species formerly considered to comprise Myrica s.l. was split into two
strongly supported clades corresponding to Myrica s.s. and Morella; this finding
strengthens the argument for recognition of these as separate genera. Within Morella,
two clades corresponded to previously recognized subgenera. Molecular dating
analyses were performed using Penalized Likelihood. Close correlations between
lineage-specific diversification and major orogenic or climatic events were inferred.
This study suggests that much of the diversity in Morella arose during the Neogene
and seed-dispersal by birds has been a significant factor in determining the modem
distribution. A study of the conservation status of Canacomyrica was conducted using
field observations and data from herbarium specimens. This species was found to
occur in just eleven fragmented localities: six outside protected areas and three
threatened by mining or bush fires. IUCN Red List status of Endangered was
recommended. The morphology and ecology of Canacomyrica was studied to
enhance knowledge of this poorly known species and provide comparative data for
use in a study of the morphology of the entire family. A new classification scheme
with keys was presented including, for the first time, Canacomyrica. New
combinations in Morella were recommended.
Type
Thesis, PhD Doctor of Philosophy
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