Released to the Net today:
Apakupakul, K., M. E. Siddall, & E. M. Burreson. 1999. Higher Level
Relationships of Leeches (Annelida: Clitellata: Euhirudinea) based on
Morphology and Gene Sequences.— Molecular Phylogenetics and
Evolution, 12(3):350-359. (August issue).
Abstract:
"The evolutionary patterns of divergence of seven euhirudinean families were
investigated by cladistic analysis of 33 euhirudinean species. Oligochaetes,
Acanthobdella peledina, and branchiobdellidans were included as outgroup taxa.
Cladistic analysis employed 1.8 kb of nuclear 18S ribosomal DNA and 651 bp
of mitochondrial cytochrome c oxidase subunit I in addition to morphological
data. The use of two molecular data sets, one nuclear gene and one
mitochondrial gene, as well as morphological data combined historical
information evolving under a variety of different constraints and therefore was
less susceptible to the biases that could confound the use of only one type of
data. Results suggest that the nuclear 18S rDNA gene yields a meaningful
historical signal for determining higher level relationships. The more rapidly
evolving CO-I gene was informative for recent or local areas of the evolutionary
hypothesis, such as within-family relationships. Analyses combining all data
from the three character sets yielded one most-parsimonious tree. Most of the
higher taxa in recent leech systematics were well corroborated in the resulting
topology. However, these results suggested paraphyly of the order
Rhynchobdellida, which contradicts the presence of a proboscis as a
synapomorphy. The medicinal leech family Hirudinidae was polyphyletic
because Haemadipsidae and Haemopidae each have a hirudinid ancestor. In
addition, all but one of the genera within the family Erpobdellidae must be either
abandoned or renamed. Unusual findings included compelling evidence of
historical plasticity in bloodfeeding behavior, having been lost at least four
times in the course of euhirudinean evolution. Biogeographic patterns supported
a New World origin for Arhynchobdellida."
-- ANNELIDA LIST
Discuss = <annelida at net.bio.net> = talk to all members
Server = <biosci-server at net.bio.net> = un/subscribes
Archives = http://www.bio.net:80/hypermail/ANNELIDA/
Resources = http://biodiversity.uno.edu/~worms/annelid.html
--
