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Molecular phylogeny of araneomorph spiders
Author(s) -
Hausdorf B.
Publication year - 1999
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1046/j.1420-9101.1999.00104.x
Subject(s) - biology , monophyly , 28s ribosomal rna , phylogenetics , evolutionary biology , zoology , convergent evolution , gene , clade , genetics , rna , ribosome
The reconstruction of the phylogeny of spiders based on morphological and ethological characters is hampered by frequent homoplasies. Therefore, fragments of the 28S rRNA gene have been sequenced to elucidate some crucial points in the evolution of spiders. The following results were obtained. (1) The 28S rRNA gene data support the monophyly of the Entelegynae. Thus, the number of different subunits and the number of hexamers which form a haemocyanin complex must have been reduced at least twice within the spiders. The character state pattern within the spiders and within the Arachnida suggests that these reductions are due to a decrease in the selection on the oxygen binding properties of the haemocyanins as a result of the evolution of tracheae. (2) The semientelegyne spiders are not a transition stage between the Haplogynae and the Entelegynae. The lack of separate fertilization ducts in these species is probably due to secondary reduction. This reduction has decisive consequences for the flow of the sperm and for sperm competition. (3) Furthermore, the 28S rRNA gene data tentatively support the hypothesis that the orb web is either a plesiomorphy or has evolved at least twice.