Evolution and phylogenetic utility of the period gene in Lepidoptera |
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Authors: | Regier JC; Fang QQ; Mitter C; Peigler RS; Friedlander TP; Solis MA |
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Institution: | Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, College Park 20742, USA. regier@glue.umd.edu |
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Abstract: | Evolution and phylogenetic utility of the period gene are explored through
sequence analysis of a relatively conserved 909-bp fragment in 26
lepidopteran species. Taxa range from tribes to superfamilies, primarily
within the putative clade Macrolepidotera plus near outgroups, and include
both strongly established and problematic groupings. Their divergence dates
probably range from the late Cretaceous through much of the Tertiary.
Comparisons within the same set of closely related species show that amino
acid substitutions in period occur 4.9 and 44 times as frequently as they
do in two other nuclear genes--dopa decarboxylase and elongation factor-1
alpha, respectively. In contrast, rates of observed synonymous substitution
are within 60% of each other for these three genes. Synonymous changes in
period approach saturation by the family level, whereas nonsynonymous and
amino acid divergences across the Macrolepidoptera are less than half the
maximal values reported for this gene. Phylogenetic analyses of period
strongly supported groupings at the family level and below. In contrast to
previous analyses at this level with other nuclear genes, much of the
information lies in nonsynonymous change. Relationships up to the
superfamily level were recovered with decreasing effectiveness, and little,
if any, signal was apparent regarding relationships among superfamilies.
This could reflect rapid radiation of the superfamilies, however, rather
than saturation in the period locus; thus, period, in combination with
other genes, remains a plausible candidate for approaching the difficult
problems of lepidopteran family and superfamily relationships.
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