Molecular phylogenetics at the population/species interface in cave spiders of the southern Appalachians (Araneae:Nesticidae:Nesticus)

This paper focuses on the relationship between population genetic structure and speciation mechanisms in a monophyletic species group of Appalachian cave spiders (Nesticus). Using mtDNA sequence data gathered from 256 individuals, I analyzed patterns of genetic variation within and between populatio...

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Bibliographic Details
Published in:Molecular biology and evolution 1997-03, Vol.14 (3), p.309-324
Main Author: Hedin, M C
Format: Article
Language:English
Subjects:
Animals
Appalachian Region
Araneae
Base Sequence
DNA, Mitochondrial - genetics
Ecology
Evolution, Molecular
Founder Effect
Geological Phenomena
Geology
Haplotypes
Models, Genetic
Molecular Sequence Data
Mutagenesis
Nesticidae
Phylogeny
Polymorphism, Genetic
Sampling Studies
Sequence Homology, Nucleic Acid
Species Specificity
Spiders - classification
Spiders - genetics
Statistics, Nonparametric
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Summary:This paper focuses on the relationship between population genetic structure and speciation mechanisms in a monophyletic species group of Appalachian cave spiders (Nesticus). Using mtDNA sequence data gathered from 256 individuals, I analyzed patterns of genetic variation within and between populations for three pairs of closely related sister species. Each sister-pair comparison involves taxa with differing distributional and ecological attributes; if these ecological attributes are reflected in basic demographic differences, then speciation might proceed differently across these sister taxa comparisons. Both frequency-based and gene tree analyses reveal that the genetic structure of the Nesticus species studied is characterized by similar and essentially complete population subdivision, regardless of differences in general ecology. These findings contrast with results of prior genetic studies of cave-dwelling arthropods that have typically revealed variation in population structure corresponding to differences in general ecology. Species fragmentation through both extrinsic and intrinsic evolutionary forces has resulted in discrete, perhaps independent, populations within morphologically defined species. Large sequence divergence values observed between populations suggest that this independence may extend well into the past. These patterns of mtDNA genealogical structure and divergence imply that species as morphological lineages are currently more inclusive than basal evolutionary or phylogenetic units, a suggestion that has important implications for the study of speciation mechanisms.
ISSN:0737-4038
1537-1719
DOI:10.1093/oxfordjournals.molbev.a025766