A molecular phylogeny for aplocheiloid fishes (Atherinomorpha, Cyprinodontiformes): the role of vicariance and the origins of annualism |
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Authors: | Murphy WJ; Collier GE |
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Institution: | Department of Biological Sciences, University of Tulsa, Oklahoma, USA. |
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Abstract: | Annual aplocheiloid killifish embryos possess a rare ability among
vertebrates to enter stages of developmental arrest (diapause) when
subjected to adverse environmental conditions. Previous morphological
analyses have presented disparate hypotheses regarding the evolution of the
intriguing life history associated with this phenomenon. We present a novel
hypothesis of aplocheiloid relationships based on 1,009 bp of sequence data
from three mitochondrial genes (cytochrome b, 12S rRNA, and 16S rRNA).
Phylogenetic analysis using maximum parsimony, neighbor- joining, and
maximum likelihood produce strongly congruent topologies. Our data confirm
the monophyly of the Neotropical family Rivulidae, while demonstrating a
paraphyletic Old World assemblage. The basal sister group position of
Indo-Malaysian and Madagascaran taxa relative to a monophyletic South
American/African dichotomy strongly indicates the role of vicariance in the
diversification of these fishes in spite of their definition as secondary
freshwater fish. The distribution of annualism onto this topology implies a
single early origin for this suite of characters, prior to the divergence
of South American and African taxa. If so, then annualism has since been
lost several times during the evolution of genera now residing in permanent
aquatic habitats. Paleoclimatic knowledge complements this scenario based
on molecular characters.
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