Evaluation of pre- and post-zygotic mating barriers, hybrid fitness and phylogenetic relationship between Cyprinodon variegatus variegatus and Cyprinodon variegatus hubbsi (Cyprinodontiformes, Teleostei)

K. V. Brix, Martin Grosell

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l-1, but incapable of long-term survival in freshwater (< 2 mM Na+). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4-1 mM Na+) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na+ uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre- and post-zygotic isolation, Na+ transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89%) with con-specific males in choice mating experiments. Partial post-zygotic isolation was also observed with significant (59-89%) reductions in hatching success of hybrid embryos compared with con-specific embryos. Na+ uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short-term (96 h) survival of juveniles acutely transferred from 7 mM Na+ to a range of more dilute (0.1-2 mM Na+) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.

Original languageEnglish
Pages (from-to)854-866
Number of pages13
JournalJournal of Evolutionary Biology
Volume26
Issue number4
DOIs
StatePublished - Apr 1 2013

Fingerprint

Cyprinodon variegatus
Cyprinodontiformes
fitness
phylogenetics
embryo
phylogeny
freshwater environment
subspecies
garden
hatching
salinity
kinetics
embryo (animal)
lake
mitochondrial DNA
fish
euryhaline species
uptake mechanisms
evaluation
experiment

Keywords

  • Hybridization
  • Osmoregulation
  • Post-zygotic isolation
  • Pre-zygotic isolation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Cite this

@article{5ad6427857bb4f8981a458101c54d855,
title = "Evaluation of pre- and post-zygotic mating barriers, hybrid fitness and phylogenetic relationship between Cyprinodon variegatus variegatus and Cyprinodon variegatus hubbsi (Cyprinodontiformes, Teleostei)",
abstract = "The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l-1, but incapable of long-term survival in freshwater (< 2 mM Na+). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4-1 mM Na+) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na+ uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre- and post-zygotic isolation, Na+ transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89{\%}) with con-specific males in choice mating experiments. Partial post-zygotic isolation was also observed with significant (59-89{\%}) reductions in hatching success of hybrid embryos compared with con-specific embryos. Na+ uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short-term (96 h) survival of juveniles acutely transferred from 7 mM Na+ to a range of more dilute (0.1-2 mM Na+) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.",
keywords = "Hybridization, Osmoregulation, Post-zygotic isolation, Pre-zygotic isolation",
author = "Brix, {K. V.} and Martin Grosell",
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T1 - Evaluation of pre- and post-zygotic mating barriers, hybrid fitness and phylogenetic relationship between Cyprinodon variegatus variegatus and Cyprinodon variegatus hubbsi (Cyprinodontiformes, Teleostei)

AU - Brix, K. V.

AU - Grosell, Martin

PY - 2013/4/1

Y1 - 2013/4/1

N2 - The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l-1, but incapable of long-term survival in freshwater (< 2 mM Na+). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4-1 mM Na+) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na+ uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre- and post-zygotic isolation, Na+ transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89%) with con-specific males in choice mating experiments. Partial post-zygotic isolation was also observed with significant (59-89%) reductions in hatching success of hybrid embryos compared with con-specific embryos. Na+ uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short-term (96 h) survival of juveniles acutely transferred from 7 mM Na+ to a range of more dilute (0.1-2 mM Na+) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.

AB - The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l-1, but incapable of long-term survival in freshwater (< 2 mM Na+). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4-1 mM Na+) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na+ uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre- and post-zygotic isolation, Na+ transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89%) with con-specific males in choice mating experiments. Partial post-zygotic isolation was also observed with significant (59-89%) reductions in hatching success of hybrid embryos compared with con-specific embryos. Na+ uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short-term (96 h) survival of juveniles acutely transferred from 7 mM Na+ to a range of more dilute (0.1-2 mM Na+) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.

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KW - Osmoregulation

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KW - Pre-zygotic isolation

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