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George N. Somero - One of the best experts on this subject based on the ideXlab platform.
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transcriptional responses to thermal acclimation in the eurythermal fish Gillichthys mirabilis cooper 1864
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2010Co-Authors: Cheryl A Logan, George N. SomeroAbstract:Thermal acclimation (acclimatization) capacity may be critical for determining how successfully an ectotherm can respond to temperature change, and adaptive shifts in gene expression may be pivotal...
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3636 The Journal of Experimental Biology 211, 3636-3649 Published by The Company of Biologists 2008
2008Co-Authors: Tyler G. Evans, George N. SomeroAbstract:doi:10.1242/jeb.022160 A microarray-based transcriptomic time-course of hyper- and hypo-osmotic stress signaling events in the euryhaline fish Gillichthys mirabilis: osmosensors to effector
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Temperature adaptation in Gillichthys (Teleost: Gobiidae) A4-lactate dehydrogenases: identical primary structures produce subtly different conformations
The Journal of Experimental Biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular `housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A4-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K mPYR) as well as differences in thermal stability. We examined the A4-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A4-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures ( T m) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A4-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A4-LDH was described using double-exponential regression; at 20 °C, G. seta A4-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40° C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that α-helical, but not β-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A4-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a staticα -helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A4-LDH forms.
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temperature adaptation in Gillichthys teleost gobiidae a4 lactate dehydrogenases identical primary structures produce subtly different conformations
The Journal of Experimental Biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular 'housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A(4)-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K(m)(PYR)) as well as differences in thermal stability. We examined the A(4)-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A(4)-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures (T(m)) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A(4)-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A(4)-LDH was described using double-exponential regression; at 20 degrees C, G. seta A(4)-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40 degrees C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that alpha-helical, but not beta-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A(4)-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a static alpha-helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A(4)-LDH forms.
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Temperature adaptation in Gillichthys (Teleost: Gobiidae) A(4)-lactate dehydrogenases: identical primary structures produce subtly different conformations.
The Journal of experimental biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular 'housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A(4)-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K(m)(PYR)) as well as differences in thermal stability. We examined the A(4)-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A(4)-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures (T(m)) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A(4)-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A(4)-LDH was described using double-exponential regression; at 20 degrees C, G. seta A(4)-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40 degrees C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that alpha-helical, but not beta-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A(4)-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a static alpha-helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A(4)-LDH forms.
Charles R. Fourtner - One of the best experts on this subject based on the ideXlab platform.
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POTASSIUM CHANNELS IN PITUITARY CELLS IN THE TELEOST, Gillichthys MIRABILIS
Comparative Biochemistry and Physiology Part A: Physiology, 1996Co-Authors: Lisa A. Romano, Christopher A. Loretz, Charles R. FourtnerAbstract:Abstract We have examined whole-cell K+ currents and a Ca2+-dependent K+ channel at the single channel level in rostral pars distalis cells of Gillichthys mirabilis. Whole-cell K+ currents activated by depolarizing pulses have an inactivating component and a sustained component. The magnitude of both of these components is increased when a hyperpolarizing prepulse is delivered prior to depolarization. Both components are partially blocked by application of 5 mM TEA+. The Ca-dependent K+ channel, (K(Ca)), was sensitive to 2 mM TEA+ in outside-out patches (O/O) but not in inside-out patches (I/O). Channel open probability (P(o)) was dependent on membrane potential (Vm), with depolarization leading to an increase in P(o). Calcium on the cytoplasmic face of I/O patches increased channel P(o) in a dose-dependent manner. A portion of the single K(Ca) channels studied displayed inactivation after depolarizing pulses. These channels may be a component of the inactivating whole-cell current.
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Characterization of an anion channel in pituitary cells of Gillichthys mirabilis
Comparative Biochemistry and Physiology Part A: Physiology, 1994Co-Authors: Lisa A. Romano, Charles R. FourtnerAbstract:Abstract Patch-clamp studies on pituitary cells from Gillichthys mirabilis show the presence of anion channels with selectivity CI > F = Br = I. These channels are voltage sensitive over the physiological range of membrane potentials and have a unitary conductance of 94 ± 15 pS in symmetrical KCl. Halides other than Cl on the cytoplasmic face of the membrane cause an increase in open probability ( P (o)). DPC causes a dose dependent decrease in P (o) without affecting conductance. Sodium on the cytoplasmic face of the membrane causes a decrease in outward current.
Peter A Fields - One of the best experts on this subject based on the ideXlab platform.
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temperature adaptation in Gillichthys teleost gobiidae a4 lactate dehydrogenases identical primary structures produce subtly different conformations
The Journal of Experimental Biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular 'housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A(4)-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K(m)(PYR)) as well as differences in thermal stability. We examined the A(4)-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A(4)-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures (T(m)) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A(4)-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A(4)-LDH was described using double-exponential regression; at 20 degrees C, G. seta A(4)-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40 degrees C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that alpha-helical, but not beta-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A(4)-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a static alpha-helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A(4)-LDH forms.
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Temperature adaptation in Gillichthys (Teleost: Gobiidae) A4-lactate dehydrogenases: identical primary structures produce subtly different conformations
The Journal of Experimental Biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular `housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A4-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K mPYR) as well as differences in thermal stability. We examined the A4-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A4-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures ( T m) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A4-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A4-LDH was described using double-exponential regression; at 20 °C, G. seta A4-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40° C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that α-helical, but not β-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A4-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a staticα -helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A4-LDH forms.
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Temperature adaptation in Gillichthys (Teleost: Gobiidae) A(4)-lactate dehydrogenases: identical primary structures produce subtly different conformations.
The Journal of experimental biology, 2002Co-Authors: Peter A Fields, Yong-sung Kim, John F Carpenter, George N. SomeroAbstract:Alternative conformations of proteins underlie a variety of biological phenomena, from prion proteins that cause spongiform encephalopathies to membrane channel proteins whose conformational changes admit or exclude specific ions. In this paper, we argue that conformational differences within globular 'housekeeping' enzymes may allow rapid adaptation to novel environments. Muscle-type lactate dehydrogenases (A(4)-LDHs) from the gobies Gillichthys seta and G. mirabilis have identical amino acid sequences but show potentially adaptive differences in substrate affinity (apparent Michaelis constants for pyruvate, K(m)(PYR)) as well as differences in thermal stability. We examined the A(4)-LDH of each species using fluorescence spectroscopy, near- and far-ultraviolet circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange (H/D) Fourier-transform infrared spectroscopy to determine whether structural differences were apparent, the extent to which structural differences could be related to differences in conformational flexibility and whether specific changes in secondary or tertiary structure could be defined. The fluorescence spectra and far-ultraviolet CD spectra of the A(4)-LDH from the two species were indistinguishable, suggesting that the two conformations are very similar in secondary and tertiary structure. Apparent melting temperatures (T(m)) followed by fluorescence and CD spectroscopy confirmed that the G. mirabilis A(4)-LDH is more thermally stable than the G. seta form. H/D exchange kinetics of Gillichthys A(4)-LDH was described using double-exponential regression; at 20 degrees C, G. seta A(4)-LDH has a higher exchange constant, indicating a more flexible and open structure. At 40 degrees C, the difference in H/D exchange constants disappears. Second-derivative analysis of H/D exchange infrared spectra indicates that alpha-helical, but not beta-sheet structure, differs in conformational flexibility between the two forms. Second-derivative ultraviolet spectra indicate that at least one of the five tyrosyl residues in the Gillichthys LDH-A monomer is located in a more hydrophobic environment in the G. mirabilis form. Homology models of A(4)-LDH indicate that Tyr246 is the most likely candidate to experience a modified environment because it is involved in subunit contacts within the homotetramer and sits in a hinge between a static alpha-helix and one involved in catalytic conformational changes. Subtle differences in conformation around this residue probably play a role both in altered flexibility and in the potentially adaptive differences in kinetics between the two A(4)-LDH forms.
Giacomo Bernardi - One of the best experts on this subject based on the ideXlab platform.
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Environmental Genomics: A Tale of Two Fishes
Molecular biology and evolution, 2009Co-Authors: Giuseppe Bucciarelli, Miriam Di Filippo, Domenico Costagliola, Fernando Alvarez-valin, Giacomo Bernardi, Giorgio BernardiAbstract:The influence of the environment on two congeneric fishes, Gillichthys mirabilis and Gillichthys seta, that live in the Gulf of California at temperatures of 10-25 degrees C, and up to 42-44 degrees C, respectively, was addressed by analyzing their genomes. Compared with G. mirabilis, G. seta showed some striking features. Substitution rates in the mitochondrial genes were found to be extremely fast, in fact faster than in noncoding control regions (D-loops), from which a divergence time of less than 0.66-0.75 Mya could be estimated. In the nuclear genome, 1) both AT --> GC/GC --> AT and transversion: transition ratios in coding sequences (CDSs) were relatively high; moreover, the ratios of nonsynonymous/synonymous changes (Ka/Ks) suggested that some genes were under positive selection; 2) DNA methylation showed a very significant decrease; and 3) a GC-rich minisatellite underwent a 4-fold amplification in the gene-rich regions. All these observations clearly indicate that the environment (temperature and the accompanying hypoxia) can rapidly mold the nuclear as well as the mitochondrial genome. The stabilization of gene-rich regions by the amplification of the GC-rich minisatellite and by the GC increase in nuclear CDSs is of special interest because it provides a model for the formation of the GC-rich and gene-rich isochores of the genomes of mammals and birds.
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Disjunct Sea of Cortez–Pacific Ocean Gillichthys mirabilis populations and the evolutionary origin of their Sea of Cortez endemic relative, Gillichthys seta
Marine Biology, 2001Co-Authors: David Huang, Giacomo BernardiAbstract:The shortjaw mudsucker, Gillichthys seta, an intertidal goby endemic to the Sea of Cortez, has been proposed to be the paedomorphic derivative of the longjaw mudsucker, Gillichthys mirabilis. G. mirabilis is a disjunct species, with populations found along the Pacific coast of central California to central Baja California, and with isolated populations found in the northern Sea of Cortez. Previous studies have suggested that the endemic paedomorph form speciated in sympatry with the Sea of Cortez population of G. mirabilis. Alternatively, this speciation event could have occurred before the separation of G. mirabilis populations into two disjunct entities. To test these alternative hypotheses, we collected adult individuals from both species throughout their ranges from December 1997 to November 1998. We amplified and sequenced 142 partial [527 base pairs (bp)] mitochondrial cytochrome b regions and 18 nuclear creatine kinase introns (140 bp). We found that Pacific populations of G. mirabilis separated into two distinct clades, possibly reflecting a phylogeographic break found in other fish species along the Baja California coast at Punta Eugenia. These two Pacific populations were well separated from Sea of Cortez populations. Furthermore, our results indicate that the split between Sea of Cortez and Pacific populations of G. mirabilis occurred well after the speciation event that separated G. mirabilis from its paedomorphic counterpart, G. seta.
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disjunct sea of cortez pacific ocean Gillichthys mirabilis populations and the evolutionary origin of their sea of cortez endemic relative Gillichthys seta
Marine Biology, 2001Co-Authors: David Huang, Giacomo BernardiAbstract:The shortjaw mudsucker, Gillichthys seta, an intertidal goby endemic to the Sea of Cortez, has been proposed to be the paedomorphic derivative of the longjaw mudsucker, Gillichthys mirabilis. G. mirabilis is a disjunct species, with populations found along the Pacific coast of central California to central Baja California, and with isolated populations found in the northern Sea of Cortez. Previous studies have suggested that the endemic paedomorph form speciated in sympatry with the Sea of Cortez population of G. mirabilis. Alternatively, this speciation event could have occurred before the separation of G. mirabilis populations into two disjunct entities. To test these alternative hypotheses, we collected adult individuals from both species throughout their ranges from December 1997 to November 1998. We amplified and sequenced 142 partial [527 base pairs (bp)] mitochondrial cytochrome b regions and 18 nuclear creatine kinase introns (140 bp). We found that Pacific populations of G. mirabilis separated into two distinct clades, possibly reflecting a phylogeographic break found in other fish species along the Baja California coast at Punta Eugenia. These two Pacific populations were well separated from Sea of Cortez populations. Furthermore, our results indicate that the split between Sea of Cortez and Pacific populations of G. mirabilis occurred well after the speciation event that separated G. mirabilis from its paedomorphic counterpart, G. seta.
David Huang - One of the best experts on this subject based on the ideXlab platform.
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Disjunct Sea of Cortez–Pacific Ocean Gillichthys mirabilis populations and the evolutionary origin of their Sea of Cortez endemic relative, Gillichthys seta
Marine Biology, 2001Co-Authors: David Huang, Giacomo BernardiAbstract:The shortjaw mudsucker, Gillichthys seta, an intertidal goby endemic to the Sea of Cortez, has been proposed to be the paedomorphic derivative of the longjaw mudsucker, Gillichthys mirabilis. G. mirabilis is a disjunct species, with populations found along the Pacific coast of central California to central Baja California, and with isolated populations found in the northern Sea of Cortez. Previous studies have suggested that the endemic paedomorph form speciated in sympatry with the Sea of Cortez population of G. mirabilis. Alternatively, this speciation event could have occurred before the separation of G. mirabilis populations into two disjunct entities. To test these alternative hypotheses, we collected adult individuals from both species throughout their ranges from December 1997 to November 1998. We amplified and sequenced 142 partial [527 base pairs (bp)] mitochondrial cytochrome b regions and 18 nuclear creatine kinase introns (140 bp). We found that Pacific populations of G. mirabilis separated into two distinct clades, possibly reflecting a phylogeographic break found in other fish species along the Baja California coast at Punta Eugenia. These two Pacific populations were well separated from Sea of Cortez populations. Furthermore, our results indicate that the split between Sea of Cortez and Pacific populations of G. mirabilis occurred well after the speciation event that separated G. mirabilis from its paedomorphic counterpart, G. seta.
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disjunct sea of cortez pacific ocean Gillichthys mirabilis populations and the evolutionary origin of their sea of cortez endemic relative Gillichthys seta
Marine Biology, 2001Co-Authors: David Huang, Giacomo BernardiAbstract:The shortjaw mudsucker, Gillichthys seta, an intertidal goby endemic to the Sea of Cortez, has been proposed to be the paedomorphic derivative of the longjaw mudsucker, Gillichthys mirabilis. G. mirabilis is a disjunct species, with populations found along the Pacific coast of central California to central Baja California, and with isolated populations found in the northern Sea of Cortez. Previous studies have suggested that the endemic paedomorph form speciated in sympatry with the Sea of Cortez population of G. mirabilis. Alternatively, this speciation event could have occurred before the separation of G. mirabilis populations into two disjunct entities. To test these alternative hypotheses, we collected adult individuals from both species throughout their ranges from December 1997 to November 1998. We amplified and sequenced 142 partial [527 base pairs (bp)] mitochondrial cytochrome b regions and 18 nuclear creatine kinase introns (140 bp). We found that Pacific populations of G. mirabilis separated into two distinct clades, possibly reflecting a phylogeographic break found in other fish species along the Baja California coast at Punta Eugenia. These two Pacific populations were well separated from Sea of Cortez populations. Furthermore, our results indicate that the split between Sea of Cortez and Pacific populations of G. mirabilis occurred well after the speciation event that separated G. mirabilis from its paedomorphic counterpart, G. seta.