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Todd T. Gleeson - One of the best experts on this subject based on the ideXlab platform.
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contributions to elevated metabolism during recovery dissecting the excess postexercise oxygen consumption epoc in the Desert Iguana dipsosaurus dorsalis
Physiological and Biochemical Zoology, 2008Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Abstract The excess postexercise oxygen consumption (EPOC), a measure of recovery costs, is known to be large in ectothermic vertebrates such as the Desert Iguana (Dipsosaurus dorsalis), especially after vigorous activity. To analyze the cause of these large recovery costs in a terrestrial ectotherm, Dipsosaurus were run for 15 s at maximal‐intensity (distance \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $35.0\pm 1.9$ \end{document} m; \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepa...
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metabolic support of moderate activity differs from patterns seen after extreme behavior in the Desert Iguana dipsosaurus dorsalis
Physiological and Biochemical Zoology, 2006Co-Authors: Edward R Donovan, Todd T. GleesonAbstract:Abstract This study examined glucose and lactate metabolism in an iguanid lizard, Dipsosaurus dorsalis, during rest and after activity patterned on field behavior (15 s of running at 1 m/s). Metabolite oxidation and incorporation into glycogen by the whole animal, the liver, and oxidative and glycolytic muscle fibers were measured using 14C‐ and 13C‐labeled compounds. Results showed that lactate metabolism is more responsive to changes that occurred between rest and recovery, whereas glucose appears to play a more steady state role. After activity, lactate oxidation produced 57 times as much ATP during 1 h of recovery than did glucose oxidation. However, lactate oxidation rates were elevated for only 30 min after activity, while glucose oxidation remained elevated beyond 1 h. Lactate was the primary source for glycogen synthesis during recovery, and glucose was the main glycogenic substrate during rest. This study supports previous research showing that brief activity in D. dorsalis is primarily supported...
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intermittent locomotor activity that increases endurance also increases metabolic costs in the Desert Iguana dipsosaurus dorsalis
Physiological and Biochemical Zoology, 2005Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Abstract Intermittent activity, alternating bouts of activity and rest, can extend endurance relative to continuous locomotion. Utilizing a rapid fatiguing activity intensity (1.08 m s−1), Dipsosaurus dorsalis ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $n=14$ \end{document} ) ran repeated bouts of varying durations (5, 15, or 30 s) interspersed with variable pause periods (100%, 200%, 400%, or 800% of the activity period) until exhausted. Total distance ran increased relative to continuous locomotion. The largest increases...
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metabolic recovery in the Desert Iguana dipsosaurus dorsalis following activities of varied intensity and duration
Functional Ecology, 2002Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Summary 1 Elevated oxygen consumption during recovery is the majority of total metabolic costs associated with short vigorous activity, thus any assessment of total costs associated with such activity should also examine the excess postexercise oxygen consumption (EPOC). This study examined EPOC and total metabolic costs in Dipsosaurus (N = 8; 75 ± 3 g) over a variety of submaximal intensities: 50%, 100% and 400% of the maximum aerobic speed (MAS = 0·27 m s−1; the speed at which VO2max is elicited). Activity duration was also varied (15, 60 and 300 s) over these intensities. 2 Total costs increased significantly with both activity intensity and duration. EPOC increased significantly with activity intensity. EPOC increased significantly with activity duration at higher intensities, but not the lowest intensity of 50% MAS. 3 These recovery costs constitute amounts of energy large enough to have an impact on energy budget analyses. The metabolic cost of an individual bout of activity and subsequent recovery was as high as 5% of the predicted daily energy expenditure, an increase of 5–8 × estimates that do not incorporate recovery. 4 To compare the relative economy of different activity regimens, the cost of activity (Cact; ml O2 g−1 km−1), was calculated as total costs, including EPOC, per unit distance travelled. Cact was independent of activity intensity over these ranges, but was inversely related to activity duration. 5 From these data, the most economical strategy to travel a certain distance would utilize a low-intensity and extended duration, as seen in regular activities such as foraging. High-intensity activities, such as escape, prey capture or mating behaviours, are thus predicted to be less economical. These should only be observed where metabolic costs would be considered secondary to the more proximal needs of the animal.
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effect of activity duration on recovery and metabolic costs in the Desert Iguana dipsosaurus dorsalis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2001Co-Authors: Thomas V Hancock, Stephen C Adolph, Todd T. GleesonAbstract:Abstract The majority of elevated O 2 consumption associated with short and vigorous activity occurs during recovery, thus an assessment of associated metabolic costs should also examine the excess post-exercise oxygen consumption (EPOC). This study examined O 2 uptake during exercise, EPOC and distance traveled during 5-, 15-, 60- and 300-s sprints at maximal treadmill intensity in Dipsosaurus ( N =10; 74.3±2.1 g). EPOC (0.08, 0.14, 0.23 and 0.18 ml O 2 g −1 , respectively) was large (80–99% of total elevated O 2 consumption) and increased significantly between 5 and 60 s. The cost of activity ( C act ; ml O 2 g −1 ·km −1 ), intended to reflect the total net costs associated with the activity, was calculated as the total elevated O 2 consumption per unit distance traveled. C act decreased with activity duration due to proportionally larger increases in distance traveled relative to EPOC volume, and is predicted by the equation C act =14.7×activity duration (s) −0.24 . The inclusion of EPOC costs provides an ecologically relevant estimate of the total metabolic cost of locomotor activity. C act exceeds standard transport costs at all durations examined due to the addition of obligate recovery costs. The differences are large enough to impact energy budget analyses for ectotherms.
Thomas V Hancock - One of the best experts on this subject based on the ideXlab platform.
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contributions to elevated metabolism during recovery dissecting the excess postexercise oxygen consumption epoc in the Desert Iguana dipsosaurus dorsalis
Physiological and Biochemical Zoology, 2008Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Abstract The excess postexercise oxygen consumption (EPOC), a measure of recovery costs, is known to be large in ectothermic vertebrates such as the Desert Iguana (Dipsosaurus dorsalis), especially after vigorous activity. To analyze the cause of these large recovery costs in a terrestrial ectotherm, Dipsosaurus were run for 15 s at maximal‐intensity (distance \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $35.0\pm 1.9$ \end{document} m; \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepa...
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intermittent locomotor activity that increases endurance also increases metabolic costs in the Desert Iguana dipsosaurus dorsalis
Physiological and Biochemical Zoology, 2005Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Abstract Intermittent activity, alternating bouts of activity and rest, can extend endurance relative to continuous locomotion. Utilizing a rapid fatiguing activity intensity (1.08 m s−1), Dipsosaurus dorsalis ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $n=14$ \end{document} ) ran repeated bouts of varying durations (5, 15, or 30 s) interspersed with variable pause periods (100%, 200%, 400%, or 800% of the activity period) until exhausted. Total distance ran increased relative to continuous locomotion. The largest increases...
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metabolic recovery in the Desert Iguana dipsosaurus dorsalis following activities of varied intensity and duration
Functional Ecology, 2002Co-Authors: Thomas V Hancock, Todd T. GleesonAbstract:Summary 1 Elevated oxygen consumption during recovery is the majority of total metabolic costs associated with short vigorous activity, thus any assessment of total costs associated with such activity should also examine the excess postexercise oxygen consumption (EPOC). This study examined EPOC and total metabolic costs in Dipsosaurus (N = 8; 75 ± 3 g) over a variety of submaximal intensities: 50%, 100% and 400% of the maximum aerobic speed (MAS = 0·27 m s−1; the speed at which VO2max is elicited). Activity duration was also varied (15, 60 and 300 s) over these intensities. 2 Total costs increased significantly with both activity intensity and duration. EPOC increased significantly with activity intensity. EPOC increased significantly with activity duration at higher intensities, but not the lowest intensity of 50% MAS. 3 These recovery costs constitute amounts of energy large enough to have an impact on energy budget analyses. The metabolic cost of an individual bout of activity and subsequent recovery was as high as 5% of the predicted daily energy expenditure, an increase of 5–8 × estimates that do not incorporate recovery. 4 To compare the relative economy of different activity regimens, the cost of activity (Cact; ml O2 g−1 km−1), was calculated as total costs, including EPOC, per unit distance travelled. Cact was independent of activity intensity over these ranges, but was inversely related to activity duration. 5 From these data, the most economical strategy to travel a certain distance would utilize a low-intensity and extended duration, as seen in regular activities such as foraging. High-intensity activities, such as escape, prey capture or mating behaviours, are thus predicted to be less economical. These should only be observed where metabolic costs would be considered secondary to the more proximal needs of the animal.
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effect of activity duration on recovery and metabolic costs in the Desert Iguana dipsosaurus dorsalis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2001Co-Authors: Thomas V Hancock, Stephen C Adolph, Todd T. GleesonAbstract:Abstract The majority of elevated O 2 consumption associated with short and vigorous activity occurs during recovery, thus an assessment of associated metabolic costs should also examine the excess post-exercise oxygen consumption (EPOC). This study examined O 2 uptake during exercise, EPOC and distance traveled during 5-, 15-, 60- and 300-s sprints at maximal treadmill intensity in Dipsosaurus ( N =10; 74.3±2.1 g). EPOC (0.08, 0.14, 0.23 and 0.18 ml O 2 g −1 , respectively) was large (80–99% of total elevated O 2 consumption) and increased significantly between 5 and 60 s. The cost of activity ( C act ; ml O 2 g −1 ·km −1 ), intended to reflect the total net costs associated with the activity, was calculated as the total elevated O 2 consumption per unit distance traveled. C act decreased with activity duration due to proportionally larger increases in distance traveled relative to EPOC volume, and is predicted by the equation C act =14.7×activity duration (s) −0.24 . The inclusion of EPOC costs provides an ecologically relevant estimate of the total metabolic cost of locomotor activity. C act exceeds standard transport costs at all durations examined due to the addition of obligate recovery costs. The differences are large enough to impact energy budget analyses for ectotherms.
Patricia Gonzalez Zamorano - One of the best experts on this subject based on the ideXlab platform.
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phylogeography and ecological niche modeling of the Desert Iguana dipsosaurus dorsalis baird girard 1852 in the baja california peninsula
Journal of Heredity, 2017Co-Authors: Tania Valdiviacarrillo, Francisco Leon, M C Blazquez, Carina Gutierrezflores, Patricia Gonzalez ZamoranoAbstract:Understanding the factors that explain the patterns of genetic structure or phylogeographic breaks at an intraspecific level is key to inferring the mechanisms of population differentiation in its early stages. These topics have been well studied in the Baja California region, with vicariance and the dispersal ability of individuals being the prevailing hypothesis for phylogeographic breaks. In this study, we evaluated the phylogeographic patterns in the Desert Iguana (Dipsosaurus dorsalis), a species with a recent history in the region and spatial variation in life history traits. We analyzed a total of 307 individuals collected throughout 19 localities across the Baja California Peninsula with 15 microsatellite DNA markers. Our data reveal the existence of 3 geographically discrete genetic populations with moderate gene flow and an isolation-by-distance pattern presumably produced by the occurrence of a refugium in the Cape region during the Pleistocene Last Glacial Maximum. Bayesian methods and ecological niche modeling were used to assess the relationship between population genetic structure and present and past climatic preferences of the Desert Iguana. We found that the present climatic heterogeneity of the Baja California Peninsula has a marked influence on the population genetic structure of the species, suggesting that there are alternative explanations besides vicariance. The information obtained in this study provides data allowing a better understanding of how historical population processes in the Baja California Peninsula can be understood from an ecological perspective.
John C Avise - One of the best experts on this subject based on the ideXlab platform.
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phylogeographic histories of representative herpetofauna of the southwestern u s mitochondrial dna variation in the Desert Iguana dipsosaurus dorsalis and the chuckwalla sauromalus obesus
Journal of Evolutionary Biology, 1992Co-Authors: Trip Lamb, Thomas R Jones, John C AviseAbstract:To determine whether genetic variation in representative reptiles of the southwestern U.S. may have been similarly molded by the geologic history of the lower Colorado River, we examined restriction site polymorphisms in the mitochondrial DNA (mtDNA) of Desert Iguanas (Dipsosaurus dorsalis) and chuckwallas (Saurom&s ohesus). Observed phylogeographic structure in these lizards was compared to that reported for the Desert tortoise (Xerobates ugassizi), whose mtDNA phylogeny demonstrates a striking genetic break at the Colorado River. Both the Desert Iguana and chuckwalla exhibit extensive mtDNA polymorphism, with respective genotypic diversities G = 0.963 and 0.983, close to the maximum possible value of 1.0. Individual mtDNA clones, as well as clonal assemblages defined by specific levels of genetic divergence, showed pronounced geographic localization. Nonetheless, for each species the distributions of certain clones and most major clonal groupings encompass both sides of the Colorado River valley, and hence are clearly incongruent with the phylogeographic pattern of the Desert tortoise. Overall, available molecular evidence provides no indication that the intraspecific phylogenies of the southwestern U.S. herpetofauna have been concordantly shaped by a singular vicariant factor of overriding significance.
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Phylogeographic histories of representative herpetofauna of the southwestern U.S.: mitochondrial DNA variation in the Desert Iguana (Dipsosaurus dorsalis) and the chuckwalla (Sauromalus obesus)
eScholarship University of California, 1992Co-Authors: Lamb T, Tr Jones, John C AviseAbstract:To determine whether genetic variation in representative reptiles of the southwestern U.S. may have been similarly molded by the geologic history of the lower Colorado River, we examined restriction site polymorphisms in the mitochondrial DNA (mtDNA) of Desert Iguanas (Dipsosaurus dorsalis) and chuckwallas (Sauromalus obesus). Observed phylogeographic structure in these lizards was compared to that reported for the Desert tortoise (Xerobates agassizi), whose mtDNA phylogeny demonstrates a striking genetic break at the Colorado River. Both the Desert Iguana and chuckwalla exhibit extensive mtDNA polymorphism, with respective genotypic diversities G = 0.963 and 0.983, close to the maximum possible value of 1.0. Individual mtDNA clones, as well as clonal assemblages defined by specific levels of genetic divergence, showed pronounced geographic localization. Nonetheless, for each species the distributions of certain clones and most major clonal groupings encompass both sides of the Colorado River valley, and hence are clearly incongruent with the phylogeographic pattern of the Desert tortoise. Overall, available molecular evidence provides no indication that the intraspecific phylogenies of the southwestern U.S. herpetofauna have been concordantly shaped by a singular vicariant factor of overriding significance. Copyright © 1992, Wiley Blackwell. All rights reserve
Tania Valdiviacarrillo - One of the best experts on this subject based on the ideXlab platform.
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phylogeography and ecological niche modeling of the Desert Iguana dipsosaurus dorsalis baird girard 1852 in the baja california peninsula
Journal of Heredity, 2017Co-Authors: Tania Valdiviacarrillo, Francisco Leon, M C Blazquez, Carina Gutierrezflores, Patricia Gonzalez ZamoranoAbstract:Understanding the factors that explain the patterns of genetic structure or phylogeographic breaks at an intraspecific level is key to inferring the mechanisms of population differentiation in its early stages. These topics have been well studied in the Baja California region, with vicariance and the dispersal ability of individuals being the prevailing hypothesis for phylogeographic breaks. In this study, we evaluated the phylogeographic patterns in the Desert Iguana (Dipsosaurus dorsalis), a species with a recent history in the region and spatial variation in life history traits. We analyzed a total of 307 individuals collected throughout 19 localities across the Baja California Peninsula with 15 microsatellite DNA markers. Our data reveal the existence of 3 geographically discrete genetic populations with moderate gene flow and an isolation-by-distance pattern presumably produced by the occurrence of a refugium in the Cape region during the Pleistocene Last Glacial Maximum. Bayesian methods and ecological niche modeling were used to assess the relationship between population genetic structure and present and past climatic preferences of the Desert Iguana. We found that the present climatic heterogeneity of the Baja California Peninsula has a marked influence on the population genetic structure of the species, suggesting that there are alternative explanations besides vicariance. The information obtained in this study provides data allowing a better understanding of how historical population processes in the Baja California Peninsula can be understood from an ecological perspective.