Joseph Szewczak | Cal Poly Humboldt (original) (raw)
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Papers by Joseph Szewczak
The Journal of Experimental Biology, Jun 1, 2001
Over the last few decades, it has become apparent that phenotypic plasticity (changes in the magn... more Over the last few decades, it has become apparent that phenotypic plasticity (changes in the magnitude of anatomical, morphological or physiological characters) and phenotypic flexibility (reversible phenotypic plasticity) of various morphological and physiological characters are widespread in the animal and plant kingdoms (for general references, see Piersma and Lindström, 1997; Schlichting and Pigliucci, 1998). It has been well documented in laboratory studies on endotherms that organ size and functional capacity are correlated with changes in both short-term aerobic performance (
Northwestern Naturalist, 2011
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
The California Department of Fish and Wildlife lists the Townsend's big-eared bat (Corynorhinus t... more The California Department of Fish and Wildlife lists the Townsend's big-eared bat (Corynorhinus townsendii, COTO) as a Species of Special Concern and a Species of Greatest Conservation Need. The only California statewide field assessment of the species' status, however, was conducted in the 1980s and 1990s. Our goal was to quantify the current distribution of COTO in California by conducting a comprehensive roost assessment at sites visited during the previous statewide survey and a geographic expansion of that effort. We sampled during two complete winters (2014-15 and 2015-16) and three spring/summer/fall periods (2015 through 2017). We searched published and unpublished records and databases for records of COTO and communicated with biologists and other individuals to gather previously unreported and new records of occurrence and potential locations. We used the basic sampling units (sampling frame consisting of 10 x 10 km [100 km 2 ] grid cells) of the North American Bat Monitoring Program (NABat) as the foundation of our survey and drew potential sampling cells by first dividing the state into Level III Ecoregions, and then randomly listing all cells in the state. Historical locations not known to be closed or otherwise uninhabitable were re-visited in the appropriate season. We surveyed 304 grid cells during this study, with 206 in summer and 98 in winter, and within
The Bulletin of the Ecological Society of America
Methods in Ecology and Evolution
Ecology and evolution, 2017
Anthropogenic noise associated with highway construction and operation can have individual- and p... more Anthropogenic noise associated with highway construction and operation can have individual- and population-level consequences for wildlife (e.g., reduced densities, decreased reproductive success, behavioral changes). We used a before-after control-impact study design to examine the potential impacts of highway construction and traffic noise on endangered golden-cheeked warblers (Setophaga chrysoparia; hereafter warbler) in urban Texas. We mapped and monitored warbler territories before (2009-2011), during (2012-2013), and after (2014) highway construction at three study sites: a treatment site exposed to highway construction and traffic noise, a control site exposed only to traffic noise, and a second control site exposed to neither highway construction or traffic noise. We measured noise levels at varying distances from the highway at sites exposed to construction and traffic noise. We examined how highway construction and traffic noise influenced warbler territory density, territ...
Bulletin of the Ecological Society of America, 2002
Respiratory Physiology Neurobiology, Nov 14, 2003
Respiratory Physiology Neurobiology, May 30, 2003
Data supporting the hypothesis that dopamine-2 receptors (D(2)-R) contribute to time-dependent ch... more Data supporting the hypothesis that dopamine-2 receptors (D(2)-R) contribute to time-dependent changes in the hypoxic ventilatory response (HVR) during acclimatization to hypoxia are briefly reviewed. Previous experiments with transgenic animals (D(2)-R 'knockout' mice) support this hypothesis (J. Appl. Physiol. 89 (2000) 1142). However, those experiments could not determine (1) if D(2)-R in the carotid body, the CNS, or both were involved, or (2) if D(2)-R were necessary during the acclimatization to hypoxia versus some time prior to chronic hypoxia, e.g. during a critical period of development. Additional experiments on C57BL/6J mice support the idea that D(2)-R are critical during the period of exposure to hypoxia for normal ventilatory acclimatization. D(2)-R in carotid body chemoreceptors predominate under control conditions to inhibit normoxic ventilation, but excitatory effects of D(2)-R, presumably in the CNS, predominate after acclimatization to hypoxia. The inhibitory effects of D(2)-R in the carotid body are reset to operate primarily under hypoxic conditions in acclimatized rats, thereby optimizing O(2)-sensitivity.
Northwestern Naturalist, 2012
Respiration Physiology, 1992
Ventilatory pattern and ventilatory responses to hypercapnia and hypoxia were investigated in tor... more Ventilatory pattern and ventilatory responses to hypercapnia and hypoxia were investigated in torpid big brown bats at body temperatures of 5, 10, 20, 30 and 37 degrees C. The pattern of breathing at temperatures below 30 degrees C was intermittent, consisting of rhythmic breathing bouts separated by apneic periods with occasional sporadic, non-rhythmic breathing episodes. Overall ventilation (Ve) was matched consistently to overall oxygen consumption (MO2) over the entire range of temperatures with a mean air convection requirement (Ve/MO2) of 1.28 L/mmol. However, calculating the air convection requirement using only oxygen uptake acquired during ventilation yielded an ectotherm-like temperature relationship. Ventilation was stimulated at all temperatures by either increased inspired CO2 or decreased inspired O2. At 20 degrees C, graded hypercapnic stimulation increased the duration of the rhythmic bouts and decreased the duration of apneas until at high CO2 (greater than 3%) breathing was continuous. Hypoxic stimulation below about 7% O2 increased ventilation by selectively increasing the non-rhythmic ventilations and decreasing rhythmic bouts.
Respiration Physiology, 1992
The effects of intermittent breathing on acid-base state and blood gases were characterized in th... more The effects of intermittent breathing on acid-base state and blood gases were characterized in the torpid bat, Eptesicus fuscus, during steady-state torpor between body temperatures (Tb) of 5 and 37 degrees C. Arterial blood samples were taken from indwelling catheters without disturbing the torpid state. Arterial pH (pHa) of samples taken without knowledge of ventilatory state rose by 0.15 units from 37 to 5 degrees C with a delta pHa/delta Tb slope over this range of -0.0055 U/degrees C. However, at and below Tb = 20 degrees C, Eptesicus fuscus breathes intermittently with typical apneic periods of 40-150 min and 4-12 min at 10 and 20 degrees C, respectively. Samples taken at the end of a ventilatory bout and near the end of an apneic period at Tb = 20 degrees C revealed cyclic changes in pH (from 7.49 +/- 0.02 to 7.34 +/- 0.01), PO2 (from 96.6 +/- 3.4 to 30.8 +/- 3.9 Torr), and PCO2 (28.2 +/- 1.4 to 45.9 +/- 1.5 Torr). Between 10 and 37 degrees C, end-ventilatory pHa varied inversely with temperature with a delta pHa/delta T slope of -0.011 U/degrees C. Because intermittent breathing is common to many animals during hibernation, these results demonstrate the importance of coordinating blood sampling with ventilatory state for a reliable interpretation of acid-base regulation under these conditions.
Integrative and Comparative Biology, 1997
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2000
Diversity and Distributions, 2015
The Journal of Experimental Biology, Jun 1, 2001
Over the last few decades, it has become apparent that phenotypic plasticity (changes in the magn... more Over the last few decades, it has become apparent that phenotypic plasticity (changes in the magnitude of anatomical, morphological or physiological characters) and phenotypic flexibility (reversible phenotypic plasticity) of various morphological and physiological characters are widespread in the animal and plant kingdoms (for general references, see Piersma and Lindström, 1997; Schlichting and Pigliucci, 1998). It has been well documented in laboratory studies on endotherms that organ size and functional capacity are correlated with changes in both short-term aerobic performance (
Northwestern Naturalist, 2011
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
The California Department of Fish and Wildlife lists the Townsend's big-eared bat (Corynorhinus t... more The California Department of Fish and Wildlife lists the Townsend's big-eared bat (Corynorhinus townsendii, COTO) as a Species of Special Concern and a Species of Greatest Conservation Need. The only California statewide field assessment of the species' status, however, was conducted in the 1980s and 1990s. Our goal was to quantify the current distribution of COTO in California by conducting a comprehensive roost assessment at sites visited during the previous statewide survey and a geographic expansion of that effort. We sampled during two complete winters (2014-15 and 2015-16) and three spring/summer/fall periods (2015 through 2017). We searched published and unpublished records and databases for records of COTO and communicated with biologists and other individuals to gather previously unreported and new records of occurrence and potential locations. We used the basic sampling units (sampling frame consisting of 10 x 10 km [100 km 2 ] grid cells) of the North American Bat Monitoring Program (NABat) as the foundation of our survey and drew potential sampling cells by first dividing the state into Level III Ecoregions, and then randomly listing all cells in the state. Historical locations not known to be closed or otherwise uninhabitable were re-visited in the appropriate season. We surveyed 304 grid cells during this study, with 206 in summer and 98 in winter, and within
The Bulletin of the Ecological Society of America
Methods in Ecology and Evolution
Ecology and evolution, 2017
Anthropogenic noise associated with highway construction and operation can have individual- and p... more Anthropogenic noise associated with highway construction and operation can have individual- and population-level consequences for wildlife (e.g., reduced densities, decreased reproductive success, behavioral changes). We used a before-after control-impact study design to examine the potential impacts of highway construction and traffic noise on endangered golden-cheeked warblers (Setophaga chrysoparia; hereafter warbler) in urban Texas. We mapped and monitored warbler territories before (2009-2011), during (2012-2013), and after (2014) highway construction at three study sites: a treatment site exposed to highway construction and traffic noise, a control site exposed only to traffic noise, and a second control site exposed to neither highway construction or traffic noise. We measured noise levels at varying distances from the highway at sites exposed to construction and traffic noise. We examined how highway construction and traffic noise influenced warbler territory density, territ...
Bulletin of the Ecological Society of America, 2002
Respiratory Physiology Neurobiology, Nov 14, 2003
Respiratory Physiology Neurobiology, May 30, 2003
Data supporting the hypothesis that dopamine-2 receptors (D(2)-R) contribute to time-dependent ch... more Data supporting the hypothesis that dopamine-2 receptors (D(2)-R) contribute to time-dependent changes in the hypoxic ventilatory response (HVR) during acclimatization to hypoxia are briefly reviewed. Previous experiments with transgenic animals (D(2)-R 'knockout' mice) support this hypothesis (J. Appl. Physiol. 89 (2000) 1142). However, those experiments could not determine (1) if D(2)-R in the carotid body, the CNS, or both were involved, or (2) if D(2)-R were necessary during the acclimatization to hypoxia versus some time prior to chronic hypoxia, e.g. during a critical period of development. Additional experiments on C57BL/6J mice support the idea that D(2)-R are critical during the period of exposure to hypoxia for normal ventilatory acclimatization. D(2)-R in carotid body chemoreceptors predominate under control conditions to inhibit normoxic ventilation, but excitatory effects of D(2)-R, presumably in the CNS, predominate after acclimatization to hypoxia. The inhibitory effects of D(2)-R in the carotid body are reset to operate primarily under hypoxic conditions in acclimatized rats, thereby optimizing O(2)-sensitivity.
Northwestern Naturalist, 2012
Respiration Physiology, 1992
Ventilatory pattern and ventilatory responses to hypercapnia and hypoxia were investigated in tor... more Ventilatory pattern and ventilatory responses to hypercapnia and hypoxia were investigated in torpid big brown bats at body temperatures of 5, 10, 20, 30 and 37 degrees C. The pattern of breathing at temperatures below 30 degrees C was intermittent, consisting of rhythmic breathing bouts separated by apneic periods with occasional sporadic, non-rhythmic breathing episodes. Overall ventilation (Ve) was matched consistently to overall oxygen consumption (MO2) over the entire range of temperatures with a mean air convection requirement (Ve/MO2) of 1.28 L/mmol. However, calculating the air convection requirement using only oxygen uptake acquired during ventilation yielded an ectotherm-like temperature relationship. Ventilation was stimulated at all temperatures by either increased inspired CO2 or decreased inspired O2. At 20 degrees C, graded hypercapnic stimulation increased the duration of the rhythmic bouts and decreased the duration of apneas until at high CO2 (greater than 3%) breathing was continuous. Hypoxic stimulation below about 7% O2 increased ventilation by selectively increasing the non-rhythmic ventilations and decreasing rhythmic bouts.
Respiration Physiology, 1992
The effects of intermittent breathing on acid-base state and blood gases were characterized in th... more The effects of intermittent breathing on acid-base state and blood gases were characterized in the torpid bat, Eptesicus fuscus, during steady-state torpor between body temperatures (Tb) of 5 and 37 degrees C. Arterial blood samples were taken from indwelling catheters without disturbing the torpid state. Arterial pH (pHa) of samples taken without knowledge of ventilatory state rose by 0.15 units from 37 to 5 degrees C with a delta pHa/delta Tb slope over this range of -0.0055 U/degrees C. However, at and below Tb = 20 degrees C, Eptesicus fuscus breathes intermittently with typical apneic periods of 40-150 min and 4-12 min at 10 and 20 degrees C, respectively. Samples taken at the end of a ventilatory bout and near the end of an apneic period at Tb = 20 degrees C revealed cyclic changes in pH (from 7.49 +/- 0.02 to 7.34 +/- 0.01), PO2 (from 96.6 +/- 3.4 to 30.8 +/- 3.9 Torr), and PCO2 (28.2 +/- 1.4 to 45.9 +/- 1.5 Torr). Between 10 and 37 degrees C, end-ventilatory pHa varied inversely with temperature with a delta pHa/delta T slope of -0.011 U/degrees C. Because intermittent breathing is common to many animals during hibernation, these results demonstrate the importance of coordinating blood sampling with ventilatory state for a reliable interpretation of acid-base regulation under these conditions.
Integrative and Comparative Biology, 1997
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2000
Diversity and Distributions, 2015