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Marchetti JR, French SS, Virgin EE, Lewis EL, Ki KC, Sermersheim LO, Brusch GA, Beard KH. Invading nonnative frogs use different microhabitats and change physiology along an elevation gradient. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:73-85. [PMID: 37902261 DOI: 10.1002/jez.2762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 09/13/2023] [Accepted: 10/11/2023] [Indexed: 10/31/2023]
Abstract
The coqui frog (Eleutherodactylus coqui) was introduced to the island of Hawai'i in the 1980s, and has spread across much of the island. There is concern they will invade higher elevation areas where negative impacts on native species are expected. It is not known if coqui change behavior and baseline physiology in ways that allow them to invade higher elevations. We investigated where coqui are found across the island and whether that includes recent invasion into higher elevations. We also investigated whether elevation is related to coqui's microhabitat use, including substrate use and height off the forest floor, and physiological metrics, including plasma osmolality, oxidative status, glucose, free glycerol, and triglycerides, that might be associated with invading higher elevations. We found coqui have increased the area they occupy along roads from 31% to 50% and have moved into more high-elevation locations (16% vs. 1%) compared to where they were found 14 years ago. We also found frogs at high elevation on different substrates and closer to the forest floor than frogs at lower elevations-perhaps in response to air temperatures which tended to be warmer close to the forest floor. We observed that blood glucose and triglycerides increase in frogs with elevation. An increase in glucose is likely an acclimation response to cold temperatures while triglycerides may also help frogs cope with the energetic demands of suboptimal temperatures. Finally, we found that female coqui have higher plasma osmolality, reactive oxygen metabolites (dROMs), free glycerol, and triglycerides than males. Our study suggests coqui behavior and physiology in Hawai'i may be influenced by elevation in ways that allow them to cope with lower temperatures and invade higher elevations.
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Affiliation(s)
- Jack R Marchetti
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - Susannah S French
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - Emily E Virgin
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - Erin L Lewis
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - Kwanho C Ki
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - Layne O Sermersheim
- Department of Biology and the Ecology Center, Utah State University, Logan, Utah, USA
| | - George A Brusch
- Biological Sciences, California State University San Marcos, San Marcos, California, USA
| | - Karen H Beard
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
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Marchetti JR, Beard KH, Virgin EE, Lewis EL, Hess SC, Ki KC, Sermersheim LO, Furtado AP, French SS. Invasive frogs show persistent physiological differences to elevation and acclimate to colder temperatures. J Therm Biol 2023; 114:103590. [PMID: 37267784 DOI: 10.1016/j.jtherbio.2023.103590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/03/2023] [Accepted: 05/05/2023] [Indexed: 06/04/2023]
Abstract
The coqui frog (Eleutherodactylus coqui) was introduced to the island of Hawai'i in the 1980s and has spread across much of the island. Concern remains that this frog will continue to expand its range and invade higher elevation habitats where much of the island's endemic species are found. We determined whether coqui thermal tolerance and physiology change along Hawai'i's elevational gradients. We measured physiological responses using a short-term experiment to determine baseline tolerance and physiology by elevation, and a long-term experiment to determine the coqui's ability to acclimate to different temperatures. We collected frogs from low, medium, and high elevations. After both the short and long-term experiments, we measured critical thermal minimum (CTmin), blood glucose, oxidative stress, and corticosterone levels. CTmin was lower in high elevation frogs than low elevation frogs after the short acclimation experiment, signifying that they acclimate to local conditions. After the extended acclimation, CTmin was lower in frogs acclimated to cold temperatures compared to warm-acclimated frogs and no longer varied by elevation. Blood glucose levels were positively correlated with elevation even after the extended acclimation, suggesting glucose may also be related to lower temperatures. Oxidative stress was higher in females than males, and corticosterone was not significantly related to any predictor variables. The extended acclimation experiment showed that coquis can adjust their thermal tolerance to different temperatures over a 3-week period, suggesting the expansion of coqui into higher elevation habitats may still be possible, and they may not be as restricted by cold temperatures as previously thought.
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Affiliation(s)
- Jack R Marchetti
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Karen H Beard
- Department of Wildland Resources, Utah State University, Logan, UT, 84322, USA.
| | - Emily E Virgin
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Erin L Lewis
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Steven C Hess
- USDA APHIS-WS National Wildlife Research Center, Hawaii Field Station, Hilo, HI, 96720, USA
| | - Kwanho C Ki
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Layne O Sermersheim
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Adriana P Furtado
- Departamento de Ciências Animais, Universidade de Brasília, Distrito Federal, 70910900, Brazil
| | - Susannah S French
- Department of Biology and the Ecology Center, Utah State University, Logan, UT, 84322, USA
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Lind CM, Meyers RA, Moore IT, Agugliaro J, McPherson S, Farrell TM. Ophidiomycosis is associated with alterations in the acute glycemic and glucocorticoid stress response in a free-living snake species. Gen Comp Endocrinol 2023; 339:114295. [PMID: 37121405 DOI: 10.1016/j.ygcen.2023.114295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/10/2023] [Accepted: 04/25/2023] [Indexed: 05/02/2023]
Abstract
Emerging fungal pathogens are a direct threat to vertebrate biodiversity. Elucidating the mechanisms by which mycoses impact host fitness is an important step towards effective prediction and management of disease outcomes in populations. The vertebrate acute stress response is an adaptive mechanism that allows individuals to meet challenges to homeostasis and survival in dynamic environments. Disease may cause stress, and coping with fungal infections may require shifts in resource allocation that alter the ability of hosts to mount an acute response to other external stressors. We examined the glucocorticoid and glycemic response to acute capture stress in a population of free-living pygmy rattlesnakes, Sistrurus miliarius, afflicted with an emerging mycosis (ophidiomycosis) across seasons. In all combinations of disease status and season, acute capture stress resulted in a significant glucocorticoid and glycemic response. While disease was not associated with elevated baseline or stress-induced corticosterone (CORT), disease was associated with an increased glucocorticoid stress response (post-stress minus baseline) across seasons. Both baseline and stress-induced glucose were lower in snakes with ophidiomycosis compared to uninfected snakes. The relationship between glucose and pre- and post-stress CORT depended on infection status, and positive correlations were only observed in uninfected snakes. The variables which explained CORT and glucose levels were different. The pattern of CORT was highly seasonal (winter high - summer low) and negatively related to body condition. Glucose, on the other hand, did not vary seasonally or with body condition and was strongly related to sex (male high - female low). Our results highlight the fact that circulating CORT and glucose are sensitive to different intrinsic and extrinsic predictor variables and support the hypothesis that disease alters the acute physiological stress response. Whether the effects of ophidiomycosis on the acute stress response result in sublethal effects on fitness should be investigated in future studies.
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Affiliation(s)
- Craig M Lind
- Stockton University, 101 Vera King Farris Dr, Galloway, NJ 08205, United States.
| | - Riley A Meyers
- Virginia Tech, Dept. Biological Sciences, Blacksburg, VA 24061, United States
| | - Ignacio T Moore
- Virginia Tech, Dept. Biological Sciences, Blacksburg, VA 24061, United States
| | - Joseph Agugliaro
- Fairleigh Dickinson University, 285 Madison Avenue, Madison, NJ 07940, United States
| | - Samantha McPherson
- Stetson University, 421 N Woodland Blvd, DeLand, FL 32723, United States
| | - Terence M Farrell
- Stetson University, 421 N Woodland Blvd, DeLand, FL 32723, United States
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French SS, Hudson SB, Webb AC, Knapp CR, Virgin EE, Smith GD, Lewis EL, Iverson JB, DeNardo DF. Glucose tolerance of iguanas is affected by high-sugar diets in the lab and supplemental feeding by ecotourists in the wild. J Exp Biol 2022; 225:274936. [PMID: 35448902 DOI: 10.1242/jeb.243932] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/17/2022] [Indexed: 12/28/2022]
Abstract
There is great interspecific variation in the nutritional composition of natural diets, and the varied nutritional content is physiologically tolerated because of evolutionarily based balances between diet composition and processing ability. However, as a result of landscape change and human exposure, unnatural diets are becoming widespread among wildlife without the necessary time for evolutionary matching between the diet and its processing. We tested how a controlled, unnatural high glucose diet affects glucose tolerance using captive green iguanas, and we performed similar glucose tolerance tests on wild Northern Bahamian rock iguanas that are either frequently fed grapes by tourists or experience no such supplementation. We evaluated both short and longer-term blood glucose responses and corticosterone (CORT) concentrations as changes have been associated with altered diets. Experimental glucose supplementation in the laboratory and tourist feeding in the wild both significantly affected glucose metabolism. When iguanas received a glucose-rich diet, we found greater acute increases in blood glucose following a glucose challenge. Relative to unfed iguanas, tourist-fed iguanas had significantly lower baseline CORT, higher baseline blood glucose, and slower returns to baseline glucose levels following a glucose challenge. Therefore, unnatural consumption of high amounts of glucose alters glucose metabolism in laboratory iguanas with short-term glucose treatment and free-living iguanas exposed to long-term feeding by tourists. Based on these results and the increasing prevalence of anthropogenically altered wildlife diets, the consequences of dietary changes on glucose metabolism should be further investigated across species, as such changes in glucose metabolism have health consequences in humans (e.g. diabetes).
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Affiliation(s)
- Susannah S French
- Department of Biology, Utah State University, Logan, UT 84322, USA.,Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Spencer B Hudson
- Department of Biology, Utah State University, Logan, UT 84322, USA.,Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Alison C Webb
- Department of Biology, Utah State University, Logan, UT 84322, USA.,Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Charles R Knapp
- Daniel P. Haerther Center for Conservation and Research, John G. Shedd Aquarium, Chicago, IL 60605, USA
| | - Emily E Virgin
- Department of Biology, Utah State University, Logan, UT 84322, USA.,Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Geoffrey D Smith
- Biology Department, Dixie State University, Saint George, UT 84770, USA
| | - Erin L Lewis
- Department of Biology, Utah State University, Logan, UT 84322, USA.,Ecology Center, Utah State University, Logan, UT 84322, USA
| | - John B Iverson
- Department of Biology, Earlham College, Richmond, IN 47374, USA
| | - Dale F DeNardo
- School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA
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Holden KG, Gangloff EJ, Miller DAW, Hedrick AR, Dinsmore C, Basel A, Kutz G, Bronikowski AM. Over a decade of field physiology reveals life-history specific strategies to drought in garter snakes ( Thamnophis legans). Proc Biol Sci 2022; 289:20212187. [PMID: 35078358 PMCID: PMC8790353 DOI: 10.1098/rspb.2021.2187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Changing climates and severe weather events can affect population viability. Individuals need to buffer such negative fitness consequences through physiological plasticity. Whether certain life-history strategies are more conducive to surviving changing climates is unknown, but theory predicts that strategies prioritizing maintenance and survival over current reproduction should be better able to withstand such change. We tested this hypothesis in a meta-population of garter snakes having naturally occurring variation in life-history strategies. We tested whether slow pace-of-life (POL) animals, that prioritize survival over reproduction, are more resilient than fast POL animals as measured by several physiological biomarkers. From 2006 to 2019, which included two multi-year droughts, baseline and stress-induced reactivity of plasma corticosterone and glucose varied annually with directionalities consistent with life-history theory. Slow POL animals exhibited higher baseline corticosterone and lower baseline glucose, relative to fast POL animals. These patterns were also observed in stress-induced measures; thus, reactivity was equivalent between ecotypes. However, in drought years, measures of corticosterone did not differ between different life histories. Immune cell distribution showed annual variation independent of drought or life history. These persistent physiological patterns form a backdrop to several extirpations of fast POL populations, suggesting a limited physiological toolkit to surviving periods of extreme drought.
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Affiliation(s)
- Kaitlyn G. Holden
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - Eric J. Gangloff
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - David A. W. Miller
- Department of Ecosystem Science and Management, Penn State University, University Park, PA 16802, USA
| | - Ashley R. Hedrick
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - Carli Dinsmore
- Department of Ecosystem Science and Management, Penn State University, University Park, PA 16802, USA
| | - Alison Basel
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - Greta Kutz
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - Anne M. Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
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