Related Experiment Video
Updated: Aug 7, 2026
06:20
A Simple Approach to Manipulate Dissolved Oxygen for Animal Behavior Observations
Published on: June 28, 2016
Weak coupling between gas exchange and water loss in lungless salamanders
Nathalie M Alomar1, Eric A Riddell2, Martha M Muñoz1
1Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT 06511.
Integrative and Comparative Biology
|August 5, 2026
Summary
Woodland salamanders (Plethodon) use skin for gas exchange and water loss. Their metabolic rate and water loss are not tightly linked, with different species adapting to varied environments.
Area of Science:
- Physiology
- Ecology
- Evolutionary Biology
Background:
- Terrestrial amphibians face a trade-off between gas exchange and water loss due to permeable respiratory surfaces.
- Woodland salamanders (Plethodon) are lungless, relying solely on cutaneous respiration, linking these two physiological processes.
Purpose of the Study:
- To investigate the relationship between metabolic rate and water loss across 30 Plethodon species.
- To determine if physiological traits are consistently coupled or can diverge despite functional links.
- To correlate these traits with environmental factors like elevation, range size, and climate.
Main Methods:
- Quantified metabolic rate and water loss rate in 30 Plethodon species.
- Analyzed the ratio between water loss and gas exchange (transpiration ratio).
- Related physiological data to elevational distributions, geographic range, and climatic conditions.
- Performed phylogenetic path analyses.
Main Results:
- Metabolic rate and water loss were not tightly correlated within Plethodon, unlike in amphibians generally.
- Metabolic rate correlated with elevation and climate; lower rates in higher, cooler environments.
- Water loss showed weaker environmental associations, but transpiration ratio varied with lower elevational limits, indicating greater hydric efficiency in species at lower elevations.
- Phylogenetic analyses suggested lower elevational limits mediate the link between physiology and range size.
Conclusions:
- Plethodon species exhibit diverse physiological strategies for cutaneous respiration, not a single shared pattern of coupling between gas exchange and water loss.
- Environmental factors, particularly elevation and climate, influence metabolic rate and hydric efficiency differently across species.
- The findings highlight the complex interplay between physiology, environment, and adaptation in terrestrial amphibians.
Related Concept Videos
01:24External and Internal Respiration
External respiration occurs in the lungs, and it is the first step in the journey of oxygen inside the body. When we inhale, oxygen enters our lungs and diffuses across the thin alveolar membrane. The alveoli are tiny, air-filled sacs that provide a vast surface area for gas exchange. Oxygen in the alveoli has a higher partial pressure (105 mmHg) than in the adjacent pulmonary capillaries (40 mmHg), establishing a pressure gradient. As a result, oxygen molecules move from the alveoli into the...
01:20Gas Exchange and Transport
Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them.
02:32Osmoregulation in Fishes
When cells are placed in a hypotonic (low-salt) fluid, they can swell and burst. Meanwhile, cells in a hypertonic solution—with a higher salt concentration—can shrivel and die. How do fish cells avoid these gruesome fates in hypotonic freshwater or hypertonic seawater environments?
01:57Adaptations that Reduce Water Loss
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
01:05Breathing
The process of breathing, inhaling and exhaling, involves the coordinated movement of the chest wall, the lungs, and the muscles that move them. Two muscle groups with important roles in breathing are the diaphragm, located directly below the lungs, and the intercostal muscles, which lie between the ribs. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity and creating more room for the lungs to expand. When the intercostal muscles contract, the ribs...
01:20Respiration and Gaseous Exchange
The intricate interplay between the cardiovascular and respiratory systems is crucial for efficiently transporting respiratory gases throughout the body. Let us explore the cardiovascular system's multifaceted functions, emphasizing its pivotal role in gas exchange.
Respiration involves the exchange of gases, especially oxygen (O2) and carbon dioxide (CO2), between the alveoli and body cells, a process facilitated by blood circulation. As a result, the cardiovascular system, which involves the...
Respiration involves the exchange of gases, especially oxygen (O2) and carbon dioxide (CO2), between the alveoli and body cells, a process facilitated by blood circulation. As a result, the cardiovascular system, which involves the...