Thermoregulatory Precision Research Articles

Thermoregulatory Behaviour of Rock Lizards in Response To Tail Loss

Abstract The consequences of tail loss on the thermal biology of high-altitude rock lizards (Lacerta monticola) were studied by comparing field body temperatures, selected body temperatures in a gradient, and behavioural patterns of thermoregulation of tailed and tailless lizards in the field. Neither field nor selected body temperatures differed significantly between these groups. Time spent basking, mean duration of basking, and basking frequency did not differ between tailed and tailless lizards. Tailless lizards seemingly adjusted for running impairment by using rocks to a greater extent than did tailed lizards, and low morning body temperatures by increasing maximal duration of basking periods and keeping shorter distances to the nearest refuge. Tailless lizards modify thermoregulatory behaviour, but obtain the same thermoregulatory precision as tailed lizards, possibly allowing maximization of physiological processes linked to tail regeneration.

Relationship of Wing Beat Frequency and Temperature During Take-Off Flight in Temperate-Zone Beetles

ABSTRACT In 24 species of temperate-zone beetles thoracic temperatures (Tth), and wing beat frequency (n) were measured over a range of ambient temperatures (Ta) during take-off flight. The sensitivity of wing beat frequency to thoracic temperature varied greatly in different species: Q10 values ranged from 0·8 to 1·3. The wing beat frequency of beetles with higher average n was more sensitive to thoracic temperature. It is suggested that the temperature sensitivity of wing beat frequency results from temperature-dependent changes in the resonant properties of the beetle flight system rather than from changes in the temperature sensitivity of the muscle or nervous system. There was large variability in thermoregulatory precision. Beetles with higher n tended to thermoregulate more precisely than beetles with lower n. Measurements of thoracic temperature before and after flight indicated endothermic heat production during pre-flight activity, but not during the brief take-off flights.

The parietal eye and thermoregulatory behavior of Crotaphytus collaris (Squamata: Iguanidae)

1. 1. Male Crotaphytus collaris with shielded parietal eyes, sham shielded parietal eyes and non-shielded controls acclimatized to 25 ± 1°C and an LD 12:12 photoperiod did not select significantly different body temperatures over a 24 hr period with uniform light (UL) over a linear thermal gradient, a point-source of light over the hot end (LH) or a point-source of light over the cold end of the gradient (LC). 2. 2. Mean body temperatures of the shielded LH lizards from 2100 to 0900 hr (32.1 ± 0.70°C) were significantly higher ( P < 0.05) than those of the non-shielded LH lizards (28.6 ± 0.86°C). 3. 3. Diel cycles of temperature selection were observed in all 3 UL groups and in the non-shielded LH group but not in the shielded LH or any of the LC groups. 4. 4. The parietal eye did not have an effect on thermoregulatory precision, but did affect diel cycles of temperature selection and, in the LH groups, body temperatures during scotophase.

Daily Variation in the Body Temperatures of Free‐Ranging Garter Snakes

This study describes how the body temperatures (Tb) of individual garter snakes varied on a daily basis under field conditions. Temperature—sensitive radio transmitters were surgically implanted into 10 Thamnophis elegans vagrans in eastern Washington. The snakes were released and monitored at 15—min intervals for periods of up to several days from June 1979 to May 1980. Operative environmental temperatures were estimated with painted metal models and were used to indicate possible Tb's. The combination of telemetered body temperatures with operative temperature data permitted detailed description of Tb variation and evaluation of the relative importance of the physical environment and behavior in determining that variation. The physical environment usually prevented the snakes from attaining preferred (selected) Tb's and thus limited when and where they could be active and potentially reduced their physiological performance. On cool days or at night, when operative temperatures (Te) were &lt;15°C, the snakes remained underground and body temperatures changed gradually. On moderate days (15° &lt; Te &lt; 30°), the snakes usually emerged but were unable to maintain preferred body temperatures, and Tb variation was marked. On warm days (Te &gt; 30°), the snakes selected Tb's within their preferred temperature range, and variation in Tb was small (e.g., range = 28.0°—32.5° X = 29.9°, SD = 1.32°). The snakes stayed within their preferred temperature range &gt;90% of the time when Te &gt; 30°. Their high thermoregulatory precision and thermal utilization presumably maintained high levels of physiological performance on warm days. Delays in emergence accounted for most instances in which the snakes did not utilize available thermal opportunities.

Effects of temperature on interactions of physiological and behavioural capacities of larval California grunion: Adaptations to the planktonic environment

The relationship between temperature-specific (11.3–27.1°C) rates of yolk utilization and temperature preference of California grunion, Leuresthes tenuis (Ayres), have been compared. Yolk-sac larvae experienced difficulty metabolizing protein at and above 25°C, and below 15°C they encountered problems with fat metabolism. These temperatures limited the range for normal embryonic development. The oil globule persisted longer than the yolk and may provide buoyancy to the anterior end as well as energy. Thermoregulatory precision increased with number of days post-hatching. Yolk-sac larvae preferred ≈ 25°C; this temperature minimized duration of the yolk-sac stage but was outside the range for maximum growth efficiency (18–23°C). Following yolk resorption, non-feeding larvae preferred 18°C, which conserved energy but still maximized growth efficiency. Until at least 69 days post-hatching, larvae past the yolk-sac stage selected temperatures that maximized growth efficiency. Physiological and behavioural results indicate that larvae selected cooler temperatures when not feeding. This has been discussed and related to an apparent general adaptive behaviour to maximize bioenergetic efficiency.

Behavioral thermoregulatory abilities of tropical coral reef fishes: a comparison with temperate freshwater and marine fishes

Eight species in six different families of tropical marine reef fishes from the Indo-West Pacific region (Naso lituratus, Zebrasoma.flavescens, Balistes fuscus, B. vidua, Forcipiger longirostris, Echidna zebra, Cromileptes altivelis, Canthigaster jactator) were tested for ability to thermoregulate behaviorally in electronic shuttleboxes. All of these species preferred mean temperatures between 20 and 30°C, but differed considerably in thermoregulatory precision. All species avoided lethal high or low temperatures (i.e., they did not die during the tests), and some species thermoregulated as precisely as temperate species. Some temperate species prefer higher temperatures (above 30°C) than do these tropical reef species.

Thermoregulatory Precision in Three Species of Whiptail Lizards (Lacertilia: Teiidae)

The mean body temperatures of the three species of Cnemidophorus were high both in the field and in the laboratory thermal gradient. Individual variation about the mean temperature was small, indicating precise thermoregulation, and the mean body temperatures (MBTs) were not significantly different for the three species. Mean body temperatures measured in the laboratory thermal gradient were slightly higher than temperatures recorded in the field. All three species displayed a similar posture when heating rapidly. The animals thermoregulated by shuttling between warm and cool areas, and this behavior resulted in sinelike fluctuations of body temperature (BT) with time. Sampling temperatures at 30-s intervals allowed analysis of short-term trends in BT and comparison of the characteristics of the sinelike curves for the three species. The average amplitude and period of the sinelike curves were compared for each species and were significantly different. The small amplitudes (less than 1.33 C) and short ave...

Thermoregulatory behavior of the pink shrimp Penaeus duorarom Burkenroad

Twelve juvenile pink shrimp.Penaeus duorarum Burkenroad, were tested individually for 3-day periods in electronic shuttle-boxes (Ichthyotrons) to determine their thermoregulatory capabilities (temperature preference and avoidance behavior). The shrimp thermoregulated more precisely at night, which was their active period (they were more than twice as active at night as they were by day). Their nocturnal mean thermal preferendum was 29.9 ± 0.2°C (mode 31°C, median 30°C, midpoint 29°C, range of voluntarily occupied temperatures 22–36°C, skewness −0.37). By day they were less active and exhibited much less thermoregulatory precision, spanning a 17–38°C range of voluntarily occupied temperatures out of a potentially available range of 0–50°C (diurnal mean 30.6 ± 0.3°C, mode 34°C, median 32°C, midpoint 27.5°C, skewness −0.76). The range of occupied temperatures was half again as great (21°C) by day as at night (14°C). The 24-hr mean (combined day and night) was 30.3 ±0.2°C (mode 31°C, median 30°C, midpoint 27.5°C, range 17–38°C, skewness −0.18).

Behavioral thermoregulation and activity in Homarus americanus

1. 1. American lobsters thermoregulated precisely for 6 days in an electronic shuttlebox (mode 16°C; range 15–21°C), with no significant difference in mean preferred temperature between night (17.1°C ± 0.15 SE) and day (17.2°C ± 0.18 SE), although mean hourly activity was 1.3 times as great at night as during the day. 2. 2. The preferred temperature falls within a zone (15–20°C) in which activity decreases with increasing temperature, while activity generally increases with temperature over the range 10–30°C; this may have implications for the adaptive value, if not the mechanism, of thermoregulatory behavior. 3. 3. During the second 6 days, thermoregulatory precision declined markedly (range 10–29°C; modes at 14°C and 26°C), perhaps representing a shift from preference to avoidance behavior, while the nocturnal activity pattern remained stable; the frequency distribution of occupied temperatures became nearly congruent with the temperature-activity relationship and complementary to the temperature distribution during the first 6 days.

Temperature Preferences of Four Fish Species in an Electronic Thermoregulatory Shuttlebox

Abstract Temperature preferences of four fish species were studied in an electronic thermoregulatory shuttlebox. The modal temperature preferences (final preferenda) of the four species were: black crappie (Pomoxis nigromaculatus), 24°C; carp (Cyprinus carpio), 29°C; chain pickerel (Esox niger), 24°C; and pumpkinseed (Lepomis gibbosus), 26°C. The species differed in thermoregulatory precision as well as in final preferred temperature, indicating the species-specific nature of thermal behavior. There was little intraspecific variation among individuals tested. The results agree well with those of other investigators using different methods and apparatus.