Vertebral number in adders, Vipera berus: direct and indirect effects on growth

Given the importance of body size, and thereby growth rate, for many reproductive parameters in snakes, morphological traits conferring an advantage in terms of growth may be important targets of selection. Studies have demonstrated effects of vertebral number of growth rate in garter snakes. In this study effects of total number of body vertebrae and of number of abnormal body vertebrae (obtained by counting number of ventral scutes and number of abnormal scutes) on growth rate in free-ranging male and female adders, Vipera berus (L.), are examined by calculating directional performance gradients (estimating linear effects) and stabilizing performance gradients (estimating curvilinear effects). After controlling for body size (SVL) female adders demonstrated a significant positive directional gradient for vertebral number, and a significant interaction between body size and vertebral number, showing that females with more vertebrae have higher size-specific growth rates, and that this effect is strongest among small, fast growing individuals. Females also showed a weak stabilizing effect of abnormal vertebrae. Males, on the other hand, showed a positive directional gradient for number of abnormal vertebrae, whereas no effect of vertebral number was observed. Indirect effects of the same variables were evaluated by use of path analysis. Generally, indirect effects were weak and did not substantially increase the amount of explained variance in growth rate. Field data showed that the correlation between vertebral number and growth rate in females was stronger in years with higher overall growth rate. To evaluate whether vertebral number and food availability show an interactive effect I used captive born juvenile adders in an experiment with two different food levels. The experiment confirmed the field data. No relationship between vertebral number and growth was observed in the low food level group, whereas in the high food level group a significant positive correlation was demonstrated. Finally, the heritability of vertebral number was examined using a mother-offspring regression and a full-sib analysis. The estimated heritabilities were 0.30 and 0.39, respectively. From these results it is concluded that both vertebral number and abnormal vertebral number may significantly affect growth in adders, but that this effect may differ between sexes and among years.     

The genetic structure of adders (Vipera berus) in Fennoscandia: congruence between different kinds of genetic markers

In order to elucidate the colonization history of Fennoscandian adders (Vipera berus), the phylogeographical patterns of two nuclear sets of DNA markers (random amplified polymorphic DNA and microsatellite) are compared with that previously obtained from mitochondrial DNA. An eastern and a western lineage within Fennoscandian adders is readily distinguishable using both sets of nuclear markers, corroborating the hypothesis that the lineages stem from separate glacial refugia. Moreover, the same contact zones as were derived from mitochondrial data are clearly identifiable. Both sets of nuclear markers detect a high level of admixture across one zone in northern Finland, with introgression reaching far west into Sweden.     

A novel method of behavioural thermoregulation in butterflies

Abstract The requirement for efficient thermoregulation has directed the coevolution of specialized morphological and behavioural traits in ectotherms. Adult butterflies exhibit three thermoregulatory mechanisms, termed dorsal, lateral and reflectance basking. In this study, we investigate a potential fourth mechanism whereby individuals perch with their wings fully spread and angled downwards such that the margins are appressed to the substrate. We find that mate‐locating male Hypolimnas bolina (L.) (Nymphalidae) adopt this posture when operational thoracic temperatures are lowest (less than approximately 34 °C). As thoracic temperature increases, males perch with wings increasingly closed and ultimately select shaded microhabitats. Using thermocouple‐implanted dead models, we show that appressed posture individuals warm faster than those adopting the conventional dorsal‐basking (horizontal wing) posture. This thermal advantage is not mitigated by shading of the outer 60–70% of the wing area, which suggests that – as with the conventional dorsal posture – only the basal wing surfaces contribute to heat gain via the absorption of solar irradiation. These investigations suggest that appression represents a novel extension of conventional dorsal basking behaviour in butterflies.     

Behavioral thermoregulation and critical thermal limits of giant keyhole limpet Megathura crenulata (Sowerby 1825) (Mollusca; Vetigastropoda)

The thermoregulatory behavior of the giant keyhole limpet Megathura crenulata was determined in a horizontal thermal gradient during the day at 18.9 °C and 18.3 °C for the night. The final preferendum determined for giant keyhole limpets was of 18.6±1.2 °C.Limpets' displacement velocity was 10.0±3.9 cm h⁻¹ during the light phase and 8.4±1.6 cm h⁻¹ during the dark phase. The thermotolerance (measured as CTMax at 50%) was determined in a keyhole limpet in three acclimation temperatures 17, 20, and 23 °C. Limpets were subjected to water increasing temperatures at a rate of 1 °C every 30 min, until they detached from the substrate. The critical thermal maximum at 50% was 27.2, 27.9 and 28.3 °C respectively.     

The distribution and status of the adder (Vipera berus L) in Scotland determined from questionnaire surveys

Abstract. During 1992 two questionnaire surveys, aimed at farmers and sections of the general public, were conducted to determine the distribution and status of the adder ( Vipera berus L.) in Scotland. In total, 94% of the Scottish mainland and inner isles were covered by the two surveys. The adder appears to be widespread throughout Scotland, although it is absent from much of the Central Valley, the Outer Hebrides and Northern Isles, and from much of the mountainous region between Inverness and Glasgow.
The distribution of the adder in Scotland was compared with the distributions of different habitat types defined in the ITE Land Class survey. Adders were strongly associated with areas of heterogeneous land use and negatively associated with intensively arable areas and rugged mountainous areas. Strong evidence was found to suggest that perceived adder abundance had declined during the last 10 years. Although the evidence suggesting that the distribution of adders in Scotland had changed was less strong, the results of the Farm Survey did indicate that it had contracted. The perceived change in status of the adder in Scotland during the last 10 years was compared with the observed changes in land use over the same period.     

Development of autonomic and behavioural thermoregulation in turkeys (Meleagris gallopavo)

1. 1.|Heat production (HP) and body temperature (T_b) measurements were conducted at ambient temperatures (T_a) between 10 and 40°C. In addition preference temperatures (PT) were determined in a temperature channel and T_b was measured at preferred T_a

2. 2.|The influence of age on T_b at constant, as well as at PT, was proved. Increasing age was accompanied by an elevation of T_b whereas HP remained constant in the mid-range of T_a

3. 3.|The lower T_b in the first days of life is suggested to result from a lower thermoregulatory set point during the postnatal period.

4. 4.|The PT were different for the observed types of behaviour. The PT at rest was higher than the PT during locomotion, food intake and drinking.

Body Temperature Changes in Free-ranging Baboons (Papio hamadryas ursinus) in the Namib Desert, Namibia

We surgically implanted temperature sensitive telemeters intraperitonealy in free-ranging baboons. Thereafter, we recorded body temperature changes while the baboons were free-ranging and under visual observation. Two distinct patterns of daily body temperature fluctuations occurred; they were related to the availability of drinking water. Core body temperature fluctuated by as much as 5.3°C and regularly exceeded 41°C. Behavioral adaptations of the baboons, notably sandbathing, appeared to be associated with the regulation of body temperature.     

Seasonal variation of mortality,detectability, and body condition in a population of the adder (Vipera berus)

We analyzed seasonal variation in mortality rates in adult males and females of the European adder (Vipera berus), using data collected during a 13‐year capture–recapture study (2005–2017) in a large population. We concurrently obtained quantitative information on the seasonal variation in the detectability and body condition of adders. Our results show strong seasonality in body condition, encounter, and capture rates of adult adders, and these patterns differ markedly between sexes and between breeding and nonbreeding females. Seasonal variation in mortality rates was however virtually nonexistent in males and moderately low in both breeding and nonbreeding females. In addition, we found no evidence for among‐year differences in the seasonal mortality schedules of males and females. During periods of intensive basking, both males and pregnant females are highly visible for humans, but are not subject to strong natural mortality. This low susceptibility to predation is presumably induced by various factors, including the limitation of overt exposure to short periods of time and specific microhabitats, the dorsal coloration pattern that provides cryptic protection and possibly also an aposematic warning signal, and presumed seasonal differences in the foraging behavior and food requirements of natural predators. Our data provide some evidence that female adders, but not males, are relatively vulnerable to predation during the seasonal migrations between the hibernation and feeding habitats. Mortality in the females was not much elevated during their breeding years, but was notably highest in the spring of the ensuing nonbreeding year. After giving birth, reproductive females are extremely emaciated and have a weakened general condition. They then run the risk of dying from starvation either before, during, or after hibernation. The higher mortality after giving birth, that is sustained over a period of ca. 9 months, should be considered as an indirect and delayed survival cost of reproduction.     

Genotyping validates photo‐identification by the head scale pattern in a large population of the European adder (Vipera berus)

Capture‐mark‐recapture procedures are a basic tool in population studies and require that individual animals are correctly identified throughout their lifetime. A method that has become more and more popular uses photographic records of natural markings, such as pigmentation pattern and scalation configuration. As with any other marking tool, the validity of the photographic identification technique should be evaluated thoroughly. Here, we report on a large‐scale double‐marking study in which European adders (Vipera berus) were identified by both microsatellite genetic markers and by the pattern of head scalation. Samples that were successfully genotyped for all nine loci yielded 624 unique genotypes, which matched on a one‐to‐one basis with the individual assignments based on the head scalation pattern. Thus, adders considered as different individuals by their genotypes were also identified as different individuals by their head scalation pattern, and vice versa. Overall, variation in the numbers, shape, and arrangement of the head scales enabled us to distinguish among 3200+ photographed individual snakes. Adders that were repeatedly sequenced genetically over intervals of 2–3 years showed no indication whatsoever for a change in the head scale pattern. Photographic records of 900+ adders that were recaptured over periods of up to 12 years showed a very detailed and precise match of the head scale characteristics. These natural marks are thus robust over time and do not change during an individual's lifetime. With very low frequency (0.3%), we detected small changes in scalation that were readily discernible and could be attributed to physical injury or infection. Our study provides a conclusive validation for the use of photo‐identification by head scale patterns in the European adder.     

Behavioural thermoregulation by the endangered crocodile lizard (Shinisaurus crocodilurus) in captivity

Understanding the factors that may affect behavioural thermoregulation of endangered reptiles is important for their conservation because thermoregulation determines body temperatures and in turn physiological functions of these ectotherms. Here we measured seasonal variation in operative environmental temperature (T_e), body temperature (T_b), and microhabitat use of endangered crocodile lizards (Shinisaurus crocodilurus) from a captive population, within open and shaded enclosures, to understand how they respond to thermally challenging environments. T_e was higher in open enclosures than in shaded enclosures. The T_b of lizards differed between the open and shaded enclosures in summer and autumn, but not in spring. In summer, crocodile lizards stayed in the water to avoid overheating, whereas in autumn, crocodile lizards perched on branches seeking optimal thermal environments. Crocodile lizards showed higher thermoregulatory effectiveness in open enclosures (with low thermal quality) than in shaded enclosures. Our study suggests that the crocodile lizard is capable of behavioural thermoregulation via microhabitat selection, although overall, it is not an effective thermoregulator. Therefore, maintaining diverse thermal environments in natural habitats for behavioural thermoregulation is an essential measure to conserve this endangered species both in the field and captivity.     

Thermoregulatory significance of basking behaviour in the raccoon dog (Nyctereutes procyonoides)

1. 1.|The raccoon dogs frequently basked in spring while keeping their dark chest area towards the sun. The importance of this behaviour for the thermal balance was examined by using a cylinder model, and the results were compared with that of the blue fox which has pale chest and no basking behaviour.

2. 2.|With no external radiation source, cooling rates of blue fox and racoon dog models were almost equal, while in the sunshine with the chest area towards the sun, raccoon dog gained and blue fox lost heat.

3. 3.|In the same sunshine, the raccoon dog lost heat if its back area was towards the sun in comparison with the situation when the chest area was towards the sun.

4. 4.|Temperatures at the skin level were much higher for sun-exposed raccoon dogs than blue foxes especially on the chest area.

5. 5.|It is concluded that the hair coat structure of the raccoon dog is especially favourable for trapping heat from the sun, and with postural adjustments the animal takes maximal advantage of this free heat.

Differences in the thermal physiology of adult Yarrow's spiny lizards (Sceloporus jarrovii) in relation to sex and body size

Sexual size dimorphism (SSD) is often assumed to reflect the phenotypic consequences of differential selection operating on each sex. Species that exhibit SSD may also show intersexual differences in other traits, including field‐active body temperatures, preferred temperatures, and locomotor performance. For these traits, differences may be correlated with differences in body size or reflect sex‐specific trait optima. Male and female Yarrow's spiny lizards, Sceloporus jarrovii, in a population in southeastern Arizona exhibit a difference in body temperature that is unrelated to variation in body size. The observed sexual variation in body temperature may reflect divergence in thermal physiology between the sexes. To test this hypothesis, we measured the preferred body temperatures of male and female lizards when recently fed and fasted. We also estimated the thermal sensitivity of stamina at seven body temperatures. Variation in these traits provided an opportunity to determine whether body size or sex‐specific variation unrelated to size shaped their thermal physiology. Female lizards, but not males, preferred a lower body temperature when fasted, and this pattern was unrelated to body size. Larger individuals exhibited greater stamina, but we detected no significant effect of sex on the shape or height of the thermal performance curves. The thermal preference of males and females in a thermal gradient exceeded the optimal temperature for performance in both sexes. Our findings suggest that differences in thermal physiology are both sex‐ and size‐based and that peak performance at low body temperatures may be adaptive given the reproductive cycles of this viviparous species. We consider the implications of our findings for the persistence of S. jarrovii and other montane ectotherms in the face of climate warming.     

Life history adaptation along a latitudinal cline in the water strider Aquarius remigis (Heteroptera: Gerridae)

We addressed the general hypothesis that life history differences among eastern populations of the North American water strider, Aquarius remigis (Heteroptera: Gerridae), along a north-south gradient are manifestations of genetic differentiation due to natural selection. We raised offspring of two field-caught populations from each of three latitudes in a common laboratory environment at 20° C and two photoperiods. Nearly all Quebec (PQ) individuals (ca. 46° N) entered diapause to reproduce the following spring (univoltine life cycle), while intermediate proportions of New York (NY; ca. 43° N) and New Jersey (NJ; ca. 41° N) individuals reproduced directly, producing a second generation (bivoltine life cycle). PQ females were smaller, developed faster, and laid smaller eggs than NY and NJ individuals; NY and NJ populations differed little in these variables. NY females had longer life spans than either PQ or NJ females, but lower oviposition rates. Total reproductive output did not differ across latitudes. Photoperiod affected body length, development time, and reproductive pathway, resulting in a latitude by environmental interaction. PQ individuals reproduced directly under 15L : 9D (summer) conditions only, while the NY and NJ populations exhibited more direct reproduction under 13L : 11D (spring or fall) conditions. Some life history characters of the NY and NJ populations displayed the higher variability indicative of phenological transition zones. These results indicate local adaptation of populations to long-term climatic patterns. Water striders appear to adapt to longer seasons by extending development, growing larger, and breeding directly. Larger body size and extended or rapid development are associated with bivoltinism and increase in egg size, but not necessarily with higher fecundity or oviposition rate. The phenological transition zone appears to be unrelated to a transition zone a little further south established by allozyme data and morphology, as all populations studied here could be electrophoretically identified as northern "type".     

Behavioural thermoregulation by subyearling fall (autumn) Chinook salmon Oncorhynchus tshawytscha in a reservoir

This study investigated behavioural thermoregulation by subyearling fall (autumn) Chinook salmon Oncorhynchus tshawytscha in a reservoir on the Snake River, Washington, U.S.A. During the summer, temperatures in the reservoir varied from 23° C on the surface to 11° C at 14 m depth. Subyearlings implanted with temperature-sensing radio transmitters were released at the surface at temperatures >20° C during three blocks of time in summer 2004. Vertical profiles were taken to measure temperature and depth use as the fish moved downstream over an average of 5·6–7·2 h and 6·0–13·8 km. The majority of the subyearlings maintained average body temperatures that differed from average vertical profile temperatures during most of the time they were tracked. The mean proportion of the time subyearlings tracked within the 16–20° C temperature range was larger than the proportion of time this range was available, which confirmed temperature selection opposed to random use. The subyearlings selected a depth and temperature combination that allowed them to increase their exposure to temperatures of 16–20° C when temperatures <16 and >20° C were available at lower and higher positions in the water column. A portion of the subyearlings that selected a temperature c. 17·0° C during the day, moved into warmer water at night coincident with an increase in downstream movement rate. Though subyearlings used temperatures outside of the 16–20° C range part of the time, behavioural thermoregulation probably reduced the effects of intermittent exposure to suboptimal temperatures. By doing so, it might enhance growth opportunity and life-history diversity in the population of subyearlings studied.     

Metabolism and thermoregulation in Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli)

1 Metabolic rates (Vo₂), body temperature (T_b), and thermal conductance (C) were first determined in newly captured Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli) from the Inner Mongolian grasslands at a temperature range from 5 to 35 °C.

2 The thermal neutral zone (TNZ) was between 25 and 32.5 °C for Maximowiczi's voles and between 25 and 30 °C for Djungarian hamsters. Mean T_b was 37.0±0.1 °C for voles and 36.2±0.1 °C for hamsters. Minimum thermal conductance was 0.172±0.004 ml O₂/g h °C for voles and 0.148±0.003 ml O₂/g h °C for hamsters.

3 The mean resting metabolic rate within TNZ was 2.21±0.05 ml O₂/g h in voles and 2.01±0.07 ml O₂/g h in hamsters. Nonshivering thermogenesis was 5.36±0.30 ml O₂/g h for voles and 6.30±0.18 ml O₂/g h for hamsters.

4 All these thermal physiological properties are adaptive for each species and are shaped by both macroenvironmental and microenvironmental conditions, food habits, phylogeny and other factors.

Behavioral thermoregulation and the role of melatonin in a nocturnal snake

Daily and seasonal variations in hormone levels influence the complex interactions between behavior and physiology. Ectothermic animals possess the unique ability behaviorally to adjust body temperature (T(b)) to control physiological rate processes. Thus, a hormone may indirectly influence a physiological rate by directly influencing the behaviors that adjust or control that rate process. Although many hormonal influences on behavioral regulation of T(b) remain uninvestigated, melatonin (MEL) generally is considered a hormone that decreases mean preferred T(b). Many ectotherms demonstrate the selection of lower T(b)'s in response to increased MEL concentrations. Here, we examined the influence of MEL on the behavioral regulation of T(b) in the nocturnal African house snake Lamprophis fuliginosus. A series of experiments with two injection regimes of MEL had no significant effect on the mean preferred T(b) of L. fuliginosus. In addition, mean preferred T(b)'s during the photophase did not differ significantly from those during scotophase. Our findings suggest that L. fuliginosus does not respond to elevated concentrations of either endogenous or exogenous MEL. To verify that the African house snake is nocturnal, we investigated activity patterns of L. fuliginosus throughout the photoperiod. The activity period of L. fuliginosus occurs in the scotophase of the photoperiod, a pattern consistent with that of nocturnal species. This suggests that nocturnal organisms such as L. fuliginosus may not respond to MEL in the same manner as many diurnal species. Our results support the hypothesis that some animals, particularly nocturnal species, may have developed alternative responses to increased plasma concentrations of MEL.     

倭蜂猴静止代谢率和体温调节的研究

通过研究倭蜂猴在不同环境温度下的静止代谢率和体温调节特征发现；倭蜂猴（Ｎｙｃｔｉｃｅｂｕｓ ｐｙｇｍａｅｃｕｓ）的ＲＭＲ为０．４９８±０．０３９６０２ｍｌ／ｈｒ．ｇ，仅为预期值的６３．７％；热中性区不明显，实测 下临界温度为３０℃；平均最低热传导为０． ０８０４±０． ００２１０２ｍｌ／ｈｒ． ｓ．℃；在室温下平均体温为３３． ８ ±０．１８℃；在冷压下体温变化较大，温调指数为０．５３５；在高温时主要以高体温和分泌唾液进行体温调节。显示典型热带原猴类动物热能代谢特征。