Food habits and the evolution of energetics in birds of paradise (Paradisaeidae)

Basal rates of metabolism, minimal thermal conductances, and body temperatures are reported for 13 species of birds of paradise that belong to nine genera. Body mass alone accounts for 91.7% of the variation in their basal rates. Basal rate in this family also correlates with food habits and the altitudinal limits to distribution. Species that feed almost exclusively on fruit have basal rates that average 79.4% of species in which >10% of the diet is insects, and species restricted to altitudes <1,000 m have basal rates that are 90.6% of those found at higher altitudes. The combination of body mass, food habits, and altitudinal distribution accounts for 99.0% of the variation in basal rate in the species studied. The application of food habits to a cladogram of the studied Paradisaeidae implies that frugivory and low basal rate were plesiomorphic in this family. The evolution of omnivory, defined as including >10% of the diet as insects, appears to have occurred at least twice, and in each case was associated with an increase in basal rate of metabolism. Basal rate increased at least thrice with a movement into the highlands. Basal rate, however, does not correlate with plumage dimorphism or with reproductive behavior. The basal rates of metabolism in manakins and birds of paradise, i.e., passerine frugivores, are greater than those found in nonpasserine frugivores. Thermal conductance correlates with body mass, which accounts for 85.8% of its variation in this family. Body temperature in paradisaeids, the mean of which was 40.2°C, may correlate with basal rate of metabolism.     

Stages in the ontogeny and a model of the evolution of bivalves (Mollusca)

Comparison of the ontogenies of bivalves of different habitats and systematic position provide two main conclusions. The first is that bivalves stick to a certain basic program of ontogeny which can be divided into six phases. The first three phases are parallel to those of some other invertebrates, the 4th phase is parallel to that of conchiferan molluscs, with, the 5th phase, bivalve characters are acquired, and in the 6th phase, genus-specific adult organization is reached. The second is that within this basic developmental programm specific differences occur. The ontogeny ofTeredora is similar to that of many marine bivalves and is characterized by a strong plasticity. The adult, in contrast, is highly specialized for living within wood. InAnodonta, the opposite is true and embryonic development even includes a parasitic stage, while the adult is of a more general organization. Due to brood-protection and embryonic nursing, the whole organogenesis ofSphaerium becomes directed towards adult organization. Ontogenetic development of a general body plan of the Bivalvia provides a model for the evolution of the first bivalves (protobranchs excluded) from univalves by a one-step alteration connected with shell mineralization and loss of the buccal mass affecting the embryo near end of embryogenesis.     

Quantum processes in evolution of regulation of living systems (mathematical modeling)

We have developed an imitation model of the appearance of regulation of physiological functions of protocell at initial stages of evolution of living system. It is based on suggestion of the appearance of signal function in spontaneously formed products of partial hydrolysis of the protocell polypeptides, based on which there appear the regulatory molecules—quanta of regulation. For construction of the model, the mathematical apparatus of final automats and of genetic algorithm is used. The model has demonstrated the positive role of involvement of regulatory peptides in the system of regulation of protocell functions to provide its viability under the changing envelopment conditions.     

Quantum processes in evolution of regulation of living system (mathematical modelling)

We have developed an imitation model of the appearance of regulation of physiological functions of protocell at the initial stages of evolution of living system. It is based on suggestion of the appearance of signal function in spontaneously formed products of partial hydrolysis of the protocell polypeptides, based on which there appear the regulatory molecules--quanta of regulation. For construction of the model, the mathematical apparatus of final automats and of genetic algorithm is used. The model has demonstrated the positive role of involvement of regulatory peptides in the system of regulation of protocell functions to provide its viability under the changing envelopment conditions.     

Ecology and energetics of encephalization in hominid evolution.

Hominid evolution is marked by very significant increase in relative brain size. Because relative brain size has been linked to energetic requirements it is possible to look at the pattern of encephalization as a factor in the evolution of human foraging and dietary strategies. Major expansion of the brain is associated with Homo rather than the Hominidae as a whole, and the energetic costs are likely to have forced a prolongation of growth rates and secondary altriciality. It is calculated here that modern human infants have energetic requirements approximately 9% greater than similar size apes due to their large brains. Consideration of energetic costs of brain allow the prediction of growth rates in hominid taxa and an examination of the implications for life-history strategy and foraging behaviour.     

Torpor, thermal biology, and energetics in Australian long-eared bats (Nyctophilus)

Previous studies have suggested that Australian long-eared bats (Nyctophilus) differ from northern-hemisphere bats with respect to their thermal physiology and patterns of torpor. To determine whether this is a general trait of Australian bats, we characterised the temporal organisation of torpor and quantified metabolic rates and body temperatures of normothermic and torpid Australian bats (Nyctophilus geoffroyi, 7 g and N. gouldi, 10 g) over a range of air temperatures and in different seasons. The basal metabolic rate of normothermic bats was 1.36 ± 0.17 ml g⁻¹ h⁻¹ (N. geoffroyi) and 1.22 ± 0.13 ml g⁻¹ h⁻¹ (N. gouldi), about 65% of that predicted by allometric equations, and the corresponding body temperature was about 36 °C. Below an air temperature of about 25 °C bats usually remained normothermic for only brief periods and typically entered torpor. Arousal from torpor usually occurred shortly after the beginning of the dark phase and torpor re-entry occurred almost always during the dark phase after normothermic periods of only 111 ± 48 min (N. geoffroyi) and 115 ± 66 min (N. gouldi). At air temperatures below 10 °C, bats remained torpid for more than 1 day. Bats that were measured overnight had steady-state torpor metabolic rates representing only 2.7% (N. geoffroyi) and 4.2% (N. gouldi) of the basal metabolic rate, and their body temperatures fell to minima of 1.4 and 2.3 °C, respectively. In contrast, bats measured entirely during the day, as in previous studies, had torpor metabolic rates that were up to ten times higher than those measured overnight. The steady-state torpor metabolic rate of thermoconforming torpid bats showed an exponential relationship with body temperature (r ² = 0.94), suggesting that temperature effects are important for reduction of metabolic rate below basal levels. However, the 75% reduction of metabolic rate between basal metabolic rate and torpor metabolic rate at a body temperature of 29.3 °C suggests that metabolic inhibition also plays an important role. Torpor metabolic rate showed little or no seasonal change. Our study suggests that Australian Nyctophilus bats have a low basal metabolic rate and that their patterns of torpor are similar to those measured in bats from the northern hemisphere. The low basal metabolic rate and the high proclivity of these bats for using torpor suggest that they are constrained by limited energy availability and that heterothermy plays a key role in their natural biology. Accepted: 22 November 1999     

Comparative energetics of the giant hummingbird (Patagona gigas)

Hummingbirds (family Trochilidae) represent an extreme outcome in vertebrate physiological design and are the only birds capable of sustained hovering. The giant hummingbird (Patagona gigas) is the largest trochilid, with a mass of ~20 g, and is found over an altitudinal range from 0 to 4,500 m above sea level. We report here measurements of daily, basal, and hovering rates of oxygen consumption in the giant hummingbird; compare these values with data from smaller hummingbirds; and assess overall metabolic and allometric limits to trochilid body size. The sustained metabolic scope (i.e., the ratio of daily energy expenditure to basal metabolic rate) in the giant hummingbird is higher than that in smaller hummingbirds but lies below a proposed theoretical maximum value for endotherms. Scaling exponents in the allometric relationships for different modes of energetic expenditure were comparable, suggesting that the giant hummingbird, although a clear outlier in terms of body size, does not obviously deviate from metabolic relationships derived from other trochilid taxa.     

Nutrition and energetics of the canary (Serinus canarius)

Canaries appear to be primarily seed-eaters, although there are no reports of their feeding ecology in the wild. In captivity, they are offered seed-based diets, preferring to consume seeds such as canary, rapeseed and millet. The mean daily dry-matter intake ranges from 3 to 4 g, which corresponds to a mean gross energy intake of approximately 70 kJ per bird per day. The efficiency of dietary metabolism is high (0.85), which equates to individual metabolizable energy intakes of 45-75 kJ per bird per day. For a canary of average body weight (22 g) the data can be fitted to a regression equation to predict a requirement of 62 kJ ME per day. This corresponds to published information on the energy requirements of other passerine species, but deviates from the predictive equation for poultry. The digestibility values for protein, fat and carbohydrate are similar to those obtained for the budgerigar, although it is likely that the digestibility coefficient is dependent upon the seed type and alimentary tract lipase and amylase activities. Nutrient requirements of canary chicks have not yet been determined, although recent studies have provided data on the nutrient intakes of developing chicks. The newly-hatched canary chick has a rapid growth rate, achieving 90% of its asymptotic body mass by 11 days of age. Gross energy intake is approximately 3 kJ per day following hatching and by day 10 is equivalent to that of an adult canary. It appears that the protein intake should lie between 16.5 and 21.9% of the diet (as is), with peak intake occurring between 8 and 10 days of age.     

Foraging energetics of arctic cormorants and the evolution of diving birds

Efficient body insulation is assumed to have enabled birds and mammals to colonize polar aquatic ecosystems. We challenge this concept by comparing the bioenergetics of cormorants ( Phalacrocorax carbo ) living in temperate and arctic conditions. We show that although these birds have limited insulation, they maintain high body temperature (42.3 °C) when diving in cold water (1–10 °C). Their energy demand at these times is extremely high (up to 60 W kg⁻¹). Free-living cormorants wintering in Greenland (water temperature −1 °C) profoundly alter their foraging activity, thus minimizing time spent in water and the associated high thermoregulatory costs. They then meet their daily food demand within a single intense dive bout (lasting 9 min on average). Their substantial energy requirements are balanced by the highest predatory efficiency so far recorded for aquatic predators. We postulate that similar behavioural patterns allowed early diving birds (Cretaceous) to colonize cold coastal areas before they evolved efficient insulation.     

Seasonal energetics of opossums (Didelphis virginiana) in Ohio

1. Female opossums acclimatized to each of the four seasons were not significantly different (P greater than 0.05) in oxygen consumption at a Ta of 0 degrees C; the overall average was 0.66 +/- 0.1 ml O2/g-hr. 2. Body weight decreased by 27% from autumn to spring; pelage density increased in winter, but thermal conductance changed very little between seasons. 3. Respirometry revealed no evidence of thermoregulatory adjustments in opossums acclimatized to winter in Ohio.     

Field energetics of free-living, lactating and non-lactating echidnas (Tachyglossus aculeatus)

We measured daily energy expenditure (DEE) and water turnover rates in lactating and non-lactating short beaked echidnas (Tachyglossus aculeatus) using the doubly labelled water technique during the lactation period in spring. Reproductively inactive echidnas were on average significantly heavier (median: 3354 g; range: 2929-3780 g; N=4) than lactating females (median: 2695 g; range: 2690-2715 g; N=3) during the equivalent time period. The median water flux rate of lactating echidnas (152 ml day(-1); range: 120-198 ml day(-1)) did not differ significantly from that of non-lactating females (170 ml day(-1); range: 128-227 ml day(-1)). The median DEE of echidnas that were lactating was 645 kJ day(-1) (range: 581-850 kJ day(-1)), which was not different from the median DEE of non-reproductive control females (763 kJ day(-1); range: 720-766 kJ day(-1)). Lactating females somehow compensate for the energy costs of milk production, resulting in a daily energy budget that is not different from that of non-reproductive females. At least part of their energy minimising strategy could involve the use of moderate heterothermy, allowing a greater proportion of daily energy expenditure to diverted to milk production.     

Hibernation and torpor in tropical and subtropical bats in relation to energetics, extinctions, and the evolution of endothermy

Torpor, the most effective means of energy conservation available to endotherms, is still widely viewed as a specific adaptation in a few high-latitude, cold-climate endotherms with no adaptive function in warm regions. Nevertheless, a growing number of diverse terrestrial mammals and birds from low latitudes (0-30°), including species from tropical and subtropical regions, are heterothermic and employ torpor. Use of torpor is especially important for bats because they are small, expend large amounts of energy when active, rely on a fluctuating food supply, and have only a limited capacity for storage of fat. Patterns of torpor in tropical/subtropical bats are highly variable, but short bouts of torpor with relatively high body temperatures (T(b)) are most common. Hibernation (a sequence of multiday bouts of torpor) has been reported for free-ranging subtropical tree-dwelling vespertilionids, cave-dwelling hipposiderids, and house-dwelling molossids. The observed range of minimum T(b) is ～6-30 °C, and the reduction of energy expenditure through the use of torpor, in comparison to normothermic values, ranges from 50 to 99%. Overall, torpor in the tropics/subtropics has been reported for 10 out of the currently recognized 18 bat families, which contain 1079 species, or 96.7% of all bats. Although it is unlikely that all of these are heterothermic, the large majority probably will be. Frequent use of torpor, including hibernation in diverse groups of tropical/subtropical bats, suggests that heterothermy is an ancestral chiropteran trait. Although data especially from the field are still scarce, it is likely that torpor, highly effective in reducing requirements for energy and water even under warm conditions, plays a crucial role in the long-term survival of the majority of small tropical and subtropical bats. Discovering how bats achieve this provides numerous opportunities for exiting new research.     

Metabolism,temperature relations,maternal behavior,and reproductive energetics in the ball python (Python regius)

Summary Thermogenic incubation has been documented in two large species of pythons, but the phenomenon has not been studied in small species with concomitantly large heat transfer coefficients. We describe behavior, metabolic rates, mass changes, and temperature relations for adult ball pythons (Python regius), the smallest member of the genus, during the reproductive cycle. Egg and hatchling metabolism and hatchling growth rates were also examined.Rates of oxygen consumption ( ) of both gravid and non-gravid snakes showed typical ectothermic responses to changing ambient temperature (T _a). TheQ ₁₀ forT _a's of 20–35°C was 2.2–2.3. The of gravid females was significantly greater than that of non-gravid snakes at allT _a. Maximum oxygen consumption ( max) during forced exercise was about 12 times resting atT _a=30°C.Eggs (5–6 per female) were laid in April. Total clutch mass was approximately 32% of the females' pre-oviposition mass. After oviposition, mother snakes coiled tightly around their clutches and remained in close attendance until the eggs hatched in June. Sudden decreases inT _a elicited abrupt but transient 2- to 4-fold increases in the of incubating females. Similar responses were not observed in non-incubating snakes. The steady-state of incubating females was independent ofT _a. In no case was body temperature (T _b) elevated more than a few tenths of a degree aboveT _a in steady-state conditions.The of developing eggs increased sigmoidally through the 58–70 day incubation period. Total oxygen consumption during incubation atT _a=29.2°C was about 3.61 per egg. Young snakes quadrupled their mass during their first year of growth.Compared to larger python species which are endothermic during incubation, ball pythons have similar aerobic scopes and higher mass-specific max. However, effective endothermy in ball pythons is precluded by high thermal conductance and limited energy stores.     

Immature Stages of Hydrobiomorpha spinosa (Orchymont, 1928) (Coleoptera: Hydrophilidae)

The preimaginal stages of the Neotropical species Hydrobiomorpha spinosa (Orchymont) are described and figured for the first time. They are compared to the larvae of the New World species Hydrobiomorpha casta (Say) and to unidentified African and Australian larvae. Bionomical notes on this species are included.     

Moult energetics of the northern elephant seal (Mirounga angustirostris)

Northern elephant seals, Mirounga angustirostris , undergo an annual moult during which they shed all of their pelage and underlying epidermis. Moulting takes place on land and lasts a mean of 32.0±6.6 days. During this time the mean mass loss of adult females was 24.7±6.1%. Mean body composition at arrival (25.6±4.8%fat) did not differ significantly from that at departure (24.9±3.2%fat). Fat catabolism accounted for 93.6%of derived energy and 41%of mass lost. Approximately 3.5%of total mass loss was associated with the shedding of the pelage and epidermis. Moulting female northern elephant seals express an average daily metabolic rate of 2.0±0.6 times that predicted for adult terrestrial mammals. This energy demand was met by losing 3.0 kg d^-1 of total body mass. These energy expenditures suggest that, similar to data for harbour seals, the moult period is a time of relatively low energy expenditure.