Fiber capillarization relative to mitochondrial volume in diaphragm of shrew.

The objective was to examine fiber capillarization in relation to fiber mitochondrial volume in the highly aerobic diaphragm of the shrew, the smallest mammal. The diaphragms of four common shrews [Sorex araneus; body mass, 8.2 +/- 1.3 (SE) g] and four lesser shrews (Sorex minutus, 2.6 +/- 0.1 g) were perfusion fixed in situ, processed for electron microscopy, and analyzed by morphometry. Capillary length per fiber volume was extremely high, at values of 8,008 +/- 1,054 and 12,332 +/- 625 mm(-2) in S. araneus and S. minutus, respectively (P = 0.012), with no difference in capillary geometry between the two species. Fiber mitochondrial volume density was 28.5 +/- 2.3% (S. araneus) and 36.5 +/- 1.4% (S. minutus; P = 0.025), yielding capillary length per milliliter mitochondria values (S. araneus, 27.8 +/- 1.5 km; S. minutus, 33.9 +/- 2.2 km; P = 0.06) as high as in the flight muscle of the hummingbird and small bats. The size of the capillary-fiber interface (i.e., capillary surface per fiber surface ratio) per fiber mitochondrial volume in shrew diaphragm was also as high as in bird and bat flight muscles, and it was about two times greater than in rat hindlimb muscle. Thus, whereas fiber capillary and mitochondrial volume densities decreased with increased body mass in S. araneus compared with S. minutus Soricinae shrews, fiber capillarization per milliliter mitochondria in both species was much higher than previously reported for shrew diaphragm, and it matched that of the intensely aerobic flight muscles of birds and mammals.     

Energetic cost of foraging in free-diving emperor penguins.

Hypothesizing that emperor penguins (Aptenodytes forsteri) would have higher daily energy expenditures when foraging for their food than when being hand-fed and that the increased expenditure could represent their foraging cost, we measured field metabolic rates (FMR; using doubly labeled water) over 4-d periods when 10 penguins either foraged under sea ice or were not allowed to dive but were fed fish by hand. Surprisingly, penguins did not have higher rates of energy expenditure when they dove and captured their own food than when they did not forage but were given food. Analysis of time-activity and energy budgets indicated that FMR was about 1.7 x BMR (basal metabolic rate) during the 12 h d(-1) that penguins were lying on sea ice. During the remaining 12 h d(-1), which we termed their "foraging period" of the day, the birds were alert and active (standing, preening, walking, and either free diving or being hand-fed), and their FMR was about 4.1 x BMR. This is the lowest cost of foraging estimated to date among the eight penguin species studied. The calculated aerobic diving limit (ADL(C)), determined with the foraging period metabolic rate of 4.1 x BMR and known O(2) stores, was only 2.6 min, which is far less than the 6-min ADL previously measured with postdive lactate analyses in emperors diving under similar conditions. This indicates that calculating ADL(C) from an at-sea or foraging-period metabolic rate in penguins is not appropriate. The relatively low foraging cost for emperor penguins contributes to their relatively low total daily FMR (2.9 x BMR). The allometric relationship for FMR in eight penguin species, including the smallest and largest living representatives, is kJ d(-1)=1,185 kg(0.705).     

Individual variation in field metabolic rate of kittiwakes (Rissa tridactyla) during the chick-rearing period

Field metabolic rate (FMR), using the doubly labelled water (DLW) method, was measured in free-ranging adult kittiwakes (Rissa tridactyla) early and late in the chick-rearing period at Svalbard, Norway. Individual variation in FMR was analysed by comparing FMR with body mass, sex, nest attendance, chick age, brood size, and basal metabolic rate (BMR). Mean FMR of kittiwakes during the chick-rearing period was 27.0+/-0.9 (SE) W kg(-1), while the individual variation (calculated as coefficient of variation [CV]) in FMR was 24%. Sex, time spent away from the nest, age of the chicks, and brood size contributed significantly to FMR and explained 65% of the variation in FMR. The FMR increased by 32% from early until late in the chick-rearing period. This occurred simultaneously with an increase in the time spent away from the nest. In 15 of 20 pairs, one of the mates had 15% or higher (mean of the 15 pairs, 22%+/-8%) FMR (W kg(-1)) than their partner, even though the mates spent equal amounts of time away from the nest. This indicates an intrapair conflict in FMR. The variation in total FMR of pairs was 40% less than the individual variation, and total FMR of pairs increased with age of the chicks. This indicates that the mates adjust their energy expenditure within a relatively constant FMR determined by the energy needs of the chicks. Individual variation in FMR could not be explained by variation in body mass or BMR. BMR measured late in the chick-rearing period was 26% lower than previous measurements of BMR from the prebreeding and incubation periods. The increase in FMR and simultaneous decrease in BMR caused a 40% increase in metabolic intensity (FMR/BMR) of kittiwakes during the chick-rearing period. It is suggested that the metabolic intensity is not a proper measure of the metabolic load in seabirds.     

Phylogenetic relationships of Caucasian shrew Sorex satunini Ogn. (mammalia) in the superspecies Sorex araneus inferred from the data of karyological analysis and the mtDNA cyt b gene sequencing

Using the data of karyological analysis, the phylogenetic relationships of Caucasian shrew Sorex satunini and the cryptic species of superspecies Sorer araneus were examined. In the population of Sorex satunini from the plain of North Ciscaucasia two deeply radiated cytochrome b genes (A and B) were identified. Genetic distance between haplotype A and B groups constituted 0.0675 +/- 0.008, which is higher than any distance in superspecies S. araneus. Possible introgression of type B haplotypes from the populations of the evolutionary lineage S. subaraneus--S. araneus in Pleistocene and the time of the appearance of the chromosomal polymorphism of S. araneus is discussed. Our results show that the use of only one mitochondrial marker can lead to false conclusions on taxonomic diversity     

The occurrence of Centrorhynchus (Acanthocephala) in shrews (Sorex araneus and Sorex minutus) in the United Kingdom

Encysted acanthocephalans belonging to the genus Centrorhynchus were found in the body cavities of Sorex araneus (common shrew) and Sorex minutus (pygmy shrew) from Boxworth, Cambridgeshire, U.K. Fifty percent of the male S. araneus and 67% of the male S. minutus examined were found to be infected, with the mean intensity (+/-SD) being 54.3 +/- 91.3 and 14.7 +/- 18.4, respectively. The species of Centrorhynchus in the shrews may be Centrorhynchus aluconis, which is distributed widely in tawny owls, Strix aluco, in the United Kingdom. Shrews appear to serve as paratenic hosts for C. aluconis.     

Small mammals and their ectoparasites from the Scottish islands of Handa (Sutherland), Muck, Pabay, Scalpay and Soay (Inner Hebrides)

Small mammals were trapped on five islands for short periods during the summers of 1964 and 1965, with the following results:
Handa: Rattus norvegicus only, probably no other species present.
Muck: Sorex araneus, S. minutus, Apodemus sylvaticus and Microtus agrestis; R. norvegicus also present.
Pabay: S. minutus and Neomys fodiens ; probably no other species present.
Scalpay: S. araneus, S. minutus and M. agrestis.
Soay: S. araneus and S. minutus ; rodents almost certainly absent.
Ectoparasites (fleas and Acarina) collected from these small mammals are tabulated.     

Field metabolic rate and water turnover of the numbat (<Emphasis Type="Italic">Myrmecobius fasciatus</Emphasis>)

The numbat (Myrmecobius fasciatus) is a diurnal and exclusively termitivorous marsupial. This study examines interrelationships between diet, metabolic rate and water turnover for wild, free-living numbats. The numbats (488±20.8 g) remained in mass balance during the study. Their basal metabolic rate (BMR) was 3.6 l CO₂ day^–1, while their field metabolic rate (FMR) was 10.8±1.22 l CO₂ day^–1 (269±30.5 kJ day^–1). The ratio FMR/BMR was 3±0.3 for numbats. We suggest that the most accurate way to predict the FMR of marsupials is from the regression log FMR=0.852 log BMR+0.767; (r²=0.97). The FMR of the numbat was lower than, but not significantly different from, that of a generalised marsupial, both before (76%) and after (62–69%) correction for the significant effect of phylogeny on FMR. However the numbat's FMR is more comparable with that of other arid-habitat Australia marsupials (98–135%), for which the regression relating mass and FMR is significantly lower than for nonarid-habitat marsupials, independent of phylogeny. The field water turnover rate (FWTR) of free-living numbats (84.1 ml H₂O day^–1) was highly correlated with FMR, and was typical (89–98%) of that for an arid-habitat marsupial after phylogenetic correction. The higher than expected water economy index for the numbat (FWTR/FMR=0.3±0.03) suggests that either the numbats were drinking during the study, the water content of their diet was high, or the digestibility of their termite diet was low. Habitat and phylogenetic influences on BMR and FMR appear to have pre-adapted the numbat to a low-energy termitivorous niche.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - EWL evaporative water loss - FWTR field water turnover rate - MR metabolic rate - PVR phylogenetic vector regression - RER respiratory exchange ratio - T_a ambient temperature - T_b body temperature - TBW total body water - CO₂ rate of carbon dioxide production - O₂ rate of oxygen consumption - WEI water economy index - WER water efflux rate - WIR water influx rateCommunicated by I.D. Hume     

Behavioral inference of diving metabolic rate in free-ranging leatherback turtles

Good estimates of metabolic rate in free-ranging animals are essential for understanding behavior, distribution, and abundance. For the critically endangered leatherback turtle (Dermochelys coriacea), one of the world's largest reptiles, there has been a long-standing debate over whether this species demonstrates any metabolic endothermy. In short, do leatherbacks have a purely ectothermic reptilian metabolic rate or one that is elevated as a result of regional endothermy? Recent measurements have provided the first estimates of field metabolic rate (FMR) in leatherback turtles using doubly labeled water; however, the technique is prohibitively expensive and logistically difficult and produces estimates that are highly variable across individuals in this species. We therefore examined dive duration and depth data collected for nine free-swimming leatherback turtles over long periods (up to 431 d) to infer aerobic dive limits (ADLs) based on the asymptotic increase in maximum dive duration with depth. From this index of ADL and the known mass-specific oxygen storage capacity (To(2)) of leatherbacks, we inferred diving metabolic rate (DMR) as To2/ADL. We predicted that if leatherbacks conform to the purely ectothermic reptilian model of oxygen consumption, these inferred estimates of DMR should fall between predicted and measured values of reptilian resting and field metabolic rates, as well as being substantially lower than the FMR predicted for an endotherm of equivalent mass. Indeed, our behaviorally derived DMR estimates (mean=0.73+/-0.11 mL O(2) min(-1) kg(-1)) were 3.00+/-0.54 times the resting metabolic rate measured in unrestrained leatherbacks and 0.50+/-0.08 times the average FMR for a reptile of equivalent mass. These DMRs were also nearly one order of magnitude lower than the FMR predicted for an endotherm of equivalent mass. Thus, our findings lend support to the notion that diving leatherback turtles are indeed ectothermic and do not demonstrate elevated metabolic rates that might be expected due to regional endothermy. Their capacity to have a warm body core even in cold water therefore seems to derive from their large size, heat exchangers, thermal inertia, and insulating fat layers and not from an elevated metabolic rate.     

Altitudinal and seasonal effects on aerobic metabolism of deer mice

Summary I compared the maximal aerobic metabolic rates ( ), field metabolic rates (FMR), aerobic reserves ( -FMR), and basal metabolic rates (BMR) of wild and recently captured deer mice from low (440 m) and high (3800 m) altitudes. To separate the effects of the thermal environment from other altitudinal effects, I examined mice from different altitudes, but similar thermal environments (i.e., summer mice from high altitude and winter mice from low altitude). When the thermal environment was similar, , FMR, and aerobic reserve of low and high altitude mice did not differ, but BMR was significantly higher at high altitude. Thus, in the absence of thermal differences, altitude had only minor effects on the aerobic metabolism of wild or recently captured deer mice.At low altitude, there was significant seasonal variation in , FMR, and aerobic reserve, but not BMR. BMR was correlated with , but not with FMR. The significant positive correlation of BMR with indicates a cost of high , because higher BMR increases food requirements and energy use during periods of thermoneutral conditions.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - partial pressure of oxygen - T _a ambient temperature - T _b body temperature - T _e operative temperature - maximal aerobic metabolic rate     

The energy economy of the arctic-breeding Kittiwake (Rissa tridactyla): a review

The present paper reviews recent studies on changes in body mass, body composition and rates of energy expenditure during the breeding season in the black-legged Kittiwake (Rissa tridactyla) on Svalbard (79 degrees N). The main characteristic of the energy budget is a pronounced decrease in body mass as well as basal metabolic rate (BMR) after the eggs have hatched. While most internal organs lose mass in direct proportion to the general decrease in body mass, the liver and kidney masses decrease to a disproportionately greater extent. Since both the liver and the kidney have high intrinsic metabolic rates, these results support an earlier notion that the reduction in body mass is an adaptation to reduce maintenance costs. Alternatively, the reduced BMR is due to a decrease in energy uptake from the gastrointestinal tract, thereby ensuring that undigested food is ready to be regurgitated to the chicks. At the end of the chick-rearing period, the field metabolic rate (FMR) reaches its highest level, probably due to an increased workload associated with chick feeding. This occurs at a time of low body mass and BMR. A pronounced increase in the metabolic scope (FMR/BMR) during the latter part of the chick-rearing period demonstrates that BMR and FMR may change independently of each other and that the ratio FMR/BMR may not be a good measure of energy stress.     

Karyotype evolution of eulipotyphla (insectivora): the genome homology of seven sorex species revealed by comparative chromosome painting and banding data

The genus Sorex is one of the most successful genera of Eulipotyphla. Species of this genus are characterized by a striking chromosome variability including XY1Y2 sex chromosome systems and exceptional chromosomal polymorphisms within and between populations. To study chromosomal evolution of the genus in detail, we performed cross-species chromosome painting of 7 Sorex species with S. granarius and S. araneus whole-chromosome probes and found that the tundra shrew S. tundrensis has the most rearranged karyotype among these. We reconstructed robust phylogeny of the genus Sorex based on revealed conserved chromosomal segments and syntenic associations. About 16 rearrangements led to formation of 2 major Palearctic groups after their divergence from the common ancestor: the S. araneus group (10 fusions and 1 fission) and the S. minutus group (5 fusions). Further chromosomal evolution of the 12 species inside the groups, including 5 previously investigated species, was accompanied by multiple reshuffling events: 39 fusions, 20 centromere shifts and 10 fissions. The rate of chromosomal exchanges upon formation of the genus was close to the average rate for eutherians, but increased during recent (about 6-3 million years ago) speciation within Sorex. We propose that a plausible ancestral Sorex karyotype consists of 56 elements. It underwent 20 chromosome rearrangements from the boreoeutherian ancestor, with 14 chromosomes retaining the conserved state. The set of genus-specific chromosome signatures was drawn from the human (HSA)-shrew comparative map (HSA3/12/22, 8/19/3/21, 2/13, 3/18, 11/17, 12/15 and 1/12/22). The syntenic association HSA4/20, that was previously proposed as a common trait of all Eulipotyphla species, is shown here to be an apomorphic trait of S. araneus.     

Shrews on small islands: epigenetic variation elucidates population stability

Three large (4 to 8 ha) and 14 small islands (0.3 to 2 ha) in a lake in eastern Finland, all situated less than 0.5 km from the mainland, were surveyed for small mammals. Three species of shrew and two species of vole were resident in July 1982: Sorex araneus on 10, S. caecutiens on 2, S. minutus on 5, Microtus agrestis on 12 and Clethrionomys glareolus on 4 islands. Immigrants were trapped from tiny islets, and the data indicate that S. caecutiens and M. agrestis are better dispersers than S. minutus and C. glareolus , respectively. Microtus agrestis, S. araneus and C. glareolus occurred non-randomly, on subsets of the larger islands, while the two small Sorex species occurred more erratically, possibly because of competition with S. araneus . Juvenile sex ratio was male-biased on the mainland but female-biased on large islands, possibly because juvenile males move more and are more likely to emigrate from an island than juvenile females.
Metrical and non-metrical (epigenetic) cranial traits gave similar patterns of population differentiation in S. araneus . Two of the three large-island populations have differentiated from the mainland populations and from each other, suggesting that the populations are relatively stable. Small-island populations, which are often less than 10 individuals in size, showed little differentiation but had more epigenetic traits fixed than large-island and mainland populations (founder effect). This suggests that the small-island populations are unstable, have a high extinction rate.     

Genetic and karyotypic structure in the shrews of the Sorex araneus group: are they independent?

The species of the common shrew (Sorex araneus) group are morphologically very similar but exhibit high levels of karyotypic variation. Here we used genetic variation at 10 microsatellite markers in a data set of 212 individuals mostly sampled in the western Alps and composed of five karyotypic taxa (Sorex coronatus, Sorex antinorii and the S. araneus chromosome races Cordon, Bretolet and Vaud) to investigate the concordance between genetic and karyotypic structure. Bayesian analysis confirmed the taxonomic status of the three sampled species since individuals consistently grouped according to their taxonomical status. However, introgression can still be detected between S. antinorii and the race Cordon of S. araneus. This observation is consistent with the expected low karyotypic complexity of hybrids between these two taxa. Geographically based cryptic substructure was discovered within S. antinorii, a pattern consistent with the different postglaciation recolonization routes of this species. Additionally, we detected two genetic groups within S. araneus notwithstanding the presence of three chromosome races. This pattern can be explained by the probable hybrid status of the Bretolet race but also suggests a relatively low impact of chromosomal differences on genetic structure compared to historical factors. Finally, we propose that the current data set (available at http://www.unil.ch/dee/page7010_en.html#1) could be used as a reference by those wanting to identify Sorex individuals sampled in the western Alps.     

Thyroid Hormones Correlate with Basal Metabolic Rate but Not Field Metabolic Rate in a Wild Bird Species

Thyroid hormones (TH) are known to stimulate in vitro oxygen consumption of tissues in mammals and birds. Hence, in many laboratory studies a positive relationship between TH concentrations and basal metabolic rate (BMR) has been demonstrated whereas evidence from species in the wild is scarce. Even though basal and field metabolic rates (FMR) are often thought to be intrinsically linked it is still unknown whether a relationship between TH and FMR exists. Here we determine the relationship between the primary thyroid hormone triiodothyronine (T3) with both BMR and FMR in a wild bird species, the black-legged kittiwake (Rissa tridactyla). As predicted we found a strong and positive relationship between plasma concentrations of T3 and both BMR and mass-independent BMR with coefficients of determination ranging from 0.36 to 0.60. In contrast there was no association of T3 levels with either whole-body or mass-independent FMR (R² = 0.06 and 0.02, respectively). In accordance with in vitro studies our data suggests that TH play an important role in modulating BMR and may serve as a proxy for basal metabolism in wild birds. However, the lack of a relationship between TH and FMR indicates that levels of physical activity in kittiwakes are largely independent of TH concentrations and support recent studies that cast doubt on a direct linkage between BMR and FMR.     

Mathematical analysis of running performance and world running records

The objective of this study was to develop an empirical model relating human running performance to some characteristics of metabolic energy-yielding processes using A, the capacity of anaerobic metabolism (J/kg); MAP, the maximal aerobic power (W/kg); and E, the reduction in peak aerobic power with the natural logarithm of race duration T, when T greater than TMAP = 420 s. Accordingly, the model developed describes the average power output PT (W/kg) sustained over any T as PT = [S/T(1 - e-T/k2)] + 1/T integral of T O [BMR + B(1 - e-t/k1)]dt where S = A and B = MAP - BMR (basal metabolic rate) when T less than TMAP; and S = A + [Af ln(T/TMAP)] and B = (MAP - BMR) + [E ln(T/TMAP)] when T greater than TMAP; k1 = 30 s and k2 = 20 s are time constants describing the kinetics of aerobic and anaerobic metabolism, respectively, at the beginning of exercise; f is a constant describing the reduction in the amount of energy provided from anaerobic metabolism with increasing T; and t is the time from the onset of the race. This model accurately estimates actual power outputs sustained over a wide range of events, e.g., average absolute error between actual and estimated T for men's 1987 world records from 60 m to the marathon = 0.73%. In addition, satisfactory estimations of the metabolic characteristics of world-class male runners were made as follows: A = 1,658 J/kg; MAP = 83.5 ml O2.kg-1.min-1; 83.5% MAP sustained over the marathon distance. Application of the model to analysis of the evolution of A, MAP, and E, and of the progression of men's and women's world records over the years, is presented.     

Variation in energy expenditure among black-legged kittiwakes: effects of activity-specific metabolic rates and activity budgets

We sought to determine the effect of variation in time-activity budgets (TABs) and foraging behavior on energy expenditure rates of parent black-legged kittiwakes (Rissa tridactyla). We quantified TABs using direct observations of radio-tagged adults and simultaneously measured field metabolic rates (FMR) of these same individuals (n=20) using the doubly labeled water technique. Estimated metabolic rates of kittiwakes attending their brood at the nest or loafing near the colony were similar (ca. 1.3 x basal metabolic rate [BMR]), although loafing during foraging trips was more costly (2.9 x BMR). Metabolic rates during commuting flight (7.3 x BMR) and prey-searching flight (6.2 x BMR) were similar, while metabolic rates during plunge diving were much higher (ca. 47 x BMR). The proportion of the measurement interval spent foraging had a positive effect on FMR (R2=0.68), while the combined proportion of time engaged in nest attendance and loafing near the colony had a negative effect on FMR (R2=0.72). Thus, more than two-thirds of the variation in kittiwake FMR could be explained by the allocation of time among various activities. The high energetic cost of plunge diving relative to straight flight and searching flight suggests that kittiwakes can optimize their foraging strategy under conditions of low food availability by commuting long distances to feed in areas where gross foraging efficiency is high.     

When nonshivering thermogenesis equals maximum metabolic rate: thermal acclimation and phenotypic plasticity of fossorial Spalacopus cyanus (Rodentia)

Many small mammals inhabiting fluctuating and cold environments display enhanced capacity for seasonal changes in nonshivering thermogenesis (NST) and thermoregulatory maximum metabolic rate (MMR). However, it is not known how this plasticity remains in a mammal that rarely experiences extreme thermal fluctuations. In order to answer this question, we determined body mass (m(b)), basal metabolic rate (BMR), NST, MMR, and minimum thermal conductance (C) on a Chilean fossorial caviomorph (Spalacopus cyanus) from a coastal population, acclimated to cold (15 degrees C) and warm (30 degrees C) conditions. NST was measured as the maximum response of metabolic rate (NST(max)) after injection of norepinephrine (NE) in thermoneutrality minus BMR. Maximum metabolic rate was assessed in animals exposed to enhanced heat-loss atmosphere (He-O2) connected with an open-flow respirometer. Body mass and metabolic variables increased significantly after cold acclimation with respect to warm acclimation but to a low extent (BMR, 26%; NST, 10%; and MMR, 12%). However, aerobic scope (MMR/BMR), calculated shivering thermogenesis (ST), and C did not change with acclimation regime. Our data suggest that physiological plasticity of S. cyanus is relatively low, which is in accordance with a fossorial mode of life. Although little is known about MMR and NST in fossorial mammals, S. cyanus has remarkably high NST; low MMR; and surprisingly, a nil capacity of ST when compared with other rodents.     

A new perspective on the evolutionary history of western European Sorex araneus group revealed by paternal and maternal molecular markers

The species of the common shrew (Sorex araneus) group are morphologically very similar, but have undergone a spectacular chromosomal evolution. We investigate here the evolutionary history of the Sorex araneus group distributed in western Europe. In particular, we clarify the position of a difficult species, S. granarius, using sex-specific (mtDNA and Y-chromosome) markers. The karyotype of S. granarius is generally considered similar to the common ancestor of the restricted group considered here. The mtDNA data (1.4 kb) confirms the close relationship between S. granarius and S. araneus sensu stricto (hereafter S. araneus s.s.), but the Y-chromosome (3.4 kb) produces a quite different picture: S. granarius is closely related to another species, S. coronatus. Comparison of mtDNA and Y-chromosome phylogenies suggests that the genetic and chromosomal evolution in this group are disconnected processes. The evolutionary history of the south-western European populations of the S. araneus group can only be understood considering secondary contacts between taxa after their divergence, implying genetic exchanges by means of hybridization and/or introgression.     

Genetic correlations between basal and maximum metabolic rates in a wild rodent: consequences for evolution of endothermy

According to the aerobic capacity model, endothermy in birds and mammals evolved as a correlated response to selection for an ability of sustained locomotor activity, rather than in a response to direct selection for thermoregulatory capabilities. A key assumption of the model is that aerobic capacity is functionally linked to basal metabolic rate (BMR). The assumption has been tested in several studies at the level of phenotypic variation among individuals or species, but none has provided a clear answer whether the traits are genetically correlated. Here we present results of a genetic analysis based on measurements of the basal and the maximum swim- and cold-induced oxygen consumption in about 1000 bank voles from six generations of a laboratory colony, reared from animals captured in the field. Narrow sense heritability (h2) was about 0.5 for body mass, about 0.4 for mass-independent basal and maximum metabolic rates, and about 0.3 for factorial aerobic scopes. Dominance genetic and common environmental (= maternal) effects were not significant. Additive genetic correlation between BMR and the swim-induced aerobic capacity was high and positive, whereas correlation resulting from specific-environmental effects was negative. However, BMR was not genetically correlated with the cold-induced aerobic capacity. The results are consistent with the aerobic capacity model of the evolution of endothermy in birds and mammals.     

Cerebrosides and sulfocerebrosides in the brain of insectivorous mammals

Brain cerebrosides (C) and sulfocerebrosides (S) of Insectivora, which represent the most ancient and primitive order of placentary mammals, were first studied. The content of C and S is higher in hedgehogs (Erinaceus europaeus, E. auritus) and mole (Talpa europaea) brains as compared to shrew (Sorex araneus) brain. Hydroxy fatty acids predominate over normal fatty acids in C of all studied insectivora brains. The fatty acid content of C and S of the Insectivora brains is similar in being rich in palmitic, stearic and behenic normal acids and hydroxybehenic and hydroxylignocerinic acids. Hydroxy fatty acids of C and S are more saturated and they have a longer chain (sum C24-26 acids) than the normal acids. C and S of insectivora and primate brains are compared. The data may be of importance for the understanding of the biochemical evolution of the nervous system of mammals.