Evaluation of maximal O₂ uptake with undergraduate students at the University of La Reunion

The maximal rate of O? consumption (VO? max) constitutes one of the oldest fitness indexes established for the measure of cardiorespiratory fitness and aerobic performance. Procedures have been developed in which VO? max is estimated from physiological responses during submaximal exercise. Generally, VO? max is estimated using the classical renowned Astrand-Ryhming test. In young adults, poor fitness and low aerobic performance are often associated with a sedentary lifestyle, which is a well-described factor for the development of obesity and its related disorders such as cardiovascular diseases and type 2 diabetes. In the Indian Ocean, the inhabitants of La Reunion Island, a French overseas department, exhibit an increasing prevalence of obesity and type 2 diabetes. At the University of La Reunion, a new laboratory course involving students was designed to teach the indirect evaluation of their VO? max from the classical Astrand-Ryhming test and using a cycle ergometer as the exercise mode. Inverse and significant correlations were established between the students' fat mass percentages and their VO? max and between their waist-to-hip ratio and VO? max as well. Results from the international physical activity questionnaire showed that most participants in this laboratory were sedentary students. Therefore, this laboratory makes the students practice and understand the use of a classical test to estimate their VO? max. It also alerts them to the correlation between a sedentary lifestyle and higher body fat content. This exercise allowed students to use a scientific method to engage the problem of sedentary lifestyle, which is a real world issue.     

Cardiovascular autonomic function correlates with the response to aerobic training in healthy sedentary subjects

Individual responses to aerobic training vary from almost none to a 40% increase in aerobic fitness in sedentary subjects. The reasons for these differences in the training response are not well known. We hypothesized that baseline cardiovascular autonomic function may influence the training response. The study population included sedentary male subjects (n = 39, 35 +/- 9 yr). The training period was 8 wk, including 6 sessions/wk at an intensity of 70-80% of the maximum heart rate for 30-60 min/session. Cardiovascular autonomic function was assessed by measuring the power spectral indexes of heart rate variability from 24-h R-R interval recordings before the training period. Mean peak O2 uptake increased by 11 +/- 5% during the training period (range 2-19%). The training response correlated with age (r = -0.39, P = 0.007) and with the values of the high-frequency (HF) spectral component of R-R intervals (HF power) analyzed over the 24-h recording (r = 0.46, P = 0.002) or separately during the daytime hours (r = 0.35, P = 0.028) and most strongly during the nighttime hours (r = 0.52, P = 0.001). After adjustment for age, HF power was still associated with the training response (e.g., P = 0.001 analyzed during nighttime hours). These data show that cardiovascular autonomic function is an important determinant of the response to aerobic training among sedentary men. High vagal activity at baseline is associated with the improvement in aerobic power caused by aerobic exercise training in healthy sedentary subjects.     

Influence of aerobic fitness and body fatness on tolerance to uncompensable heat stress.

This study examined the independent and combined importance of aerobic fitness and body fatness on physiological tolerance and exercise time during weight-bearing exercise while wearing a semipermeable protective ensemble. Twenty-four men and women were matched for aerobic fitness and body fatness in one of four groups (4 men and 2 women in each group). Aerobic fitness was expressed per kilogram of lean body mass (LBM) to eliminate the influence of body fatness on the expression of fitness. Subjects were defined as trained (T; regularly active with a peak aerobic power of 65 ml x kg LBM(-1) x min(-1)) or untrained (UT; sedentary with a peak aerobic power of 53 ml x kg LBM(-1) x min(-1)) with high (High; 20%) or low (Low; 11%) body fatness. Subjects exercised until exhaustion or until rectal temperature reached 39.5 degrees C or heart rate reached 95% of maximum. Exercise times were significantly greater in T(Low) (116 +/- 6.5 min) compared with their matched sedentary (UT(Low); 70 +/- 3.6 min) or fatness (T(High); 82 +/- 3.9 min) counterparts, indicating an advantage for both a high aerobic fitness and low body fatness. However, similar effects were not evident between T(High) and UT(High) (74 +/- 4.1 min) or between the UT groups (UT(Low) and UT(High)). The major advantage attributed to a higher aerobic fitness was the ability to tolerate a higher core temperature at exhaustion (the difference being as great as 0.9 degrees C), whereas both body fatness and rate of heat storage affected the exercise time as independent factors.     

Declining sex ratios in Canada

OBJECTIVE: To examine the trends in the proportion of annual live births that were male in Canada and to compare the trends with those in the United States. DESIGN: Analysis of census data. SETTING: Canada as a whole and 4 main regions (West, Ontario, Quebec and Atlantic). SUBJECTS: All live births from 1930 to 1990. OUTCOME MEASURES: Sex ratio (expressed as the proportion of total live births that were male [male proportion]) overall and by region. RESULTS: The male proportion in Canada decreased significantly after 1970 (p < 0.001); this represented a cumulative loss of 2.2 male births per 1000 live births from 1970 to 1990. Although a decrease was observed in all four regions studied, only that in the Atlantic region was significant (p < 0.001), representing a cumulative loss of 5.6 male births per 1000 live births from 1970 to 1990. A significant decrease in the male proportion was also observed in the United States from 1970 to 1990 (p < 0.001), although to a lesser degree than that observed in Canada, and represented a cumulative loss of 1.0 male births per 1000 live births. CONCLUSIONS: The decreased sex ratio in Canada adds to the growing debate over changes in biological markers and their potential causes. In addition, the study illustrates the potential use of the sex ratio as a widely available, unambiguous measure of the reproductive health of large populations.     

Trends in the twinning rate in Johannesburg, South Africa, 1969-1989 and estimated twinning rates for 1990.

Birth statistics for the Johannesburg Metropolitan Region were collected for 757 151 confinements from 1969 to 1989 (467513 Black, 194375 White, 67250 Coloured and 28013 Indian confinements). From 1969 to 1978 data on the sexes of twins were also collected for 375 203 of the confinements (203 504 Black, 129 631 White, 28 253 Coloured and 13 815 Indian confinements). A twin confinement was defined as two deliveries during one confinement. Twinning rates (TRs), defined as the number of twin confinements per 1000 total confinements, were calculated per year for each population group and from 1969-1978 estimates of the relative proportions of dizygotic (DZ) and monozygotic (MZ) twins were calculated and thus the relative DZTRs and MZTRs. A significant decline in Black and Coloured TRs was observed between 1969 and 1989. A significant decline in Black DZTR but not Black MZTR was observed between 1969 and 1978, the Coloured twin sample was too small to show significant trends over this period. It is probable that the overall decline in Black twinning may be explained by a decline in the DZTR. An analysis of birth statistics for 159 748 confinements (134 504 Black and 25 244 White confinements) collected as part of a prospective study of TRs in the Johannesburg Metropolitan Region from 1988 to 1990, indicated that the Black TR continued to decline at least until the end of 1990. TRs in the Johannesburg Metropolitan Region calculated from City Health Department birth statistics collected from 1988 to 1990 were: 13.8 and 10.77 for the Black and White populations, respectively. TRs for this period calculated from the combined birth statistics of 14 hospitals, nursing homes and maternity clinics across the region were: 12.4 and 10.88 for the Black and White populations, respectively.     

Anemia and the transition of nomadic hunter-gatherers to a sedentary life-style: Follow-up study of a Kalahari community

Iron profiles of communities of hunter-gatherers and former hunter-gatherers conducted between 1969 and 1987 at Dobe in the Kalahari Desert of Botswana exhibited pronounced differences during periods of rapid culture change. The loss of good health and particularly the increase in anemia through time was attributed to notable changes in diet, although changes in mobility patterns were considered a secondary cause. In 1988 and 1989, studies were conducted at Kutse, also in the Kalahari Desert of Botswana, to ascertain the frequency of anemia at a recently sedentary community in which residents still relied primarily on wild animals for meat. Although not identical, the hematological presentation in 1989 was similar to that in 1988. The studies together suggest that our findings characterize the pattern of health and disease at Kutse, which is unrelated to any specific year or to diet. Additional measures of disease, specifically ESR (erythrocyte sedimentation rate) and oral temperatures, support an interpretation of anemia of chronic disease as the cause of hypoferremia at Kutse. Morbidity is high, in spite of adequate diets, because the residents are transitional from a nomadic to a sedentary lifestyle and from a relatively dispersed to an aggregated settlement pattern. These changes have introduced new health problems. © 1996 Wiley-Liss, Inc.     

Does physical inactivity cause nonalcoholic fatty liver disease?

While physical activity represents a key element in the prevention and management of many chronic diseases, we and others believe that physical inactivity is a primary cause of obesity and associated metabolic disorders. Unfortunately, accumulating evidence suggests that we have engineered physical activity out of our normal daily living activity. One such consequence of our sedentary and excessive lifestyle is nonalcoholic fatty liver disease (NAFLD), which is now considered the most common cause of chronic liver disease in Westernized societies. In this review, we will present evidence that physical inactivity, low aerobic fitness, and overnutrition, either separately or in combination, are an underlying cause of NAFLD.     

Physical Training Improves Body Composition of Black Obese 7- to 11-Year-Old Girls

We determined the effect of supervised physical training, without dietary intervention, on body composition of obese girls. The subjects were 25 obese 7-to 11-year-old black girls, divided into physical training and lifestyle education groups which were comparable on baseline body composition; 22 girls finished all aspects of the study. Twelve girls engaged in aerobic training (10 weeks, 5 days/week) while 10 engaged in weekly lifestyle discussions without formal physical training. Total body and regional body composition were measured with dual energy x-ray absorptiometry, skin folds and circumferences. Aerobic fitness was measured by heart rate response to sub maximal treadmill exercise. The physical training group attended 94% of scheduled sessions and kept their heart rates at an average of 163 bpm for 28 minutes/session. The lifestyle group attended 95% of their sessions; they remained stable in aerobic fitness and most body composition measurements. The physical training group showed a significant improvement in aerobic fitness and a significant decline of 1.4% body fat. Skin fold and circumference indices of fatness also declined significantly in physical training, without dietary intervention, improved the fitness and body composition of obese black girls.     

Leisure time sport activities and maximal aerobic power during late adolescence

The pattern of leisure time sport activity was estimated by retrospective recalls and expressed in terms of an annual sport activity score. The activity score was related to the development of maximal aerobic power during the period of late adolescence in German children. Both girls and boys reduced their activity pattern from 14 to 18 years of age, boys more than girls. At each age boys were more active than girls. A slight tendency towards better fitness with increased habitual physical activity was noticed, but many sedentary children exhibited a good performance capacity and some children with a high level of leisure time sport activity were characterized by a low level of maximal aerobic power. A statistical analysis revealed that the observed tendency to better fitness with increased habitual physical activity could be explained by an age factor with no additional effect of variation in sport activity score.     

Levels of brain lipids in white matter from undernourished Sinclair (S-1) miniature swine

I t H as been suggested previously that animal models are the preferred method for biochemical study concerned with protein-calorie malnutrition (K irsch , S aunders and B rock , 1968; D obbing , 1970). That the brain is one of the least vulnerable organs to be affected by dietary deprivation has been reported for swine (P latt , H eard and S tewart , 1964; T umbleson , T insley , C orwin , F latt and F lynn , 1969; T umbleson , T insley , M ulder and F lait , 1970), rhesus monkeys (O rdy , S amorajski and H ershberger , 1970) and rats (B rown and G uthrie , 1968). However, alteration of brain composition as a result of protein-calorie malnutrition at a young age may have important effects on the mental and behavioural activities of the maturing subjects (W inick , 1970; C ravioto , 1970). In a previous study on the effect of undernutrition in young miniature swine, it was noted that there was an elevation in the levels of cholesterol and glucose in serum of pigs fed the low protein diet (T umbleson et al. , 1969). The duration of such elevations was usually 2–8 weeks after administration of the test diet. Since cholesterol, as well as other chemical constituents, in serum is important for the biosynthesis of brain membranes, the present study was designed to assess the effect of undernutrition on levels of major brain lipids.     

Book reviews

Book reviewed in this article:
C oncepts in V iral P athogenesis III (1989). Edited by A.L. Notkins & M.B.A. Old-stone.
A C olour A tlas of M eat I nspection (1990). By J. Infante Gil & J. Costa Durao.
P romiscuous P lasmids of G ram -N egative B acteria (1989). Edited by Christopher M. Thomas.
S hort P rotocols in M olecular B iology (1989). Edited by F.M. Ausubel et al.
G enetics of B acterial D iversity (1989). Edited by D.A. Hopwood & K.F. Chater.
Y east G enetics . A M anual of M ethods (1989). By J.F.T. Spencer, D.M. Spencer & I.J. Burce.
M etals and M icro -O rganisms (1989). By M.N. Hughes & R.K. Poole.
S eed -B orne D isease and S eed H ealth T esting of R ice (1989). By P. C. Agarwal, C.N. Mortensen & S.B. Mathur.     

Besprechungen

Book reviewed in this article: Weygoldt , Peter (1970): Courtship behaviour and sperm transfer in the Giant Whip Scorpion, Mastigoproctus giganteus (Lucas) (Uropygi, Thelyphonidae) (Werben und Samenübertragung beim großen Geisseiskorpion). Warner , G. F. (1970): Behaviour of two species of Grapsid Crab during intraspecific encounters (Verhalten der grapsoiden Krabben Aratus pisoni und Goniopsis cruentata bei Kämpfen mit Artgenossen). Hazlett , Brian A. (1970): Tactile stimuli in the social behaviour of Pagurus bernhardus (Decapoda, Paguridae) (Sozial bedeutsame Berührungsreize beim Einsiedlerkrebs P. b.). Fox , M. W. (1970): A comparative study of the development of facial expressions in Canides; wolf, coyote and foxes (Eine vergleichende Untersuchung der Entwicklung des Gesichtsausdrucks bei Caniden: Wolf, Kojote und Füchse). Holcomb , Larry C. (1970): Prolonged incubation behaviour of redwinged Blackbird incubating several egg sizes (Längeres Brüten von Rotschulterstärlingen auf Eiern verschiedener Größen). Barlow , George W., und Richard F. Green (1970): The problems of appeasement and of sexual role in the courtship behavior of the Blackchin Mouthbreeder, Tilapia melanotheron (Pisces: Cichlidae) (Beschwichtigendes und werbendes Verhalten beim Senegalbarsch, T. m.). Slewing , R. (1969): Lehrbuch der vergleichenden Entwicklungsgeschichte der Tiere. Morrell , Gillian M., und John R. G. Turner (1970): Experiments on mimicry: I. The response of wild birds to artificial prey (Modellversuche im Freiland zur Mimikry-Frage. I. Verhalten von Vögeln vor künstlichen Beuteattrappen). Beach , Frank A. (1970): Coital behaviour in dogs. VIII. Social affinity, dominance, and sexual preference in the Bitch (Paarungsverhalten bei Hunden. VIII. Bekanntschaft und Ranghöhe; wen bevorzugt die Hündin?) Darchen , R. (1969): Sur la biologie de Trigona (Apotrigona) nebulata komiensis Cock. Pflugfelder , O. (1970): Lehrbuch der Entwicklungsgeschichte und Entwicklungsphysiologie der Tiere. Portmann , A. (1969): Einführung in die vergleichende Morphologie der Wirbeltiere, 4. Auflage. Schultz , A. H. (1969): The life of primates (Das Leben der Herrentiere). Matthews , L. H. (1969): The life of mammals I. (Das Leben der Säuger). Grzimeks Tierleben, Band 11: Säugetiere 2 (1969). ed. Fox , M. W. (1968): Abnormal behavior in animals (Abnormes Verhalten von Tieren). Frisch , Otto v. (1969): Über Länder und Meere, Geheimnis der Tierwanderung. Walsh , J. (1969): Die Wasser steigen. Reuter , Wolfgang (1969): Von Lippizanern und der Spanischen Reitschule. Glover , P. E. (1968): A list of mammals from the Mau-Mara area of Massailand. Wolf , G. (1967): Der wissenschaftliche Dokumentationsfilm und die Encyclopaedia Cinematographica.     

Oxygenated-blood colour change thresholds for perceived facial redness, health, and attractiveness

Blood oxygenation level is associated with cardiovascular fitness, and raising oxygenated blood colouration in human faces increases perceived health. The current study used a two-alternative forced choice (2AFC) psychophysics design to quantify the oxygenated blood colour (redness) change threshold required to affect perception of facial colour, health and attractiveness. Detection thresholds for colour judgments were lower than those for health and attractiveness, which did not differ. The results suggest redness preferences do not reflect a sensory bias, rather preferences may be based on accurate indications of health status. Furthermore, results suggest perceived health and attractiveness may be perceptually equivalent when they are assessed based on facial redness. Appearance-based motivation for lifestyle change can be effective; thus future studies could assess the degree to which cardiovascular fitness increases face redness and could quantify changes in aerobic exercise needed to increase facial attractiveness.     

Insulin resistance in Chileans of European and indigenous descent: evidence for an ethnicity x environment interaction

Background

Effects of urbanisation on diabetes risk appear to be greater in indigenous populations worldwide than in populations of European origin, but the reasons are unclear. This cross-sectional study aimed to determine whether the effects of environment (Rural vs. Urban), adiposity, fitness and lifestyle variables on insulin resistance differed between individuals of indigenous Mapuche origin compared to those of European origin in Chile.

Methodology/Principal Findings

123 Rural Mapuche, 124 Urban Mapuche, 91 Rural European and 134 Urban European Chilean adults had blood taken for determination of HOMA-estimated insulin resistance (HOMA_IR) and underwent assessment of physical activity/sedentary behaviour (using accelerometry), cardiorespiratory fitness, dietary intake and body composition. General linear models were used to determine interactions with ethnicity for key variables. There was a significant “ethnicity x environment” interaction for HOMA_IR (Mean±SD; Rural Mapuche: 1.65±2.03, Urban Mapuche: 4.90±3.05, Rural European: 0.82±0.61, Urban European: 1.55±1.34, p _{(interaction)} = 0.0003), such that the effect of urbanisation on HOMA_IR was greater in Mapuches than Europeans. In addition, there were significant interactions (all p<0.004) with ethnicity for effects of adiposity, sedentary time and physical activity on HOMA_IR, with greater effects seen in Mapuches compared to Europeans, an observation that persisted after adjustment for potential confounders.

Conclusions/Significance

Urbanisation, adiposity, physical activity and sedentary behaviour influence insulin resistance to a greater extent in Chilean Mapuches than Chileans of European descent. These findings have implications for the design and implementation of lifestyle strategies to reduce metabolic risk in different ethnic groups, and for understanding of the mechanisms underpinning human insulin resistance.     

Effects of habitat heterogeneity and local adaptation on the body condition of a forest passerine at the edge of its distributional range

We studied fluctuating asymmetry and feather growth rates as indicators of fitness of blackcaps ( Sylvia atricapilla ) breeding at the border of their distribution range in the Iberian Peninsula. Iberian blackcaps increase their abundance with increasing rainfall and ground cover of brambles. In border habitats, they are sedentary and morphologically different from migrants, suggesting that they could be adapted to peripheral conditions. We tested whether juvenile body condition depends on (1) distance from the centre of the range, (2) mean precipitation or (3) bramble cover. Controlling for environmental variation, we tested for differences between migratory and sedentary populations. Body condition varied across the Iberian gradient in parallel with changes in precipitation. Controlling for this effect, sedentary populations were in better body condition than migratory populations. Our results support the idea that environmental heterogeneity causes fitness to fluctuate across species' ranges, and also that local adaptation may mean that peripheral populations are more than a 'tail end' of the species.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 479–488.     

Relationship between aerobic fitness and metabolic power metrics in elite male soccer players

The aim was to assess the relationship between aerobic fitness and metabolic power metrics in elite male soccer players, and the possible differences that playing positions might impose during match play over new metabolic power metrics. Sixty-two elite professional male soccer players (13 central backs, 13 side backs, 22 midfielders, and 14 forwards) took part in the study. Players were monitored during eleven months of full training (including pre-season and in-season) and over all official matches (Serie A matches, Italy Cup matches). Aerobic fitness tests were conducted one week after the start of the preseason, and 8, 24 and 36 weeks after the beginning of the Championship. Players’ aerobic fitness and metabolic power metrics were considered as the mean of all seasonal testing and of pooling data of 38 championship matches and 3 or 6 Italy Cup matches for all the calculations respectively. The velocity at 4 mmol·L^-1 (VL₄) was significantly related to metabolic power metrics match variables with correlation ranging from trivial to very large (r = 0.32 to r = 0.89). Receiver-operating-characteristic (ROC) analysis showed that speed at VL₄ was sensitive in detecting high metabolic power distance (HMPD) changes in all but central back players as revealed by area under the curve (central back .78, 95%CI .47 to .95; full back .93, 95%CI .64 to 0.99; midfielder .88, 95%CI .67 to 0.98; forward .90, 95%CI .62 to 0.99). This study’s findings provide further evidence for the ecological validity of aerobic fitness in elite male soccer players. Players having a HMPD cut-off equal to or higher than > 1450 m for central backs, > 1990 m for full backs, > 2170 m for midfielders and > 1670 m for forwards may be considered as possessing superior aerobic fitness status. In light of this study’s findings, the VL₄ test may be considered a valid test to evaluate meaningful information for direct generic aerobic training in soccer players.     

Rabbit Oryctolagus cuniculus populations in Scotland since the introduction of myxomatosis

A Rabbit survey of Scotland was carried out in 1991 following the methods used for previous surveys in 1969, 1970, 1973 and 1974. The survey was split into direct field and postal questionnaire sections, and the results from the two were compared. Rabbit infestations were categorized as slight and serious. Slight infestation proved to be an inconsistent indicator of Rabbits, but the percentage of serious infestations was highly correlated across sampling areas, and was also related to the average loss estimated by farmers. The pattern of recovery of Rabbit populations after myxomatosis varied between different parts of the country. In the East, Northeast and eastern Highlands the percentage of serious infestations was 26.5% in 1991, as compared to previous survey estimates of 55.9% before 1954 and 1.5% in 1969/70. In the Central, West, South and South-west serious Rabbit problems disappeared after 1954 and are now only at the level of 5 %. It is estimated that Rabbits caused £11,790,000 worth of damage to agriculture in Scotland during 1990/91.     

Prolonged electrical muscle stimulation exercise improves strength and aerobic capacity in healthy sedentary adults.

This investigation evaluated training responses to prolonged electrical muscle stimulation (EMS) in sedentary adults. Fifteen healthy subjects (10 men, 5 women) with a sedentary lifestyle completed a 6-wk training program during which they completed an average of 29 1-h EMS sessions. The form of EMS used by the subjects was capable of eliciting a cardiovascular exercise response without loading the limbs or joints. It achieved this by means of inducing rapid, rhythmical contractions in the large leg muscles. A crossover study design was employed with subjects undergoing their habitual activity levels during the nontraining phase of the study. The training effect was evaluated by means of a treadmill test to determine peak aerobic capacity [peak oxygen consumption (Vo(2))], a 6-min walking distance test, and measurement of body mass index (BMI) and quadriceps muscle strength. At baseline, the mean values for peak Vo(2), 6-min walking distance, quadriceps strength, and BMI were 2.46 +/- 0.57 l/min, 493.3 +/- 36.8 m, 360.8 +/- 108.7 N, and 26.9 +/- 3.4 kg/m(2), respectively. After training, subjects demonstrated statistically significant improvements in all variables except BMI. Peak Vo(2) increased by an average of 0.24 +/- 0.16 l/min (P < 0.05), walking distance increased by 36.6 +/- 19.7 m (P < 0.005), and quadriceps strength increased by 87.5 +/- 55.9 N (P < 0.005); we did not observe a significant effect due to training on BMI (P > 0.05). These results suggest that EMS can be used in sedentary adults to improve physical fitness. It may provide a viable alternative to more conventional forms of exercise in this population.     

Books

Books reviewed in this article:
B ohlen , D.H. 1989. The Birds of Illinois.
B undy , G., C onnor , R.J. & H arrison , C.J.O. 1989. Birds of the Eastern Province of Saudi Arabia.
D wenger , R. 1989. Die Dohle. Pp. 148, 40 black-and-white photographs, maps.
D ymond , J.N., F raser , P.A. & G antlett , S.J.M. 1989. Rare Birds in Britain and Ireland.
Fa aborg , J. 1988. Ornithology. An ecological approach.
G ill , F.B. 1990. Ornithology.
F ord , H.A. 1989. Ecology of Birds: An Australian perspective.
G ill , F.B. 1990. Ornithology.
G onzales , P.C. & R ees , C.P. 1988. Birds of the Philippines.
G uraya , S.S. 1989. Ovarian Follicles in Reptiles and Birds.
M c I ntyre , J.W. 1988. Spirit of the Northern Lakes: the Common Loon.
N ewton , I. (ed.) 1989. Lifetime Reproduction in Birds.
O tte , D. & E ndler , J.A. 1989. Speciation and its Consequences.
O uellet , H. (ed.) 1989. Acta XIX Congressus Internationalis Ornithologici, Volumes 1 & 2.
P ennycuick , C.J. 1989. Bird Flight Performance: A practical calculation manual.
P eterjohn , B.G. 1989. The Birds of Ohio.
P range , H. 1989. Der Graue Kranich.
S icutch , A.F. 1989. Birds Asleep.
T homson , M.C. & E ly , C. 1989. Birds in Kansas
B ohlen , D.H. 1989. The Birds of Illinois.
P eterjohn , B.G. 1989. The Birds of Ohio.
Voous, K.H. 1988. Owls of the Northern Hemisphere.
V uilleumier , F. & M onasterio , M. (eds.) 1986. High Altitude Tropical Biogeography.     

Genetic variation within the Hereford breed of cattle

Genetic differentiation among Hereford populations from Britain, Ireland, Sweden, Canada and New Zealand together with six other beef breeds was assessed using blood type polymorphisms. Changes in the genetic structure of the British Hereford population over time were also examined. Loci surveyed were seven red cell antigen systems (A, B, C, F, L, S, Z), and two serum protein loci (transferrin and albumin). Within group variation was measured by the average expected heterozygosity, and between group relationships by genetic distance. There was significant genetic differentiation among Hereford populations from different countries. Differences between Hereford groups, however, were not as large as differences between breeds. There were also significance differences among British herds. The proportion of Canadian genes in the British 'hybrid' population was estimated to have increased from 0·42 (±0·34) in the 1970s to 0·98 (±0·11) in the 1990s. Canadian Hereford groups were found to be less heterozygous than other groups, and replacement of the British population with Canadian animals may lead to loss of variation. Breeding strategies that preserve original native genes in British Hereford populations should be considered by commercial breeders, in order to prevent the long-term loss of genetic variation within the breed.