Comparison of the stability of morphometric and nonmetric skeletal characteristics of inbred mice with regard to environmental exposure in prenatal development

The influence of some environmental factors on size and shape of mandible in BALB/cJLacSto inbred mice was studied during prenatal development by multivariate morphometric methods. The factors under study were: introduction of methylthiouracil into the diet of pregnant females; injections of pregnant females with adrenocorticotropic or parathyroid hormones; keeping the females at low temperatures (two regimes). It was established that the changes of mandible shape caused by the changes of conditions of prenatal development did not achieve the level of differences between strains, and mouse strain identification was possible under various conditions of animal's keeping. It has been shown by comparison of these results with preceding data that the nonmetric skeletal traits were more stable to the influence of the same factors than morphometric ones. This gives us the foundations to consider the method of evaluation of phenetic distances between natural groups of animals for the set of non-metric threshold skeletal traits more suitable for detection of genetical differentiation of wild populations.     

Metrical and Non-metrical Skull Variations in Norwegian Wild Mink (Mustela vison Schreber)

Variations in fifteen metrical measurements and six non-metrical traits in 131 mink skulls were investigated. The skulls were subdivided geographically into three samples: Eastern Norway, Western Norway and Trøndelag. Separation into juveniles and adults was in accordance with the criterion that all sutures are closed in adults. This seemed to work well. No age or sex variations were found in the non-metrical traits. Relatively little geographic variation found in either the metrical measurements or the non-metrical traits indicated little genetic variation. Gene-flow is regarded as one of the reasons for this.     

Ovarian reproductive function after exposure to diethylstilbestrol in neonatal life

Inbred and random-bred NMRI mice were treated with diethylstilbestrol (DES, 5 micrograms per day) or vehicle (olive oil) on Days 1-5 after birth. At the age of 8 wk, females were treated with saline or eCG and hCG to induce ovulation. Ova never occurred in the ampulla of the uterine tube of saline-treated, DES-treated females when these mice were not mated. After gonadotropin treatment, ova were found in the ampulla of all olive oil-treated females and in approximately 80% of DES-treated females. The number of ovulated ova was similar in both groups. Twenty percent of gonadotropin-treated, DES-treated females had ova in the ampulla and a vaginal plug after being caged with males but none became pregnant. Ovaries from inbred control or DES-treated females were grafted to the ovarian bursa of control or DES-treated ovariectomized hosts. DES-treated hosts, carrying control or DES-exposed ovaries, never became pregnant. Control females, with control ovaries or DES-exposed ovaries, became pregnant; pregnancy rate and litter size were similar for control mice regardless of whether they were supporting DES-exposed or control ovaries. Oocytes from ovaries exposed neonatally to DES can thus give rise to apparently normal offspring. The results also indicate DES-induced nonovarian disturbances, e.g. tubal and/or endometrial function, both of which are important for fertility. In the grafting experiments, a high mortality rate was found in inbred DES-exposed females caged with males. All deaths were associated with vaginal concrements (vaginal stones) and intestinal complications.     

Components of phenotypic variation in avian ornamental and non-ornamental feathers

Phenotypic variation, measured as the coefficient of variation (CV), is usually larger in secondary sexual characters than in ordinary morphological traits. We tested if intraspecific differences in the CV between ornamental and non-ornamental feather traits in 67 evolutionary events of feather ornamentation in birds were due to differences in (1) the allometric pattern (slope of the regression line when regressing trait size on an indicator of body size), or (2) the dispersion of observations around the regression line. We found that only dispersion of observations around the regression line contributed significantly to total variation. A large dispersion of observations around the regression line for ornamental feathers is consistent with these characters showing condition-dependence, supporting indicator models of sexual selection more strongly than a pure Fisher process. Ornamental feathers in males demonstrated negative allometry when regressed on tarsus length, which is a measure of skeletal body size. This finding is consistent with ornamental feather traits being subject to directional selection due to female mate preferences, where large body size is less important than in male–male competition. This pattern of phenotypic variation for avian secondary sexual characters contrasts with patterns of variation for insect genitalia, supposedly subject to sexual selection, since the latter traits only differ from ordinary morphology traits in allometry coefficient. The prevailing regime of selection (directional or stabilizing) and the effects of environmental factors are proposed to account for these differences among traits.     

华北人头骨非测量性状的观察

本文报告了一组华北人头骨上63项和另两项多年以前描述过而近年未见研究的非测量性状的出现情况,并作为一项新的性状描述了二分髁管。     

Fertility Control in Free-Ranging Elk Using Gonadotropin-Releasing Hormone Agonist Leuprolide: Effects on Reproduction,Behavior, and Body Condition

ABSTRACT Overabundant elk (Cervus elaphus) populations have become a significant problem in many areas of North America. This is particularly true for protected areas where high densities of elk can cause long-term ecological degradation. When lethal control is not acceptable in these environments, resource managers must often consider alternative methods for reducing the size of resident elk populations. A potential management alternative is controlling the fertility of female elk. A promising new approach to wildlife contraception involves the use of biodegradable implants containing the gonadotropin-releasing hormone (GnRH) agonist leuprolide. During fall 2002-spring 2004, we compared pregnancy rates, reproductive behavior, daily activity patterns, and body condition of 17 free-ranging female elk treated with a leuprolide formulation with 17 untreated females, in Rocky Mountain National Park, Colorado, USA. After treatment, the pregnancy rate of treated elk was 0%, whereas 79% of control elk became pregnant. The effects of treatment were reversed the subsequent year with the pregnancy rate of treated females 100% compared with 91% for controls. Reproductive behaviors were similar for treated and control elk during the breeding and postbreeding seasons; treated elk did not exhibit postrut reproductive behaviors. Moreover, we found no differences in daily activity patterns of experimental groups during the breeding or postbreeding seasons. Treated elk did not show improved body condition over pregnant females. Instead, treated females catabolized proportionately more body fat during winter after treatment and at a higher rate than pregnant control elk. However, this effect was reversed the next spring with no difference in body fat between treated and control elk. We conclude from this experiment that leuprolide, administered as a controlled release formulation, offers a safe and effective method of controlling fertility in free-ranging female elk. However, practical application is limited by treatment duration and the need to treat females before the breeding season.     

Variations of supraorbital bony structures in Sienese skulls

Various non-metrical traits were examined in the supraorbital region in a series of skulls of recorded sex (147 males, 130 females), age (18-80 years) and provenance (Siena and surroundings), using a standard method of categorization and notation introduced by two of the authors in 1983. The results are discussed from a topographic-anatomical point of view in relation to trait variation and with respect to the usefulness of the method applied for population studies.     

Analysis of oocyte quality in recombinant inbred mouse strains developed from KE and CBA strains that differ in fertilization efficiency

Recombinant inbred (RI) mouse strains were developed from reciprocal crosses between two inbred strains differing in the proportion of fertilized ova (CBA, 100%; KE, 77%), to analyse the underlying factors. A correlation (r = 0.83, P < 0.01) between fertilization efficiency within 22 RI strains and after mating RI females with KE males proved that oocyte quality was involved. The following oocyte parameters were analysed in RI and progenitor strains: time of meiotic maturation, rapidity of enzymatic removal of egg investments, and proportion of fertilized ova with supplementary spermatozoa in the perivitelline space. Among the RI strains, high incidence of supplementary spermatozoa was correlated with lower efficiency of fertilization (r = -0.58, P < 0.05) and with slow meiotic maturation (r = -64, P < 0.01), suggesting that delayed maturation may affect oocyte ability of being fertilized by the first penetrating spermatozoon. However, significant correlations were also found between characters which coexist within the progenitor strains, but are not likely to be physiologically related; this suggests that RI strains have inherited large blocks of progenitor genomes, not disrupted by recombination. The strain distribution pattern (SDP) of the analysed traits revealed CBA-like, KE-like, and intermediate phenotypes, indicating that they are polygenically determined. No linkages were found between the studied traits and 12 enzymatic markers. However, the SDP for fertilization efficiency showed a preponderance of non-matching strains (15/19) in relation to agouti locus; the known instability of this chromosome region makes it possible that a putative linkage was disrupted by recombination when RI strains were created.     

Quantitative genetics of skeletal nonmetric traits in the rhesus macaques on Cayo Santiago. I. Single trait heritabilities

The use of skeletal nonmetric traits in studies of biological relationships often involves the assumption that variation in these traits is genetic. Studies of nonmetric traits in human groups and in inbred strains of mice and rabbits have indicated a genetic component to nonmetric trait variation. Skeletons of animals with known matrilineage membership were obtained from the Cayo Santiago skeletal collection in order to obtain a direct estimate of the heritabilities of several nonmetric traits in the free-ranging population of rhesus macaques on Cayo Santiago. Falconer's (1965) method was used to calculate heritability. Heritability estimates range from zero to one, and half of them are greater than 0.5. This indicates that there is a considerable amount of genetic variation for these traits among the Cayo macaques. There is a significant tendency for traits scoring the number of foramina to have lower heritabilities than those scoring hyperstotic or hypostotic traits.     

Comparative effects of inbreeding and outbreeding on the ontogeny of Heliconius erato phyllis (Lepidoptera: Nymphalidae)

Inbreeding depression has been reported in various groups of organisms, including insects. Estimates of inbreeding consequences were obtained by comparing 12 life‐history and morphological traits among nine inbred families (F = 0.25) and 16 outbred families (F = 0) of the Neotropical butterfly Heliconius erato phyllis. A Student's t‐test showed statistically significant differences for pupal weight and right forewing area, both in males and in females, between inbred and outbred families. Survival during development, from egg hatching to adulthood, also differed significantly between inbred and outbred families. The average number of haploid lethal equivalents was 0.17 for pupal weight, 0.15 for forewing area and 0.71 for survival from hatching to adulthood. The results of this study confirm that the consequences of inbreeding are more deleterious to life history traits than to morphological ones.     

Morphological and reproductive variation among populations of the Pacific molly Poecilia butleri

In viviparous organisms, pregnant females typically experience an increase in body mass and body volume. In this study, the prediction that variation in reproductive traits among populations of viviparous organisms should be related to variation among populations in body shape was tested in the Pacific molly Poecilia butleri, a viviparous fish that inhabits western Mexico and northern Central America. Variation among 10 populations in four reproductive traits was examined: brood size, individual embryo mass, total reproductive allotment and degree of maternal provisioning of nutrients to developing embryos. Variation among these populations in body shape was also examined. Significant variation among populations was observed in both brood size and reproductive allotment but not in embryo mass or degree of maternal provisioning. Significant variation among populations was also observed in body shape. After correcting for female size, however, reproductive traits and body shape were not associated among populations. This suggests that selective pressures acting on reproduction do not necessarily affect morphology and vice versa. Several factors might contribute to this unexpected lack of association between reproductive traits and morphology.     

Morphological variability between wild populations and inbred stocks of a Chinese minnow, Gobiocypris rarus

Gobiocypris rarus, a small, native cyprinid fish, is currently widely used in research on fish pathology, genetics, toxicology, embryology, and physiology in China. To develop this species as a model laboratory animal, inbred strains have been successfully created. In this study, to explore a method to discriminate inbred strains and evaluate inbreeding effects, morphological variation among three wild populations and three inbred stocks of G. rarus was investigated by the multivariate analysis of eight meristic and 30 morphometric characters. Tiny intraspecific variations in meristic characters were found, but these were not effective for population distinction. Stepwise discriminant analysis and cluster analysis of conventional measures and truss network data showed considerable divergence among populations, especially between wild populations and inbred stocks. The average discriminant accuracy for all populations was 82.1% based on conventional measures and 86.4% based on truss data, whereas the discriminant accuracy for inbred strains was much higher. These results suggested that multivariate analyses of morphometric characters are an effective method for discriminating inbred strains of G. rarus. Morphological differences between wild populations and inbred strains appear to result from both genetic differences and environmental factors. Thirteen characters, extracted from stepwise discriminant analysis, played important roles in morphological differentiation. These characters were mainly measures related to body depth and head size.     

The anthropological evidence for change through Romanisation of the Poundbury population.

Poundbury Camp cemetery was in use for about 500 Years and was the burial ground for an Iron Age Durotrigian group, a rural Roman settlement and an urban Romano-British community. Low variance of metrical characters and persistence of familial traits in the three groups suggest a continuity of the population and in situ growth. However evidence for an anthropological response to the cultural romanisation of the population has been found in a number of skeletal traits including squatting which was most often adopted by Durotrigian females. Dietary changes are indicted by variation in concentrations of trace elements, including lead, in the bones.     

Common genetic and environmental factors among craniofacial traits in Belgian nuclear families: Comparing skeletal and soft-tissue related phenotypes

The major objective of this study was to determine the possible effects of common genetic and environmental factors among 18 craniofacial anthropometric traits, with special attention to the differences between skeletal and soft-tissue related phenotypes. The studied sample consisted of 122 nuclear families living in Brussels and included 251 males and 258 females aged from 13 to 72 years. Univariate and bivariate quantitative genetic analyses were performed using a variance components procedure implemented in SOLAR software.All phenotypes were significantly influenced by additive genetic factors with heritability estimates ranging from 0.46 (nose height) to 0.72 (external biocular breadth). Sex, age and their interactions explained 7-46% of the total phenotypic variance of the traits. Bivariate analysis revealed that several traits share a common genetic and/or environmental basis while other traits show genetic and environmental independence from one another. More and greater genetic and environmental correlations were observed among skeletal phenotypes, than among soft-tissue traits and between both categories. Apart from the tissue composition, other characteristics of the craniofacial morphology such as the orientation (e.g. heights, breadths) have shown to be important factors in determining pleiotropy and common environmental effects between some pairs of traits. In conclusion, the results confirm that overall head configuration is largely determined by additive genetic effects, and that common genetic and environmental factors affecting craniofacial size and shape are stronger for the skeletal traits than for the soft-tissue traits.     

Sexual dimorphism and growth trade‐offs in Blue Tit Cyanistes caeruleus nestlings

The outcome of sibling competition for food is often determined by variation in body size within the brood and involves trade‐offs; traits that enhance competitive ability within the nest may be developed at the expense of traits that enable effective flight at fledging, or vice versa. We quantified growth of skeletal, body mass and feather traits in male and female Blue Tit Cyanistes caeruleus nestlings. Males were significantly heavier, had longer tarsi and tended to have greater head–bill lengths than females, whereas females were similar to males in wing flight feather growth. These differences in growth may result from sexual differences in selection of the traits. Females are likely to prioritize feather growth to facilitate synchronized fledging with the rest of the brood, and to enhance escape from predators. We suggest that males are heavier and develop longer tarsi because body size is an important determinant of male reproductive success.     

Effects of altitude, ethnicity-religion, geographical distance, and occupation on adult anthropometric characters of eastern Himalayan populations

With a view to estimating the effect of altitude on body dimensions vis-à-vis ethnicity-religion, geographical distance, and occupation, a comprehensive multivariate statistical analysis was performed on data pertaining to 16 anthropometric characters collected from 1,103 individuals (643 males and 460 females) belonging to two ethnic groups-Sherpa and Lepcha. Samples were drawn from several locations in the eastern Himalayan region-Darjeeling and Kalimpong in West Bengal (India), and Nepal, situated at low (1,000-2,000 meters) and high (above 3,500 meters) altitudes. The individuals sampled practice different occupations and follow different religions. Significant age and sex effects were observed. The data were age-adjusted, and sexes were treated separately. A test of equality of mean vectors indicated heterogeneity among population groups. Almost all characters were found to contribute significantly to the ability to discriminate between the groups. The overall probability of correctly classifying an individual based on body dimensions into the group in which she or he actually belongs was high (between 0.64 and 0.77). Shape and size factors could be identified that explained about 50% of the total variance and yielded a reasonable separation of the groups. Results of four different types of multivariate statistical analyses were in agreement, and showed that altitude is most highly associated with body dimensions.     

Impact of inbreeding on performance of the predator Podisus maculiventris

Effects of inbreeding on the development and reproduction of the predatory pentatomid Podisus maculiventris were assessed throughout 30 generations following introduction in the laboratory. Developmental and reproductive fitness of two mildly inbred lines did not differ dramatically from that of a reference population. In most generations, egg weight, egg hatch and developmental rate of nymphs were greater in the reference strain than in both inbred strains, but fecundity and longevity did not differ among strains. In the 30th generation, fecundity of all strains had dropped to about half of that observed in the 15th generation, which was presumably related to non-genetic factors. There were consistent differences among strains for adult body weight and size, indicating heritable variation. A positive relationship between weight at day 14 and humeral width of P. maculiventris females was found, but neither of these parameters was associated with total fecundity. In the 30th generation, predators from both inbred lines had generally similar predation capacities to those from the reference population. No significant relationship could be detected between body weights and predation rates of either nymphs or adults. The use of inbreeding to minimize selective adaptation during rearing or to select for favourable traits in P. maculiventris is discussed.     

Differential effects of offspring and maternal inbreeding on egg laying and offspring performance in the burying beetle Nicrophorus vespilloides

We investigate the effect of offspring and maternal inbreeding on maternal and offspring traits associated with early offspring fitness in the burying beetle Nicrophorus vespilloides. We conducted two experiments. In the first experiment, we manipulated maternal inbreeding only (keeping offspring outbred) by generating mothers that were outbred, moderately inbred or highly inbred. Meanwhile, in the second experiment, we manipulated offspring inbreeding only (keeping females outbred) by generating offspring that were outbred, moderately inbred or highly inbred. In both experiments, we monitored subsequent effects on breeding success (number of larvae), maternal traits (clutch size, delay until laying, laying skew, laying spread and egg size) and offspring traits (hatching success, larval survival, duration of larval development and average larval mass). Maternal inbreeding reduced breeding success, and this effect was mediated through lower hatching success and greater larval mortality. Furthermore, inbred mothers produced clutches where egg laying was less skewed towards the early part of laying than outbred females. This reduction in the skew in egg laying is beneficial for larval survival, suggesting that inbred females adjusted their laying patterns facultatively, thereby partially compensating for the detrimental effects of maternal inbreeding on offspring. Finally, we found evidence of a nonlinear effect of offspring inbreeding coefficient on number of larvae dispersing. Offspring inbreeding affected larval survival and larval development time but also unexpectedly affected maternal traits (clutch size and delay until laying), suggesting that females adjust clutch size and the delay until laying in response to being related to their mate.     

Strain differences in teratogenic susceptibility to trypan blue between WM and BDIX rat strains

Female rats of WM (Wistar-Mishima)/Nem strain were mated with WM/Nem (group W) or BDIX/Nem males (group WB), and BDIX/Nem females were mated with BDIX/Nem (group B) or WM/Nem males (group BW). On day 8 of gestation, pregnant females were treated intraperitoneally with 1% aqueous solution of trypan blue at a dose of between 20 and 120 mg/kg of body weight. On day 20 of gestation, fetuses were examined for external, visceral, and skeletal malformations. In group W, fetal mortality increased dose dependently at doses higher than 20 mg/kg, and incidences of external, visceral, and skeletal malformations were significantly higher than control at doses of 30 mg/kg and more. In group B, fetal mortality and the incidence of external malformations were significantly higher than control only in the group treated with 120 mg/kg, and no significant increase of visceral and skeletal malformations was shown. It was confirmed that BDIX strain is much more resistant to trypan blue teratogenicity than WM strain. In group BW, nearly the same teratogenic effects were shown as in group W in terms of fetal mortality and incidence of malformations. However, in group WB, teratogenic effects were not so remarkable as in group BW, suggesting patroclinous effects in teratogenic susceptibility to trypan blue. In group BW, sex differences in teratogenic susceptibility were found; male fetuses were more susceptible to trypan blue than females.     

Temperature preference differences between strains of Mus musculus,associated variables,and ecological implications

Summary Temperature preference differences were found between three inbred strains of mice, Balb/c having a lower preference than C3H and C57Bl. Hybrids with Balb/c had preferences between the inbred strains, while the C3HxC57Bl hybrid was close to the component inbred strains. Mice choosing low temperatures were heavier, had higher body temperatures and lower hair densities than those choosing high temperatures. Arguments are presented for regarding these associations as adaptive, and being morphological and physiological correlates of the behavioural measure temperature preference, a trait itself of ecological significance in habitat selection. It is considered that these traits are subjected to stabilizing selection for the optimum for a given population, to provide the most efficient habitat selection for that population.Tail length is not so intimately associated with temperature preference and shows overdominance in the direction of long tails unlike the other traits measured. In any case, published data show that while there is a general tendency for shorter tails to occur in environments with low temperatures and vice versa, this is not always true, so that tail length is not necessarily a good guide to the habitat selected.Mice were measured at two ages (15 to 18 days, and 55 to 58 days) for temperature preference, body weight and tail length. Developmental changes were found in that the preferred temperature was lower in the older mice. Furthermore, relative changes between age groups for all traits differed between some genotypes, indicating varying developmental changes according to genotype.