浙江丽水虎纹蛙形态特征的两性异形和食性

用数显游标卡尺测量了407只2001—2003年9月下旬至10月上旬浙江丽水罚没的死亡虎纹蛙的体长等10个形态指标,结果表明:雌性成体体长(SUL)大于雄性成体,幼体形态无显著两性差异;ANCOVA去除SUL差异的影响后,雌性成体的头长和后肢长大于雄性成体,前肢长、眼径和耳径则小于雄性成体。前肢两侧对称性的偏移度成体大于幼体,雌性大于雄性;后肢两侧对称性成幼体和两性无显著差异。10个形态指标主成分分析的前三个主成分共解释64·6%的变异:第一主成分中头宽、眼径和耳径,第二主成分中后肢长,第三主成分中眼间距和鼻间距分别有较高的正负载系数。用NikonSMZ-1000解剖镜鉴别277只个体胃内容物中的食物种类,发现其秋季食物以节肢动物为主;成幼体和两性食物生态位宽度为3·42~5·25,食物生态位重叠度较高为0·93~0·98。分析表明,虎纹蛙局部形态特征的两性差异微弱,而体长两性异形差异显著;雌体具有较大的体形与食性无关,而可能与生育力选择的作用有关。     

Lipid synthesis and deposition by adult Richardson's ground squirrels in the natural environment

Summary Adult male Richardson's ground squirrels,Spermophilus richardsonii, were estimated to have emerged from hibernation in late February to early March, and adult females in mid to late March. Half of the females trapped in late March were not pregnant, as against 10% after that time. In late March males and all females had similar WAT (white adipose tissue) deposits. Between late March and early June, WAT deposits in males increased from 14 g to 64 g (a rate of 5.6 g per week). In non-parous females WAT deposits increased from 13 g to 48 g from late March to late May (4.2 g per week). Fat deposits decreased during lactation but thereafter increased from 8 g to 29 g (a rate of 6.0 g per week) between early May and early June. In males the rate of fatty acid synthesis in BAT (brown adipose tissue), liver and WAT did not change from late March to late May, and rates in the corresponding tissues of non-pregnant females were similar to those in males. Fatty acid synthesis decreased during late pregnancy and lactation. After lactation, the rate of fatty acid synthesis in all tissues increased to that in males and non-pregnant females. Males initiated fattening 5–7 weeks earlier than females. It is concluded that compared with adult males, the later immergence of adult female Richardson's ground squirrels into hibernation is due primarily to later initiation of fattening and less to differences in rate of lipid synthesis after the reproductive period. Rates of fatty acid synthesis in liver and BAT were several times greater than that in WAT. The former tissues may contribute fatty acids for prehibernatory fattening.Abbreviations BAT brown adipose tissue - WAT white adipose tissue     

Sexual dimorphism,weight gain and glucose intolerance in a B- and T-cell deficient mouse model

BackgroundEstrogen is thought to aid maintenance of insulin sensitivity potentially through modulation of a counter-regulatory mechanism that interferes with the contribution of adaptive and innate immune systems to visceral fat deposition. We evaluated the impact of estrogen on long-term high fat diet (HFD) intake in B- and T-cell deficient and immunocompetent animals comparatively.MethodsA total of 16 BALB and 16 SCID mice, 8 of each sex and strain, were randomized to receive low fat diet, 4.1% fat or HFD, 35% fat, such that there was a group of both each sex and each strain receiving each diet. Biweekly levels of adiponectin, leptin and insulin levels were assessed and a glucose tolerance test (GTT) was performed after 13 weeks.ResultsUnlike their male counterparts, HFD-fed SCID females neither gained weight, nor became insulin resistant. Meanwhile, in the HFD-fed BALB groups both males and females gained weight similarly, but remarkable sexual dimorphism was nonetheless observed. The females had notable higher adiponectin levels as compared to males (10–60 μg/mL vs. 6–10 μg/mL respectively) causing the adiponectin-to-leptin (A/L) ratio to reach 80 one week after HFD initiation. The A/L dropped to 10, still higher than males, by week 13, but dropped to 2 by the end of the study in agreement with inverse insulin trends. None of the HFD-fed female groups developed insulin resistance (IR) by week 13, while all male counterparts had. Similar results were observed in the HFD-fed SCID groups whereby the females did not develop IR and had a higher A/L; however, adiponectin levels were comparable between groups (5–11 μg/mL).ConclusionsThe present study provides lacking evidence indicating that estrogen may be sufficient to prevent weight gain and development of glucose intolerance in high-fat fed B- and T-cell deficient mice.     

Effects of expression of human or bovine growth hormone genes on sperm production and male reproductive performance in four lines of transgenic mice.

Reproductive performance was studied in transgenic males from lines expressing and transmitting four hybrid genes: mouse metallothionein-I/human growth hormone (GH) (MT/hGH), MT/hGH placental variant (MT/hGH.V), MT/bovine GH (MT/bGH) and phosphoenolpyruvate carboxykinase/bGH (PEPCK/bGH). Each male was exposed to three normal females for 1 week and to three different normal females for another week. Females were examined for vaginal plugs and necropsied on day 14 of pregnancy. Males were killed for analysis of organ weights, numbers of testicular spermatids, numbers of epididymal sperm and measurements of plasma glucose concentration. Fertility of MT/hGH and MT/hGH.V transgenic males was significantly lower than in normal males, primarily because most males failed to impregnate any females. In females that became pregnant, the numbers of corpora lutea, total fetuses and live fetuses did not differ from those in females mated to normal (nontransgenic) males. Fetal crown-rump length on day 14 of pregnancy did not differ between litters sired by normal or by transgenic males. Weights of testes and seminal vesicles were significantly greater in all four types of transgenic male, but daily sperm production per unit weight (g-1) of testis was not affected and epididymal sperm reserves were either normal or slightly higher than normal. Plasma glucose concentrations were significantly higher in PEPCK/bGH mice than in other mice. Average or individual reproductive performance of transgenic males from the various lines did not correlate with any of the parameters examined except for significantly heavier seminal vesicles in MT/hGH and MT/hGH.V males than in normal males; these transgenic males exhibited a high incidence of infertility. Since hGH and hGH.V, but not bGH, are lactogenic in rodents, it was concluded that chronic stimulation of GH and prolactin receptors by ectopically produced human GHs in transgenic mice compromises male fertility by an unknown mechanism. Reduced fertility of transgenic males with MT/hGH or MT/hGH.V hybrid genes is due to failure to inseminate or impregnate females rather than to reduced numbers of spermatozoa or gross changes in the male reproductive system.     

SEXUAL DIMORPHISM AND SEX RATIO IN THE YELLOWSHOULDERED WIDOWBIRD EUPLECTES MACROURUS SOROR

Savalli, U.M. 1994. Sexual dimorphism and sex ratio in the Yellowshouldered Widowbird Euplectes macrourus soror. Ostrich. 65: 297–301.

Yellowshouldered (Yellowbacked) Widowbirds Euplectes macrourus soror are sexually dimorphic in plumage and size. At Kakamega, western Kenya, adult males were all black except for the yellow shoulders, contrary to previous reports that yellow-mantled individuals were predominant in this area. Males were larger than females, with wing length the best single measure to distinguish sex (since immature males are streaky brown, like females). Immature males had shorter wings and tails than did adult males, but did not differ in other measures of size. The sex ratio of netted birds was near 1:1, but nearly half of the males were immature. The breeding sex ratio was nearly even in one year but heavily male biased the second, suggesting that not all females may breed.     

A comparison of the mating behavior of adolescent and adult female rhesus macaques (Macaca mulatta)

This study compares adult and adolescent female rhesus macaques with regard to (1) characteristics of their copulatory partners, (2) their proceptive behaviors, and (3) adult male behaviors toward them during estrus. We conducted focal follows of 24 adolescent and 65 adult free-ranging estrous female rhesus macaques on Cayo Santiago during two mating seasons. Compared to adult females, adolescents presented sexually to males at higher rates; copulated more frequently with rankless young male, and extra-group males; and, in one of two mating seasons, were ignored more frequently by males to whom they presented sexually. Adolescents tended to copulate with ranked, resident males at higher frequencies on days when the operational sex ratio (adult males:estrous adult females) was high. Males directed “muzzle-up” signals to adolescents at lower rates than to adults in one of two mating seasons, although this effect vanished when males who might have fathered adolescent females were excluded from analysis. Adolescents did not differ consistently from adults in strength of the correlation between proximity maintenance (dyadic Hinde's Index) and copulation rate, or in approach rate to males. Adolescent females, relative to adult females, presented sexually more to rankless young males, but did not present more to ranked, resident males. Both proximate (e.g. endocrine) and ultimate (e.g. differential fecundity; female-female mate competition) explanations may account for the reported differences between adult and adolescent female rhesus macaque sexuality.     

Implications of individual growth status on the future sex of the European eel

Sex-related differences in growth status was demonstrated in eels Anguilla anguilla reared indoors at 17, 20 or 26° C, from the elver stage. Growth status was defined as length increase, weight increase and length–weight relationship. Eels attaining at least 10 g body weight (180–220 mm body length) were tagged with Passive Integrated Transponders (PIT). Length and weight were measured at 6-week intervals, until individuals stopped growing or had attained 150 g weight (380–450 mm). Sex-specific data from potentially undifferentiated eels were provided by retrospective classification of sex. Comparisions between sexes were made within groups graded by length or weight data from the beginning of each 6-week period. There was no consistent difference in absolute length increase between small males and females, but below 40–60 g initial body weight, males displayed on average a higher weight increase than females. Males also had lower length at weight than females, even in the smallest weight groups. Early growth status may influence the future sex of undifferentiated eels, but other approaches are needed for distinction between cause and effect.     

Body weight and some biometrical traits of ring-necked pheasants (Phasianus colchicus) at different ages

Although the growth of pheasants is an important issue, there are few publications providing information on body weight and morphometrics of pheasants at different ages. The aim of this study was to investigate body weight, tarsus length, wing length and wingspan in farmed pheasants aged 3-16 weeks. The study was carried out on 50 pheasants (31 females and 19 males). All one-day old birds were marked and kept until the 16th week of life. In the 3rd 8 h 12th and 16th weeks of life all pheasants were weighted and tarsus length, wing length and wingspan were measured. Male chicks appeared to be significantly heavier than females (P< or = 0.01) already in the third week of life. Also their wings were longer and their wingspan attained higher values (P < or = 0.05). Absolute gains of the majority of traits also differed between sexes (being larger in males) in all studied periods. Values of body weight, tarsus length and wingspan noted in the third week of life were significantly correlated with all later measurements. Thus body weight and some biometrical traits of pheasant chicks measured already at the 3rd week of life could be applied as predictors of future body weight and size.     

Nutritional status of Efe pygmies and Lese horticulturists

We assessed the nutritional status of 90 pygmies (Efe) and 211 members of a neighboring horticultural Lese in the Ituri forest in northeast Zaire. Clinical signs of iron and iodine deficiency were highly prevalent, but the frequency of these and other clinical signs of nutritional deficiency did not differ between the two groups. Infectious diseases such as yaws, cellulitis, and filiariasis were common. Absolute heights and weights of both Efe males and females aged 2–18 years were less than the 5th percentile of the National Center for Health Statistics standards. Weights for height of both groups were within the normal range. Weights and heights, expressed as percentages of the 50th percentile for age and sex, were significantly lower (P < .001) in Efe males and females than among Lese males and females, but weights for height did not differ significantly. Z-Scores of height and weight were also significantly lower in Efe males and females than among their Lese counterparts. The differences in weight and height, expressed either as a percentage of the 50th percentile or as Z-scores, were most apparent in older adolescents and persisted among adults. The normal weight for height among both populations indicated that acute undernutrition did not exist at the time of the survey. Despite comparable levels of adult fatness, measured by triceps skinfold thickness, heights of Efe males and females were lower than those of the Lese. These observations support the hypothesis that genetic differences account for the short stature of the Ituri pygmy. However, because the environments shared by the two groups are not identical and because other practices differ, nutritional effects cannot be excluded.     

Growth and mortality in mountain hares: the effect of sex and date of birth

Summary Current theory suggests that high juvenile growth effort, may result in higher mortality. This prediction is tested in mountain hares (Lepus timidus), by examination of post-weaning growth and mortality of males and females. Dates of birth were estimated from weight at first capture and growth in body weight and hind foot length was described by the logistic growth equation. Although adult female hares are on average larger than males, this results from a longer period of growth and not from a faster growth rate. There was no clear sex bias in mortality, a slight but not significantly greater proportion of males suffered mortality during the growth period. Predictions as to sex difference in mortality should specify which aspects of growth (rate or duration) are the agents of mortality, since the two parameters are not necessarily positively associated. Overall asymptotic body size decreased and rate of growth increased from early through to late-born young. Rate of growth in hind foot length was greater in late-born males but not in late-born females as compared with those born earlier. It is hypothesized that late-born males are more tightly constrained to complete growth and subsequent sexual maturation earlier than late-born females.     

Life-history responses of the rice stem borer Chilo suppressalis to temperature change: Breaking the temperature–size rule

Temperature is a key environmental factor for ectotherms and affects a large number of life history traits. In the present study, development time from hatching to pupation and adult eclosion, pupal and adult weights of the rice stem borer, Chilo suppressalis were examined at 22, 25, 28 and 31 °C under L18:D 6. Larval and pupal times were significantly decreased with increasing rearing temperature and growth rate was positively correlated with temperature. Larval and pupal developmental times were not significantly different between females and males. The relationship between body weight and rearing temperature in C. suppressalis did not follow the temperature–size rule (TSR), both males and females gained the highest body weight at 31 °C. Females were significantly larger than males at all temperatures, showing a female biased sex size dimorphism (SSD). Contrary to Rensch's rule, SSD and body weight in C. suppressalis tended to increase with rising temperature. Male pupae lost significantly more weight at metamorphosis compared to females. We discuss the adaptive significance of the reverse-TSR in the moth's life history.     

Hemoglobin adducts in 1,3-butadiene exposed Czech workers: Female–male comparisons

We previously reported results of a molecular epidemiological study of female and male 1,3-butadiene (BD) exposed Czech workers showing that females appeared to absorb or metabolize less BD per unit exposure concentration than did males, based on metabolite concentrations in urine (Chem. Biol. Interact. 166 (2007) 63–77). However, that unexpected observation could not be verified at the time because the only additional BD metabolite measurement attempted was for 1,2,3,4-diepoxybutane (DEB) as reflected in specific N,N[2,3-dihydroxy-1,4-butyl]valine (pyr-Val) hemoglobin adduct concentrations, which were not quantifiable in any subject with the method then employed. Neither somatic gene mutations nor chromosome aberrations were associated with BD exposure levels in that study, consistent with findings in an earlier Czech study of males only. We have since measured production and accumulation of the 1,2-dihydroxy-3,4-epoxybutane (EBD) metabolite as reflected in N-[2,3,4-trihydroxy-butyl]valine (THB-Val) hemoglobin adduct concentrations. The mean THB-Val concentration was significantly higher in exposed males than in control males (922.3 pmol/g and 275.5 pmol/g, respectively), but exposed and control females did not differ significantly (224.5 pmol/g and 181.1 pmol/g, respectively). In both the control and exposed groups mean THB-Val concentrations were significantly higher for males than females. THB-Val concentrations were significantly correlated with mean 8-h TWA exposures for both males and females, but the rate of increase with increasing BD exposure was significantly lower for females. THB-Val concentrations also increased with increasing urine M2 metabolite [isomeric mixture of 1-hydroxy-2-{N-actylcysteinyl}-3-butene and 2-hydroxy-1-{N-acetylcysteinyl}-3-butene] concentrations in both sexes but the rate of increase was also lower in females than in males. There were no significant correlations between THB-Val concentrations and either somatic gene mutations or chromosome aberrations in either males or females. These results using another biomarker to measure a second metabolite of BD support the original conclusion that females absorb or metabolize less BD than males per unit exposure and indicate that the size of the difference increases with exposure. This observation in humans differs from findings in rodents where at prolonged exposures to high BD levels the females form higher amounts of hemoglobin adducts than do males, a difference that disappears at shorter duration lower exposure levels, while female susceptibility to BD induced mutations and tumorgenesis in rodents appears to persist at all BD exposure levels.     

The biology of the stoat (Mustela erminea) in the National Parks of New Zealand III. Morphometric variation in relation to growth,geographical distribution,and colonisation

Abstract

A total of 1599 stoats were collected from 14 study areas (including all 10 National Parks) from 1972 to 1976. Samples were larger in summer, and contained more females. Young stoats are born in September-October, and females reach adult weight by the following March, though males not until after August. There was significant geographic variation in the body size of adult stoats sampled: males from lowland podocarp/broadleaved forests averaged 3% smaller than males from upland beech forests in skull length, and 4% smaller in head-and-body length. This pattern was repeated, less clearly, in females and in young (approximately 2–5 months old). In contrast with stoats in Britain, assumed to be still the same size as the colonising stock introduced into New Zealand in 1884 and subsequently, males from lowland podocarp forests were unchanged or possibly smaller, and males from upland beech forests were larger; females were larger in all habitats. In males, the extent of geographic variation is almost as great in New Zealand as in the whole of continental Europe. Possible explanations of this pattern are discussed.     

Time course of androgenic modulation of odor preferences and odor cues in male meadow voles, Microtus pennsylvanicus.

During the breeding season, male meadow voles prefer female over male odors and females prefer male over female odors. Testosterone control of males' odor preferences and production of odors attractive to females differ. A male meadow vole's preference for female versus male odor was still evident 1 week after castration, but not 1 week later. This preference was reinstated in testosterone-treated male voles 2 weeks after the onset of hormone replacement. The attractiveness of male odors to females did not disappear until 3 weeks after castration. The attractiveness of male odors was reinstated 1 week after castrated males were treated with testosterone. The time course for the androgenic modulation of production of odors attractive to females may facilitate breeding. For example, at the end of the breeding season males may emit an odor that is still attractive to females. Similarly, at the beginning of the breeding season males may emit an odor that is attractive to females.     

Long-term alcohol exposure prior to conception results in lower fetal body weights

BACKGROUND: It is well known that alcohol consumption during pregnancy can result in lower birth weight babies but many women stop consuming alcohol prior to conception as a part of pregnancy planning. The purpose of this study was to determine whether alcohol consumption prior to conception may also have an effect on fetal development. METHODS: Male and female C57BL/6J mice at 4, 6, or 8 weeks of age received either a single administration of alcohol (3.0 g/kg) via intragastric gavage (IG) each day for at least 60 days, or an isovolumetric IG administration of sterile water. After 60 treatment days, males and females within each age and treatment group were mated overnight. Females continued to receive daily alcohol treatments until conception. Males continued to receive treatments until all females were successfully mated. At conception, females were isolated and left undisturbed. On embryonic day 14, fetus number, size, and weight was determined. RESULTS: Maternal food consumption, body weight at conception, and delay to conception onset did not differ between the two treatment groups or among the three age groups. Fetal body weights did not differ among the three age groups. Fetuses from females treated with alcohol had lower body weights compared to those treated with water. Male treatments did not seem to affect fetal body weight. CONCLUSIONS: Fetal growth and development can be affected by alcohol consumption prior to the time of conception. Alcohol consumption prior to conception is a potential risk factor to fetal outcome and an important consideration for those females planning to have children.     

Pup growth in the fur seals Arctocephalus tropicalis and A. gazella on Marion Island

Subantarctic fur seal Arctocephalus tropicalis and Antarctic fur seal A. gazella pups at Marion Island were weighed frequently until weaning, which occurs earlier in A. gazella (112 days) than in A. tropicalis (± 300 days). The mean birth weight of both species was the same (4·2 kg) and males grew faster than females. Arctocephalus gazella growth was linear to weaning and faster than A. tropicalis growth, which was linear to 120 days of age, slowing until 203 days of age, and thereafter losing weight but recovering perceptibly prior to weaning. Tagging had no apparent effect on pup growth. Faster growth in males than in females is part of the differential growth patterns which lead to adult sexual dimorphism. Arctocephalus gazella pup growth at Marion Island is faster than at South Georgia, indicating that conditions at this, their most northerly breeding locality, are not limiting for pup growth. The decrease in A. tropicalis pup body weight in July/August may result from either a scarcity of food in winter or weaning having been initiated. The two groups (polar and non-polar) of fur seals exhibit two strategies, which include differences in pup growth and suckling period; the polar species have a short suckling period and rapid pup growth and are predominantly pelagic over winter, while the more temperate species have a longer suckling period and slower pup growth and are less pelagic over winter.     

浙江丽水中国石龙子的食性、两性异形和雌性繁殖

丽水分布的中国石龙子（Ｅｕｍｅｃｅｓ ｃｈｉｎｅｎｓｉｓ）摄入的食物均为无脊椎动物,分别属于环节、软体和节肢动物,涉及３０余科,成体和幼体的食物生态位宽度分别为７．２６和６．６９,成体的幼体的食物生态们重叠度为０．５９。性成熟雄性个体大于雌体。成雄和幼体的头长和头宽随体长ＳＶＬ的增长速率大于成雌,成雄头长随ＳＶＬ的增长速度显著大于幼体,成雌和幼体的头长随ＳＶＬ的增长速率无显著差异。成雄头部大于成雌     

Movement patterns and gallery use by the sexually dimorphic Wellington tree weta

The Wellington tree weta, Hemideina crassidens, is a harem-polygynous nocturnal insect whose males defend and mate groups of females residing in cavities in trees. In this study I examined sexual differences in gallery use (number of galleries occupied per unit time), distance travelled per night and activity patterns after sunset. In addition, I investigated how gallery size affected each of these variables. On average, males and females did not differ in the number of galleries visited per night, or in the distance they travelled per night; however, adult males were more likely to be seen earlier in the night than later. Although males and females did not differ in their gallery use or distance travelled, adult males occupied a significantly greater number of galleries and travelled greater distances per night at sites with small galleries than did males at sites with large galleries. These results suggest that habitat structure of a forest patch influences intrasexual tree weta behaviour.     

The nature of a primary feeding habit in different age-sex classes of yellow baboons (Papio cynocephalus).

Two feeding habits of 30 baboons selected equally from five age-sex classes were studied at Mikumi National Park, Tanzania. The finding, gathering, and preparing of sedge corms and of seeds of tamarind fruit were described in detail. Adults obtained these foods faster than younger animals, although even small juveniles and weaned infants were efficient in gathering and preparing them. While gathering sedges or tamarinds, adult males sat in one place longer than others and obtained more food per sitting. Adults ate more pieces of food per minute than juveniles, but adult rates of eating did not differ by sex. The adult rate of food intake was inconsistent with the assumption of different food requirements for males and females of a species with pronounced sexual dimorphism.