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1.
大型溞母溞暴露于氨氮所产子代对氨氮毒性的耐受性 总被引:2,自引:0,他引:2
采用大型溞(Daphnia magna)作为受试生物,在测定了氨氮对大型溞的急慢性毒性效应的基础上,进一步研究了在慢性毒性试验中暴露于氨氮环境下的母溞所产子代对氨氮的毒性响应.急性毒性试验结果表明,氨氮对大型溞的24 h和48 h的LC50分别为165.97和69.54 mg/L.21 d慢性试验结果表明:大型溞的生长指标——脱皮数是对氨氮最为敏感的毒性参数;其慢性毒性下限值(LCL)和慢性毒性上限值(UCL)分别为1.88和3.75 mg/L;据此计算出的慢性毒性值(CHV)为2.66 mg/L,急慢性比(ACR)为26.14.在慢性试验中,暴露于毒物的母体所产的子代幼溞,与对照组相比,其48 h LC50都有所增大(增幅为13.7%~56.2%),说明对毒物的适应性有所增强. 相似文献
2.
毒死蜱是目前全世界使用和销售量最大的有机磷杀虫剂之一。为探讨围生期毒死蜱暴露致8周雄性子鼠睾丸组织的氧化损伤,选择健康Wistar妊娠母鼠于妊娠期(gestation days,GD)第6天至子鼠出生后(postnatal days,PND)21天通过灌胃染毒0、0.75、1.35和2.70 mg·kg~(-1)剂量的毒死蜱,待雄性子鼠8周龄取左侧睾丸实施组织病理学检查,右侧睾丸用以检测丙二醛(maleic dialdehyde,MDA)的含量和谷胱甘肽S转移酶(glutathione S transferases,GST)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)、总超氧化物歧化酶(total superoxide dismutase,T-SOD)的活力。结果表明,与对照组比较,随着染毒剂量的增加子鼠体重和睾丸、附睾脏器系数有下降的趋势(P0.05);而MDA呈升高趋势(P0.05)。各组T-SOD和1.35、2.70 mg·kg~(-1)剂量组GSH-Px活力的下降及2.70 mg·kg~(-1)剂量组GST活力的升高均有统计学意义(P0.05)。睾丸组织病理学检查结果可见2.70mg·kg~(-1)剂量组睾丸组织有明显的损伤,管腔中精液量减少,生精细胞脱落增多。上述研究结果提示母鼠于围生期暴露于毒死蜱,可通过氧化损伤诱导子代雄性大鼠睾丸的毒性作用。 相似文献
3.
Gine Roll Skjærvø Bård G. Stokke Eivin Røskaft 《Behavioral ecology and sociobiology》2009,63(8):1133-1140
The aim of this study was to test the hypothesis that parent–offspring conflict over parental investment might have led to
the rarity of dizygotic twins in humans. We explored the theoretical prediction that twins maximize their inclusive fitness
by the death of a co-twin, while mothers of twins maximize fitness by raising both twins to independence. We used life history
data (1700–1900) from two parishes in Central Norway to compare differences in inclusive fitness (measured as number of children
reared to the age of 16 years, using Hamilton's rule) between twins and mothers of twins. Our results show that twins maximize
their inclusive fitness by the death of a co-twin, while mothers of twins raise more children by rearing both twins to adulthood.
However, because twins growing up as singletons may produce higher or at least equal number of offspring than the sum of the
two twins growing up together, mothers might gain more grandchildren by allowing twins to grow up as singletons. To conclude,
both selfish twins and their mothers might benefit by the death of a co-twin, indicating that there is no parent–offspring
conflict responsible for the rareness of twins in these human populations. Finally, we discuss the results in the light of
“The Insurance Egg Hypothesis” and “The Natural Selection Hypothesis”. 相似文献
4.
5.
Effects of age and sex ratios on offspring recruitment rates in translocated black rhinoceros 下载免费PDF全文
Jay V. Gedir Peter R. Law Pierre du Preez Wayne L. Linklater 《Conservation biology》2018,32(3):628-637
Success of animal translocations depends on improving postrelease demographic rates toward establishment and subsequent growth of released populations. Short‐term metrics for evaluating translocation success and its drivers, like postrelease survival and fecundity, are unlikely to represent longer‐term outcomes. We used information theory to investigate 25 years of data on black rhinoceros (Diceros bicornis) translocations. We used the offspring recruitment rate (ORR) of translocated females—a metric integrating survival, fecundity, and offspring recruitment at sexual maturity—to detect determinants of success. Our unambiguously best model (AICω = 0.986) predicted that ORR increases with female age at release as a function of lower postrelease adult rhinoceros sex ratio (males:females). Delay of first postrelease reproduction and failure of some females to recruit any calves to sexual maturity most influenced the pattern of ORRs, and the leading causes of recruitment failure were postrelease female death (23% of all females) and failure to calve (24% of surviving females). We recommend translocating older females (≥6 years old) because they do not exhibit the reproductive delay and low ORRs of juveniles (<4 years old) or the higher rates of recruitment failure of juveniles and young adults (4–5.9 years old). Where translocation of juveniles is necessary, they should be released into female‐biased populations, where they have higher ORRs. Our study offers the unique advantage of a long‐term analysis across a large number of replicate populations—a science‐by‐management experiment as a proxy for a manipulative experiment, and a rare opportunity, particularly for a large, critically endangered taxon such as the black rhinoceros. Our findings differ from previous recommendations, reinforce the importance of long‐term data sets and comprehensive metrics of translocation success, and suggest attention be shifted from ecological to social constraints on population growth and species recovery, particularly when translocating species with polygynous breeding systems. 相似文献
6.
Offspring should be selected to influence maternal effort to maximize their own fitness, whereas mothers are selected to limit
investment in present progeny. In mammals, this leads to a conflict over the amount of milk provided and the timing of weaning.
The intensity and time course of such conflict has so far mostly been investigated experimentally in altricial rodents. However,
it is expected that offspring options for conflict will depend on developmental state. We therefore investigated in the highly
precocial domestic guinea pig (Cavia aperea f. porcellus) who decides over nursing performance and weaning and how pup state influences these decisions. Specifically, we tested whether
a threshold mass of pups predicts weaning time. By exchanging older litters against neonates and vice versa, we produced a
situation in which females differed in lactational stage from the cross-fostered pups. Our results indicate that females decide
about the timing of weaning, as cross-fostered younger pups were weaned at a much younger age than controls and older pups
benefited from continuing lactation of foster mothers. Growth rates did not differ in the treatment groups, and different
weaning ages resulted in differing weaning mass refuting the hypothesis that weaning is based on a threshold mass of offspring.
This constitutes clear evidence that in a precocial rodent, the guinea pig, decisions about maternal care are primarily determined
by maternal state and little influenced by pup state despite the extreme precociality of offspring. We suggest that precocial
pups show little resistance to early weaning when food is abundant, as they reach sufficient nutritional independence by the
middle of lactation to enable independent survival. 相似文献
7.
José M. Aparicio 《Behavioral ecology and sociobiology》1997,41(2):129-137
Lesser kestrels (Falco naumanni) lay clutches which appear excessive as only 3% of them yield as many young as eggs laid. Four hypotheses may explain the
adaptive value of producing surplus eggs: (1) the bet-hedging hypothesis assumes that the environment varies unpredictably
and surplus eggs serve to track uncertain resources; (2) the ice-box hypothesis suggests that surplus offspring serve as a
reserve food during a period of shortage; (3) the progeny choice hypothesis says that parents produce surplus offspring in
order to choose these with higher fitness; and (4) the insurance-egg hypothesis proposes that extra eggs are an insurance
against the failure of any egg. To test the significance of this strategy in the lesser kestrel, an experiment manipu-lating
brood size at hatching was carried out over 2 years, with good and bad feeding conditions. The experiment consisted of adding
a chick to experimental broods where one egg failed to hatch or removing a randomly selected chick from experimental broods
where all eggs had hatched. Independently of annual food availability, pairs with brood sizes reduced by one chick fledged
more nestlings than pairs with brood size equalling their clutch sizes. Body condition of young was also better in the former
group, but only in 1993 (a high-food year). Independently of year, mean local survival of parents with complete broods at
hatching was lower than for parents raising reduced broods. These results supported only the insurance-egg hypothesis which
says that surplus eggs may be an insurance against the failure of any egg, but parents may suffer reproductive costs when
all eggs hatch.
Received: 17 January 1997 / Accepted after revision: 27 April 1997 相似文献
8.
Provisioning weaned young is an important part of the cooperative rearing system of marmosets and tamarins (family: Callitrichidae). Juvenile callitrichids receive a substantial proportion of their diet from all adult group members, whereas juveniles of most other primate species only receive food from the mother infrequently via scrounging. We conducted a longitudinal study of provisioning to 21 young wild golden lion tamarins through their first year of life in two Brazilian reserves. Juveniles were predicted to experience higher provisioning rates at the site with mature forest (the presumed ancestral habitat) and in territories that contained a higher proportion of preferred habitat within the mature forest reserve. Key measures of provisioning did not differ substantially between habitat types. The rates at which juveniles begged for food were very similar across habitats, while the influence of habitat on the rates at which juveniles received food was small and varied across age groups. The most pronounced differences between the reserves were: adult resistance to food-transfer attempts was less frequent, food-offering calls before food transfer were more frequent, and the proportion of prey provisioned was higher in the reserve in which earlier successional-stage forest predominated. Within the mature forest reserve, begging success of young juveniles covaried positively with preferred habitat. Rather than overt caretaker–offspring conflict, an information–feedback loop between juveniles and adults appears to drive provisioning changes as juveniles mature. Direct measures of resource abundance are needed to help clarify the mechanisms by which forest successional stage influences provisioning. 相似文献
9.
Many vertebrates grow up in the company of same or different-age siblings, and relations among them can be expected to significantly
influence individual life histories and the development of individual morphological, physiological, and behavioral phenotypes.
Although studies in birds still dominate and have stimulated most theoretical considerations, the increasing number of mammalian
studies promises to broaden our understanding of this complex field by enabling interesting comparisons with the rather different
bird system. It therefore seems timely to bring together recent studies of sibling relations in mammals and to demonstrate
what these can offer in the way of fresh insights. In this brief review, intended to accompany a series of papers on a diverse
range of mammals, we outline the current state of sibling research in mammals, comparing it to the better studied birds. Most
obviously, in mammals, mother and young are in much closer contact during early life than in birds, and siblings can influence
each other’s development as well as the mother’s physiology while still in utero. During nursing, mammalian young also encounter
a very different feeding situation to bird siblings. These contrasts should help stimulate further debate, as well as provide
further opportunities to study the relative importance of maternal versus sibling effects on individual development. Finally,
we discuss the need to balance studies of sibling competition and conflict with a consideration of the benefits accruing to
individuals from sibling presence and the need for long-term studies of the influence of early sibling relations on individual
development and life histories.
This contribution represents the introduction to the special issue “Sibling competition and cooperation in mammals”. 相似文献
10.
探讨妊娠期染毒全氟辛酸(perfluorooctanoic acid,PFOA)对子代雄鼠发育毒性的影响.将50只妊娠0 d小鼠随机分5组,每组10只,妊娠0~17 d每天按0、1、2.5、5和12.5 mg·kg~(-1)BW饲喂PFOA,产后仔鼠正常饲养,记录仔鼠存活数.产后21 d,检测仔鼠血清睾酮水平并计算睾丸指数;HE染色观察睾丸组织结构变化;RT-PCR法检测睾丸组织Dlk1-Dio3印记基因簇各目的基因mRNA的表达情况.结果显示,随PFOA染毒剂量增加,仔鼠存活数显著降低,血清睾酮含量极显著性降低(p0.01);睾丸指数无统计学意义;睾丸组织有不同程度的损伤并呈剂量依赖性;Dlk1-Dio3印记基因簇各目的基因的表达量都有降低趋势,其中Gtl2、Rian、Dio3均显著性降低(p0.05).结果表明,妊娠期染毒PFOA能够降低仔鼠存活数,损伤睾丸组织结构,并能够扰乱生殖激素,降低睾丸组织Dlk1-Dio3印记基因簇各目的基因mRNA的表达. 相似文献