基于亲权鉴定的千岛湖社鼠家群遗传结构与亲缘关系特征研究

于2009年7月至2010年11月,对浙江千岛湖两个岛屿上的社鼠(Niviventer confucianus)种群进行标志重捕,并采用8个高多态性的微卫星位点,对两个岛屿的社鼠种群进行家群分析和亲权鉴定,探讨了社鼠家群的亲缘关系特征。结果显示,8个微卫星位点能可靠地对两个岛屿社鼠种群进行亲权鉴定,A岛已确定亲缘关系的71只社鼠分为12个家群,家群中的个体数最多达到19个,B岛已确定的49只社鼠个体共分为11个家群,家群中的个体数最多达到14个。家群内部成员之间的亲缘关系表现为配对繁殖的个体对间亲缘系数最小,揭示了社鼠倾向于选择亲缘关系较远的异性作为配偶。家群中雄性后代个体之间与雌性个体之间的亲缘关系相比,两岛表现情况相反,该结果暗示两岛屿上社鼠扩散行为可能有所不同。通过计算与同一雄性(或同一雌性)交配的个体间的亲缘系数,发现两个岛屿上的社鼠在与不同异性交配时也存在选择性,即避免选择亲缘关系较近的异性作为混交的对象。     

植物亲缘识别的研究进展

植物的亲缘识别(kin recognition)指植物通过识别周边个体与自己的亲缘关系, 调整自身的生长生态策略、促进亲缘个体的生存与繁衍。研究表明, 植物主要通过特定的叶片挥发物、根系分泌物、感光载体等途径, 识别周边个体与自己的亲缘关系, 改变自身形态学策略(如根系大小、根冠比、种子数量等)或者生理代谢策略(次生代谢物质、防御蛋白等), 调整与周边个体的竞争强度, 缓和与近亲缘个体之间的竞争, 加强与远亲缘或非亲缘个体的竞争。同时亲缘识别的强度也受环境因子(养分等)的影响。结合目前的研究进展, 该文分析了导致亲缘识别的研究结果存在差异或争议的主要原因, 认为主要与实验材料的选择、亲缘关系的界定标准、环境条件及测定的指标不统一有关。将来的研究应重点从生理生化、分子、代谢水平上深入研究植物亲缘识别的机理。     

繁殖期根田鼠种群密度对其种群统计参数及个体皮质酮水平的作用

为探讨引起种群密度制约的近因,本研究通过在野外建立的4个面积为50 m×30 m的封闭围栏,研究了繁殖期根田鼠种群密度对其种群统计参数及个体皮质酮水平的作用.在围栏设置高密度和低密度种群,测定了繁殖期根田鼠种群密度对种群补充率、存活率、变化率及个体皮质酮水平的作用.高密度种群的补充率和变化率较低密度种群显著降低,但其种群建群者存活率和子代存活率较低密度无显著变化.种群补充率和变化率分别与种群建群者数量呈显著回归关系.高密度处理建群者的血浆皮质酮含量和脾脏指数均显著高于低密度处理.上述结果说明,繁殖期根田鼠种群对其补充率和变化率存在密度制约作用,围栏种群建群者的数量是产生密度制约的唯一制约因子.密度制约与社群应激之间存在密切关联.社群应激可能是种群产生密度制约的近因之一.     

天鹅洲迁地保护江豚种群近亲繁殖状况评估

长江江豚(Neophocaena asiaeorientalis asiaeorientalis)已处于极度濒危状况,迁地保护被认为是避免其灭绝最有希望的保护措施。本文选用21个多态性微卫星标记对2010年10月天鹅洲迁地保护江豚种群进行了亲子鉴定和亲缘关系分析,以检测该种群的近亲繁殖状况,为种群管理提供参考信息。本研究从18个体中检测到3个父-母-子家庭,以及母子和父子各1对。由于检测到的亲子关系较少,单从亲子鉴定结果不能判断该种群是否存在近亲繁殖。然而,亲缘关系分析结果表明,该迁地保护江豚种群的平均亲缘系数r为0.118 2,候选亲本间亲缘系数r为0.115 2,均显著高于长江江豚自然种群。而且,天鹅洲迁地保护江豚种群中具有亲缘关系的个体对达26.14%,高于自然种群6倍以上。此外,该种群的近交系数(Fis)为0.046。基于亲缘系数和近交系数的分析结果均表明,该种群存在较高的近交风险或者可能已经发生近交。本研究建议将种群中亲缘关系最多的雌性F34和雄性M45移出,并以每代(约5年)按雌雄1∶1的比例引进2头可繁殖个体,以降低近亲繁殖风险。此外,建议尽快为该迁地保护江豚种群构建遗传谱系,以便今后开展种群遗传管理。     

中国动物园白鹤圈养种群统计学与遗传学分析

根据《圈养白鹤中国地区谱系簿2012》提供的数据,应用种群管理软件SPARKSv1.6和PMxv1.0对中国动物园白鹤圈养种群进行统计学和遗传学分析。结果显示该种群面临着许多困难,未知性别比例过高(截止到2012年10月31日,中国动物园白鹤圈养种群数量达到92只,其中雄性24只,雌性29只,未知性别39只)、年龄结构不合理(育龄个体数量充足,但幼龄个体数量仅有14只,约占现存种群的15.22%)、基因多样性丢失快(野外来源个体数量较多,达到58只,约占总数的63.04%,但是实际参与繁殖的奠基者仅有7只;该群体中某些奠基者的后代数量较多,种群平均亲缘关系值MK=0.15,从而导致现有种群只保留了野生个体85.25%的基因多样性)、种群数量增长乏力(2006～2012年种群的平均增长率λ=0.98)。因此,为了建立一个健康的白鹤圈养种群,应尽快开展性别鉴定工作,改善饲养环境条件,减少创伤引发的死亡,同时采用各种技术(如人工授精)增加潜在奠基者的繁殖机会,从而尽快扩大种群数量,并减少后代过多个体奠基者的繁殖机会。     

水稻品种抗性对褐飞虱和白背飞虱种群动态的影响

用ＴＮ１、Ｎ２２、ＡｓＤ７和Ｐｔｂ３３等４个抗虫性差异明显的水稻品种测定了褐飞虱和白背飞虱在它们上面的栖息率、落卵量、卵存活率、若虫存活和发育状况,以及后代种群数量表现。结果表明,Ｐｔｂ３３通过减少２种飞虱的栖息率、落卵量,降低卵和若虫存活率,延长若虫的发育时间,抑制后代的种群数量增长,表现出明显的抗性。Ｎ２２对白背飞虱、ＡｓＤ７对褐飞虱的后代种群建立与发展均表现明显的抑制作用。２种飞虱在ＴＮ１上     

广聚萤叶甲地理种群间交配选择及子代的发育表现

为探究分布于我国不同地域的广聚萤叶甲(Ophraella communa)种群之间的分化现状,本文对来自南京、长沙和福州等3个地理种群的交配选择行为及杂交后代发育表现进行了研究.结果表明,在试验观察的6 h内南京种群与福州种群间个体发生交配的概率显著低于对照(种群内雌雄个体间的交配),但南京种群与长沙种群个体间发生交配的概率与对照无显著差异;南京和福州种群的雄性与同种群雌性交配选择次数显著多于与异种群雌性交配的次数,但南京与长沙种群间个体交配的次数与对照无显著差异.3个地理种群间个体杂交后代在卵孵化率、幼虫化蛹率和成虫羽化率等发育特性上与对照(种群内个体自交)无显著差异.根据研究结果推测,广聚萤叶甲南京种群与福州种群间在个体交配行为上存在着一定程度的交配前隔离.     

布氏田鼠合作贮食行为及其影响因素

合作贮食是社会性动物应对食物匮乏的重要对策,但其内在的生态学机制尚未阐明。本文以布氏田鼠为研究对象,根据亲缘关系划分为亲缘组和非亲缘组。在人工实验箱中录像统计不同组别合作贮食行为占用时间的差异,探究亲缘关系对合作贮食行为的影响,并利用相关性分析探究亲缘组个体对贮食的贡献—收益关系以及与贮食行为相关的个体特征因素。结果表明,在组间水平上,与非亲缘组相比,亲缘组的布氏田鼠表现更多的合作贮食。在亲缘组个体水平上,不同个体对贮食的参与度和贡献度存在很大差异。个体对合作贮食的付出与其取食的收益呈显著负相关关系,并且个体合作贮食贡献越大,其睾丸指数和睾酮含量降低越显著。研究结果说明,亲缘关系的存在有利于布氏田鼠的合作贮食,但合作贮食贡献大的个体,其繁殖受到了抑制。     

上海动物园圈养斑嘴环企鹅种群统计学与遗传学分析

根据1984—2017年上海动物园圈养斑嘴环企鹅Spheniscus demersus数据,应用Sparks 1.6和PMx 1.0进行数据整理、统计学和遗传学分析。结果显示,该种群数量呈增长状态,但也存在如下问题:(1)种群中未知性别比例过高,占46.25%;(2)种群年龄结构不合理,0~4岁及7~8岁个体数量不足,育龄个体中未知性别的数量较多;(3)雌雄个体0~1岁、10~13岁的死亡率偏高,曲霉菌病是致死的主要原因;(4)参与繁殖的奠基者数量(9只)和潜在奠基者数量(1只)少,分属2个家系,且后代数和贡献值明显不均衡,种群的平均亲缘关系值为0.097 2,种群的平均近亲繁殖系数为0.099 5,存在近亲繁殖现象;(5)虽然现有种群保留了野生个体90.28%的基因多样性,但未来丢失也较快。因此,为了建立健康的斑嘴环企鹅种群,应尽快引进新的血统,开展性别鉴定工作,采取预防为主、防治结合的方式降低曲霉菌病的致病率;采用各种技术如人工授精技术提高企鹅受精率,为繁殖个体,尤其是后代数量过少的奠基者个体提供均等的繁殖机会,从而加强上海动物园圈养斑嘴环企鹅的种群管理。     

神农架川金丝猴人工补食群的遗传多样性和亲缘关系

以湖北神农架国家级自然保护区的川金丝猴人工补食群体为研究对象,利用微卫星遗传标记对该群体的遗传多样性和亲缘关系进行研究,并对其种群的遗传多样性发展趋势进行了预测。结果显示,12个微卫星位点在该补食群体中共检测到50个等位基因,平均观察杂合度和平均期望杂合度分别为0.668和0.630,多态信息含量为0.442-0.696,平均0.567。亲权鉴定中共鉴定出11个父-母-子单元,各单元未有近亲繁殖的状况。亲缘系数结果显示具有亲缘关系的个体对达21.64%,群体平均亲缘系数为0.1108,现6个家庭单元中有两对候选亲本具有亲缘关系,表明该群体存在较高的近交风险。遗传多样性变化趋势的模拟结果表明,种群的数量对遗传多样性的影响比较大,群体中雄雌比例也对遗传多样性的损失有影响;为避免近亲交配,保持群体的遗传多样性水平,建议进一步做好人工补食群金丝猴的个体识别,完善家庭系谱,明确繁殖个体的遗传背景;引入一批有效的建群者来增加种群的数量及优化雄雌的比例。     

Kin selection is implicated in partial sib-mating populations with constant viability differences before mating

The change in the frequency of a rare mutant allele under constant sex-differentiated viability selection in an infinite, partial full-sib mating population is studied. The diplo-diploid and haplo-diploid polygynous models are considered with a Poisson distribution for the number of offspring produced by every mated female. Reproduction is followed by weak selection among the offspring and then mating to form the next generation. It is shown that the rate of change with respect to the frequency of the mutant allele and the intensity of selection can be expressed in terms of costs or benefits of substituting the mutant type for the wild type, which correspond to average excesses in viability in females and males, multiplied by coefficients of relatedness to the individuals affected by such a substitution and reproductive values associated to the sexes of these individuals. This reveals hidden interactions between mated individuals and between males for mating, the former having positive effects on the reproductive success of related individuals and the latter having negative effects. Such interactions are the result of reproductive constraints when a fixed proportion of females must mate with a male sib and all females are fertilized as long as one mate is available. However, they affect the change in allele frequency because there is inbreeding or relatedness between mates and more generally relatedness between interacting individuals. Surprisingly, the effects of these interactions cancel out in a diploid population when the number of offspring is large enough so that the possibility for a female to have no male sib to mate with can be neglected and the viability differences are the same in both sexes.     

Fluctuating populations and kin interaction in mammals

Kin selection in animals favors less aggressive interaction among related individuals. If the genetic relatedness among neighbors changes with population structure and density, behavioral interaction may also change according to the population structure. Charnov and Finerty proposed a hypothesis that kin selection in voles causes population cycles if the relatedness among neighbors decreases as density increases. Field experiments have recently tested this hypothesis. Furthermore, field studies of social interaction in voles have increased in number, so that the effects of kinship on reproductive success can be reviewed. These studies indicate that although kin interaction might be an important factor affecting social behavior and reproductive success in voles, the relationships both between kinship and degree of amicable behavior or reproductive rate, and between relatedness among neighbors and population density, are far less simple than had been supposed.     

Estimating differential reproductive success from nests of related individuals, with application to a study of the mottled sculpin, Cottus bairdi

Understanding how variation in reproductive success is related to demography is a critical component in understanding the life history of an organism. Parentage analysis using molecular markers can be used to estimate the reproductive success of different groups of individuals in natural populations. Previous models have been developed for cases where offspring are random samples from the population but these models do not account for the presence of full- and half-sibs commonly found in large clutches of many organisms. Here we develop a model for comparing reproductive success among different groups of individuals that explicitly incorporates within-nest relatedness. Inference for the parameters of the model is done in a Bayesian framework, where we sample from the joint posterior of parental assignments and fertility parameters. We use computer simulations to determine how well our model recovers known parameters and investigate how various data collection scenarios (varying the number of nests or the number of offspring) affect the estimates. We then apply our model to compare reproductive success among different age groups of mottled sculpin, Cottus bairdi, from a natural population. We demonstrate that older adults are more likely to contribute to a nest and that females in the older age groups contribute more eggs to a nest than younger individuals.     

No evidence of inbreeding avoidance despite demonstrated survival costs in a polygynous rodent

Individuals are generally predicted to avoid inbreeding because of detrimental fitness effects. However, several recent studies have shown that limited inbreeding is tolerated by some vertebrate species. Here, we examine the costs and benefits of inbreeding in a largely polygynous rodent, the yellow-bellied marmot (Marmota flaviventris). We use a pedigree constructed from 8 years of genetic data to determine the relatedness of all marmots in our study population and examine offspring survival, annual male reproductive success, relatedness between breeding pairs and the effects of group composition on likelihood of male reproduction to assess inbreeding in this species. We found decreased survival in inbred offspring, but equal net reproductive success among males that inbred and those that avoided it. Relatedness between breeding pairs was greater than that expected by chance, indicating that marmots do not appear to avoid breeding with relatives. Further, male marmots do not avoid inbreeding: males mate with equal frequency in groups composed of both related and unrelated females and in groups composed of only female relatives. Our results demonstrate that inbreeding can be tolerated in a polygynous species if the reproductive costs of inbreeding are low and individuals that mate indiscriminately do not suffer decreased reproductive success.     

Inferred Paternity and Male Reproductive Success in a Killer Whale (Orcinus orca) Population

We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating ("resident") eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same "pod" (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was <30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck.     

Relatedness in wild chimpanzees: influence of paternity, male philopatry, and demographic factors

In chimpanzees (Pan troglodytes), high-ranking males are expected to have high reproductive success and females typically emigrate upon reaching maturity. Although high average relatedness among males in the same social groups has been assumed, previous reports have indicated that relatedness among males is not necessarily significantly higher than that among females. The paternity of 11 offspring and the relatedness of 50 individuals in the M group of chimpanzees at Mahale Mountains National Park, Tanzania, were investigated using DNA analyses. We determined the fathers of 10 offspring. Two different alpha males sired a total of five offspring, whereas the other males had low reproductive success. The proportion of paternal half-sibling pairs among the 10 offspring was 15.6%. The average relatedness among mature males was significantly higher than that among mature females. The existence of an old male and the long tenure of one alpha male may have contributed to this significant difference. The average dyadic relatedness among mature natal individuals was significantly higher than that in natal-immigrant pairs in which the individuals came from different groups. The average relatedness among immigrant females was similar to that in pairs of natal and immigrant females, suggesting that the immigrants came from various groups. Thus, female transfer acts to maintain low average relatedness within the group. A comparison of our results to those from other study sites suggests that although the average relatedness among adult males does not reach the level of half-siblings, under some circumstances it can exceed the relatedness of females.     

Multilocus heterozygosity, parental relatedness and individual fitness components in a wild mountain goat, Oreamnos americanus population

Matings between relatives lead to a decrease in offspring genetic diversity which can reduce fitness, a phenomenon known as inbreeding depression. Because alpine ungulates generally live in small structured populations and often exhibit a polygynous mating system, they are susceptible to inbreeding. Here, we used marker-based measures of pairwise genetic relatedness and inbreeding to investigate the fitness consequences of matings between relatives in a long-term study population of mountain goats ( Oreamnos americanus ) at Caw Ridge, Alberta, Canada. We first assessed whether individuals avoided mating with kin by comparing actual and random mating pairs according to their estimated genetic relatedness, which was derived from 25 unlinked polymorphic microsatellite markers and reflected pedigree relatedness. We then examined whether individual multilocus heterozygosity H , used as a measure of inbreeding, was predicted by parental relatedness and associated with yearling survival and the annual probability of giving birth to a kid in adult females. Breeding pairs identified by genetic parentage analyses of offspring that survived to 1 year of age were less genetically related than expected under random matings. Parental relatedness was negatively correlated with offspring H , and more heterozygous yearlings had higher survival to 2 years of age. The probability of giving birth was not affected by H in adult females. Because kids that survived to yearling age were mainly produced by less genetically related parents, our results suggest that some individuals experienced inbreeding depression in early life. Future research will be required to quantify the levels of gene flow between different herds, and evaluate their effects on population genetic diversity and dynamics.     

微卫星标记在种群生物学研究中的应用

微卫星是以几个碱基 (一般为 1～ 6个 )为重复单位组成的简单的串联重复序列 ,具有丰度高、多态性高、共显性标记、选择中性、可自动检测等优点。本文着重介绍了微卫星在种群生物学研究中的应用。微卫星位点可以提供具高分辨率的遗传信息 ,这一特点使微卫星既适合于个体水平上的研究 ,又适合于种群水平上的研究。在个体水平上包括个体识别、交配系统和亲本分析、基因流等研究。微卫星是常用的个体识别手段 ,但在克隆植物遗传结构研究方面的应用还很有限 ;微卫星提高了交配系统和亲本分析、基因流等研究的准确性。在种群水平上微卫星可用于遗传结构、有效种群大小、种群的系统发育重建等研究。微卫星在很多物种 (包括珍稀物种 )的遗传结构研究中得到应用 ;利用微卫星标记确定有效种群大小、检测有效种群大小的波动可以促使我们正确理解种群遗传结构动态和种群进化过程 ;微卫星在种群的系统发育重建研究方面有很大的应用潜力。然而微卫星并不是研究所有问题的唯一选择。文中还讨论了在实际工作中应如何正确利用分子标记等问题     

Mixed reproductive strategies of the Common moorhen on a microscale as revealed by genetic data

External factors shaping reproductive strategies within a population are still poorly understood. How individuals use space and where they decide to build a nest may influence reproductive strategies, as individuals that are close in space may more frequently interact socially. Here, we investigated a population (n = 58 from 15 nests) of the Common moorhen in the Loir river (Western France) using microsatellite data (54 alleles). We found a surprisingly low level of genetic monogamy, a low relatedness among offspring in some nests and a low relatedness between the social parents and the offspring. Nest heterozygosity was highest close to the geographic center of the population. The mating strategies of the Common moorhen were highly variable, despite the social monogamy of the species, and were, to some extent, influenced by the microspatial structure. We discuss how our results contribute to the understanding of parent–offspring and offspring–offspring relationships.