Knowledge Resource Center for Ecological Environment in Arid Area
| 长爪沙鼠的社会行为和社群遗传结构的密度制约性 | |
| 其他题名 | Density-dependent social behavior and genetic structure of social group in Mongolian gerbils (Meriones unguiculatus) |
| 邓可 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 王德华 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 关于种群调节的社会生物学假说 (socio-biological hypothesis) 认为，种群中动物个体间的亲缘关系及社会行为与种群的动态变化密切相关。长爪沙鼠 (Meriones unguiculatus) 是一种全年保持集群生活的社会性啮齿动物，遗传分析表明该鼠社群内个体间的平均遗传系数较高，而社群之间存在明显的遗传分化，故其社群通常是以家族为单位的“家群”。长爪沙鼠繁殖活动主要集中于春、夏季，秋季繁殖休止、家群成员开始贮食准备越冬。由此，沙鼠年生活史繁殖期和贮食期鲜明。此外，野外实验表明长爪沙鼠种群密度、种群增长率呈现季节性波动和年度差异。然而，长爪沙鼠如何调整社会行为以响应生态背景变化、其对家群遗传结构及未来种群发展的影响机制仍不清楚。本研究于2014-2016年，采用标志重捕法对长爪沙鼠自然种群进行了动态监测，通过中立竞技场测定了不同家群个体间的社会行为，运用社会网络分析法定量研究了长爪沙鼠的社会交往格局，并结合微卫星DNA标记技术分析了种群遗传特征及家群遗传结构，探讨了长爪沙鼠社会行为的生活史适应特征及其对种群密度的响应机制。主要结果与结论如下：1. 行为分析结果发现：遗传系数和空间距离对不同家群个体间的冲突行为均没有显著影响，且未显示出密度制约性。友好行为则不然，即在高密度期，长爪沙鼠不同家群个体的友好行为受彼此遗传系数和空间距离的影响。遗传系数越大、空间距离越近，友好行为的持续时间越长。在低密度期，友好行为不受个体间遗传系数影响；但该行为的持续时间随着空间距离增加而缩短。进一步分析显示友好行为仅发生在空间距离小于40 m的个体之间，表明亲缘关系和熟悉性在调节不同家群个体间社会行为均起到一定作用。探究行为的持续时间随个体间空间距离增加而减少，暗示了长爪沙鼠能够分辨邻近熟悉个体和距离较远的陌生个体。我们还发现长爪沙鼠不同家群个体间的4类行为生活史或性别适应特征明显，且对密度制约具有不同的响应模式。例如，友好行为不存在显著的生活史、性别和密度差异；而冲突行为显示在高密度年份，雌鼠间的争斗性贮食期较繁殖期显著增加，雄鼠在两个阶段没有明显变化；相反在低密度年份，雄鼠间的争斗性繁殖阶段要显著高于贮食阶段，雌鼠未表现出显著的生活史差异。此外，雄鼠间的攻击性在低密度年份较高密度年份显著升高。由此可见，长爪沙鼠个体间行为特征反映了雌、雄鼠应对不同生活史阶段相应选择压力的行为策略。2. 社会网络分析结果表明：在群体水平上，长爪沙鼠贮食期的同配性 (assortativity) 显著大于繁殖期的同配性，反映了家群内个体之间的交往强度在贮食期显著上升。繁殖期较为频繁的群间交往有利于获得额外的繁殖机会，而贮食期长爪沙鼠的社会交往主要集中在家群成员之间，将能量更多地分配至贮食及食物资源保卫上，有利于整个家群的越冬存活。在个体水平上，节点中心度 (degree centrality) 在贮食期显著上升，表明长爪沙鼠在该时期的直接联系个体数量显著多于繁殖期的个体数量，即集群性增强；而贮食期个体社会交往强度间的差异性较繁殖期显著升高，反映了长爪沙鼠在贮食期选择社交伙伴有更强的偏好。另一方面，个体的接近中心度 (closeness centrality) 和中间中心度 (betweenness centrality) 在贮食期显著降低，意味着个体在整个种群社会网络中传播和控制信息的能力显著降低，从个体水平反映了社会网络的连通性下降。长爪沙鼠的个体社会网络指标不存在性别差异，表明雌、雄个体在社会网络中与其他个体接触的机率相当。此外，随着种群密度下降，长爪沙鼠倾向于减少家群间的社会交往。3. 遗传分析结果显示：长爪沙鼠种群的等位基因数和观测杂合度存在显著的年间差异，随种群密度减小而显著降低，但多态信息含量保持高度多态水平。长爪沙鼠的遗传多样性与密度显著正相关，我们认为主要原因是低密度期由遗传漂变导致等位基因丧失的同时，又没有足够的外来个体弥补个体多样性的下降，暗示了外来迁入对维持种群高水平遗传多样性的重要性。长爪沙鼠的近交系数显示出显著的年间差异，但与密度的相关性并不显著，我们推测可能原因是近交系数对种群密度变化的响应存在时滞性。该结果支持种群波动社会生物学假说中Charnov和Finerty提出的低密度期近亲交配强度增加的预测。此外，长爪沙鼠家群间遗传分化系数在繁殖期和贮食期间的差异未显示出稳定的年间特征，而不同生活史阶段平均群内配对遗传系数不存在显著差异，且在不同种群密度下保持一致。我们的结果进一步证实了长爪沙鼠以家群为单位聚群生活，此特征不随种群密度或年生活史进程而发生显著变化，反映了长爪沙鼠家群遗传结构的物种特性。综上所述，通过本项研究明确了长爪沙鼠不同家群个体间的行为表现、社会交往格局及其对生活史和种群密度变化的响应模式，以及家群遗传特征的相应变化，为全面理解长爪沙鼠社会行为生活史对策的适应意义，明晰亲缘关系-社会行为在该鼠种群调节中的作用机理提供了理论数据，亦为深入探索干旱区群居型鼠类种群管理对策提供了理论依据和新的视角。 |
| 英文摘要 | Socio-biological hypothesis predict that temporal changes in kin structure can drive population dynamics by affecting spacing behaviour and social tolerance. Mongolian gerbils (Meriones unguiculatus) are a social rodent that live in social group year-around, and genetic data have demonstrated social groups are family groups because of high within-group genetic relatedness and inter-group genetic differentiation. Reproductions mainly occur from March to August and cease in late autumn, most members of a group take part in hoarding food for winter. Therefore, there are 2 distinct life-history stages in Mongolian gerbils: breeding season (March - August) and food-hoarding season (September - October). In addition, field studies have suggested that gerbils display seasonal and annual fluctuations of density and population growth rate. However, how gerbils modify their social behavior to respond to changes in ecological context, and its genetic consequences remains unknown. In this study, we used neutral arena to test social behavior between gerbils from different family groups, used a combination of behavioral tests (neutral arena), social network analysis and microsatellite DNA markers to explore the adaptation of social behavior to life history and the response to density fluctuations. The main results and conclusions were as follow:1. Pairwise relatedness and spatial distance had significant effects on amicable behavior but not on agonistic behavior. During high-density period, the duration of amicable behavior between inter-group gerbils significantly increased with increasing relatedness or decreasing spatial distance. During low-density period, pairwise relatedness had no significant effect on amicable behavior, whereas the duration of amicable behavior significantly decreased with increasing spatial distance. In addition, amicable behavior only occurred between gerbils whose spatial distance was less than 40 m, suggesting that both kinship and familiarity play a role in social associations in Mongolian gerbils. The duration of exploratory behavior significantly decreased with increasing spatial distance, implying gerbils can discriminate familiar neighbors from unfamiliar individuals.We also found that the effects of relatedness and spatial distance on social behavior showed inconsistent patterns in different sexes or life-history stages. For example, we found no significant life-history difference, sex difference or density difference in amicable behavior. In high-density year, the aggression of female gerbils but not males increased during food-hoarding season. In low-density year, however, the aggression of male gerbils during breeding season were significantly higher than that during food-hoarding season, whereas there was no significant life-history difference in aggression. Moreover, the aggression of males were significantly higher in low-density year than that in high-density year. Therefore, our finding revealed differential behavioral strategies to cope with selective pressures at different life-history stages between males and females.2. At the group level, the assortment coefficients for social groups during food-hoarding season were significantly higher than that during breeding season, which suggest that association strength within family group increased during food-hoarding season. Frequent inter-group associations during breeding season may facilitate extra copulations, while gerbils preferentially associated with group members and allocated more energy to hoarding and food defence during food-hoarding season, which in favor of winter survival. At the individual level, the enhanced degree centrality and social differentiation suggest that gerbils have more direct partners and stronger differentiation of the strength of associations during food-hoarding season than during breeding season. Additionally, we found that closeness and betweenness centrality decreased significantly during food-hoarding season. This result not only indicates that there may be an inevitable loss of control over other individuals in the network but also reflects a decrease in the connectivity of social networks. Unexpectedly, we found no significant sex difference in any social attribute, which imply the opportunities to associate with other gerbils are similar in males and females. Mongolian gerbils reduced inter-group associations with decreasing population density.3. There were significant differences in number of allels and observed heterozygosity among years, and both of them decreased significantly with density decline, whereas polymorphic information content (PIC) kept high levels among years. Genetic diversity changed with changes in population density, and the relationship was positive. A possible reason is that at low density, there was not enough immigrants to offset decreased allels result from genetic drift, which reflect the importance of immigration to maintain genetic diversity. Inbreeding coefficient showed a significant difference among years, but had no significant correlation with density, indicating a delayed response to changes in density. This result was consistent with Charnov & Finerty model, which predicted that high level of inbreeding at low density. In addition, inter-group genetic differentiation was higher during food-hoarding season than during breeding season, whereas mean within-group relatedness showed no life-history difference. Our results futher confirm the consistent kin clusters in Mongolian gerbils, which reflect species-specific family group genetic structure.To sum up, our results reveal behavioral traits between inter-group gerbils, social association patterns and their response to population dynamic and genetic consequence. These findings provide theoretical basis and new insight to study the role of behavior-kinship in population dynamic and regulation in rodents inhabiting semi-arid or ard regions. |
| 中文关键词 | 社会生物学假说 ; 亲缘选择理论 ; 生活史 ; 遗传多样性 ; 熟悉性 ; 社会网络分析法 ; 中心度 |
| 英文关键词 | Socio-biological Hypothesis Kin Selection Theory Life History Genetic Diversity Familiarity Social Network Analysis Centrality |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院动物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287887 |
| 推荐引用方式 GB/T 7714 | 邓可. 长爪沙鼠的社会行为和社群遗传结构的密度制约性[D]. 中国科学院大学,2017. |
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