Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠沙蜥的巢址选择及其生态适应意义 | |
| 其他题名 | The ecological consequence and adaptive significance of nest-site choice in the toad-headed agama (Phrynocephalus przewalskii) |
| 李树然 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 杜卫国 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 母体效应能影响后代适合度，生活史进化以及种群动态。近年来，母体效应对于生物生态适应和进化进程的重要性受到了生态学家和进化生物学家的广泛关注。对于卵生爬行动物，母体的巢址选择行为，包括选择巢址，构建巢穴等，是极为重要的母体效应，因为卵生爬行动物通常缺乏亲代抚育行为，其胚胎大部分时间在母体体外发育，母体选择产卵地决定了胚胎的发育环境，进而修饰后代的表型。本研究以内蒙古荒漠草原上的荒漠沙蜥（Phrynocephalus przewalskii）为研究对象，通过三年的野外研究，系统地探究了荒漠沙蜥的巢址选择，巢穴结构，并通过野外操纵实验探究巢址选择与巢穴结构对荒漠沙蜥后代适合度的影响。 首先，为了探究荒漠沙蜥的巢址选择行为，本研究追踪带有无线电发射器和标记的怀卵荒漠沙蜥母体，测定其产卵前后活动模式，定位产卵巢址的位置，对比巢址与随机位置的环境因子差异。结果表明，荒漠沙蜥母体产卵前会离开平时活动区域选择新的位置构建巢穴，产完卵后又回到最初的活动区域；母体选择开阔的位置构建地下巢穴，巢穴内的土壤温度和湿度均高于随机位置；荒漠沙蜥母体的巢址选择行为未表现出明显的季节性变异，导致巢穴内的温度随着环境温度发生季节性变化，先升高后降低。 其次，为了探究荒漠沙蜥巢穴结构对其巢穴环境及繁殖成功率的影响，本研究记录野外荒漠沙蜥母体构建的地下巢穴的结构，然后构建模拟自然巢穴的有洞穴结构的人工巢穴和无洞穴结构的人工巢穴，对比自然巢穴和两种人工巢穴的环境因子的差异，并对比荒漠沙蜥卵在两种人工巢穴内的孵化情况以及幼体爬到地面的成功率。结果发现，荒漠沙蜥的巢穴是由一条斜向下的洞道以及末端膨大的空腔构成的洞穴，这种结构能够提高巢穴内的空气湿度，但对土壤温度、土壤湿度以及氧气浓度没有影响。更重要的是，这种结构能够提高荒漠沙蜥胚胎存活率以及孵出幼体爬到地面的成功率。 然后，为了揭示荒漠沙蜥巢址选择的适应意义，本研究运用野外操纵手段，监测荒漠沙蜥自然巢穴与随机选择的人工模拟巢穴内的环境条件，并对比其中卵的孵化率、孵化期以及后代的生长、存活与繁殖。结果发现，荒漠沙蜥母体选择的巢穴温度和土壤湿度均高于随机位置的巢穴；相比于随机位置的巢穴，母体选择的巢穴内的胚胎发育速率更快，并且具有更高的存活率，同时母体选择巢穴孵出的幼体在越冬前的生长速率更快，雌性幼体在第二年达到性成熟以及参与繁殖的比例更高。 最后，为了揭示母体巢址选择行为对荒漠沙蜥胚胎发育及后代表型变异的影响，本研究通过对野外荒漠沙蜥自然巢穴间进行卵交互移植孵化实验，剖分区组效应、窝效应和孵化巢址效应对胚胎发育、幼体形态以及生长等表型变异的贡献，并对比在各自母体巢穴与被交换到其他母体巢穴中进行孵化的卵的胚胎发育及孵出幼体表型的差异。结果表明，这三种效应总共对后代表型的贡献达到了68.9%（42.5-94.5%），其中区组效应对孵化期、初生头体长和身体状况以及越冬前头体长、身体状况以及生长率的变异解释最好，而孵化巢址效应对孵化率、初生体重和越冬前体重的变异解释最好，而窝效应的贡献相对来说最小。此外，同窝的移植与非移植卵孵出幼体的特征无显著差异，表明荒漠沙蜥母体并不选择针对自己后代的特定巢址环境。 综上，本研究首次揭示了荒漠蜥蜴巢址选择的行为模式，包括巢穴位置的选择以及巢穴结构的构建，并且首次在自然条件下直接证明了巢穴结构能够决定爬行动物繁殖成功率。同时本研究系统地证明了荒漠蜥蜴巢址选择行为（巢址以及巢穴结构）能够为胚胎发育提供适宜的温湿度条件，进而提高后代多个生活史阶段（从胚胎到性成熟阶段）的适合度，将爬行动物巢址选择行为的适应意义拓展到了对后代成体阶段的影响。 |
| 英文摘要 | The importance of maternal effects in the processes of ecological adaption and evolutionary change has attracted increasing attention since maternal effects can influence offspring fitness, the evolution of life-history traits, and population dynamics. For oviparous reptiles, maternal nest-site choice behaviour (e.g. nest site selection, nest construction) is a primary trait of maternal effect. Most oviparous reptiles lack parental care, leaving their embryos directly exposed to unstable external environments. Moreover, maternal oviposition-selection behaviour can determine the development environments of their embryos and modify offspring phenotypes. In the present study, through three-year fieldwork, we explored the nest-site choice behaviour, the structure of nests and experimentally tested the effect of nest site and nest structure on offspring fitness in the toad-headed agama (Phrynocephalus przewalskii) in the desert steppe of Inner Mongolia.First, to detect the nest-site choice behaviour in toad-headed agama, we tracked gravid female lizards with radio transmitters and marks, and located their nest sites. We determined the movement pattern of lizards before and after nesting, and compared the environmental factors between nest sites and random sites. We found gravid females left their home ranges before oviposition and constructed new burrows as nests for their eggs. After oviposition, females returned to their initial home ranges. Female lizards nested in sparser sites. Correspondingly, the nest sites had higher soil temperatures and moistures than random sites. Female lizards did not shift nesting behaviours seasonally. Consequently, nest temperatures shifted seasonally, rising first and then decreasing, corresponding to seasonal shift in ambient temperatures.Second, we recorded the nest structure to explore the effect of nest structure on nest environments and reproductive success in the toad-headed agama. Then we constructed artificial nests with or without the nest structure to determine how nest structure influences nest environments, egg survival and successful emergence of hatchlings. Our results indicated that female P. przewalskii constructed burrow nest consisting of an inclined tunnel and an expanded chamber. The burrow nests had higher and more stable humidity than non-burrow nests, but similar soil temperatures, soil moistures and oxygen concentration with non-burrow nests. More importantly, egg survival and the emergence success of hatchlings were significantly higher for burrow nests than for non-burrow nests. Then, to investigate the adaptation significance of nest-site choice in P. przewalskii, we quantified the thermal and hydric conditions of nest sites that were chosen by female toad-headed agama. We also determined the effect of nest-site choice on embryonic development and survival and on offspring growth, survival, and maturity by comparing the embryos and offspring from maternally and randomly chosen nest sites. We found that female toad-headed agama chose warm and moist nest sites that improved the developmental rate and survivorship of embryos and promoted the post-hatching growth, sexual maturity, reproduction, and fitness of offspring, thereby improving their reproductive success. At last, we conducted a cross-fostering experiment to detect the influences of maternal nest-site choice behaviour on embryonic development and hatchling phenotype in P. przewalskii. We translocated eggs between nests in the field and evaluated the relative contributions of block, clutch and incubation nest to phenotypic variation of embryonic development, hatchling morphology (snout-vent length, body mass and body condition) and growth. We also compared embryonic development and hatchling phenotype between natal and non-natal nests. Our results showed the three effects contributed 68.9% (42.5-94.5%) to offspring phenotypic variation. In details, block explained most phenotypic variation in incubation length, hatchling snout-vent length and body condition at birth and before hibernation, and growth rate. Incubation nest best explained phenotypic variation in hatching success, hatchling body mass at birth and before hibernation. Clutch contributed least to the phenotypic variation. Furthermore, hatchlings from natal nests and non-natal nests had similar phenotypic traits, which indicated that female toad-headed agama did not select nests specific to reaction norms of their own offspring. In conclusion, current study first revealed the nesting behaviour, including nest-site selection and nest construction, in desert lizard. Current study also provided direct evidence that maternal nest construction behavior could determine parental reproductive success in reptile. Moreover, this study demonstrated that maternal nest-site choice behaviour (nest site and nest structure) in desert lizards could provide suitable thermal and hydric conditions for embryos and hence improve offspring fitness across multiple life-history stages, from embryonic stage to sexual maturity. |
| 中文关键词 | 母体效应 ; 巢址选择 ; 巢穴结构 ; 胚胎发育 ; 后代表型 |
| 英文关键词 | Maternal effect Nest site choice Nest structure Embryonic development Offspring phenotype |
| 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/2XILL650/287882 |
| 推荐引用方式 GB/T 7714 | 李树然. 荒漠沙蜥的巢址选择及其生态适应意义[D]. 中国科学院大学,2017. |
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