Reproduction in the Iguana Conolophus subcristatus on Fernandina Island, Galapagos: Clutch Size and Migration Costs
Reproduction in the Iguana Conolophus subcristatus on Fernandina Island, Galapagos: Clutch Size and Migration Costs
复制标题
加拉帕戈斯费尔南迪纳岛鬣蜥的繁殖：窝大小和迁徙成本
DOI：
10.1086/284103
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发表时间：
1983
影响因子：
2.9
通讯作者：
D. Werner
中科院分区：
文献类型：
--
作者：
D. Werner
加拉帕戈斯费尔南迪纳岛上的成年陆地鬣蜥（Conolophus subcristatus）生活在一个不可预测的、没有捕食者的环境中。他们缺乏竞争对手。种群结构允许直接比较对不同环境的适应，因为可以假设整个种群具有相同的遗传背景。繁殖努力显然是不同的生境质量的函数。来自良好栖息地的雌性不仅产下更大的窝，而且在恶劣条件下保持更高比例的储备以供生存。另一方面，在不同的栖息地的差异选择应该有利于后代的女性适应恶劣的条件。数以千计的雌性利用岛上的火山口筑巢。牠们可以在空中迁徙超过10公里，到达1，495米高的山顶，最后爬进900米深的破火山口筑巢。因此，移徙的费用很高，估计占生殖努力的一半。相对离合器质量（RCM）是最低的记录为鬣蜥，也是低相比，一些较小的蜥蜴。如果迁移成本被添加到离合器重量的相应值之间的平均值和其他蜥蜴的最大值。对于一个由资源（成年人）控制的长寿物种来说，这个值出乎意料地高。鸡蛋的价格很低。这大概是一种适应极端的捕食压力和孵化后不久，当鹰，也可能蛇集中在巢址。其他鬣蜥和陆鬣蜥种群所使用的合适筑巢区域并没有被费尔南迪纳的Conolophus使用。到达破火山口的高投资和相关风险必须通过在那里筑巢的优势来抵消。三种可能性进行了讨论。(1)火山口的气候条件可能使种群能够在最有利的季节（温暖，多雨）产卵和交配;（2）巢被发现在琥珀色加热的土壤中，可以用来集中孵化到一个比产卵更短的时间（一种反捕食机制）;（3）性别决定的孵化温度的基础上。
Adult land iguanas (Conolophus subcristatus) on Fernandina Island, Galapagos, live in an unpredictable, predator-free environment. They lack resource competitors. The population structure allows direct comparison of adaptations to varying environments because the entire population can be assumed to share the same genetic background. Reproductive effort apparently varies as a function of habitat quality. Females from good habitats not only lay larger clutches but also maintain higher proportions of reserves for survival during harsh conditions. On the other hand, differential selection in varying habitats should favor offspring from females adapted to harsh conditions. Thousands of females use the island's caldera for nesting. They may migrate (aerial) distances exceeding 10 km to the 1,495-m high summit and finally climb into the 900-m deep caldera for nesting. Migration costs are accordingly high and are estimated to constitute half the reproductive effort. The relative clutch mass (RCM) is the lowest recorded for iguanines, and is also low compared to a number of smaller lizards. If migration costs are added to the clutch weight the corresponding value is between the mean and maximum for other lizards. The value is unexpectedly high for a long-lived species controlled by resources (adults). The expenditure per egg is low. This presumably is an adaptation to the extreme predation pressure at and shortly after hatching, when hawks and probably also snakes concentrate at the nest sites. Suitable nesting areas used by other iguanine and land iguana populations are not used by Conolophus on Fernandina. The high investment and associated risks to reach the caldera must be counterbalanced by advantages of nesting there. Three possibilities are discussed. (1) Climatic conditions in the caldera may enable the population to place egg production and mating in the most favorable (warm, rainy) season; (2) nests were found in fumarole-heated soil which could be used to concentrate hatching into a much shorter period than laying (an antipredator mechanism); (3) sex determination on the basis of incubation temperature.