Age-specific variation in reproduction is largely explained by the timing of territory establishment in the New Zealand stitchbird Notiomystis cincta
Age-specific variation in reproduction is largely explained by the timing of territory establishment in the New Zealand stitchbird Notiomystis cincta
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DOI：
10.1111/j.1365-2656.2007.01234.x
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发表时间：
2007-05-01
影响因子：
4.8
通讯作者：
Forslund, Par
中科院分区：
文献类型：
--
作者：
Low, Matthew;Part, Tomas;Forslund, Par
1.利用连续8年来自327个巢穴的数据，我们研究了针叶鸟(或Hihi)种群繁殖的年龄差异，并讨论了繁殖性能的差异如何与领土建立和繁殖的时间有关。在整个种群中，所有生殖参数都呈二次曲线关系，主要是在第一和第二繁殖季节之间增加，第四年以后下降。纵向分析表明，到第六年，羽毛成熟和被招募的雏鸡数量出现了衰老的迹象。第一年和第二年之间的生殖增长是低质量的雌性在第一个繁殖季节后死亡(差异选择假说)和幸存的雌性在第二年表现出生殖改善(个体改进/约束假说)的结果。交配经验或地域质量对两年间繁殖的改善没有影响。影响繁殖产量的关键变量是繁殖时机。在任何给定的季节，开始产卵的鸟类都更有可能产下多只幼鸟。这是第一岁的鸟和年龄较大的鸟之间的主要区别；通常一岁的鸟开始产卵的时间较晚，因此产卵较少。大约一半的第一年的鸟类直到繁殖季节开始后才建立它们的领地。领土建立的延迟导致这些鸟类推迟繁殖，这导致它们的繁殖量比所有其他鸟类都要低。在繁殖开始前成功建立领地的第一年的鸟类，其繁殖率与较年长的鸟类相似。雌性在第一年建立领地的时间与前一个繁殖季节的孵化日期呈正相关。我们推测，这是因为孵化较晚的雌鸟不能有效地与同群中孵化较早的成员争夺领土，这推迟了它们在第一年的建立和繁殖。因此，这种社会约束很可能是导致这一群体特定年龄的生殖差异的主要因素。
1. Using data from 327 nests over a consecutive 8-year period we examined age-specific variation in reproduction in a population of stitchbirds (or hihi) Notiomystis cincta and related how differences in reproductive performance were linked to the timing of territory establishment and breeding.2. Across the population all reproductive parameters showed a quadratic relationship with an increase mainly between the first and second breeding season and a decline after the fourth year. A longitudinal analysis showed evidence of senescence by the sixth year in the numbers of chicks fledged and recruited.3. Reproductive increases between years 1 and 2 were the result of poor-quality females dying after their first breeding season (differential selection hypothesis) in combination with surviving females showing improvements in reproduction in their second year (individual improvement/constraint hypothesis).4. There was no effect of mate experience or territory quality on improvements in breeding between years.5. The key variable influencing reproductive output was the timing of breeding. Birds that started laying earlier were more likely to lay multiple clutches in any given season. This was the main difference between first-year and older birds; generally first-year birds initiated egg laying later and consequently laid fewer clutches.6. Approximately half of all first-year birds did not establish their territory until after the breeding season had begun. This delay in territory establishment resulted in these birds delaying breeding, which resulted in them having a lower reproductive output relative to all other birds. First-year birds that managed to establish their territory before breeding commenced, had similar rates of reproduction as older birds.7. There was a positive relationship between the timing of territory establishment during a female's first year and her hatching date in the previous breeding season. We hypothesize that this was because late-hatched females were less able to effectively compete for territories against earlier-hatched members of their cohort, and this delayed their establishment and breeding in their first year. Thus, this social constraint is likely to be a major factor driving age-specific reproductive variation in this population.