Historic Biogeography of Polynesian Birds: Effects of Physical Characters of Islands on Faunal Attributes

[9714819]南太平洋岛屿现代陆鸟群落的分析对生物地理学理论作出了重要贡献。然而，在东波利尼西亚（马克萨斯岛、社会岛、土阿莫土岛、皮特凯恩岛和库克岛群），陆鸟的自然多样性模式和特有性已经被人类造成的灭绝所掩盖。史前东波利尼西亚鸟类在物种丰富度（岛群之间和岛群内）方面比来自同一岛屿的现代鸟类同质得多，与岛屿面积、海拔或隔离程度无关。大多数特有物种仅限于不会飞的物种。关于东波利尼西亚鸟类的数据并不早于2000年前人类的到来。这项新研究将通过收集和分析从汤加、萨摩亚和斐济等不太遥远的西波利尼西亚群岛精确确定年代的史前遗址中收集的骨头组合，在更长的时间尺度（长达10万年）内检验南太平洋鸟类群落的组成和稳定性。在西波利尼西亚可以发现更古老的动物记录，因为当地的掠食性鸟类在人类出现之前的洞穴里就有集中的骨头。新的数据将为估计人类出现前后西波利尼西亚陆鸟的物种丰富度、分类多样性和更替（灭绝/定植）率提供机会。结果表明，与传统生物地理学理论相反，岛屿面积(10（- 104 km2）、海拔高度（101-103 m）和隔离距离（0-800 km）的变化对前人类时期西波利尼西亚鸟类的物种丰富度和分类多样性影响不大，且周转率很低。换句话说，这些鸟类群落在自然条件下丰富而稳定，殖民化和灭绝率极低。从古生物学的角度来看，真正的海洋岛屿上物种的存在可能并不像研究现代鸟类的人普遍认为的那样短暂。

9714819 Steadman Analyses of modern landbird communities on South Pacific islands have made important contributions to biogeographic theory. In East Polynesia (Marquesas, Society, Tuamotu, Pitcairn, and Cook island groups), however, natural patterns of diversity and endemism among landbirds have been obscured by human-caused extinction's. Prehistoric East Polynesian avifaunas were much more homogeneous than modern avifaunas from the same islands in species richness (both between and within island groups), regardless of island area, elevation, or isolation. Most endemism was restricted to flightless species. Data on East Polynesian birds do not precede the arrival of humans at 2000 yr BP. The new research will examine the composition and stability of South Pacific bird communities over much longer time scales (up to 100,000 yr BP) by collecting and analyzing bone assemblages from precisely dated prehistoric sites in the less remote West Polynesian island groups of Tonga, Samoa, and Fiji. Older faunal records can be developed in West Polynesia because indigenous predatory birds have concentrated bones in caves there during pre-human times. The new data will provide an opportunity to estimate species richness, taxonomic diversity, and turnover (extinction/colonization) rates in West Polynesian landbirds both before and after human presence. It is predicted that, counter to classic biogeographic theory, variation in island area (10( - 104 km2), elevation (101-103 m), and isolation (0-800 km) had little influence on species richness or taxonomic diversity in West Polynesian avifaunas in pre-human times, and that turnover rates were very low. In other words, these bird communities were rich but stable under natural conditions, with extremely low rates of colonization and extinction. From a paleontological perspective, the existence of species on true oceanic islands may not be as ephemeral as is generally believed by those who study modern birds.