Fountain Emily D, Malumbres-Olarte Jagoba, Cruickshank Robert H, Paterson Adrian M
Department of Forest and Wildlife Ecology, University of Wisconsin-Madison , Madison, WI , USA ; Department of Ecology, Faculty of Agriculture and Life Sciences, Lincoln University , Lincoln, Christchurch , New Zealand.
Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen , Copenhagen , Denmark ; Department of Ecology, Faculty of Agriculture and Life Sciences, Lincoln University , Lincoln, Christchurch , New Zealand.
PeerJ. 2015 Feb 5;3:e749. doi: 10.7717/peerj.749. eCollection 2015.
Human alteration of islands has made restoration a key part of conservation management. As islands are restored to their original state, species interactions change and some populations may be impacted. In this study we examine the coxella weevil, (Hadramphus spinipennis Broun) and its host-plant Dieffenbach's speargrass (Aciphylla dieffenbachii Kirk), which are both open habitat specialists with populations on Mangere and Rangatira Islands, Chathams, New Zealand. Both of these islands were heavily impacted by the introduction of livestock; the majority of the forest was removed and the weevil populations declined due to the palatability of their host-plant to livestock. An intensive reforestation program was established on both islands over 50 years ago but the potential impacts of this restoration project on the already endangered H. spinipennis are poorly understood. We combined genetic and population data from 1995 and 2010-2011 to determine the health and status of these species on both islands. There was some genetic variation between the weevil populations on each island but little variation within the species as a whole. The interactions between the weevil and its host-plant populations appear to remain intact on Mangere, despite forest regeneration. A decline in weevils and host-plant on Rangatira does not appear to be caused by canopy regrowth. We recommend that (1) these populations be monitored for ongoing effects of long-term reforestation, (2) the cause of the decline on Rangatira be investigated, and (3) the two populations of weevils be conserved as separate evolutionarily significant units.
人类对岛屿的改造使恢复成为保护管理的关键部分。随着岛屿恢复到原始状态，物种间的相互作用发生变化，一些种群可能会受到影响。在本研究中，我们调查了考克斯拉象鼻虫（Hadramphus spinipennis Broun）及其寄主植物迪芬巴赫氏针茅草（Aciphylla dieffenbachii Kirk），它们都是开阔栖息地的 specialists，在新西兰查塔姆群岛的芒格雷岛和朗伊蒂拉岛有种群分布。这两个岛屿都因家畜引入而受到严重影响；大部分森林被砍伐，象鼻虫种群因寄主植物对家畜的适口性而减少。50多年前，这两个岛屿都开展了密集的重新造林计划，但这个恢复项目对已经濒危的H. spinipennis的潜在影响却知之甚少。我们结合了1995年以及2010 - 2011年的遗传和种群数据，以确定这两个岛屿上这些物种的健康状况和现状。每个岛屿上的象鼻虫种群之间存在一些遗传变异，但整个物种内的变异很小。尽管森林在再生，但在芒格雷岛，象鼻虫与其寄主植物种群之间的相互作用似乎仍然完好无损。朗伊蒂拉岛上象鼻虫和寄主植物的减少似乎不是由树冠层再生引起的。我们建议：（1）监测这些种群，以了解长期重新造林的持续影响；（2）调查朗伊蒂拉岛数量下降的原因；（3）将这两个象鼻虫种群作为独立的具有进化意义的单元加以保护。
