Department of Environmental Studies, University of California-Santa Cruz, Santa Cruz, CA 95064, USA.
Conserv Biol. 2012 Oct;26(5):778-89. doi: 10.1111/j.1523-1739.2012.01885.x. Epub 2012 Jul 19.
Extinctions can leave species without mutualist partners and thus potentially reduce their fitness. In cases where non-native species function as mutualists, mutualism disruption associated with species' extinction may be mitigated. To assess the effectiveness of mutualist species with different origins, we conducted a meta-analysis in which we compared the effectiveness of pollination and seed-dispersal functions of native and non-native vertebrates. We used data from 40 studies in which a total of 34 non-native vertebrate mutualists in 20 geographic locations were examined. For each plant species, opportunistic non-native vertebrate pollinators were generally less effective mutualists than native pollinators. When native mutualists had been extirpated, however, plant seed set and seedling performance appeared elevated in the presence of non-native mutualists, although non-native mutualists had a negative overall effect on seed germination. These results suggest native mutualists may not be easily replaced. In some systems researchers propose taxon substitution or the deliberate introduction of non-native vertebrate mutualists to reestablish mutualist functions such as pollination and seed dispersal and to rescue native species from extinction. Our results also suggest that in places where all native mutualists are extinct, careful taxon substitution may benefit native plants at some life stages.
灭绝会使物种失去共生伙伴，从而可能降低它们的适应性。在非本地物种充当共生者的情况下，与物种灭绝相关的共生关系破坏可能会得到缓解。为了评估具有不同起源的共生物种的有效性，我们进行了一项荟萃分析，比较了本地和非本地脊椎动物的传粉和种子传播功能。我们使用了来自 40 项研究的数据，其中共检查了 20 个地理位置的 34 种非本地脊椎动物共生者。对于每个植物物种，机会主义的非本地脊椎动物传粉者通常不如本地传粉者有效。然而，当本地共生者被根除时，非本地共生者的存在似乎会提高植物的种子结实率和幼苗表现，尽管非本地共生者对种子萌发有负面影响。这些结果表明，本地共生者可能不容易被替代。在某些系统中，研究人员提出了分类群替代或故意引入非本地脊椎动物共生者，以重新建立传粉和种子传播等共生功能，并使本地物种免于灭绝。我们的结果还表明，在所有本地共生者都灭绝的地方，谨慎的分类群替代可能会使某些生命阶段的本地植物受益。
