Why mistletoes are more aggregated in disturbed forests? The role of differential host mortality
Why mistletoes are more aggregated in disturbed forests? The role of differential host mortality
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DOI：
10.1016/j.foreco.2017.03.028
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发表时间：
2017-06-15
影响因子：
3.7
通讯作者：
Medel, Rodrigo
中科院分区：
文献类型：
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作者：
Fonturbel, Francisco E.;Salazar, Daniela A.;Medel, Rodrigo
槲寄生依靠生物种子传播，以确保它们在适当的宿主植物上的招聘，因为它们的种子必须存放在安全的地点，以便附着。与大多数寄主-寄生系统一样，槲寄生的空间分布依赖于寄主的空间排列和种子传播者的行为。我们使用了槲寄生Tristerix corymbosus，这是唯一的树栖有袋类动物Dromiciops gliroides分散，它能够寄生在广泛的主机。我们以前发现T。corymbosus mistletoes是更丰富和密集聚集在干扰的栖息地，相比，在类似水平的分散器丰度和主机的可用性。为了解释这种模式，我们测试了两个非相互排斥的假设：（1）在干扰的栖息地更大的资源可用性修改的扩散行为，减少其家庭范围，（2）植物物种在干扰的栖息地是更好的主机，并提供更高的生存概率。我们对300棵槲寄生进行了采样（98棵在原始森林，202棵在受干扰的栖息地），并于2011年11月至2015年3月对这些槲寄生进行了跟踪，以估计存活率并进行点模式分析。此外，我们还利用VHF遥测技术在两种生境中追踪了10只长喙龙，以估计它们的家域面积。槲寄生聚集在两种生境类型，在干扰生境与密集的植物丛更强。此外，在家域上，个体间差异不显著。gliroides之间的栖息地，尽管结构和资源的可用性差异。然而，槲寄生的生存显着不同的栖息地，槲寄生的生存概率为82.87%的干扰栖息地，而在非干扰栖息地的生存概率为53.33%。在未受干扰的栖息地最常见的宿主物种是Pluchea absinthioides，一种季节性灌木，槲寄生的存活概率为29%。然而，在干扰的栖息地，最常见的主机是不耐荫的灌木Chiletelia chilensis和Rhaphithamnus spinosus，死亡率非常低。在干扰栖息地发现的聚集模式很可能出现差异主机死亡率，而不是行为的变化，种子传播媒介。(C)2017爱思唯尔B. V.保留所有权利。
Mistletoes rely on biotic seed dispersal to ensure their recruitment on appropriate host plants, as their seeds must be deposited on safe sites to allow attachment. As most host-parasite systems, mistletoe's spatial distribution depends on the spatial arrangement of the hosts and on the seed disperser's behavior. We used the mistletoe Tristerix corymbosus, which is solely dispersed by the arboreal marsupial Dromiciops gliroides, and it is capable to parasitize a wide range of hosts. We previously found T. corymbosus mistletoes to be more abundant and densely aggregated in disturbed habitats, compared to neigh-boring native forests, at similar levels of disperser abundance and host availability. To explain this pattern, we tested two non-mutually exclusive hypotheses: (1) the larger resource availability in disturbed habitats modify the disperser behavior reducing its home range, and (2) plant species in disturbed habitats are better hosts and offer higher survival probabilities. We sampled 300 mistletoes (98 at the native forest and 202 at the disturbed habitat), which were followed from November 2011 to March 2015 for estimating survival rates and conducting point-pattern analyses. Besides, we tracked ten Dromiciops gliroides individuals using VHF telemetry at both habitats to estimate the home range areas in the two habitats. Mistletoes were aggregated in both habitat types, being stronger at the disturbed habitat with dense plant clumps. Besides, no differences were found on home range of individual D. gliroides between habitats despite structural and resource availability differences. However, mistletoe survival significantly differed between habitats, as mistletoes had a survival probability of 82.87% at the disturbed habitat, whereas survival probability at the non-disturbed habitat was 53.33%. The most common host species at the non-disturbed habitat is Pluchea absinthioides, a seasonal shrub where mistletoes had a survival probability of 29%. At the disturbed habitat, however, the most common hosts are the shade-intolerant shrubs Aristotelia chilensis and Rhaphithamnus spinosus, which had very low mortality rates. The aggregation pattern found at the disturbed habitat is likely to emerge from differential host mortality rather than behavioral changes on the seed disperser vector. (C) 2017 Elsevier B.V. All rights reserved.