Differences between native and invasive Caulerpa taxifolia: a link between asexual fragmentation and abundance in invasive populations
Differences between native and invasive Caulerpa taxifolia: a link between asexual fragmentation and abundance in invasive populations
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本土花旗蕉和入侵花旗蕉之间的差异：无性分裂与入侵种群丰度之间的联系
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发表时间：
2005
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通讯作者：
Jeffrey T. Wright
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作者：
Jeffrey T. Wright
热带和亚热带海洋绿藻Caulerpa axifolia已经入侵了世界各地的几个温带地区，包括澳大利亚东南部。在这项研究中，我研究了来自澳大利亚温带东南部的入侵紫杉与来自澳大利亚亚热带莫雷顿湾的原生紫杉在被认为对其入侵成功至关重要的特征上的不同之处：菌体大小和密度、无性繁殖水平(碎片化)和总生物量。与预测的入侵杉木的大尺寸相反，摩顿湾的本地种群比入侵种群有更大的匍匐茎和叶子。然而，与本地种群相比，入侵种群始终具有更高的匍匐茎密度、叶片密度和破碎的叶片密度，以及更大的生物量。入侵地的平均密度超过4,700个匍匐茎和9,000个叶/m2，高达27,000个匍匐茎和95,000个叶/m2，是世界上报道的最高的紫杉属。入侵地叶片碎片化的平均密度高达6000株/m2，其中45%的匍匐茎可通过叶片碎片化直接与无性繁殖有关。重要的是，在入侵地点，无性繁殖与丰富度之间有很强的相关性，表现为碎片化的叶子密度与总生物量之间的正相关。这些发现首次描述了本地和入侵紫杉属之间的数量差异，并证明了入侵种群中高水平的无性繁殖和高丰度之间的联系。尽管高水平无性繁殖的原因和后果仍有待探索，但这项研究表明，在紫杉入侵温带栖息地期间，人口统计和生活史特征的变化可能有助于它在那里的成功。
The tropical and subtropical marine green alga Caulerpa taxifolia has invaded several temperate regions throughout the world, including southeastern Australia. In this study, I examined how invasive C. taxifolia from temperate southeastern Australia differed from native C. taxifolia from subtropical Moreton Bay, Australia, in the traits proposed as being important to its invasion success: thallus size and density, levels of asexual reproduction (fragmentation) and total biomass. Against the prediction of a large size for invasive C. taxifolia, native populations from Moreton Bay had larger stolons and fronds than invasive populations. However, invasive populations consistently had much higher densities of stolons, fronds and fragmented fronds; and a greater biomass compared to native populations. Average densities at invasive sites exceeded 4,700 stolons and 9,000 fronds/m2 and were as high as 27,000 stolons and 95,000 fronds/m2, whichare the highest reported for C. taxifolia anywhere. Average densities of fragmented fronds at invasive sites were as high as 6,000/m2 and up to 45% of all stolons at invasive sites could be directly linked to asexual recruitment via fragmented fronds. Importantly, at invasive locations there was a strong association between asexual reproduction and abundance demonstrated by positive correlations between the density of fragmented fronds and total biomass. These findings are the first to describe quantitative differences between native and invasive C. taxifolia and to demonstrate a link between the high levels of asexual reproduction and high abundance in invasive populations. Although the causes and consequences of high levels of asexual reproduction remain to be explored, this study suggests that changes in demographic and life-history traits during the invasion by C. taxifolia into temperate habitats may contribute to its success there.