CONTRASTING PATTERNS OF RADIATION IN AFRICAN AND AUSTRALIAN RESTIONACEAE
CONTRASTING PATTERNS OF RADIATION IN AFRICAN AND AUSTRALIAN RESTIONACEAE
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非洲和澳大利亚雷索科植物辐射模式的对比
DOI：
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发表时间：
2003
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通讯作者：
B. G. Briggs
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作者：
H. Linder;P. Eldenas;B. G. Briggs
摘要南部非洲和澳大利亚西南部地中海气候区的植物区系物种丰富。由于这两个地区在各自的大陆上处于相似的纬度和相似的位置，它们可能有相似的新生代气候历史。在这里，我们通过比较非洲和澳大利亚雷公藤科的谱系积累速度来检验这两个地区物种丰富度的演化遵循类似的时间进程的预测。Restionaceae(Poales)是南部非洲开普弗洛里斯特省Fynbos植被和西澳大利亚州西南部弗洛里斯特省Kwongan植被的典型且往往是优势成分。从rbcL和trnL-F序列的组合数据集和一个大的形态数据集估计了该家族的系统发育；这些数据集基本上是一致的。Restionaceae的单系被支持，并证实了一个非洲支系(∼350种)和一个澳大利亚支系(146种)的基生分裂。也有人支持进一步划分这两个大的姐妹支系，但非洲支系内部的最终分辨率非常弱。化石花粉记录提供了澳大利亚和非洲雷公藤科的共同祖先的最低年龄为-7100万年前，这个日期被用来校准一个分子钟。分子时钟被似然比检验拒绝；因此，使用非参数速率平滑来平滑谱系之间的速率变化。速率校正的年龄被用来构建随时间推移的谱系曲线图。在古近纪，澳大利亚的谱系多样性增加，与恒定出生率模型的预测一致，而非洲的谱系多样性在中新世表现出显著的多样性增加。不完全采样掩盖了新近纪的模式，但将这种趋势扩展到现代现存的多样性表明，物种形成速度的加速在非洲支系中继续存在，而澳大利亚支系保持了恒定的多样化速率。非洲雷公藤科和澳大利亚雷公藤科在形态和解剖上的相似性似乎排除了形态创新作为洲际差异的可能解释。这些差异很可能是由于温带澳大利亚的地理范围和生态差异比温带非洲更大，这可能为基本的雷公藤科谱系提供了避难所，而南部非洲更多山的地形可能为更快、更新的物种形成提供了选择性制度。
Abstract The floras of the Mediterranean-climate areas of southern Africa and southwestern Australia are remarkably species rich. Because the two areas are at similar latitudes and in similar positions on their respective continents, they have probably had similar Cenozoic climatic histories. Here we test the prediction that the evolution of the species richness in the two areas followed a similar temporal progression by comparing the rates of lineage accumulation for African and Australian Restionaceae. Restionaceae (Poales) are typical and often dominant elements in the fynbos vegetation of the Cape Floristic Region of southern Africa and the kwongan vegetation of the Southwestern Floristic Province of Western Australia. The phylogeny of the family was estimated from combined datasets for rbcL and trnL-F sequences and a large morphological dataset; these datasets are largely congruent. The monophyly of Restionaceae is supported and a basal division into an African clade (∼350 species) and an Australian clade (146 species) corroborated. There is also support for a futher subdivision of these two large sister-clades, but the terminal resolution within the African clade is very weak. Fossil pollen records provided a minimum age of the common ancestor of Australian and African Restionaceae as 64–71 million years ago, and this date was used to calibrate a molecular clock. A molecular clock was rejected by a likelihood ratio test; therefore, rate changes between the lineages were smoothed using nonparametric rate smoothing. The rate-corrected ages were used to construct a plot of lineages through time. During the Palaeogene the Australian lineage diversity increased consistent with the predictions of the constant birthrate model, while the African lineage diversity showed a dramatic increase in diversification rate in the Miocene. Incomplete sampling obscures the patterns in the Neogene, but extending the trends to the modern extant diversity suggests that this acceleration in the speciation rate continued in the African clade, whereas the Australian clade retained a constant diversification rate. The substantial morphological and anatomical similarity between the African and Australian Restionaceae appear to preclude morphological innovations as possible explanations for the intercontinental differences. Most likely these differences are due to the greater geographical extent and ecological variation in temperate Australia than temperate Africa, which might have provided refugia for basal Restionaceae lineages, whereas the more mountainous terrain of southern Africa might have provided the selective regimes for a more rapid, recent speciation.