The evolution of rewards: seed dispersal, seed size and elaiosome size
The evolution of rewards: seed dispersal, seed size and elaiosome size
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DOI：
10.1111/j.1365-2745.2006.01116.x
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发表时间：
2006-05-01
影响因子：
5.5
通讯作者：
Rodgerson, L
中科院分区：
文献类型：
--
作者：
Edwards, W;Dunlop, M;Rodgerson, L
我们研究了蚂蚁传播种子的奖励与我们使用了来自我们自己的数据集的种子和elaiosome大小，该数据集包含87种金合欢属物种，补充了来自先前公布的数据集的22种，以及来自25科51属的98种“其他物种”，对于两个数据集，使用标准主轴（SMA）回归来确定ln（延伸体大小）和ln（种子大小）之间的关系。对于其他数据集，我们还确定了独立于属间差异的种间关系，独立于科间、属间和科间差异的属间关系。我们使用SMA来检验组间斜率的差异，我们发现在较大数据集的所有子集中有一个显著的共同斜率。在所有数据集中，ln（elaiosome大小）和ln（种子大小）之间关系的估计共同斜率和95%置信区间均高于1（1.24，95% CI = 1.17-1.32），表明正异速生长。坡度也显着积极的和惊人的相似，金合欢物种的数据集和其他物种的数据集。类似的正异速生长在“其他”物种数据集中表现为属与科之间，以及独立于属平均值的物种之间（“种效应”）.分类学水平之间的显著和一致的关系，独立于其他水平的关系，沿着种水平的显著关系，以及斜率的相似性，这表明，独立的收敛到一个潜在的功能关系，已经持续了很长的进化时期。因此，我们的研究结果表明，蚂蚁一直是种子性状选择的代理人。这种功能关系可能是由于蚂蚁觅食行为之间的权衡奖励（elaiosome）和传播的成本（由种子大小决定）。斜率> 1则表明蚂蚁需要比比例更大的奖励来移除更大的种子。
We examine the relationship between the reward offered to ants to disperse seeds (elaiosome size) and seed size, and the possible mechanisms that may generate this relationship in Australian plant species.We used seed and elaiosome sizes from our own data set containing 87 Acacia species, supplemented with 22 species from a previously published data set, and 98 'Other species' from 51 genera in 25 families, also from published data.The relationship between ln(elaiosome size) and ln(seed size) was determined using standard major axis (SMA) regression for both data sets. For the Other data set we also determined the relationship among species independent of the differences between genera, among genera independent of the differences between families, among genera and among families. We used SMA to test for differences in slopes between groups.We found a significant common slope amongst all subsets of the larger data set. The estimated common slope and the 95% confidence interval for the relationship between ln(elaiosome size) and ln(seed size) across all data sets fell above one (1.24, 95% CI = 1.17-1.32), suggesting positive allometry. Slopes were also significantly positive and strikingly similar between the Acacia species data set and the Other species data sets. Similar positive allometry was shown in the 'other' species data set among genera and families, and among species independent of genus means ('species effects').Significant and consistent relationships between taxonomic levels, independent of relationships at other levels, along with significant relationships at the species level, and similarity of slopes, suggest independent convergence towards an underlying functional relationship that has persisted over long evolutionary periods. Our results therefore suggest that ants have been agents of selection on seed traits.Such a functional relationship might result from a trade-off in ant foraging behaviour between the benefit of the reward (elaiosome) and the cost of the dispersal (determined by seed size). Slopes > 1 would then suggest that ants need more than proportionally larger rewards to remove larger seeds.