Qian Hong, Ricklefs Robert E
Research and Collections Center, Illinois State Museum, Springfield, IL 62703, USA.
Ecol Lett. 2007 Aug;10(8):737-44. doi: 10.1111/j.1461-0248.2007.01066.x.
Species turnover, or beta diversity, has been predicted to decrease with increasing latitude, but few studies have tested this relationship. Here, we examined the beta diversity-latitude relationship for vascular plants at a continental scale, based on complete species lists of native vascular plants for entire states or provinces in North America (north of Mexico). We calculated beta diversity as the slope of the relationship between the natural logarithm of the Jaccard index (lnJ ) for families, genera or species, and both geographic distance and climate difference within five latitude zones. We found that beta diversity decreased from south to north; within latitude zones, it decreased from species to genera and families. Geographic and climatic distance explained about the same proportion of the variance in lnJ in zones south of c. 50 degrees N. North of this latitude, nearly all the explained variance in lnJ was attributable to geographic distance. Therefore, decreasing beta diversity from south to north reflects decreasing climate differentiation within more northerly latitude zones, and primarily post-glacial dispersal limitation north of 50 degrees N.
物种更替，即β多样性，据预测会随着纬度的增加而降低，但很少有研究验证这种关系。在此，我们基于北美（墨西哥以北）各州或省份的本地维管植物完整物种清单，在大陆尺度上研究了维管植物的β多样性与纬度的关系。我们将β多样性计算为科、属或物种的Jaccard指数自然对数（lnJ）与五个纬度带内地理距离和气候差异之间关系的斜率。我们发现β多样性从南向北降低；在纬度带内，它从物种到属再到科逐渐降低。在北纬约50度以南的区域，地理和气候距离对lnJ方差的解释比例大致相同。在该纬度以北，lnJ中几乎所有被解释的方差都归因于地理距离。因此，β多样性从南向北降低反映了更偏北纬度带内气候差异的减小，以及北纬50度以北主要是冰期后扩散限制的影响。
