Departamento de Ecología, University of Granada, E-18071 Granada, Spain.
Syst Biol. 2012 Jul;61(4):567-77. doi: 10.1093/sysbio/syr127. Epub 2012 Jan 5.
Understanding the origin of diversity is a fundamental problem in biology. Evolutionary diversification has been intensely explored during the last years due to the development of molecular tools and the comparative method. However, most studies are conducted using only information from extant species. This approach probably leads to misleading conclusions, especially because of inaccuracy in the estimation of extinction rates. It is critical to integrate the information generated by extant organisms with the information obtained from the fossil record. Unfortunately, this integrative approach has been seldom performed, and thus, our understanding of the factors fueling diversification is still deficient. Ecological interactions are a main factor shaping evolutionary diversification by influencing speciation and extinction rates. Most attention has focused on the effect of antagonistic interactions on evolutionary diversification. In contrast, the role of mutualistic interactions in shaping diversification has been much less explored. In this study, by combining phylogenetic, neontological, and paleontological information, we show that a facultative mutualistic plant-animal interaction emerging from frugivory and seed dispersal has most likely contributed to the diversification of our own lineage, the primates. We compiled diet and seed dispersal ability in 381 extant and 556 extinct primates. Using well-established molecular phylogenies, we demonstrated that mutualistic extant primates had higher speciation rates, lower extinction rates, and thereby higher diversification rates than nonmutualistic ones. Similarly, mutualistic fossil primates had higher geological durations and smaller per capita rates of extinction than nonmutualistic ones. As a mechanism underlying this pattern, we found that mutualistic extinct and extant primates have significantly larger geographic ranges, which promotes diversification by hampering extinction and increasing geographic speciation. All these outcomes together strongly suggest that the establishment of a facultative mutualism with plants has greatly benefited primate evolution and fueled its taxonomic diversification.
理解多样性的起源是生物学中的一个基本问题。由于分子工具和比较方法的发展，进化多样化在过去几年中得到了深入研究。然而，大多数研究仅使用现存物种的信息进行。这种方法可能导致误导性的结论，特别是因为灭绝率的估计不准确。将现存生物产生的信息与化石记录中获得的信息相结合是至关重要的。不幸的是，这种综合方法很少被采用，因此，我们对推动多样化的因素的理解仍然不足。生态相互作用是通过影响物种形成和灭绝率来塑造进化多样化的主要因素。大多数注意力都集中在拮抗相互作用对进化多样化的影响上。相比之下，互利相互作用在塑造多样化中的作用却很少被探索。在这项研究中，通过结合系统发育、新生和古生物学信息，我们表明，一种从果实和种子传播中产生的兼性互利植物-动物相互作用很可能促成了我们灵长类动物的进化多样化。我们编译了 381 种现存和 556 种灭绝灵长类动物的饮食和种子传播能力。利用成熟的分子系统发育关系，我们证明了互利的现存灵长类动物具有更高的物种形成率、更低的灭绝率，因此具有更高的多样化率，而非互利的灵长类动物则不然。同样，互利的化石灵长类动物具有更高的地质持续时间和更低的人均灭绝率，而非互利的化石灵长类动物则不然。作为这种模式的潜在机制，我们发现互利的灭绝和现存灵长类动物具有明显更大的地理范围，这通过阻碍灭绝和增加地理物种形成来促进多样化。所有这些结果都强烈表明，与植物建立一种兼性互利关系极大地促进了灵长类动物的进化，并推动了其分类多样化。
