Department of Botany, Ecology Unit, University of Ibadan, Ibadan, Nigeria.
Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
PLoS One. 2018 Sep 5;13(9):e0202421. doi: 10.1371/journal.pone.0202421. eCollection 2018.
Mexican sunflower, Tithonia diversifolia (Asteraceae), is an invasive tropical plant species native to Central America. It has spread in more than 70 countries across Asia, Africa and Australia. In Africa, this species is known to disturb native crops and plant communities, but its negative impacts remain underestimated. Moreover, its potential invasion risk has not been investigated so far. A fundamental aspect in the identification and prediction of habitats susceptible to biological invasions lies in the ability of an organism to conserve or change its ecological niche as part of the invasion process. Here, we compared the realised climatic niche of T. diversifolia between its Central American and African ranges. In addition, reciprocal distribution models were calibrated on its native and invaded ranges. Models were combined and projected to current and future climatic conditions in Africa to estimate the potential distribution of this species. Niche overlap given by Schoner's D index was low (0.23), equivalency and similarity tests suggested that the climatic niche of T. diversifolia is not similar in both ranges. However the low expansion (U = 0.09) and very high stability (S = 0.92) indices support climatic niche conservatism for this species in Africa, although it has not filled its entire niche so far. Our combined reciprocal models highlight highly suitable areas for this species in humid regions throughout East, Central and West Africa, then in some parts of South Africa and Madagascar. Future projections indicated that the distribution of climatically suitable habitats will likely remain stable.
墨西哥向日葵，黄秋英（菊科），是一种原产于中美洲的热带入侵植物物种。它已经在亚洲、非洲和澳大利亚的 70 多个国家传播。在非洲，这种物种被认为会干扰本地作物和植物群落，但它的负面影响仍然被低估。此外，其潜在的入侵风险迄今尚未得到调查。在识别和预测易受生物入侵影响的栖息地方面，一个基本方面在于生物体作为入侵过程的一部分保持或改变其生态位的能力。在这里，我们比较了黄秋英在中美洲和非洲范围内的实际气候生态位。此外，还在其本土和入侵范围内校准了相互分布模型。将模型组合并投影到非洲当前和未来的气候条件下，以估计该物种的潜在分布。由 Schoner's D 指数给出的生态位重叠较低（0.23），等价性和相似性检验表明，该物种的气候生态位在两个范围内并不相似。然而，低扩张（U = 0.09）和非常高的稳定性（S = 0.92）指数支持该物种在非洲的气候生态位保守性，尽管它目前尚未填补其整个生态位。我们的组合互惠模型突出了该物种在东非、中非和西非以及南非和马达加斯加部分地区的潮湿地区的高度适宜区域。未来的预测表明，气候适宜栖息地的分布可能保持稳定。
