Diversification across a heterogeneous landscape

Adaptation to contrasting environments across a heterogeneous landscape favors the formation of ecotypes by promoting ecological divergence. Patterns of fitness variation in the field can show whether natural selection drives local adaptation and ecotype formation. However, to demonstrate a link between ecological divergence and speciation, local adaptation must have consequences for reproductive isolation. Using contrasting ecotypes of an Australian wildflower, Senecio lautus in common garden experiments, hybridization experiments, and reciprocal transplants, we assessed how the environment shapes patterns of adaptation and the consequences of adaptive divergence for reproductive isolation. Local adaptation was strong between ecotypes, but weaker between populations of the same ecotype. F1 hybrids exhibited heterosis, but crosses involving one native parent performed better than those with two foreign parents. In a common garden experiment, F2 hybrids exhibited reduced fitness compared...异质景观中，生物对迥异生境的适应性通过推动生态分化，促进了生态型（ecotype）的形成。野外种群的适合度变异模式，可用于判断自然选择是否驱动了本地适应与生态型的形成。然而，若要证明生态分化与物种形成之间存在关联，本地适应必须对生殖隔离产生影响。本研究以澳大利亚野生植物Senecio lautus的不同生态型为材料，通过同质园试验（common garden experiment）、杂交试验与互易移植试验，探究了环境如何塑造适应性模式，以及适应性分化对生殖隔离的影响。研究发现，不同生态型间的本地适应程度较强，而同生态型内的种群间本地适应则较弱。F1杂种（F1 hybrid）表现出杂种优势（heterosis），但仅含一个本地亲本的杂交组合，其表现优于双亲均为外来亲本的组合。在同质园试验中，F2杂种（F2 hybrid）的适合度相较于……有所降低。