School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK.
Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa.
J Evol Biol. 2021 Jan;34(1):60-72. doi: 10.1111/jeb.13609. Epub 2020 Mar 9.
Human activities alter patterns of biodiversity, particularly through species extinctions and range shifts. Two of these activities are human mediated transfer of species and contemporary climate change, and both allow previously isolated genotypes to come into contact and hybridize, potentially altering speciation rates. Hybrids have been shown to survive environmental conditions not tolerated by either parent, suggesting that, under some circumstances, hybrids may be able to expand their ranges and perform well under rapidly changing conditions. However, studies assessing how hybridization influences contemporary range shifts are scarce. We performed crosses on Pyura herdmani and Pyura stolonifera (Chordata, Tunicata), two closely related marine invertebrate species that are ecologically dominant and can hybridize. These sister species live in sympatry along the coasts of southern Africa, but one has a disjunct distribution that includes northern hemisphere sites. We experimentally assessed the performance of hybrid and parental crosses using different temperature regimes, including temperatures predicted under future climate change scenarios. We found that hybrids showed lower performance than parental crosses at the experimental temperatures, suggesting that hybrids are unlikely to expand their ranges to new environments. In turn, we found that the more widespread species performed better at a wide array of temperatures, indicating that this parental species may cope better with future conditions. This study illustrates how offspring fitness may provide key insights to predict range expansions and how contemporary climate change may mediate both the ability of hybrids to expand their ranges and the occurrence of speciation as a result of hybridization.
人类活动改变了生物多样性的模式，特别是通过物种灭绝和分布范围的变化。其中两种活动是人类介导的物种转移和当代气候变化，这两种活动都允许以前隔离的基因型接触和杂交，从而改变物种形成的速度。杂交种已经被证明能够在父母双方都不能耐受的环境条件下生存，这表明在某些情况下，杂交种可能能够扩大其分布范围，并在快速变化的条件下表现良好。然而，评估杂交如何影响当代分布范围变化的研究很少。我们对 Pyura herdmani 和 Pyura stolonifera（脊索动物，被囊动物）进行了杂交，这是两种密切相关的海洋无脊椎动物，在生态上占主导地位，可以杂交。这两个姐妹物种在南非沿海地区同域分布，但有一种不连续的分布，包括北半球的地点。我们使用不同的温度范围，包括未来气候变化情景预测的温度，实验评估了杂种和亲本杂交的性能。我们发现杂种在实验温度下的表现低于亲本杂交，这表明杂种不太可能将其分布范围扩展到新环境。反过来，我们发现分布范围更广的物种在广泛的温度范围内表现更好，这表明这种亲代物种可能更能适应未来的条件。这项研究说明了后代的适应性如何为预测分布范围的扩展提供关键的见解，以及当代气候变化如何调节杂交种扩展其分布范围的能力和杂交导致的物种形成的发生。
