Taulavuori Kari, Taulavuori Erja, Saravesi Karita, Jylänki Tanja, Kainulainen Aila, Pajala Jonna, Markkola Annamari, Suominen Otso, Saikkonen Kari
Department of Ecology and Genetics University of Oulu Oulu Finland.
Centre for Environmental Research Kevo Subarctic Research Institute University of Turku Turku Finland.
Ecol Evol. 2017 May 30;7(12):4507-4517. doi: 10.1002/ece3.3026. eCollection 2017 Jun.
Global warming has been commonly accepted to facilitate species' range shifts across latitudes. Cross-latitudinal transplantations support this; many tree species can well adapt to new geographical areas. However, these studies fail to capture species' adaptations to new light environment because the experiments were not designed to explicitly separate species' responses to light and temperature. Here we tested reaction norms of tree seedlings in reciprocal transplantations 1,000 km apart from each other at two latitudes (60°N and 69°N). In contrast to past studies, we exposed our experimental plants to same temperature in both sites (temperature of 60°N growing site is recorded to adjust temperature of 69°N site in real time via Internet connection) while light environment (photoperiod, light quality) remained ambient. Shoot elongation and autumn coloration were studied in seedlings of two deciduous trees ( and ), which were expected to respond differently to day length. as a member of Rosaceae family was assumed to be indifferent to photoperiod, while responds strongly to day length. We hypothesized that (1) southern and northern populations of both species perform differently; (2) southern populations perform better in both sites; (3) autumn phenology of southern populations may delay in the northern site; (4) and is less dependent on light environment. According to the hypotheses, shoot elongation of northern population was inherently low in both species. An evolutionary consequence of this may be a competitive success of southern populations under warming climate. Southern population of was delayed in autumn coloration, but not in growth cessation. was less responsive to light environment. The results suggest that light provides selection pressure in range shifts, but the response is species dependent.
全球变暖普遍被认为会促进物种在纬度上的范围转移。跨纬度移植实验支持了这一点；许多树种能够很好地适应新的地理区域。然而，这些研究未能捕捉到物种对新光照环境的适应情况，因为实验并非旨在明确区分物种对光照和温度的反应。在此，我们在两个纬度（北纬60°和北纬69°）相距1000公里的相互移植实验中测试了树苗的反应规范。与以往研究不同的是，我们让实验植物在两个地点都处于相同温度下（记录北纬60°生长地点的温度，通过互联网连接实时调整北纬69°地点的温度），而光照环境（光周期、光质）保持自然状态。我们研究了两种落叶树（ 和 ）树苗的茎伸长和秋季变色情况，预计它们对日照长度的反应会有所不同。作为蔷薇科的一员， 被认为对光周期不敏感，而 对日照长度反应强烈。我们假设：（1）两个物种的南方和北方种群表现不同；（2）南方种群在两个地点都表现更好；（3）南方种群的秋季物候在北方地点可能会延迟；（4） 对光照环境的依赖性较小。根据这些假设，两个物种北方种群的茎伸长在本质上都较低。这一现象在进化上的一个结果可能是在气候变暖的情况下南方种群具有竞争优势。 的南方种群秋季变色延迟，但生长停止没有延迟。 对光照环境的反应较小。结果表明，光照在范围转移中提供了选择压力，但反应因物种而异。
