Sweeney Joseph Y, Kuehne Heidi A, Sniegowski Paul D
Department of Biology, University of Pennsylvania, 415 S. University Avenue, Philadelphia, PA 19104, USA.
FEMS Yeast Res. 2004 Jan;4(4-5):521-5. doi: 10.1016/S1567-1356(03)00171-5.
Saccharomyces cerevisiae and its close congener S. paradoxus are typically indistinguishable by the phenotypic criteria of classical yeast taxonomy, but they are evolutionarily distinct as indicated by hybrid spore inviability and genomic sequence divergence. Previous work has shown that these two species coexist in oak-associated microhabitats at natural woodland sites in North America. Here, we show that sympatric populations of S. cerevisiae and S. paradoxus from a single natural site are phenotypically differentiated in their growth rate responses to temperature. Our main finding is that the S. cerevisiae population exhibits a markedly higher growth rate at 37 degrees C than the S. paradoxus population; we also find possible differences in growth rate between these populations at two lower temperatures. We discuss the implications of our results for the coexistence of these yeasts in natural environments, and we suggest that thermal growth response may be an evolutionarily labile feature of these organisms that could be analyzed using genomic approaches.
酿酒酵母及其近缘种奇异酵母，依据经典酵母分类学的表型标准通常难以区分，但正如杂种孢子不育和基因组序列差异所表明的，它们在进化上是不同的。此前的研究表明，这两个物种在北美天然林地与橡树相关的微生境中共存。在此，我们表明，来自单一自然地点的酿酒酵母和奇异酵母同域种群在对温度的生长速率响应方面存在表型差异。我们的主要发现是，酿酒酵母种群在37摄氏度时的生长速率明显高于奇异酵母种群；我们还发现在两个较低温度下，这些种群之间可能存在生长速率差异。我们讨论了我们的结果对于这些酵母在自然环境中共存的意义，并提出热生长响应可能是这些生物体的一个在进化上不稳定的特征，可以使用基因组方法进行分析。
