Regulation of growth and toxicity of a mixotrophic microbe: implications for understanding range expansion in Prymnesium parvum
Regulation of growth and toxicity of a mixotrophic microbe: implications for understanding range expansion in Prymnesium parvum
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DOI：
10.1086/677198
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发表时间：
2014-09-01
影响因子：
1.8
通讯作者：
Allison, Brenda
中科院分区：
文献类型：
--
作者：
Hambright, K. David;Easton, James D.;Allison, Brenda
在美国南部及其他地区的内陆水生系统中，产毒海洋触生藻 Prymnesium parvum 的范围迅速扩大，引起了人们对这种入侵性水华形成物种的生态学和进化生物学的极大兴趣。研究人员推测，次优环境中毒性和异养性的增加使得这些新的内陆栖息地中的水华得以发展，这些栖息地似乎代表了与 P. parvum 感知的最佳生态位相比的极端情况。我们使用基于实验室的研究来阐明盐度和养分有效性对小叶藻生长和毒性的作用，该环境条件以美国西南部的富营养化水库为代表，其中小叶藻水华现在很常见。我们发现有证据表明，有利于 P. parvum 产毒的营养条件对于生长和开花形成来说并不是最理想的，而有利于高生长率的条件则不太有利于产毒。相比之下，生长和毒性都与盐度呈正相关。考虑到已记录的 P. parvum 生物地理学，以及 P. parvum 的产毒作用可能是为了支持异养营养物的获取而进化的，我们的结果表明，P. parvum 在美国和整个美国的明显范围扩张是由咸味和营养丰富的系统可用性的增加所驱动的，而不是由其产毒能力驱动的。
The rapid range expansion of the toxigenic marine haptophytic alga Prymnesium parvum in inland aquatic systems across the southern USA and beyond has prompted great interest in the ecology and evolutionary biology of this invasive bloom-forming species. Researchers have speculated that increased toxicity and heterotrophy in suboptimal environments allow blooms to develop in these new inland habitats that seem to represent extremes relative to P. parvum's perceived optimal niche. We used a laboratory-based study to elucidate the roles of salinity and nutrient availabilities in P. parvum growth and toxicity under environmental conditions representative of hypereutrophic reservoirs of the southwestern USA in which P. parvum blooms are now common. We found evidence that nutrient conditions favoring toxigenesis in P. parvum are suboptimal for growth and bloom formation, whereas conditions conducive to high growth rates are less favorable for toxigenesis. In contrast, both growth and toxicity scaled positively with salinity. Taken in the context of the documented biogeography of P. parvum and that toxigenesis in P. parvum probably evolved in support of heterotrophic nutrient acquisition, our results suggest that P. parvum's apparent range expansion into and across the USA is driven by increasing availabilities of salty and nutrient-rich systems, rather than by its toxigenic abilities.