4月8日，國際著名雜志《自然—地球科學(xué)》Nature Geoscience的一項(xiàng)報告指出,，作為世界上唯一一種最重要的海洋鈣化有機(jī)體,，海洋球石藻可通過自身進(jìn)化以應(yīng)對海洋酸化。
海水酸化,，由海洋吸收大氣中二氧化碳所引起,，可嚴(yán)重?fù)p害海洋鈣化有機(jī)體。到目前為止,，有關(guān)海水酸化對海洋生物影響的研究都聚焦在個體生命周期內(nèi)的生理應(yīng)答上,，卻很大程度上忽視了進(jìn)化的潛在可能。
在一系列實(shí)驗(yàn)中,，Thorsten Reusch和同事將海洋球石藻暴露于高濃度的二氧化碳中,，在海洋球石藻經(jīng)過約500次無性繁殖后，他們對其在海水酸化條件下的狀態(tài)進(jìn)行了評估,。結(jié)果發(fā)現(xiàn),，雖然在海水酸化條件下，所有的藻類生存狀態(tài)都變差,，但與對照條件的藻類相比,，處于高濃度二氧化碳條件的那一些藻類卻表現(xiàn)出更高的生長速率以及鈣化物質(zhì)的部分復(fù)原。
研究人員表示,，這種同步進(jìn)化能有助于在全球氣候變化的情況下維持海洋微生物的功能,。（生物谷Bioon.com）
doi:10.1038/ngeo1441
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Adaptive evolution of a key phytoplankton species to ocean acidification
Kai T. Lohbeck, Ulf Riebesell & Thorsten B. H. Reusch
Ocean acidification, the drop in seawater pH associated with the ongoing enrichment of marine waters with carbon dioxide from fossil fuel burning, may seriously impair marine calcifying organisms. Our present understanding of the sensitivity of marine life to ocean acidification is based primarily on short-term experiments, in which organisms are exposed to increased concentrations of CO2. However, phytoplankton species with short generation times, in particular, may be able to respond to environmental alterations through adaptive evolution. Here, we examine the ability of the world’s single most important calcifying organism, the coccolithophore Emiliania huxleyi, to evolve in response to ocean acidification in two 500-generation selection experiments. Specifically, we exposed E. huxleyi populations founded by single or multiple clones to increased concentrations of CO2. Around 500 asexual generations later we assessed their fitness. Compared with populations kept at ambient CO2 partial pressure, those selected at increased partial pressure exhibited higher growth rates, in both the single- and multiclone experiment, when tested under ocean acidification conditions. Calcification was partly restored: rates were lower under increased CO2 conditions in all cultures, but were up to 50% higher in adapted compared with non-adapted cultures. We suggest that contemporary evolution could help to maintain the functionality of microbial processes at the base of marine food webs in the face of global change.
