Calcareous nannoplankton evolution: a tale of two oceans
Calcareous nannoplankton evolution: a tale of two oceans
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钙质超小型浮游生物的进化：两个海洋的故事
DOI：
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发表时间：
2005
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影响因子：
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通讯作者：
P. Bown
中科院分区：
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作者：
P. Bown
白垩系/第三系界线上、下钙质微型浮游生物多样性、演化速率和物种寿命均表现出明显的差异。在排除大灭绝事件、初始起源和辐射的影响后，中生代微型浮游生物多样性具有相对持续增加、低背景演化速率和高物种寿命的特点。新生代的多样性变化更大，始新世和新近纪的多样性显著下降，几乎没有恢复。新生代的进化速率也一直高于中生代，物种寿命较低。在这两个时代的nannoplankton气候变冷的反应是特别揭示：在白垩纪的冷间隔看到更大的古生物地理分化和高纬度nannoplankton省，支持多样化的社区，而冷却在始新世和新近纪与多样性下降，选择性灭绝的温水类群，和高纬度省份减少多样性。它似乎可能是广泛的稳定，亚热带和热带贫营养水体的存在促进了广泛的K-策略钙质nannoflancoma（和甲藻）的中生代大部分时间到早第三纪的多样化。然而，向冰室气候的转变改变了海洋，有利于r-strategic硅藻，而牺牲了其他浮游植物群体。始新世的深度冷却建立了新的冷水栖息地，限制了钙质微型浮游生物的栖息和多样化，但促进了硅藻在高纬度地区的扩张和多样化。硅藻成为最具竞争力的浮游植物群体，在所有环境中蓬勃发展，但特别是那些高和脉冲营养输入，虽然它们的扩张也可能是由构造和生物因素，增加了生物限制二氧化硅流入海洋。
Calcareous nannoplankton diversity, evolutionary rates and species longevity show markedly different characters above and below the Cretaceous/Tertiary boundary. Excluding mass extinction events, and the initial origination and radiation, Mesozoic nannoplankton diversity is characterized by relatively continuous increase with low background evolutionary rates and high species longevity. Cenozoic diversity is more variable and features significant Eocene and Neogene diversity declines, with little or no recovery. Cenozoic evolutionary rates are also consistently higher than those of the Mesozoic, and species longevity is low. The response of nannoplankton to climate cooling in the two eras is particularly revealing: cold intervals in the Cretaceous saw greater paleobiogeographical differentiation and high-latitude nannoplankton provinces that supported diversifying communities, whereas, cooling in the Eocene and Neogene coincided with diversity declines, the selective extinction of warm-water taxa, and high-latitude provinces with reduced diversity. It appears likely that the presence of widespread stable, subtropical and tropical oligotrophic water masses promoted the diversification of the broadly K-strategist calcareous nannoplankton (and dinoflagellates) for much of the Mesozoic and into the early Paleogene. The switch to an icehouse climate, however, transformed the oceans, favouring the r-strategist diatoms at the expense of the other phytoplankton groups. The profound Eocene cooling established new, cold-water habitats that limited calcareous nannoplankton habitation and diversification, but promoted diatom expansion and diversification at high latitudes. Diatoms became the most competitive of the phytoplankton groups, flourishing in all environments but particularly those with high and pulsed nutrient inputs, although their expansion may also have been aided by tectonic and biological factors that increased the flux of biolimiting silica to the oceans.