Possible evolution of mobile animals in association with microbial mats
Possible evolution of mobile animals in association with microbial mats
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DOI：
10.1038/ngeo1142
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发表时间：
2011-06-01
影响因子：
18.3
通讯作者：
Konhauser, Kurt O.
中科院分区：
文献类型：
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作者：
Gingras, Murray;Hagadorn, James W.;Konhauser, Kurt O.
复杂的动物最早是在埃迪卡拉纪时期进化出来的，大约在6.35亿到5.42亿年前，当时海洋刚刚完全充氧。这些动物的移动的形式的原地化石与微生物沉积结构有关（1-3），动物的痕迹化石通常形成于与海底表面平行的沉积物-水界面处或以下（4，5）。这一证据表明，最早的移动的动物居住的环境中有大量的微生物种群，并可能开采微生物结合的沉积物作为食物资源（6-8）。在这里，我们报告协会的移动的动物昆虫幼虫，寡毛纲和穴居海岸蟹与微生物垫在现代高盐度泻湖在委内瑞拉。泻湖的特点是低浓度的溶解O-2和普遍的biomats占主导地位的产氧蓝藻，两者类似的条件下埃迪卡拉纪。我们发现，在白天，生物垫中的O-2水平是上覆水柱中的四倍。因此，我们得出结论，动物收获的食物和O-2从生物垫。在这样做的过程中，这些动物产生了类似于埃迪卡拉年代岩石中发现的水平洞穴。我们认为，早期的移动的动物可能在埃迪卡拉纪的类似环境中进化，有效地利用了在低氧环境中形成的富含O-2的绿洲。
Complex animals first evolved during the Ediacaran period, between 635 and 542 million years ago, when the oceans were just becoming fully oxygenated. In situ fossils of the mobile forms of these animals are associated with microbial sedimentary structures(1-3), and the animal's trace fossils generally were formed parallel to the surface of the seabed, at or below the sediment-water interface(4,5). This evidence suggests the earliest mobile animals inhabited settings with high microbial populations, and may have mined microbially bound sediments for food resources(6-8). Here we report the association of mobile animals-insect larvae, oligochaetes and burrowing shore crabs-with microbial mats in a modern hypersaline lagoon in Venezuela. The lagoon is characterized by low concentrations of dissolved O-2 and pervasive biomats dominated by oxygen-producing cyanobacteria, both analogous to conditions during the Ediacaran. We find that, during the day, O-2 levels in the biomats are four times higher than in the overlying water column. We therefore conclude that the animals harvest both food and O-2 from the biomats. In doing so, the animals produce horizontal burrows similar to those found in Ediacaran-aged rocks. We suggest that early mobile animals may have evolved in similar environments during the Ediacaran, effectively exploiting oases rich in O-2 that formed within low oxygen settings.