33.7
土地殖民化
Over three and a half billion years ago, lifeforms could survive only in aquatic environments. Later, some prokaryotes, such as cyanobacteria, began fixing carbon dioxide to produce sugars through photosynthesis.
These photosynthetic organisms released oxygen, and it accumulated in the atmosphere.
Evidence suggests that single-celled photosynthetic microbes colonized moist terrestrial surfaces more than two billion years ago.
While land environments provided abundant sunlight and carbon dioxide, two crucial components for photosynthesis, they also presented challenges such as desiccation, UV exposure, and lack of structural support.
Multicellular plants and fungi gradually evolved the ability to live on land around 470 million years ago.
This transition required several adaptations. Some cells formed shoots that capture light, while others formed root-like structures that anchor the plant and absorb water and nutrients.
Other structural changes also helped plants survive on land. For example, a waxy cuticle limited evaporation.
Cell walls provided structural support, while vascular tissue helped move water through larger plants.
Around 450 million years ago, arthropods were the first animals to evolve the ability to live on land.
These organisms had external skeletons and belonged to the group that includes modern insects, arachnids, and crustaceans.
Early tetrapods evolved around 380 million years ago. Their lobe-finned fish ancestors had features like lungs and stronger limb bones that helped them move from water onto land. They later diversified into amphibians, reptiles, birds, and mammals.
Plants that had already colonized land formed the base of early terrestrial food webs, supporting both arthropods and tetrapods. Through this gradual process, plants, fungi, and animals colonized Earth’s landmasses and eventually evolved into the diverse species that exist today.
早期地球环境的变化推动了有机体的进化。随着海洋中的原核生物开始光合作用，它们产生氧气。最终，氧气使海洋饱和并进入大气，导致大气氧浓度增加，大约在23亿年前被称为氧气旋转。因此，可以使用氧气进行细胞呼吸的生物体具有优势。超过1.5年前，真核细胞和多细胞生物也开始出现。最初，所有这些物种都被限制在地球的海洋中。
最早生活在陆地上的生物是光合原核生物，它们生活在靠近海岸的潮湿环境中。尽管缺乏水，陆地环境提供了充足的阳光和二氧化碳用于光合作用。大约5亿年前，现在的植物祖先能够在干燥的环境中定居，但它们需要适应以防止脱水。它们开发了不依赖水的繁殖方法，并保护胚胎不被干燥。这些早期植物还进化出一个维管系统，包括根系获取水和营养物以及获取阳光和二氧化碳的射程。
植物和真菌似乎同时在陆地上定居。它们在陆地上的共同进化是许多植物和真菌之间互利关系的结果，在现代有机体和一些最早的植物化石中都可以看到；真菌有助于吸收营养和水分，同时受益于植物提供的营养；
大约在4.5亿年前，节肢动物是第一个在陆地上定居的动物物种。最初的四足动物后来也进化成生活在陆地上，在殖民地的植物物种中发现了丰富的食物。两栖动物主宰陆地动物生活达一亿年之久。后来，恐龙和哺乳动物将成为最丰富的陆生动物。
Over three and a half billion years ago, lifeforms could survive only in aquatic environments. Later, some prokaryotes, such as cyanobacteria, began fixing carbon dioxide to produce sugars through photosynthesis.
These photosynthetic organisms released oxygen, and it accumulated in the atmosphere.
Evidence suggests that single-celled photosynthetic microbes colonized moist terrestrial surfaces more than two billion years ago.
While land environments provided abundant sunlight and carbon dioxide, two crucial components for photosynthesis, they also presented challenges such as desiccation, UV exposure, and lack of structural support.
Multicellular plants and fungi gradually evolved the ability to live on land around 470 million years ago.
This transition required several adaptations. Some cells formed shoots that capture light, while others formed root-like structures that anchor the plant and absorb water and nutrients.
Other structural changes also helped plants survive on land. For example, a waxy cuticle limited evaporation.
Cell walls provided structural support, while vascular tissue helped move water through larger plants.
Around 450 million years ago, arthropods were the first animals to evolve the ability to live on land.
These organisms had external skeletons and belonged to the group that includes modern insects, arachnids, and crustaceans.
Early tetrapods evolved around 380 million years ago. Their lobe-finned fish ancestors had features like lungs and stronger limb bones that helped them move from water onto land. They later diversified into amphibians, reptiles, birds, and mammals.
Plants that had already colonized land formed the base of early terrestrial food webs, supporting both arthropods and tetrapods. Through this gradual process, plants, fungi, and animals colonized Earth’s landmasses and eventually evolved into the diverse species that exist today.
From Chapter 33:
