Mixotrophy, i.e. the capability of both phototrophy and phagotrophy within a single organism, is a prominent trophic mode in aquatic ecosystems. Mixotrophic strategies can be highly advantageous when feeding or photosynthesis alone does not sustain metabolic needs. In the current review, we discuss the functional types of mixotrophic marine protists (herein mixoplankton) within the context of evolution. Permanent plastids have been established in large due to gene transfer from prey and/or endosymbionts to the host cell. In some kleptoplastidic mixoplankton, prior gene transfers and active transcription of plastid related genes in the host can help maintain and extend retention of the current kleptoplast. In addition to kleptoplasts, the prey nucleus is also sometimes retained and actively transcribed to help maintain and even replicate the kleptoplasts. Endosymbiotic relations can vary considerably in the extent to which hosts control symbionts. For example, some endosymbionts are heavily modified to increase photosynthetic efficiency, or are controlled in their cell division. It can be proposed that many kleptoplasts and endosymbionts are in fact en route to becoming permanent plastids. Conditions such as increased temperature and limiting nutrients seem to favour phagotrophy by mixoplankton. However, responses of mixoplankton to changing environmental conditions like light irradiance, temperature, nutrient and prey availability are variable and species-specific. Studying mixotrophs with temporary plastids could elucidate past and future evolutionary mechanisms and dynamics of processes like phagotrophy and the establishment of (secondary) permanent plastids.

中文翻译：

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浮游生物的生态进化观点

混合营养，即单一生物体内同时具有光营养和吞噬营养的能力，是水生生态系统中一种突出的营养模式。当单独的饲喂或光合作用不能维持代谢需要时，混合营养策略可能会非常有利。在当前的审查中，我们讨论了进化背景下混合营养型海洋生物的功能类型（此处为浮游生物）。由于基因从猎物和/或共生共生体转移到宿主细胞中，因此已经建立了永久的质体。在某些变质体浮游植物中，宿主体内先前的基因转移和质体相关基因的主动转录可以帮助维持和延长当前变质体的保留。除了kleptoplasts，猎物核有时也被保留并被主动转录，以帮助维持甚至复制kleptoplasts。内共生关系在宿主控制共生体的程度上可以有很大的不同。例如，某些内共生菌被大量修饰以增加光合作用效率，或者被控制在它们的细胞分裂中。可以提出实际上许多变质体和共生共生体正在成为永久的质体。温度升高和营养物质有限等条件似乎有利于浮游动物吞噬营养。但是，浮游植物对不断变化的环境条件（如光照，温度，养分和猎物可利用性）的反应是可变的，且因物种而异。