Abbreviation of larval development and extension of brood care as key features of the evolution of freshwater Decapoda
Abbreviation of larval development and extension of brood care as key features of the evolution of freshwater Decapoda
复制标题
幼虫发育和育雏护理扩展的缩写作为淡水十足目进化的关键特征
DOI：
10.1111/j.1469-185x.2012.00241.x
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发表时间：
2013
影响因子：
10
通讯作者：
G. Vogt
中科院分区：
文献类型：
--
作者：
G. Vogt
从海洋栖息地到淡水栖息地的过渡是生命进化的主要步骤之一。在十足甲壳类动物中，自三叠纪以来，淡水虾、淡水小龙虾、淡水蟹和淡水异类动物在不同的地质时期定居在淡水中。有些家族甚至通过淡水路线或直接通过海岸在陆地栖息地定居。由于这些分类群都没有重新入侵过它们的原始环境，十足类似乎特别适合研究对淡水的生活史适应。海洋、淡水和陆地十足动物的进化比较表明，卵数的减少、幼虫发育的缩短、育雏期的延长和卵磷脂的萎缩是它们适应淡水环境的关键。海洋十足类动物通常有大量的小卵，并通过长时间的浮游幼虫周期发育，而淡水小龙虾、初级淡水蟹和海壳类动物的规律是生产少量的大卵，直接发育和延长育雏期，直到幼年阶段。两栖淡水虾类和淡水蟹类以及所有通过海岸入侵陆地的陆生十足类动物都保持了海洋型浮游生物的发育。幼虫发育的缩短和育苗期的延长被解释为对淡水生境中流体动力参数、物理化学因素和浮游植物可利用性的特别强烈变化的适应。这些生活史的变化增加了后代的适应性，显然是自然选择的结果，解释了它们在淡水中的多重起源。没有证据表明它们在现存淡水种群的海洋祖先中早期进化，也没有证据表明它们在征服淡水方面具有预适应作用。淡水十足类动物从相对r -策略向K -策略转变的代价与繁殖力、雌性的未来繁殖和生长有关，也许与物种的大小有关，但与物种的寿命无关。幼崽抚育的直接发育和扩展与种群间传播和基因流动的减少有关，这可能解释了直接发育的淡水十足类动物高度的物种形成和地方性。在淡水十足动物中，直接发育和扩展的育雏照顾也有利于社会系统的进化，从简单的亚社会组织到群居组织。雌雄同体和孤雌生殖在一些陆生穴居小龙虾和入侵开阔水域的小龙虾中分别进化而来，它们可能通过社会生态特征的时空变化来适应限制性或新的环境。在栖息地迅速丧失、环境污染和全球变暖的条件下，直接发育者的扩散能力降低可能成为严重劣势，淡水小龙虾、原生淡水蟹、鳞虾和内陆淡水虾的灭绝威胁高于两栖淡水虾和次生淡水蟹。
The transition from marine to freshwater habitats is one of the major steps in the evolution of life. In the decapod crustaceans, four groups have colonized fresh water at different geological times since the Triassic, the freshwater shrimps, freshwater crayfish, freshwater crabs and freshwater anomurans. Some families have even colonized terrestrial habitats via the freshwater route or directly via the sea shore. Since none of these taxa has ever reinvaded its environment of origin the Decapoda appear particularly suitable to investigate life‐history adaptations to fresh water. Evolutionary comparison of marine, freshwater and terrestrial decapods suggests that the reduction of egg number, abbreviation of larval development, extension of brood care and lecithotrophy of the first posthatching life stages are key adaptations to fresh water. Marine decapods usually have high numbers of small eggs and develop through a prolonged planktonic larval cycle, whereas the production of small numbers of large eggs, direct development and extended brood care until the juvenile stage is the rule in freshwater crayfish, primary freshwater crabs and aeglid anomurans. The amphidromous freshwater shrimp and freshwater crab species and all terrestrial decapods that invaded land via the sea shore have retained ocean‐type planktonic development. Abbreviation of larval development and extension of brood care are interpreted as adaptations to the particularly strong variations of hydrodynamic parameters, physico‐chemical factors and phytoplankton availability in freshwater habitats. These life‐history changes increase fitness of the offspring and are obviously favoured by natural selection, explaining their multiple origins in fresh water. There is no evidence for their early evolution in the marine ancestors of the extant freshwater groups and a preadaptive role for the conquest of fresh water. The costs of the shift from relative r‐ to K‐strategy in freshwater decapods are traded‐off against fecundity, future reproduction and growth of females and perhaps against size of species but not against longevity of species. Direct development and extension of brood care is associated with the reduction of dispersal and gene flow among populations, which may explain the high degree of speciation and endemism in directly developing freshwater decapods. Direct development and extended brood care also favour the evolution of social systems, which in freshwater decapods range from simple subsocial organization to eusociality. Hermaphroditism and parthenogenesis, which have evolved in some terrestrial crayfish burrowers and invasive open water crayfish, respectively, may enable populations to adapt to restrictive or new environments by spatio‐temporal alteration of their socio‐ecological characteristics. Under conditions of rapid habitat loss, environmental pollution and global warming, the reduced dispersal ability of direct developers may turn into a severe disadvantage, posing a higher threat of extinction to freshwater crayfish, primary freshwater crabs, aeglids and landlocked freshwater shrimps as compared to amphidromous freshwater shrimps and secondary freshwater crabs.