Byrne Maria, Hart Michael W, Cerra Anna, Cisternas Paula
Department of Anatomy and Histology, F13, University of Sydney, NSW 2006, Australia.
Biol Bull. 2003 Dec;205(3):285-94. doi: 10.2307/1543292.
The Cryptasterina group of asterinid sea stars in Australasia comprises cryptic species with derived life histories. C. pentagona and C. hystera have planktonic and intragonadal larvae, respectively. C. pentagona has the gonochoric, free-spawning mode of reproduction with a planktonic lecithotrophic brachiolaria larva. C. hystera is hermaphroditic with an intragonadal lecithotrophic brachiolaria, and the juveniles emerge through the gonopore. Both species have large lipid-rich buoyant eggs and well-developed brachiolariae. Early juveniles are sustained by maternal nutrients for several weeks while the digestive tract develops. C. hystera was reared in vitro through metamorphosis. Its brachiolariae exhibited the benthic exploration and settlement behavior typical of planktonic larvae, and they attached to the substratum with their brachiolar complex. These behaviors are unlikely to be used in the intragonadal environment. The presence of a buoyant egg and functional brachiolaria larva would not be expected in an intragonadal brooder and indicate the potential for life-history reversal to a planktonic existence. Life-history traits of species in the Cryptasterina group are compared with those of other asterinids in the genus Patiriella with viviparous development. Modifications of life-history traits and pathways associated with evolution of viviparity in the Asterinidae are assessed, and the presence of convergent adaptations and clade-specific features associated with this unusual mode of parental care are examined.
澳大利亚和新西兰的隐海盘车海星属(Cryptasterina)的海星种类包含具有衍生生活史的隐秘物种。五角隐海盘车(C. pentagona)和希氏隐海盘车(C. hystera)分别具有浮游幼虫和性腺内幼虫。五角隐海盘车具有雌雄异体、自由产卵的繁殖方式,其幼虫为浮游性卵黄营养型短腕幼虫。希氏隐海盘车是雌雄同体,具有性腺内卵黄营养型短腕幼虫,幼体通过生殖孔产出。这两个物种都有富含脂质的大型浮力卵和发育良好的短腕幼虫。早期幼体在消化道发育期间由母体营养维持数周。希氏隐海盘车在体外饲养至变态。其短腕幼虫表现出浮游幼虫典型的底栖探索和附着行为,它们用短腕复合体附着在基质上。这些行为不太可能在性腺内环境中使用。在性腺内育幼的物种中不太可能出现浮力卵和功能性短腕幼虫,这表明其生活史有可能逆向转变为浮游生活。将隐海盘车属物种的生活史特征与其他具有胎生发育的帕氏海星属(Patiriella)海星的特征进行了比较。评估了与海星科胎生进化相关的生活史特征和途径的变化,并研究了与这种不寻常的亲代抚育方式相关的趋同适应和分支特异性特征的存在情况。