Evolution of poecilogony from planktotrophy: cryptic speciation, phylogeography, and larval development in the gastropod genus Alderia.

摘要: Poecilogony, a rare phenomenon in marine invertebrates, occurs when alternative larval morphs differing dispersal potential or trophic mode are produced from single genome. Because both poecilogony and cryptic species prevalent among sea slugs the suborder Sacoglossa (Gastropoda: Opisthobranchia), molecular data needed to confirm cases of variable development place them phylogenetic context. The nominal Alderia modesta produces long-lived, feeding larvae throughout North Atlantic Pacific, but California can also produce short-lived that metamorphose without feeding. We collected morphological, developmental, for 17 sites spanning eastern western Pacific Atlantic. Estuaries south Bodega Harbor, California, contained (hereafter sp.) with development, sister strictly planktotrophic A. modesta. smaller sp. seasonally toggled between planktotrophy lecithotrophy, some individuals sharing mitochondrial DNA haplotypes. sibling overlapped Tomales Bay, showed no evidence hybridization; laboratory mating trials suggest postzygotic isolation has arisen. Intra- interspecific divergence times were estimated using clock calibrated geminate sacoglossans. Speciation occurred about 4.1 million years ago during major radiation large inland embayments may have isolated ancestral populations. diverged 1.7 ago, suggesting trans-Arctic gene flow was interrupted by Pleistocene glaciation. Both late population expansion, southern likely experienced more pronounced bottleneck. Reduced body size incurred selection against obligate limiting fecundity face high mortality rates warm months. Alternatively, be an adaptive response seasonal opening estuaries, facilitating long-lived larvae. An improved understanding forces controlling shifts yield insight into evolutionary promoting transitions nonfeeding