Meeting Abstract
P3.179 Monday, Jan. 6 15:30 Reconstructing changes in 3D body shape during the pregnancy of three species of viviparous fish (Poeciliidae): effects of placentation and superfetation FLEUREN, M.*; QUICAZAN-RUBIO, E.M.; VOESENEK, C.J.; VAN LEEUWEN, J.L.; POLLUX, B.J.A.; Experimental Zoology Chair Group, Wageningen University; Experimental Zoology Chair Group, Wageningen University; Experimental Zoology Chair Group, Wageningen University; Experimental Zoology Chair Group, Wageningen University; Experimental Zoology Chair Group, Wageningen University mike.fleuren@wur.nl
Viviparity confers a high reproductive burden to females, because they carry their offspring for a long period of time and often undergo a large change in mass and volume. Viviparous organisms have evolved a number of different reproductive adaptations that help reduce the burden during gestation. We recently proposed that placentation and superfetation are two such reproductive adaptations. Placentotrophic fish produce small egg cells with relative low amounts of yolk that are supplied with nutrients over the course of development, resulting in large differences in body volume between the early and last days of gestation. Superfetation, having multiple broods of different developmental stages, reduces the amount of simultaneously present late-stage embryos and thus the volume and mass changes associated with this stage. We illustrate this using three species that differ in the level of post-fertilization maternal provisioning and superfetation: Poeciliopsis gracilis (Matrotrophy Index: 0.7; Superfetation Index: 2), Poeciliopsis turneri (MI: 41; SI: 2) and Phalloptychus januarius (MI: 23, SI: 14). At multiple time points during their pregnancy, females are photographed from 3 orthogonal directions. The multiple images are analysed using semi-automated in-house software, yielding highly accurate three-dimensional body models. Shape parameters derived from the body models are then used to assess changes in the 3D body shape of females during gestation. Ultimately, we are interested in comparing the pregnancy-related changes in 3D body shape between viviparous species that differ in their level of placentation and/or superfetation.
