The evolution of a placenta is not linked to increased brain size in poeciliid fishes

Maternal investment is hypothesized to have a direct influence on the size of energetically costly organs, including the brain. In placental organisms, offspring are supplied with nutrients during prenatal development, potentially modulating brain size. Previous research has predominantly focused on mammalian species that exhibit both pre- and postnatal provisioning, in which effects on brain size have been observed during both developmental stages. Here, using eight poeciliid fish species, we test if those species with placental structures (i.e., matrotrophy) invest more resources into offspring brain development than species without placental structures (i.e., lecithotrophy). The prediction is that matrotrophy may entail higher nutrient provisioning rates to the developing embryo, resulting in larger offspring brain sizes, compared to species with a lecithotrophic strategy. To test this prediction, we took non-invasive brain size measurements during the first four weeks of life, compa..., , # Data from: The evolution of a placenta is not linked to increased brain size in poeciliid fishes Authors: P. K. Rowiński1, J. Näslund1,2, W. Sowersby1,3, S. Eckerström-Liedholm1 and B. Rogell1,2 1Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden 2Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 17893 Drottningholm, Sweden 3Arthur Rylah Institute for Environmental Research, Department of Energy, Environment and Climate Action, Heidelberg, 3084, Victoria, Australia. Authors for correspondence: Piotr K. Rowiński email [[e-mail]](mailto:[e-mail]) Present address: Department of Water and Fisheries, Länsstyrelsen Västernorrland, 871 86 Härnösand, Sweden Björn Rogell email [[e-mail]](mailto:[e-mail]) Present address: Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sci..., ,