Mutation Speeds up Sperm of Zebra Finches (IMAGE) Max-Planck-Gesellschaft Caption The sex chromosome Z of male zebra finches comes in two variants. Males who possess a copy of these variant each enjoy particular reproductive success. Credit MPI f. Ornithology Usage Restrictions Use of images is limited to editorial coverage of scientific topics relating to the activities of the Max Planck Society. Any kind of commercial use (including, in particular, the exploitation of images by means of sale or incorporation in image databases or image catalogues) as well as any promotional use/use for merchandise purposes, disclosure to third parties or granting of related rights to third parties is expressly not permitted. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.