title: Endopolyploidy as a potential driver of animal ecology and evolution.
abstract: Endopolyploidy - the existence of higher-ploidy cells within organisms that are otherwise of a lower ploidy level (generally diploid) - was discovered decades ago, but remains poorly studied relative to other genomic phenomena, especially in animals. Our synthetic review suggests that endopolyploidy is more common in animals than often recognized and probably influences a number of fitness-related and ecologically important traits. In particular, we argue that endopolyploidy is likely to play a central role in key traits such as gene expression, body and cell size, and growth rate, and in a variety of cell types, including those responsible for tissue regeneration, nutrient storage, and inducible anti-predator defences. We also summarize evidence for intraspecific genetic variation in endopolyploid levels and make the case that the existence of this variation suggests that endopolyploid levels are likely to be heritable and thus a potential target for natural selection. We then discuss why, in light of evident benefits of endopolyploidy, animals remain primarily diploid. We conclude by highlighting key areas for future research such as comprehensive evaluation of the heritability of endopolyploidy and the adaptive scope of endopolyploid-related traits, the extent to which endopolyploid induction incurs costs, and characterization of the relationships between environmental variability and endopolyploid levels.
authors.affiliation: Department of Biology, University of Iowa, 143 Biology Building, Iowa City, IA 52242, U.S.A.
authors.forename: Maurine
authors.initials: M
authors.lastname: Neiman
authors.affiliation: Biology Department, Mount Allison University, Sackville, NB E4L 1G7, Canada.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Beaton
authors.affiliation: Department of Biosciences, University of Oslo, Box 1066, Blindern, 0316 Oslo, Norway.
authors.forename: Dag O
authors.initials: DO
authors.lastname: Hessen
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, U.S.A.
authors.forename: Punidan D
authors.initials: PD
authors.lastname: Jeyasingh
authors.affiliation: Department of Biology, Program in Ecology and Evolutionary Biology, University of Oklahoma, 730 Van Vleet Oval, Room 304, Norman, OK 73019, U.S.A.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Weider
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004463:Ecology; D014644:Genetic Variation; D011123:Polyploidy; D012641:Selection, Genetic
keywords: chromosomal evolution; endomitosis; endoreduplication; endoreplication; genome evolution; phenotypic plasticity; ploidy level; polyploid; polyteny; somatic polyploidy