title: Emerging issues in the evolution of animal nuptial gifts.
abstract: Uniquely positioned at the intersection of sexual selection, nutritional ecology and life-history theory, nuptial gifts are widespread and diverse. Despite extensive empirical study, we still have only a rudimentary understanding of gift evolution because we lack a unified conceptual framework for considering these traits. In this opinion piece, we tackle several issues that we believe have substantively hindered progress in this area. Here, we: (i) present a comprehensive definition and classification scheme for nuptial gifts (including those transferred by simultaneous hermaphrodites), (ii) outline evolutionary predictions for different gift types, and (iii) highlight some research directions to help facilitate progress in this field.
authors.affiliation: Department of Biology, Tufts University, Medford, MA 02155, USA sara.lewis@tufts.edu.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Lewis
authors.affiliation: Department of Biological Sciences, University of Derby, Derby DE22 1GB, UK.
authors.forename: Karim
authors.initials: K
authors.lastname: Vahed
authors.affiliation: Department of Ecological Science, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands.
authors.forename: Joris M
authors.initials: JM
authors.lastname: Koene
authors.affiliation: Evolutionary Biology, Bielefeld University, Bielefeld 33615, Germany Department of Behavioural Ecology, University of Bern, Hinterkappelen 3032, Switzerland.
authors.forename: Leif
authors.initials: L
authors.lastname: Engqvist
authors.affiliation: Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Luc F
authors.initials: LF
authors.lastname: Bussière
authors.affiliation: Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK Jesus College, University of Oxford, Oxford OX1 3DW, UK.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Perry
authors.affiliation: Department of Zoology, University of Toronto Mississauga, Ontario, Canada L5L 1C6.
authors.forename: Darryl
authors.initials: D
authors.lastname: Gwynne
authors.affiliation: Department of Biology, Humboldt University, Berlin 10115, Germany.
authors.forename: Gerlind U C
authors.initials: GU
authors.lastname: Lehmann
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003307:Copulation; D005260:Female; D005502:Food; D037921:Gift Giving; D008297:Male; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology*
keywords: sexual conflict; simultaneous hermaphrodite; spermatophore