title: No inbreeding depression in sperm storage ability or offspring viability in Drosophila melanogaster females.
abstract: Mating between relatives usually decreases genetic quality of progeny as deleterious recessive alleles are expressed in inbred individuals. Inbreeding degrades sperm traits but its effects on sperm storage and fate within females are currently unknown. We quantified the relationship between the degrees of inbreeding relevant to natural populations (f=0, 0.25 and 0.50) and the number of sperm inseminated and stored, sperm swimming speed, long-term sperm viability while in storage, pattern of sperm precedence, mating latency, and offspring viability of female Drosophila melanogaster. The use of transgenic flies that have either red or green fluorescent sperm heads allowed us to distinguish two ejaculates in the female reproductive tract and facilitated quantification of sperm storage and use traits. We found no inbreeding depression in either long- or short-term sperm storage ability. The most inbred females exhibited significantly longer mating latency, which could be explained by males preferring to mate with outbred females. On the other hand, as no evidence for cryptic male choice in the form of ejaculate tailoring of sperm number was found, the most inbred females might just be less eager to mate. We also found no evidence that the degree of maternal inbreeding influenced offspring viability. Comparison with a contemporaneous study of male inbreeding consequences for ejaculate quality suggests that inbreeding depression is more severe in males than in females in our study population.
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014, Finland; Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: outi.alahonkola@gmail.com.
authors.forename: Outi
authors.initials: O
authors.lastname: Ala-Honkola
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA; The George Washington University, Biological Sciences, 2023 G St. NW, Washington, DC 20052, USA. Electronic address: maniermk@gmail.com.
authors.forename: Mollie K
authors.initials: MK
authors.lastname: Manier
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: sklupold@syr.edu.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lüpold
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: emrdoge@syr.edu.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Droge-Young
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: wfcollin@gmail.com.
authors.forename: William F
authors.initials: WF
authors.lastname: Collins
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: jbelote@syr.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Belote
authors.affiliation: Department of Biology, Syracuse University, Syracuse, NY 13244, USA. Electronic address: sspitnic@syr.edu.
authors.forename: Scott
authors.initials: S
authors.lastname: Pitnick
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D049452:Green Fluorescent Proteins; D007178:Inbreeding; D008164:Luminescent Proteins; D008297:Male; D012098:Reproduction; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D000097573:Red Fluorescent Protein
chemical_list: D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein
keywords: AR1; Drosophila melanogaster; GFP; GLS; Inbreeding depression; L-ratio; LMM; ML; Male choice; P(2); PBS; REML; RFP; SOM; SPTH; SR; Sperm storage; autocorrelation structure of order 1; generalised least squares; green fluorescent protein; likelihood ratio; linear mixed model; maximum likelihood; phosphate buffered saline; proportion of offspring sired by the second male to mate; red fluorescent protein; restricted maximum likelihood; seminal receptacle; spermathecae; supplementary online material