title: Testes mass, but not sperm length, increases with higher levels of polyandry in an ancient sex model.
abstract: There is strong evidence that polyandrous taxa have evolved relatively larger testes than monogamous relatives. Sperm size may either increase or decrease across species with the risk or intensity of sperm competition. Scorpions represent an ancient direct mode with spermatophore-mediated sperm transfer and are particularly well suited for studies in sperm competition. This work aims to analyze for the first time the variables affecting testes mass, ejaculate volume and sperm length, according with their levels of polyandry, in species belonging to the Neotropical family Bothriuridae. Variables influencing testes mass and sperm length were obtained by model selection analysis using corrected Akaike Information Criterion. Testes mass varied greatly among the seven species analyzed, ranging from 1.6 ± 1.1 mg in Timogenes dorbignyi to 16.3 ± 4.5 mg in Brachistosternus pentheri with an average of 8.4 ± 5.0 mg in all the species. The relationship between testes mass and body mass was not significant. Body allocation in testes mass, taken as Gonadosomatic Index, was high in Bothriurus cordubensis and Brachistosternus ferrugineus and low in Timogenes species. The best-fitting model for testes mass considered only polyandry as predictor with a positive influence. Model selection showed that body mass influenced sperm length negatively but after correcting for body mass, none of the variables analyzed explained sperm length. Both body mass and testes mass influenced spermatophore volume positively. There was a strong phylogenetic effect on the model containing testes mass. As predicted by the sperm competition theory and according to what happens in other arthropods, testes mass increased in species with higher levels of sperm competition, and influenced positively spermatophore volume, but data was not conclusive for sperm length.
authors.affiliation: Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina.
authors.forename: David E
authors.initials: DE
authors.lastname: Vrech
authors.affiliation: Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina.
authors.forename: Paola A
authors.initials: PA
authors.lastname: Olivero
authors.affiliation: Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina.
authors.forename: Camilo I
authors.initials: CI
authors.lastname: Mattoni
authors.affiliation: Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina.
authors.forename: Alfredo V
authors.initials: AV
authors.lastname: Peretti
mesh_terms: D000818:Animals; D005075:Biological Evolution; D048429:Cell Size; D016000:Cluster Analysis; D004542:Ejaculation; D005260:Female; D008297:Male; D008954:Models, Biological; D009929:Organ Size; D019655:Quantitative Trait, Heritable; D012098:Reproduction; D012725:Sexual Behavior; D012726:Sexual Behavior, Animal; D013094:Spermatozoa / Q000166:cytology*; D013737:Testis / Q000033:anatomy & histology*
references.citation: Proc Biol Sci. 1993 Sep 22;253(1338):245-54
references.pmid: 8234363
references.citation: Trends Ecol Evol. 2004 Feb;19(2):87-93
references.pmid: 16701234
references.citation: Evolution. 2008 Oct;62(10):2580-91
references.pmid: 18691259
references.citation: Proc Natl Acad Sci U S A. 2009 Jan 27;106(4):1128-32
references.pmid: 19164576
references.citation: PLoS One. 2011 Jan 11;6(1):e16014
references.pmid: 21264312
references.citation: J Morphol. 1983 Aug;177(2):205-212
references.pmid: 30060638
references.citation: Biol Lett. 2011 Apr 23;7(2):261-4
references.pmid: 21068028
references.citation: PLoS One. 2013;8(1):e53904
references.pmid: 23468826
references.citation: PLoS One. 2010 Mar 08;5(3):e9581
references.pmid: 20221392
references.citation: Cladistics. 2005 Oct;21(5):446-494
references.pmid: 34892945
references.citation: Am Nat. 2002 Dec;160(6):712-26
references.pmid: 18707460
references.citation: Proc Biol Sci. 2000 Feb 7;267(1440):307-13
references.pmid: 10714886
references.citation: Evolution. 2008 Feb;62(2):494-9
references.pmid: 18070085
references.citation: J Morphol. 2010 Apr;271(4):383-93
references.pmid: 20101728
references.citation: J Evol Biol. 2008 Mar;21(2):471-9
references.pmid: 18205777
references.citation: Tissue Cell. 2008 Dec;40(6):411-6
references.pmid: 18579173
references.citation: Evolution. 2007 Nov;61(11):2684-92
references.pmid: 17941836
references.citation: J Theor Biol. 1982 May 21;96(2):281-94
references.pmid: 7121030
references.citation: Science. 1982 May 14;216(4547):753-5
references.pmid: 17730138
references.citation: Biol Lett. 2005 Jun 22;1(2):235-8
references.pmid: 17148175
references.citation: Trends Ecol Evol. 1989 Mar;4(3):74-9
references.pmid: 21227319
references.citation: Proc Biol Sci. 1992 Feb 22;247(1319):89-95
references.pmid: 1349186
references.citation: Annu Rev Entomol. 1998;43:153-74
references.pmid: 15012387
references.citation: Evolution. 2009 Oct;63(10):2513-24
references.pmid: 19490075
references.citation: J Evol Biol. 2009 May;22(5):1143-50
references.pmid: 19309491
references.citation: Evolution. 1991 Mar;45(2):314-328
references.pmid: 28567878
references.citation: J Evol Biol. 2005 Jan;18(1):60-9
references.pmid: 15669961
references.citation: PLoS One. 2011;6(6):e21244
references.pmid: 21731682
references.citation: Am Nat. 1997 May;149(5):933-54
references.pmid: 18811256
references.citation: Proc Biol Sci. 1997 Mar 22;264(1380):385-92
references.pmid: 9107054
references.citation: J Ultrastruct Res. 1973 Dec;45(5):366-83
references.pmid: 4358361
references.citation: J Evol Biol. 2005 May;18(3):557-67
references.pmid: 15842485
references.citation: J Reprod Fertil. 1985 Sep;75(1):153-75
references.pmid: 4032369
references.citation: Proc Biol Sci. 1991 Mar 22;243(1308):181-5
references.pmid: 1675796
references.citation: Evolution. 1998 Apr;52(2):415-431
references.pmid: 28568329
references.citation: Br Med Bull. 1979 May;35(2):121-7
references.pmid: 387158
references.citation: BMC Evol Biol. 2011 Jan 13;11:12
references.pmid: 21232104
references.citation: Proc Biol Sci. 2002 Nov 22;269(1507):2309-16
references.pmid: 12495497
references.citation: Nat Methods. 2012 Jul;9(7):671-5
references.pmid: 22930834
references.citation: Evolution. 1997 Jun;51(3):937-945
references.pmid: 28568571
references.citation: Biol Rev Camb Philos Soc. 2010 Nov;85(4):897-934
references.pmid: 20560928
references.citation: Proc Natl Acad Sci U S A. 1995 Nov 7;92(23):10614-8
references.pmid: 7479851