Immunological female role tested on artificial plugs in three scorpion species

Abstract

MO) 2 16 Abstract 17Within arachnids, genital plugs are morphologically diverse, and they can be formed by 18 male, female or be a contribution of both sexes. Although several species of scorpions with 19 genital plugs are known, the physiological effects on the female after being plugged have not 20 been well studied yet. This work compares three scorpion species, two with genital plugs and one 21 without. We first describe the genital plugs morphology of two Urophonius species. Second, 22 through the placement of artificial genital plugs in the female genital atrium, we tested 1) whether 23 there are interspecific differences in the immune encapsulation response on the artificial genital 24 plug, 2) if there are an effect in the hemocyte load in the hemolymph, and 3) if individual's 25 immunological parameters and body weight are correlated. Additionally, we describe and 26 quantify the hemocytes in these species. In both species of Urophonius, genital plugs were found 27 covering the female genital aperture and blocking the genital atrium. The plugs consist of three 28 zones that are distinct in morphology and coloration. We found different patterns of 29 encapsulation and melanization on the artificial plug according to the species, with a greater and 30 more specific response in females of plug producing species. Also, these species showed a 31 decrease in the hemocyte load one month after the placement of the artificial plug, possibly due 32 to the recirculation of the hemocytes into the genital area. In addition, correlations were found 33 between the body weight and the immunological parameters, as well as between different 34 immunological parameters. Our results suggest that females contribute to the formation of genital 35 plugs by adding material and generating the darkening of the genital plugs in certain zones. This 36 comparative study can help to provide a wider framework of different physiological 37 consequences related to a particular postcopulatory mechanism such as the genital plugs. 3 38 Scorpions 40 41 Introduction 42Among the many reproductive strategies that organisms exhibit, there are some that 43 involve males' adaptations favored by sperm competition to increase their reproductive success 44 [1][2][3]. Males would compete for the monopolization of females toward preventing, reducing or 45 avoiding sperm competition [2,4]. Genital plugs are structures that block or cover some portion 46 of the female genitalia after mating, and consequently can prevent sperm competition, acting as 47 mechanical or visual impairments [5][6] or by a physiological or behavioral alteration, such as 48 decreased female receptivity [7][8][9][10]. The plugging of females is a widespread phenomenon in the 49 animal kingdom, including insects and arachnids [4,[11][12][13][14]. Within arachnids, genital plugs are 50 morphologically diverse, varying according to the taxa. In general, genital plugs can be formed 51 by the coagulation of the male's ejaculate or glandular substances [12,[15][16][17][18][19][20][...