Paschoal Lucas Rezende Penido, Zara Fernando José
Programa de Pós-Graduação em Ciências Biológicas (Zoologia), Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, São Paulo 13506-900, Brazil; Faculdades de Inovação e Tecnologia de Minas Gerais (FIT-MG), Passos, Minas Gerais 37900-060, Brazil.
Programa de Pós-Graduação em Ciências Biológicas (Zoologia), Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, São Paulo 13506-900, Brazil; Laboratório de Morfologia de Invertebrados/LMI, Departamento de Biologia e Centro de Aquicultura (CAUNESP), Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Universidade Estadual Paulista (UNESP), Jaboticabal, São Paulo 14884-900, Brazil.
Zoology (Jena). 2022 Aug;153:126029. doi: 10.1016/j.zool.2022.126029. Epub 2022 Jul 6.
The Amazon River prawn Macrobrachium amazonicum shows populations with four well-defined morphotypes in males. Dominant males of morphotypes green claw 1 (GC1) and green claw 2 (GC2) have large bodies and chelipeds and a higher reproductive success in comparison with the submissive morphotypes - translucent claw (TC) and cinnamon claw (CC). However, recently, some populations of the species do not have dominant morphotypes. Here, we compared the patterns of spermatic production and concentration among morphotypes and populations with three different phenotypes: (i) large-size amphidromous prawns, and (ii) large-size ("i" and "ii" with dominant morphotypes) and (iii) small-size hololimnetic prawns (without morphotypes). We described the spermatogenesis and the histochemical features of vasa deferentia (VD) and evaluated the relationship between the investment in spermatic production and sexual weapons acquisition in males of different phenotypes. The spermatic production and concentration in populations with four morphotypes were similar between morphotypes. The exception was the CC morphotype in which males had the seminiferous tubules filled with spermatocytes and low spermatic concentration. The spermatogenesis, spermiogenesis, and VD structure were not different among the studied phenotypes and populations. The seminal fluid of M. amazonicum is comprised by glycoproteins and by concentric layers of secretions of types I, II (basophilic), and III (eosinophilic). We could infer that males of dominant morphotypes allocate a higher amount of energy to the development of strong sexual weapons at the expense of the energy allocated to the reproductive system during the sequential growth. Inversely, small-size males direct more energy toward the spermatic production and transference at the expense of sexual weapons. Therefore, there is a clear trade-off between the investment in the gonadal and sexual weapons development in males of M. amazonicum.
亚马逊河对虾马氏沼虾的雄性群体表现出四种界限分明的形态类型。形态类型绿爪1（GC1）和绿爪2（GC2）的优势雄性个体体型大、螯足大，与顺从形态类型——半透明爪（TC）和肉桂色爪（CC）相比，繁殖成功率更高。然而，最近该物种的一些群体没有优势形态类型。在这里，我们比较了具有三种不同表型的形态类型和群体之间的精子产生模式和浓度：（i）大型洄游性对虾，以及（ii）大型（“i”和“ii”具有优势形态类型）和（iii）小型全湖栖对虾（无形态类型）。我们描述了精子发生过程以及输精管（VD）的组织化学特征，并评估了不同表型雄性在精子产生投资和性武器获取之间的关系。具有四种形态类型的群体中，各形态类型之间的精子产生和浓度相似。例外的是CC形态类型，该形态类型的雄性精曲小管充满精母细胞，精子浓度较低。在所研究的表型和群体之间，精子发生、精子形成和VD结构没有差异。马氏沼虾的精液由糖蛋白以及I型、II型（嗜碱性）和III型（嗜酸性）分泌物的同心层组成。我们可以推断，优势形态类型的雄性在连续生长过程中，将更多的能量分配到强壮性武器的发育上，而牺牲了分配给生殖系统的能量。相反，小型雄性将更多能量导向精子产生和转移，而牺牲了性武器。因此，马氏沼虾雄性在性腺发育和性武器发育的投资之间存在明显的权衡。
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