Sperm Morphology in Neotropical Primates

Abstract

Simple SummaryThe spermatozoon is a highly differentiated cell, whose morphology has been affected throughout evolution by selective forces such as the competition between the sperm of rival males (sperm competition) and the joint evolution of male and female reproductive tracts (coevolution). The study of its morphology is important when analyzing the relationships between different species. In this contribution we analyzed new specimens and produced a database with all the spermatozoa dimensions recorded to date, comprising 75 individuals from 20 species and 8 genera, representing 2 families of neotropical primates (Cebidae and Atelidae). After an evolutionary analysis, we observed two different trends for the Cebidae and Atelidae families. Narrower and shorter spermatozoa seem to be the ancestral (oldest) form for Cebidae, with an evolutionary trend toward spermatozoa with wider and larger heads in the derived (younger) species. In Atelidae, on the contrary, narrower heads are observed in the more derived groups. We analyzed these results in the context of sperm competition and mating systems in these groups. More studies are needed to improve our knowledge of the evolution of the spermatozoa in neotropical primates.AbstractThe morphological and morphometric characterization of spermatozoa has been used as a taxonomic and phylogenetic tool for different species of mammals. We evaluated and compared the sperm morphometry of five neotropical primate species: Alouatta caraya, Ateles belzebuth and Ateles chamek of family Atelidae; and Cebus cay (=Sapajus cay) and Cebus nigritus (=Sapajus nigritus) of family Cebidae. After the collection of semen samples, the following parameters were measured on 100 spermatozoa from each specimen: Head Length, Head Width, Acrosome Length, Midpiece Length, Midpiece Width and Tail Length. Considering the available literature on sperm morphometry, we gathered data of 75 individuals, from 20 species, 8 genera and 2 families. These data were superimposed on a phylogeny to infer the possible direction of evolutionary changes. Narrower and shorter spermatozoa seem to be the ancestral form for Cebidae, with a trend toward wider and larger heads in derived groups. The spermatozoa of Atelidae may show an increase in total length and midpiece length. Sperm heads would have become narrower in the more derived groups of Ateles. Sperm length may increase in the more derived species in both families. Our results are discussed in the context of sperm competition and sexual selection.

Differences in sperm morphology between Alouatta palliata and Alouatta pigra are consistent with the intensity of sperm competition in each species

“…Comparisons of our measures of sperm length between A. palliata, A. pigra, and published A. caraya data (52.01 µm, Steinberg et al, 2019) suggest similar mean total lengths among these howler monkeys.…”

“…We used ImageJ® (Schneider et al, 2012) to measure 10 predetermined measurements of each sperm cell from the head, midpiece, and tail (Figure 2; Steinberg et al, 2019; Swanson et al, 2016; World Health Organization, 2021). We categorized these as head length, head width, head circumference, midpiece length, midpiece width 1 (near the head), midpiece width 2 (in the middle), midpiece width 3 (near the tail), midpiece area, tail length, and total length.…”

“…In primates, sperm morphology has been characterized in representative species of several families including Cercopithicidae, Lorisidae, and Lemuridae (Gould & Martin, 1978), Hominidae, Pongidae, and Cebidae (Martin, Gould, & Warner, 1975), and Callitrichidae and Atelidae (Steinberg et al, 2019; Swanson et al, 2016; Valle, Arakaki, et al, 2013; Valle, Carvalho, et al, 2013; Valle et al, 2012), illuminating the great diversity of sperm morphologies across primates. Recently, research has expanded into determining how and why sperm morphology differs between closely related primate species (Martinez & Garcia, 2020), yet such research is primarily focused on enhancing artificial reproductive technologies (e.g., in Saimiri , Comizzoli & Holt, 2022; Sampaio et al, 2017) or broadening the representation of primate species in the sperm morphometric literature (Steinberg et al, 2019). To better understand how divergent mating systems affect sperm morphology in closely related primate species, we compared sperm morphology between two endangered (IUCN, 2021) howler monkey sister species: the Mexican howler monkey, Alouatta palliata mexicana (henceforth A. palliata ), and the Guatemalan black howler monkey, Alouatta pigra .…”

A Systematic Review of the Impact of Mitochondrial Variations on Male Infertility

“…A recent study provides evolutionary evidence in support of a role for paternal mtDNA in fertilization, with data collected from two neotropical primate families (Cebidae and Atelidae) suggesting that the midpiece-containing mtDNA has evolved to become larger and wider in the younger species (Atelidae) compared to the narrower and shorter midpiece in the ancestral species (Cebidae) [ 21 ].…”

Short Communication: Characteristics of the endangered Javan banteng (Bos javanicus) spermatozoa

“…Any abnormalities in spermatozoa morphology will compromise fertility and even cause sterility in males (Cao et al 2017;Feyisa et al 2018;Oehninger and Kruger 2021). The morphology and morphometry of spermatozoa have been studied from various species and showed diversity among species (Villaverde et al 2013;Cursino and Duarte 2016;Yániz et al 2016;Rossi et al 2018;Steinberg et al 2019;Andraszek et al 2020). Morphometric dimensions of spermatozoa have also been linked to fertility, inbreeding, and phylogenetic studies (Villaverde et al 2013;Lawrence et al 2017).…”