Primary Sexual Characters Research Articles

Basic Intersexuality (Abnormal Hermaphroditism) in the Blackmouth Catshark, Galeus melastomus, (Rafinesque, 1810), from the Southern Tyrrhenian Sea (Central Mediterranean Sea)

The present paper represents the first description of abnormal hermaphroditism in Galeus melastomus (Rafinesque, 1810). The black mouth cat shark specimen, collected in summer from southern Tyrrhenian Sea at the entrance of Salerno gulf, showed a basic intersexuality characterized by the presence of male secondary and female primary sexual characters. The reproductive system has been described with an accurate morphological analysis, also including a histological assessment of oocytes. Results showed the presence of only right clasper, not exceeding the pelvic fin in length, with the absence of internal males’ sexual organs. Concerning the female primary characters, the analysis of histological assessment showed the structure of mature oocyte, confirming the maturity stage of a mature female in active extruding stage, as highlighted by the macroscopic morphological analysis. Despite in many marine organisms’ hermaphroditism is a physiological condition showed by specimens during their lifecycle, in Elasmobranchs this is considered an abnormal condition, with some exceptions. The lack of information on hermaphroditism in elasmobranchs form the Mediterranean Sea requires an increase of scientific community’s attention, improving the knowledge on the reproductive biology of this sensitive taxon. This is essential to enhance the conservation of elasmobranchs populations in the entire Mediterranean basin.

Holothuriophilus trapeziformis Nauck, 1880 (Decapoda: Pinnotheridae) from the Pacific coast of Mexico: taxonomic revision based on integrative taxonomy.

BackgroundHolothuriophilus trapeziformis Nauck, 1880 is a holothurian-dweller pinnotherid crab representing one of the two species of the genus distributed along the Pacific coast of Mexico and Chile, respectively. While the parasitic ecological interaction with its host is well established, the morphology of the male remains unknown, and DNA information for the species is not available. Furthermore, the only morphological trait separating both species of the genus is subjective and corresponds to the presence or absence of a gap between the fingers of the chelae. Our goal is to complete and clarify the taxonomic status of H. trapeziformis and describe the male morphology with the use of the integrative taxonomy, providing additional characters to differentiate this species.MethodsWe collected new biological material in the Pacific coast of Mexico including the topotypes. We also reviewed material from national collections to integrate morphology (based on a complete and detailed description and illustration of the species using light microscopy), ecological data (based on the identification of the host and the place where it was located within the host), and the mtCOI gene information (commonly known as DNA barcode) to differentiate Holothuriophilus trapeziformis from other related crabs.ResultsThis species presents marked sexual dimorphism only in the primary sexual characters. For the first time we describe morphological variability of traditionally stable characters. In addition to the gap between the fingers of the chelae, Holothuriophilus trapeziformis differs from H. pacificus (Poeppig, 1836) by their ornamentation, the shape of the male abdomen, and the gonopod. Cytocrome Oxidase 1 gene (COI) distance divergence was >3% between both Holothuriophilus species forming a clear clade. DNA barcoding indicates only one taxon, with a maximum divergence of 2.2%. All the specimens have the same Barcode Index Number (BIN; BOLD: ADE9974). All the hosts for H. trapeziformis were identified as Holothuria (Halodeima) inornata Semper, 1868; the presence of the crab in the host’s coelomic cavity was confirmed, and for the first time we found it within the intestine. The geographical distribution is the Pacific coast of Mexico. Based on the data presented here, the taxonomic status of Holothuriophilus trapeziformis is now complete.

The Evolution of Primary Sexual Characters in Animals. Edited by Janet L. Leonard and Alex Córdoba‐Aguilar. Oxford and New York: Oxford University Press. $79.95. xi + 537 p.; ill.; index. ISBN: 978‐0‐19‐532555‐3. 2011.

Previous articleNext article No AccessNew Biological BooksThe Evolution of Primary Sexual Characters in Animals. Edited by Janet L. Leonard and Alex Córdoba‐Aguilar. Oxford and New York: Oxford University Press. $79.95. xi + 537 p.; ill.; index. ISBN: 978‐0‐19‐532555‐3. 2011.Göran ArnqvistGöran ArnqvistAnimal Ecology and Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden Search for more articles by this author Animal Ecology and Evolutionary Biology Centre, Uppsala University, Uppsala, SwedenPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 86, Number 2June 2011 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/659916 Views: 26Total views on this site Citations: 1Citations are reported from Crossref Copyright © 2011 by The University of Chicago Press. All rights reserved.PDF download Crossref reports the following articles citing this article:Shao-Kun Guo, Ya-Jun Gong, Jin-Cui Chen, Pan Shi, Li-Jun Cao, Qiong Yang, Ary Anthony Hoffmann, Shu-Jun Wei Increased density of endosymbiotic Buchnera related to pesticide resistance in yellow morph of melon aphid, Journal of Pest Science 93, no.44 (Jun 2020): 1281–1294.https://doi.org/10.1007/s10340-020-01248-0

Age‐related variation in primary sexual characters in a passerine with male age‐related fertilization success, the bluethroat Luscinia svecica

In passerine species with frequent extrapair mating, young (second calendar year) males often have a lower fertilization success than older (after second calendar year) males. This pattern might be explained by male‐ or female‐driven mechanisms, such as female preference for older males or higher competitive ability of older males. In this study we measured the size of the testes, the seminal glomera and the cloacal protuberance as well as the size and motility of the sperm, in individual bluethroats Luscinia svecica. In this species, nearly all extrapair fertilizations (EPFs) are obtained by older males. We found that the mass of the testes and the seminal glomera were highly positively correlated and that older males had significantly larger testes (38%), seminal glomera (15%) and cloacal protuberance (23%) than young males. In contrast, there was no difference between age groups in average sperm size or sperm motility. Our results are consistent with the idea that higher fertilization success by older males in this species is due to their higher rate of sperm production, allowing larger ejaculates and/or more frequent copulations. Unequal sperm production capacities by young and older males have important implications for the interpretation of paternity patterns in extrapair mating systems.

Ontogeny of sexual dimorphism in the Long‐tailed ManakinChiroxiphia linearis: long maturation of display trait morphology

Males of dimorphic species often show ornaments that are thought to have evolved through female choice or/and male–male competition. The sexual differentiation of similar morphologies occurs during ontogeny, resulting in differential sex and age‐specific selection. The Long‐tailed Manakin is a dimorphic species with a highly skewed mating system, the males of which delay plumage maturation over 3 to 4 years. We describe ontogenetic changes in feather morphology in this species through sexual maturity. Males showed a significant increase in length of the central rectrices with age, hence their degree of sexual dimorphism increased from zero in 1‐year‐old males to 189.5% in adults. In contrast, male tail length decreased with age. Wing length did not vary significantly with age, but females had relatively longer wings than males. Wing loading was greater in females and decreased with age in males. In adults, rectrix length was positively correlated with testis volume, supporting the hypothesis that secondary sexual characters can signal the condition of primary sexual characters. Rectrix length showed positive allometry with body size in males less than 4 years old, whereas older males showed negative allometry and females showed isometry. Wing area and wing loading shifted from negative to positive allometry in males of 2 to 3 years of age. Changes in male morphology during ontogeny in the Long‐tailed Manakin appeared to be associated with their specific display behaviours. Age‐related changes in allometric growth of rectrices in the Long‐tailed Manakin suggested that young males invest disproportionately more in the length of this trait relative to their body size. This investment could act as a signal of competitive ability to move status position in their orderly queue.

Dichogamy and Sexual Dimorphism in Floral Traits in the Andromonoecious Euphorbia boetica

Euphorbia boetica (Euphorbiaceae) is a functional andromonoecious species that shows both intra- and interfloral dichogamy, hermaphrodite cyathia being protogynous. Sexual dimorphism of the cyathia of E. boetica is examined according to their gender and arrangement on the inflorescence. Data were obtained from two natural populations, where the distribution of male and hermaphrodite cyathia in the inflorescence was recorded. The size, pollen production and viability, and nectar secretion were measured in both types of cyathia. Most cyathia were male at the first levels of the inflorescence, then hermaphrodite cyathia predominated at the successive levels, although at the last levels the proportion of male cyathia increased. Male cyathia at basal positions lack ovaries, whereas those at distal positions showed vestigial ovaries. The size of the cyathia varied significantly depending on the level of the inflorescence where they were produced: those of the last levels were usually smaller. The hermaphrodites were significant bigger than males; however, these differences were due to the differential distribution of each cyathium type in the inflorescence. Male cyathia produced significantly more pollen and nectar than hermaphrodites. In Euphorbia boetica, basal male cyathia could be explained by the presence of protogyny, and apical male cyathia seem to respond to a preemption of resources. A true dimorphism affecting primary sexual characters and related to gender function appears at lower levels of the inflorescence, whereas an apparent size dimorphism due to positional effects occurs at upper positions. Longevity and distribution of cyathia, and their pattern of nectar production, could improve both male and female fitness.

Where is the Human Baculum?

Humans are unique among the primates in many characteristics, especially the primary and secondary sexual characters. One of these characteristics is that human males are the only member of the old world simian group (apes and old world monkeys) without a baculum. The loss of this bone in Homo sapiens is considered with respect to its function and appearance in other hominids. It is hypothesized that its loss in humans is related to upright posture, mating systems, and sperm competition. I predict that as more fossils are discovered or bones associated with current collections reexamined. all hominids before, and possibly including Homo erectus will be found to possess a baculum. Keywords: human mating systems, penis, sperm competition, bacula, human evolution 1. Introduction Modern man is anatomically unique amongst his near relatives the primates, most obviously in being hairless, erect and wholly bipedal. Sexual characters are especially different in Homo Sapiens (Short, 1981) and can be divided into two categories, primary and secondary. Primary characters are those directly related to copulation and are formed early in development. These include the organs of gamete transfer, as well as grasping appendages to secure the female. Secondary sexual characteristics, which become evident during puberty and adulthood, have received more attention, usually under the term sexual selection (Darwin, 1871; Trivers, 1972). Humans are distinctly different from other primates with regard to several primary sexual characters, including concealed ovulation (Benshoof and Thornhill,1979; Alexander and Noonan,1979; Burley, 1979; Smith, 1984, but see Sillen-Tullberg and Moller, 1993), possession of a hymen (Burley, 1979; Katchadorian, 1990; Hobday et al., in press), and permanent breasts (Short, 1980; Cant, 1981; Smith, 1984; Caro, 1987). An additional difference is that the human penis lacks a baculum (Hill, 1972; Short, 1979). In this paper I shall first explain the form and function of both bacula and penis and summarize likely functions, offer a possible explanation for the enlargement of the penis and loss of the baculum in H. Sapiens, and finally consider some comparative evidence to support my hypothesis. 2. The Baculum What is a Baculum?. The baculum (also called a penis bone, os priapi, or os penis) is a heterotypic hone present in the penis of various male mammals. Morphologically it is the most diverse of all bones and is often elongated. The distal end is complex in shape with great interspecific variability, implying that it has been subject to much selection (Eberhard, 1985; Dixson, 1987a, b; Fooden 1988). A female counterpart, the os clitordoris or baubellum, is present in some species (Hershkovitz, 1977; Hancox, 1987; Williams-Ashman and Reddi, 1991). Both form from ossification of the mesenchyme tissues within the organ. Because bacula growth occurs with maturity, it has been used to age males of some species (Hancox, 1987; Chen et. al., 1988). A baculum is found in 6 orders of Eutherian mammals (Table 1). It may have evolved separately in each mammal order in which it occurs (Hershkovitz ,1977). Of the non-primate orders, only in the Carnivore family Hyeniidae is the baculum absent. In the primates it is found in all the Catyrrhini (Hill, 1972), all prosimians but Tarsius, while in the Platyrrhini it is absent in several genera belonging to different families (Ateles, Lagothrix, Alouatta and some specimens of Chiropotes and Cacajao) (Hershkovitz, 1977; Dixson, 1987a, b). Among the apes and old world monkeys, H. Sapiens is the only member without a baculum (Table 1). These species are considered the most specialized members of their respective groups, and the lack of bacula is considered degenerative (Hershkovitz, 1977). In species with a baculum it is often a major element of the penis, and so it is logical to first consider the function of the penis. …

Testes asymmetry, condition and sexual selection in birds: an experimental test

The functional significance of the marked directional asymmetry in testes size observed in many bird species is obscure. Moller suggested that (i) the smaller of the two testes serves a compensatory role and increases in size (and hence reduces asymmetry) when the larger one is defective in some way, and (ii) as a consequence, the degree of directional asymmetry in testes size reflects male quality and covaries positively with the expression of secondary sexual traits. We conducted an experimental test of these two hypotheses in the zebra finch, Taeniopygia guttata. Neither hypothesis was supported. First, there was no significant relationship between the size of the left testis and relative testes asymmetry. Second, we obtained no support for the hypothesis that the degree of directional asymmetry in testes mass covaried with condition. On the contrary, directional asymmetry in testes mass was significantly greater in birds whose condition was experimentally reduced, compared with control birds. Moreover, we found no significant relationships between testes asymmetry and secondary sexual traits. We conclude that directional asymmetry in testes size does not reflect male condition in the zebra finch.

ONTOGENY OF FEMALE PRIMARY SEXUAL CHARACTERS IN THE MAJID CRABS CHIONOECETES OPILIO AND HYAS COARCTATUS

ABSTRACT To investigate the development of primary sexual characters in the family Majidae, the spermathecae, ovaries, and oviducts of juvenile female Chionoecetes opilio and Hyas coarctatus were examined, using histology, histochemistry, and electron microscopy, and compared to those of mature females. Females were divided into 3 developmental categories, with corresponding size ranges, based on anatomical criteria: immature, premature, and mature. Immature crabs were still temporally remote from the terminal molt, had white ovaries, and the spermatheca presented a thin tissule separation between the dorsal and ventral regions. No stratified glandular epithelium was present; only a columnar epithelium lined the lumen. This epithelium tested slightly positive for amine-containing substances. Premature females were temporally close to terminal molt, had orange ovaries, and retained the tissule separation between the dorsal and ventral regions of the spermatheca. In addition, they presented a stratified glandular epithelium which developed beneath the columnar epithelium lining the lumen. The latter degenerated and sloughed into the lumen as the former developed. Mature females had undergone the terminal molt, and were examined both prior to and following egg extrusion. No trace remained of the columnar epithelium which was present in the preceding two categories. In mature females which had extruded eggs, the tissule separation between dorsal and ventral regions of the spermatheca was also absent. Neutral mucopolysaccharides dominated in the secretions of the dorsal glandular epithelium of both types of mature female. These results establish the primary sexual characters in female C. opilio and H. coarctatus, and also document the sequence of aquisition of these characters.

Sexual selection in plants: pros and cons.

Sexual selection has long been regarded as a special mode of selection in animals. Various authors have argued in a growing number of publications since 1979 that sexual selection is also operative in plants, and consequently, two divergent concepts of sexual selection are now being stated in the literature, the original Darwinian concept and the new plant-centered concept. An essential feature of the Darwinian concept is the distinction between primary and secondary sexual characters. Sexual selection is a process producing secondary sexual characters in males; such characters are well known in animals but are unknown in plants. Proponents of sexual selection in plants do not mention the subject of primary and secondary sexual characters, and they make no effort to establish the existence of secondary sexual characters in plants. The evidence they do present for sexual selection in plants consists of primary sexual characters and other reproductive traits that are products of selection modes other than sexual selection.

Directional selection on directional asymmetry: testes size and secondary sexual characters in birds

A standard example of directional asymmetry with one side of the body having a larger character value than the other is testes size in many vertebrates. The relation between directional asymmetry in testes size and the expression of secondary sexual characters (a measure of phenotypic quality) in two bird species, the barn swallow, Hirundo rustica, and the house sparrow, Passer domesticus, was used to test whether directional asymmetry was subject to directional selection. Testes size, which was positively related to the size of the secondary sexual character, demonstrated directional asymmetry, with the left testis generally being larger than the right testis. The amount of directional asymmetry was positively related to the expression of the secondary sexual character, suggesting that males with the largest degree of directional asymmetry were at a selective advantage, since males with the most extravagant secondary sexual characters have the highest mating success. These relations were not confounded by variables such as body mass, body size and age. Males in poor condition (with small secondary sexual characters) may be unable to develop large degrees of directional asymmetry, and deviations from directional asymmetry may therefore be viewed as a measure of developmental homeostasis.

Observation and Experiments on Sex-Change in the European Oyster (O. edulis.): Part I. The Change from Female to Male

The gonads of 1,121 oysters have been examined at various periods from a few hours to twelve months after the individuals had spawned as females; the material for the research was obtained by collection and experiment. In 702 individuals taken with young in the mantle cavity the gonad shows a progressive development of maleness in its primary sexual characters; within a mean period of 2¼ hours after spawning eggs, the gonad was found in 50 per cent of cases with only young spermmasses developing, followed at later periods by a progressive ripening of the sperm-masses, until in individuals carrying shelled and black-coloured larvae 77 per cent contained abundant ripe sperm-masses as well as advanced developing sperm-masses.In 444 individuals examined at various periods after extruding their larvæ, the development of sperm was found to continue for about a month after egg-spawning, and to abate in about the second month. In from 2 to 3 months after egg-spawning sperm-development is completed and the male phase begins to wane, and a small percentage of individuals may become female or actively female-functioning again. In 12 months after the last egg-spawning a significant number of individuals become once more functional females.The varieties of mixed sexes found in O. edulis are denned and their frequencies shown by an analysis of samples—from two widely separated beds—examined at the beginning of the breeding season in 1926. Experiments on the rate of growth of sperm-masses and on determining of age at different stages of development in embryos and larvæ are given.