Direct Sperm Transfer Research Articles

Sexually dimorphic claws predict courtship and mating sequence in the intertidal oribatid mite Fortuynia atlantica (Acari, Oribatida)

Fortuynia atlantica, is a sexually dimorphic oribatid mite and although observations are lacking, direct sperm transfer is assumed. We found an additional sexual dimorphism in claw morphology, with females showing relatively smaller and more curved claws, which may point to a possible direct contact during reproduction. Males possess lateral notogastral projections and these could be used as ‘handles’ by the females in the course of some kind of mating. The claws of the females are large enough to embrace the male’s lateral projections and the females’ first legs are long enough to attach to the males’ body from behind without hampering its movement with the rest of the legs. Based on these indications, we propose a hypothetical mating scenario where the male attracts females via pheromones, the female approaches from behind and clasps with the claws of the leg I the ’handles’ of the male. This stimulates the male to deposit a stalkless spermatophore and in a final step the male leads the still attached female over the spermatophore to absorb it. Observation of living specimens is ultimately necessary to verify the existence of the proposed or any other mating behaviour.

Micro-Computed Tomography Reveals a Remarkable Twin Intromittent Organ in Spiders – A Novelty for Arachnids With Direct Sperm Transfer

The modification of male pedipalps into secondary sexual intromittent organs is one of the hallmark characteristics of spiders, yet understanding the development and evolution of male genitalia across the order remains a challenging prospect. The embolus – the sclerite bearing the efferent spermatic duct or spermophor, and used to deliver sperm directly to the female genitalia during copulation – has always been considered the single unambiguously homologous palpal sclerite shared by all spider species, fundamental to the bauplan of the order and to the evolution and functional morphology of spider reproductive systems. Indeed, after two centuries of comparative research on spider reproduction, the presence of a single spermophor and embolus on each of a male spider’s two pedipalps remains a central tenet of evolutionary arachnology. Our findings challenge this premise, and reveal a remarkable twin intromittent organ sperm transfer system in a lineage of Australian palpimanoid spiders, characterized by a bifurcate spermophor and the presence of two efferent ducts leading to a pair of embolic sclerites on each pedipalp. This is the first time such a remarkable conformation has been observed in any group of arachnids with direct sperm transfer, complicating our understanding of palpal sclerite homologies, and challenging ideas about the evolution of spider genitalia.

Putative mating plugs of harvestmen (Opiliones, Laniatores)

In many species of scorpions (Order Scorpiones) and spiders (Order Araneae), mating plugs (gel-like or sclerotized) are deposited in the female reproductive tract, minimizing the possibilities of further matings. Although harvestmen (Order Opiliones) have direct sperm transfer via copulatory organs (penis or spermatopositor in the male and ovipositor in the female), prior studies of the reproductive anatomy of these arachnids have not reported the occurrence of these structures. With the aid of scanning electron microscopy, we observed distinct masses of amorphous, gel-like material in the distal openings of the ovipositors of six different specimens including representatives of the families Cosmetidae (Cynorta marginalis and Flirtea picta), Gonyleptidae (Discocyrtulus bresslaui and Geraeocormobius sylvarum), Kimulidae (Kimula sp.) and Metasarcidae (Metasarcus clavifemur). Dissection of one of these structures from a specimen of the cosmetid harvestman C. marginalis revealed a detailed endocast of the internal surfaces of the female reproductive tract. Considerable interspecific variation in the relative sizes and shapes (smooth and rough) of the amorphous gel-like structures were observed, but evidence of sclerotized components (i.e., parts of the male genitalia) was not found. The location and morphology of the gel-like structures are consistent with observations of mating plugs in other arachnids. The composition, source (male, female or both) and function of these amorphous gel-like structures (i.e. effective matting plug) requires additional study.

Sex-specific repeatabilities and effects of relatedness and mating status on copulation duration in an acridid grasshopper.

In species with direct sperm transfer, copulation duration is a crucial trait that may affect male and female reproductive success and that may vary with the quality of the mating partner. Furthermore, traits such as copulation duration represent the outcome of behavioral interactions between the sexes, for which it is important—but often difficult—to determine which sex is in phenotypic control. Using a double‐mating protocol, we compared copulation durations between (1) virgin and nonvirgin and (2) sibling and nonsibling mating pairs in rufous grasshoppers Gomphocerippus rufus. Nonvirgin copulations took on average approximately 30% longer than virgin copulations, whereas relatedness of mating partners was not a significant predictor of copulation duration. Longer nonvirgin copulations may represent a male adaptation to sperm competition if longer copulations allow more sperm to be transferred or function as postinsemination mate guarding. The absence of differences between pairs with different degrees of relatedness suggests no precopulatory or preinsemination inbreeding avoidance mechanism has evolved in this species, perhaps because there is no inbreeding depression in this species, or because inbreeding avoidance occurs after copulation. Controlling for the effects of male and female mating status (virgin vs. nonvirgin) and relatedness (sibling vs. nonsibling), we found significant repeatabilities (R) in copulation duration for males (R = 0.33; 95% CI: 0.09–0.55) but not for females (R = 0.09; 95% CI: 0.00–0.30). Thus, copulation durations of males more strongly represent a nontransient trait expressed in a consistent manner with different mating partners, suggesting that some aspect of the male phenotype may determine copulation duration in this species. However, overlapping confidence intervals for our sex‐specific repeatability estimates indicate that higher sampling effort is required for conclusive evidence.

Fine Structure and Functional Morphology of the Spermatodactyl in Males of Heterozerconidae (Gamasida)

At present, little is known about the biology of Heterozerconidae (Heterozerconina), a very interesting family of gamasid mites. They are podospermic with males having the genital orifice in presternal position and with a sperm transfer process on the chelicerae. This spermatodactyl arises near the basal region of the fixed digit and seems to have a helicoid “duct.” Since they are podospermic, the females show a sperm access system as well. On the other hand, Discozerconidae (also in Heterozerconina) show a slender spermatodactyl arising from the movable digit. Other families among Gamasida have males whose chelicerae are modified as gonopods involved for a direct sperm transfer. Even though behavioral observations support the idea that gonopods are involved in collecting the spermatophores from the male genital opening and transferring them into the female body, still, little is known on the functional morphology and ultrastructure of these gonopods. Here, a preliminary description of the morphology, fine structure and organization of the gonopods in males of Heterozerconidae is reported and the possible functional implications are discussed. Since the position of Heterozerconina has been one of the least understood questions in gamasid systematics, comparing the ultrastructure and organization of the spermatodactyl in Heterozerconidae males with gonopods in other families among gamasid mites (Phytoseiidae and Veigaiidae) might help in better understanding their position in the group.

Influence of mating duration on fecundity and fertility in two aphidophagous ladybirds

Abstract: The influence of different mating durations on fecundity and fertility has been studied in two aphidophagous ladybirds, Cheilomenes sexmaculata and Coelophora saucia. Pre‐oviposition period decreased while fecundity and fertility increased with increase in mating duration in both the ladybird species. The increase in fecundity with longer mating durations is probably due to the female response because of cryptic female choice. Mating of 10‐s duration resulted in oviposition but of unviable eggs probably because of lack of sperm transfer. A minimum duration of 1 min of mating was probably essential for fertilization of the eggs. Absence of spermatophore in the reproductive tract of females is indicative of direct sperm transfer in both the ladybird species. Trend of fertility (similar fertility at 1 and 5 min followed by increase at 60 min which was again similar to that at complete mating) indicates probable sperm transfer in spurts in C. sexmaculata while continuous transfer in C. saucia is indicated by continuous increase in fertility with increase in mating duration.

Mating biology of the leaf-cutting antsAtta colombica andA. cephalotes

Copulation behavior has often been shaped by sexually selected sperm competition or cryptic female choice. However, manipulation of previously deposited ejaculates is unknown in the social Hymenoptera and the degree to which sperm competes after insemination or is actively selected by females has remained ambiguous. We studied the mating process in the leaf-cutting ants Atta colombica and A. cephalotes, which belong to one of the few derived social insect lineages where obligate multiple mating has evolved. As copulations often occur at night and in remote places, direct observations were impossible, so we had to reconstruct the sequential copulation events by morphological analysis of the male and female genitalia and by tracking the process of sperm transfer and sperm storage. We show that Atta male genitalia have two external rows of spiny teeth, which fit into a specialized pouch organ in the female sexual tract. Reconstruction of the sperm storage process indicated that sperm is transferred to the spermatheca during or immediately after ejaculation and without being mixed with sperm and seminal fluids from other males. A convergent mechanism of direct sperm transfer to the spermatheca of queens is known from two species of dwarf honeybees. Direct sperm transfer may restrict female control over the sperm storage process and the number of males that contribute to the stored sperm.

Spawning, copulation and inbreeding coefficients in marine invertebrates

Patterns of population genetic variation have frequently been understood as consequences of life history covariates such as dispersal ability and breeding systems (e.g. selfing). For example, marine invertebrates show enormous variation in life history traits that are correlated with the extent of gene flow between populations and the magnitude of differentiation among populations at neutral genetic markers (FST). Here we document an unexpected correlation between marine invertebrate life histories and deviation from Hardy-Weinberg equilibrium (non-zero values of FIS, the inbreeding coefficient). FIS values were significantly higher in studies of species with free-spawned planktonic sperm than in studies of species that copulate or have some form of direct sperm transfer to females or benthic egg masses. This result was robust to several different analytical approaches. We note several mechanisms that might contribute to this pattern, and appeal for more studies and ideas that might help to explain our observations.

Sperm Storage, Internal Fertilization, and Embryonic Dispersal in Vent and Seep Tubeworms (Polychaeta: Siboglinidae: Vestimentifera)

Vestimentiferan tubeworms are ecologically important members of deep-sea chemosynthetic communities, including hydrothermal vents and cold seeps. Some are community dominants and others are primary colonists of new vent sites; they include some of the longest living and fastest growing marine invertebrates. Their mechanisms of propagation, dispersal, and genetic exchange have been widely discussed. Direct sperm transfer from males to females has been documented in one species, Ridgeia piscesae, but others are known to discharge what are apparently primary oocytes. Brooding of embryos has never been observed in any vestimentiferan. These observations have led to the supposition that fertilization might be external in most species. Here we report sperm storage at the posterior end of the oviduct in five species, including tubeworms from both vents and seeps. We show experimentally that most eggs are inseminated internally, that fertilization rate is typically lower than 100%, that meiosis is completed after eggs are released from the female, and that the dispersal phase includes the entire embryonic period.

Aligned 18S and Insect Phylogeny

The nuclear small subunit rRNA (18S) has played a dominant role in the estimation of relationships among insect orders from molecular data. In previous studies, 18S sequences have been aligned by unadjusted automated approaches (computer alignments that are not manually readjusted), most recently with direct optimization (simultaneous alignment and tree building using a program called "POY"). Parsimony has been the principal optimality criterion. Given the problems associated with the alignment of rRNA, and the recent availability of the doublet model for the analysis of covarying sites using Bayesian MCMC analysis, a different approach is called for in the analysis of these data. In this paper, nucleotide sequence data from the 18S small subunit rRNA gene of insects are aligned manually with reference to secondary structure, and analyzed under Bayesian phylogenetic methods with both GTR+I+G and doublet models in MrBayes. A credible phylogeny of Insecta is recovered that is independent of the morphological data and (unlike many other analyses of 18S in insects) not contradictory to traditional ideas of insect ordinal relationships based on morphology. Hexapoda, including Collembola, are monophyletic. Paraneoptera are the sister taxon to a monophyletic Holometabola but weakly supported. Ephemeroptera are supported as the sister taxon of Neoptera, and this result is interpreted with respect to the evolution of direct sperm transfer and the evolution of flight. Many other relationships are well-supported but several taxa remain problematic, e.g., there is virtually no support for relationships among orthopteroid orders. A website is made available that provides aligned 18S data in formats that include structural symbols and Nexus formats.

Phallus morphology in caecilians (Amphibia, Gymnophiona) and its systematic utility

Introduction 143Abbreviation used in text 144Abbreviations used in figures 144Morphology 144Disposition of the cloaca 144Divisions of the cloaca 146Urodeum 146Blind sacs 146Anterior phallodeum 147Posterior phallodeum 148Phallodeal ornamentation 148Composition of phallodeal structures 148Relationship between the uneverted cloaca and the phallus 149Systematics 149Is phallus morphology species specific? 149Species differentiation and generic identity 152Discussion 152Acknowledgements 153References 153The cloaca of male caecilian amphibians (Gymnophiona) is a tube that comprises an anterior urodeum and a posterior phallodeum. The phallodeum everts (with the urodeum lying inside it) to form a phallus used for direct sperm transfer in copulation. Phallodeal morphology is rich in detail and variation, and has therefore been considered a potentially useful and much needed tool for caecilian phylogenetics and species-level taxonomy. Despite this, it has been almost entirely ignored in caecilian systematics, there is confusion regarding some aspects of morphology, and variation within and among species is poorly understood. A short review and reconsideration of phallus morphology is presented, and the systematic potential assessed. The anterior part of the phallodeum appears to offer the most obvious systematic potential, and the morphology of longitudinal ridges and their ornamentation here seem to have diagnostic and/or phylogenetic value for some taxa. Although there is evidence of intraspecific variation, at least some of which is associated with ontogeny and reproductive condition, individuals of the same species generally have a common pattern of phallodeal ridges and ornamentation, and congeners often share a similar pattern. However, these patterns are not universally species specific, at least among uraeotyphlids. Although variation needs to be better understood, the male cloaca offers great potential for caecilian systematics.

Canalized pathways of change and constraints in the evolution of reproductive modes of microarthropods

This study investigates how the course of evolutionary change of an organismal pattern is canalized by organismal properties. As an example we use the mechanisms of indirect sperm transfer of some microarthropod groups. Miniaturized droplet spermatophores, characterized by a rather similar pattern of structural and functional components, are shown to have evolved independently in the Acari-Actinotrichida and the Pseudoscorpiones within the Arachnida, and in the Entognatha (Collembola and Diplura-Campodeoidea), Symphyla, Pauropoda and Pselaphognatha within the Antennata. At least in the phylogenetic lineages leading to the various antennatan groups, evolution of miniaturized spermatophores took place in a similar sequence of transformation steps. It is likely that — originally — large sac-spermatophores, with a rigid sheath, were deposited on the ground. The subsequent sequence of evolution involved carrying structures, a viscous sheath of the spermatophore-droplets, a stable water balance of the spermatophore under habitat conditions, and miniaturized spermatophore-droplets with immobilized sperm cells. Finally, mate dissociation became a common mode of behaviour in all groups mentioned. Each of the transformation steps was not only an adaptation to a particular selective condition, but additionally a precondition for further adaptive innovation. In this way the sequence of evolutionary change was rigidly determined. Moreover, integration of subsequently evolved components of the spermatophores into a complex network of interacting components obviously caused constraints of interaction, which in turn have affected evolutionary stability of the character-patterns. Using water mites as an example, it is shown how in a changed environment few behavioural changes have initiated an evolutionary sequence which finally has led convergently in several lineages to semidirect or direct sperm transfer and to a massive repatterning of the original reproduction pattern.

REVIEW Evolution of phytophagy in trombidiform mites

This paper reviews the evolutionary aspects of obligate phytophagy (excluding mycophagy and phycophagy) in the mite suborder Trombidiformes. Phytophagy in the other acariform suborder, Sarcoptiformes, is limited to just a few species, amidst otherwise saprophagous or fungivorous taxa, that attack the living tissues of higher plants. The phylogenetic relationships of lineages that contain taxa of plant-feeding mites are reviewed briefly, to facilitate hypotheses about the number of times that phytophagy has arisen within the Trombidiformes. The relationship between the two most important plant-feeding taxa, the Tetranychoidea and Eriophyoidea, is so distant that their obligate phytophagy represents independent events. Outgroup comparisons allow an estimate of the relative ages when phytophagy arose. This background facilitates analyses of the evolutionary patterns of attributes relevant to phytophagy as a way of life. Styliform modifications of chelate chelicerae for predation or fungivory were fundamental pre-adaptations for effective phytophagy. Dispersal among the major lineages of phytophagous mites seems generally passive, with little evidence of phoretic behaviour. Continued individual mobility seems to be needed during ontogeny and adulthood, such that no scale-like or sac-like instars have arisen. Trends towards physogastric reproduction and ovoviviparity are not evident. Arrhenotokous sex determination predominates among lineages of phytophagous mites. The primary sex ratios are not usually highly female biased. Direct sperm transfer does not seem to have been advantageous or disadvantageous to adaptive radiations of plant-feeding lineages. Adaptive trends towards thelytoky are scattered and do not seem to have played major roles in speciation, diversification or trends towards increasing host specificity in lineages. Alternate asexual and sexual generations and life cycles on different species of hosts, as occur among families of aphid and scale insects, are not known. Among unrelated lineages of trombidiform mites, there appears to have been convergent evolution of attributes, such as those noted above, in response to similar selective pressures for a phytophagous way of life. The patterns of attributes discussed need experimental analysis and detailed documentation to test their accuracy and generality and to understand the selective pressures that have formed them.

The structure and evolution of male cauda and petiole with a cladistic analysis of Chinese species of the genus Arrenurus (Acari: Arrenuridae)

Abstract Two morphological forms of petioles and two morphological forms of cauda are defined respectively based on discrete morphological study of the male cauda and petiole in 22 species belonging to four subgenera, Arrenurus, Micruracarus, Megaluracarus and Truncaturus of the genus Arrenurus. The relationships between the 22 species were studied with a cladistic analysis using 29 morphological characters. The results show that there appear to be six phylogenetic lines in male cauda and petiole of the genus. It is considered that the development of male cauda, petiole and IV-L-4 spur, is driven by behavioural evolution of reproductive mechanism from non-mating (indirect sperm transfer) to mating (direct sperm transfer). The possible evolutionary line(s) and relationships between forms of male cauda and petiole are discussed in detail and illustrated. The results of the cladistic analysis support the monophyly of the genus Arrenurus but do not support the present subgeneric classification of the genus. B...

The structure and evolution of male cauda and petiole with a cladistic analysis of Chinese species of the genus Arrenurus (Acari: Arrenuridae)

Two morphological forms of petioles and two morphological forms of cauda are defined respectively based on discrete morphological study of the male cauda and petiole in 22 species belonging to four subgenera, Arrenurus, Micruracarus, Megaluracarus and Truncaturus of the genus Arrenurus. Therelationships between the 22 species were studied with a cladistic analysis using 29 morphological characters. The results show that there appear to be six phylogenetic lines in male cauda and petiole of the genus. It is considered that the development of male cauda, petiole and IV-L-4 spur, is driven by behavioural evolution of reproductive mechanism from non-mating (indirect sperm transfer) to mating (direct sperm transfer). The possible evolutionary line(s) and relationships between forms of male cauda and petiole are discussed in detail and illustrated. The results of the cladistic analysis support the monophyly of the genus Arrenurus but do not support the present subgeneric classification of the genus.Based on phylogenetic relationships among studied species in best resolved trees, a classification of seven species groups is presented, which might lead to a better and more practical subgeneric classification with further studies using more taxa.

Ultrastructure of the Genital Organs in the Interstitial Syllid Petitia amphophthalma (Annelida, Polychaeta)

Abstract The gonochoristic syllid Petitia amphophthalma is one of the truly interstitial polychaetes. P. amphophthalma does not show any epitokous modifications at maturity such as those that usually occur in syllids. The reproductive structures are unique: the male genital organs consist of a seminal vesicle in chaetigers 6–10, subdivided into a dorsal part tightly filled with spermatozoa and a ventral part with contents in different stages of spermatogenesis, one pair of sperm ducts and conspicuous gland cells situated in chaetigers 10 and 11. Their glandular secretions are discharged into the sperm duct together with those of other types of gland cells that form the duct. The oocytes develop freely within the body cavity of the females. Each of the fertile segments possesses a paired oviduct ending in a large ciliated funnel. Sperm ducts and oviducts are probably modifications of excretory organs; nephridia are absent in segments where gonoducts occur. A direct sperm transfer by lytic opening of the integument of the female and internal fertilization are inferred. Copyright © 1996 Published by Elsevier Science Ltd on behalf of the Royal Swedish Academy of Sciences

Mating and sperm transfer in Apis florea

Summary — The mating flights of 3 virgin queens of Apis florea have been observed. The queens carried no mating sign when they returned to their colonies. In 2 of the queens, dissected several minutes following their return, spermatozoa were found in the spermatheca. The filling of the spermatheca during mating and the anatomical structure of the Apis florea drone’s endophallus suggested direct sperm transfer into the spermatheca. The 3rd queen was dissected 16 h after mating. At that time, more than 200 eggs were present in the previously empty comb. The queens had 0.48, 0.72 and 1.35 million spermatozoa in the spermatheca. On average, drones of A. florea were found to produce about 0.44 million spermatozoa. So, the queens were presumely mated by 1, 2 and 3 drones, respectively.

Pregnancies after ultrasound-guided fallopian insemination with cryostored donor semen

Twenty-nine patients, previously treated unsuccessfully with a median 9.5 cycles of conventional intracervical donor insemination, were offered fallopian catheterization on the side of the dominant follicle and direct insemination at the presumed site of fertilization, the ampullary-isthmic junction. Forty-five of 50 cycles were associated with successful tubal catheterization and 6 of these cycles were conceptional. Five viable intrauterine pregnancies resulted. We conclude: (1) that direct sperm transfer to the fallopian tubes is possible without the need for anesthesia or operation; and (2) that at the time of ovulation, the fallopian tube isthmus can be catheterized without later interfering with ovum or embryo transport to the uterus. Optimum timing for fallopian catheterization in relation to ovulation and the risk of side effects both remain to be established.

EJECTION AND INGESTION OF THE SPERMATOPHORE BY THE FEMALE LADYBIRD BEETLE, HARMONIA AXYRIDIS PALLAS (COLEOPTERA: COCCINELLIDAE)

Sperm transfer in the aphidophagous ladybird beetle, Harmonia axyridis Pallas, is by a spermatophore (unpublished data). Although the utilization of spermatophores in insects has been considered to be a more primitive method of insemination than direct sperm transfer, males of many orders produce spermatophores (Chapman 1969; Gerber 1970; Leopold 1976). The remains of the spermatophore, after the sperm has migrated to the spermatheca, is ejected by the female in some species and dissolved within the female genital tract in others (Chapman 1969; Leopold 1976). In Coccinellidae, Fisher (1959) reported on spermatophore formation of Chilocorus spp. and indicated that the female ejected the empty spermatophore 18–24 h after copulation. In this paper evidence is presented that H. uxyridis females not only eject the empty spermatophore but also feed on it.

Mating behavior in the tydeid miteHomeopronematus anconai (Acari: Tydeidae)

The mating behavior ofHomeopronematus (Pronematus) anconai (Baker) is described. This is the first report of direct sperm transfer in the family Tydeidae (Acari: Actinedida). Male guarding of pharate females and male agonistic behavior was observed. Successful mating occurred only during the first day of active female life. Specialized male structures, a hook on femur IV and a modified seta on genu IV, were examined by scanning electron microscope. These structures appear to be involved in holding the female during copulation.