Papers by Alfredo Peretti
PloS one, 2015
In nuptial gift-giving species females sometimes select their potential mates based on the presen... more In nuptial gift-giving species females sometimes select their potential mates based on the presence and size of the gift. But in some species, such as the Neotropical polyandrous spider Paratrechalea ornate male gifts vary in quality, from nutritive to worthless, and this male strategy can be in conflict with female nutritional benefits. In this species, males without gifts experience a reduction in mating success and duration, while males that offer worthless or genuine nutritive gifts mate with similar frequencies and durations. The female apparently controls the duration of copulation. Thus, there is scope for females to favour males offering gifts and further if these are nutritious, via post-copulatory processes. We first tested whether females differentially store sperm from males that offer the highest nutritional benefits by experimentally presenting females with males that offer either nutritive or worthless gifts (uninterrupted matings). Second, we carried out another set ...
Tissue & cell, 2009
The ultrastructure of spermatozoa is a widely accepted source of characters for phylogenetic stud... more The ultrastructure of spermatozoa is a widely accepted source of characters for phylogenetic studies. In this study the fine structure of sperm cells of representatives of six different New and Old World families (Ammotrechidae, Daesiidae, Eremobatidae, Galeodidae, Karschiidae, Solpugidae) of solifuges (Arachnida, Solifugae) were investigated in order to reveal putative characters suitable for subsequent systematic and phylogenetic analyses. The spermatozoa of solifuges represent a relatively simple type of sperm cells. In general, their spermatozoa are roundish, oval shaped (Ammotrechidae, Daesiidae, Eremobatidae, Solpugidae) or plate-shaped (Karschiidae) with or without membrane protuberances and devoid of a flagellum. Only in Galeodidae, very conspicuous thin and elongated sperm cells occur. The spermatozoa either occur as single cells (Eremobatidae, Solpugidae) or in groups of loose knit cells (Ammotrechidae) or in highly ordered groups (Karschiidae). In contrast to the other fa...
Some current interpretations of male-female sexual interactions have implied that males can contr... more Some current interpretations of male-female sexual interactions have implied that males can control female mating decisions. Here we analysed the main characteristics of female sexual receptivity of the mountain scorpion Zabius fuscus based on the premating behavioural patterns of virgin and inseminated females from natural or artificially interrupted matings. Males were used repeatedly in successive tests to evaluate females' levels of sexual receptivity (positive Z accept, intermediate, negative Z reject) and behavioural flexibility. Duration and frequency values of male behaviour patterns were correlated with the female's response. During the sexual recognition phase, the male performed vibratory movements of the body, termed vibration, which did not vary between the three groups of females (positive, intermediate and negative). In contrast, frequencies of occurrence of the principal male stimulatory behaviours, cheliceral massage and rubbing with legs, differed significantly between the three groups of females, reflecting a clear flexibility of male sexual behaviour according to the initial female response. Scorpion males appeared to use luring rather than coercive behaviours when facing resisting females. The observed patterns do not support the position that males override female means of mating control. Furthermore, morphologically based data indicate that postmating sexual receptivity in females is not affected by other male characteristics such as body or spermatophore size.
PLoS ONE, 2014
There is strong evidence that polyandrous taxa have evolved relatively larger testes than monogam... more There is strong evidence that polyandrous taxa have evolved relatively larger testes than monogamous relatives. Sperm size may either increase or decrease across species with the risk or intensity of sperm competition. Scorpions represent an ancient direct mode with spermatophore-mediated sperm transfer and are particularly well suited for studies in sperm competition. This work aims to analyze for the first time the variables affecting testes mass, ejaculate volume and sperm length, according with their levels of polyandry, in species belonging to the Neotropical family Bothriuridae. Variables influencing testes mass and sperm length were obtained by model selection analysis using corrected Akaike Information Criterion. Testes mass varied greatly among the seven species analyzed, ranging from 1.6 ± 1.1 mg in Timogenes dorbignyi to 16.3 ± 4.5 mg in Brachistosternus pentheri with an average of 8.4 ± 5.0 mg in all the species. The relationship between testes mass and body mass was not significant. Body allocation in testes mass, taken as Gonadosomatic Index, was high in Bothriurus cordubensis and Brachistosternus ferrugineus and low in Timogenes species. The best-fitting model for testes mass considered only polyandry as predictor with a positive influence. Model selection showed that body mass influenced sperm length negatively but after correcting for body mass, none of the variables analyzed explained sperm length. Both body mass and testes mass influenced spermatophore volume positively. There was a strong phylogenetic effect on the model containing testes mass. As predicted by the sperm competition theory and according to what happens in other arthropods, testes mass increased in species with higher levels of sperm competition, and influenced positively spermatophore volume, but data was not conclusive for sperm length.
Journal of Ethology, 2007
Ethology Ecology & Evolution, 2007
In this paper we want to call the attention of sexual selection researchers to the role and poten... more In this paper we want to call the attention of sexual selection researchers to the role and potential of fine-scaled observations which may affect interpretations of sexual phenomena. The following example can describe the problem in short. During the seventies, J.R. linley and collaborators detailed several aspects of the reproductive behaviour of the biting midge Culicoides melleus (e.g. linley & aDams 1��4, linley & mooK 1975). They found that the female delivered stylized kicks to the male during copulation. One of the main fine observations showed that the "kicking" behaviour of a female was not an attempt to physically reject the mounted male but to communicate her sexual receptivity, which depended on her mating history. A superficial description of that behaviour may have led present day researchers to encapsulated its meaning in the phrase "kick the male to displace it". In turn the phrase could lead to an explanation in terms of sexual conflict and the real meaning of this behaviour, communication, would have been lost.
Canadian Journal of Zoology, 2006
In various animal species, male sexual dimorphic characters may be used during intrasexual contes... more In various animal species, male sexual dimorphic characters may be used during intrasexual contests as ornaments to attract females, or to hold them before, during, or after copulation. In the well-known harvestman, Phalangium opilio L., 1758, the behavioral functions of these male sexually dimorphic structures have never been studied in detail. Therefore, in addition to a morphometric study, 21 male contests and 43 sexual interactions were analyzed. Our observations revealed that during contests, the male cheliceral horns form a surface by which the contestants use to push each other face-to-face while rapidly tapping their long pedipalps against the pedipalps of the opponent, occasionally twisting the opponent's pedipalp. Scanning electron micrographs revealed contact mechanoreceptors on the pedipalp that would detect the intensity-frequency of contact with the contender's pedipalp. Larger males won almost all contests, whereas the loser rapidly fled. During sexual interactions, the longer pedipalps of the male held legs IV of the female, whereas males with shorter pedipalps held the female by legs III. No contact with the male pedipalps and chelicerae by the females was visible before, during, or after copulation. Soon after copulating, males typically bent over the female, positioning their cheliceral horns against the females's dorsum. Consequently, our data show that the cheliceral horns and the longer pedipalps of the male seem to play an important role, during both intersexual and intrasexual encountering.
Biological Journal of the Linnean Society, 1999
Females of several scorpion species are currently deemed to be sexual cannibals, but this reputat... more Females of several scorpion species are currently deemed to be sexual cannibals, but this reputation is, however, largely built on anecdotal evidence from the older literature. Theoretical models predict that given the low rates of female-male encounter, males should allow themselves to be cannibalized after sperm transfer. The present paper examines the information available for a number of species to determine (a) whether sexual cannibalism is as widespread as previously suggested, and (b) whether it is likely to involve male selfsacrifice. Information on three scorpions currently regarded as sexual cannibals is presented: the bothriurids Bothriurus bonariensis (C.L. Koch) and Urophonius jheringii Pocock, and the buthid Leiurus quinquestriatus (Hemprich & Ehrenberg). No post-mating cannibalism was ever observed in these species, nor in another 19 representatives of four families. In L. quinquestriatus only two cases of cannibalism of the male by the female occurred, both in the beginning of courtship and after long periods of food deprivation. We suggest that if sexual cannibalism occurs in scorpions, it is most likely to be of an 'economic' type, where females perceive males as prey rather than mates, and not a 'self-sacrificial', post-mating cannibalism enhancing the fitness of the offspring of the male.
Behaviour, 2010
One male strategy to prevent female re-mating is post-copulatory mate guarding. In the pholcid sp... more One male strategy to prevent female re-mating is post-copulatory mate guarding. In the pholcid spider Holocnemus pluchei last male's fertilization success is around 74% and females remain receptive after copulation. It is, thus, reasonable to suppose that males should engage in post-copulatory mate guarding. Chronologically, the present study focused on the following aspects: (1) to determine if male permanence near females corresponds to mate guarding. For this, a second male (intruder) was introduced. Time of permanence, distance and behaviour of residents did not change whether or not an intruder was present; (2) to investigate the duration of mate guarding and male distance to the female in a time series intervals after copulation. Males remained close to females during 14 h keeping a distance of less than 15 cm; (3) to evaluate whether guarding duration is influenced by female sexual receptivity. We found that 24 h after the first copulation, when the resident was placed again next to the female, he tried to re-mate; and (4) to examine differences in paternity in relation to whether or not the resident exerted guarding. P2 was higher when second males copulated again within the first 6 h compared to 24 h after the first copulation.
Arthropod Structure & Development, 2008
Solifugae possess an evertable, adhesive pedipalpal organ (suctorial organ) at the tip of the dis... more Solifugae possess an evertable, adhesive pedipalpal organ (suctorial organ) at the tip of the distal tarsus of each pedipalp that is unique among arachnids. When inverted inside the pedipalp, the suctorial organ is covered with two cuticular lips, a dorsal upper lip and a ventral lower lip, but it can be protruded rapidly in order to facilitate grasping prey or climbing on bushes or even climbing on smooth surfaces due to its remarkable adhesive properties. In this study, the suctorial organs of different species from old world families Galeodidae and Karschiidae and new world families Ammotrechidae and Eremobatidae were investigated by means of light microscopy, scanning and transmission electron microscopy. In all representatives, the suctorial organ is formed by an evertable, cuticular pad with a complex internal stabilizing structure. The procuticle of this pad consists of a lattice-like basal plate and numerous stalked structures connected to this basal plate. The shafts of the stalked structures are regularly organized and ramify apically. The surface of the suctorial organ is constituted of a very thin epicuticle overlaying the ramifying apices forming ridges and furrows on the ventral side of the suctorial organ.
Animal Behaviour, 2006
Female behaviour during copulation that could function as communication with the male is probably... more Female behaviour during copulation that could function as communication with the male is probably more common than previously appreciated, but its functional significance remains little studied. Stridulation during copulation by the female of the spider Physocylus globosus (Taczanowski, 1873), documented here for the first time, is common and noncoercive, thus permitting simple tests regarding its possible function. Males squeezed females rhythmically with their enlarged, powerful genitalia throughout copulation, and more male genitalic squeezes were associated with increased paternity when females mated with two males. Contextual associations suggest that female stridulation represents attempts to induce the male to interrupt genitalic squeezes: female stridulation was more common when the male was squeezing her; females were more likely to stridulate when individual male squeezes were longer, and when the male had not responded to a previous stridulation by loosening a squeeze; females were more likely to refrain from stridulating when the male loosened a squeeze; males were more likely to loosen squeezes when the female stridulated; and female stridulation was associated with rejection of males in other contexts. Males that responded to female stridulation more consistently by loosening their squeezes obtained greater paternity. Possible female communicatory behaviour during copulation is known in other species. Future attention to female as well as to male behaviour, and to possible dialogues during copulation, promises to be valuable in understanding sexual interactions.
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Papers by Alfredo Peretti