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Frequencies of body vibrations performed by males (in black) and received by females (in white). The vibration index was calculated as the number of body vibration bouts per minute.
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The road tarantula Eupalaestrus weijenberghi shows a strongly female-biased sex ratio since adult females live several years while adult males live only for 2 months. In this scenario selective males could be expected. However, several factors such as the rates of reproduction of each sex, degree of sexual selectivity and synchronicity of female re...
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Sexual conflict is now recognised as an important driver of sexual trait evolution. However, due to their variable outcomes and effects on other fitness components, the detection of sexual conflicts on individual traits can be complicated. This difficulty is exemplified in the beetle Callosobruchus maculatus, where longer matings increase the size...
There is a current debate over the net fitness consequences of sexual selection. Do preferred males increase female fitness
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Sexual selection leads to the evolution of various traits that increase male fitness under male-male competition including sperm competition. In many taxa, bimodal distributions of copulation and/or intromission duration are known to be the result of adaptation to sperm competition risk avoidance. However, the stalk-eyed seed bug, Chauliops fallax...
Since inbreeding in Tetranychus urticae can reduce offspring fitness, sexual selection may favour disassortative mate choice with respect to relatedness of the mating partners. We tested whether T. urticae shows this preference for mating with unrelated partners. We chose an experimental set-up with high potential for female choosiness, since femal...
Citations
... In general, tarantula males and females have a polygynous strategy and try to copulate several times during their reproductive period (Shillington & Verrell, 1997;Copperi, 2013;Pérez-Miles, 2020), although some females can be monogamous in the reproductive season (Alcock, 1993;Pérez-Miles et al., 2007). Males always invest their mating effort in walking and searching for receptive females with which to copulate (Shillington & Verrell, 1997;Pérez-Miles, 2020). ...
... Males always invest their mating effort in walking and searching for receptive females with which to copulate (Shillington & Verrell, 1997;Pérez-Miles, 2020). However, female receptivity often declines after the first copulation (Pérez-Miles et al., 2007;Copperi, 2013), and thus the number of females available for copulation decreases at the end of the breeding season (Kasumovic et al., 2007;Pérez-Miles, 2020). This reduction in the possibility to copulate could explain the short reproductive period of male tarantulas, and their short life-cycle in the wild (Costa & Pérez-Miles, 2002;Pérez-Miles et al., 2005, 2007. ...
... If successful mating occurs, females wait until December to lay the egg-sacs, as reported in other tarantula species, which can keep the sperm viable for 9 months in their receptacles , 2007. Also, these copulated females could reduce their receptiveness during the highest peak (Aisenberg & Costa, 2005;Mendez et al., 2017;Pérez-Miles et al., 2007). This could provide a selective advantage to those males in terms of increased paternity due to the sperm mix occurring inside the spermathecae of females, which implies that males reproducing in March will probably be the last males copulating with females. ...
In tarantulas, the reproductive season in their natural habitat is characterized by the presence of walking males. Grammostola vachoni is a tarantula from Argentina, and previous studies have reported that the breeding season occurs only in spring. However, walking males are also observed in other months. Thus, our objectives here were to study the dynamics of G. vachoni in the reproductive season, to compare male activity with climate data and to estimate whether temperature affects male locomotor performance. Two peaks of walking male activity were found (from the end of October to December, and in March). The number of walking females registered was low and was also bimodal. No significant differences between the sexes in activity with regard to temperature and atmospheric pressure were observed, but females were more likely to be observed under the highest humidity conditions. The months of the reproductive season were very similar in their climate characteristics. Male locomotor performance was strongly affected by extreme temperatures, and the optimum experimental temperature was higher than the environmental activity temperature. This study suggests a diplochronous cycle for G. vachoni, which might be a historical constraint or might indicate selection.
... Preparation for mating Each species has its own reproduction period (see Sect. 15.4) and, depending on the species, females may copulate twice a year or every second year (Petrunkevitch 1911;Prentice 1997;Shillington and Verrell 1997;Costa and Pérez-Miles 2002). Females of some species may copulate several times (Petrunkevitch 1911), whereas others become reluctant after their first copulation (Pérez-Miles et al. 2007). In nature, the female remains in her retreat until a male approaches, detects her pheromones and starts his courtship. ...
Tarantulas are animals that you either love or find disgusting. Some people are fascinated with them, whereas others fear them because of ignorance or aversion to what they consider dangerous on the basis of their appearance. Despite their reputation, many people study, maintain and use these spiders. The interest in keeping and propagating tarantulas has increased worldwide in recent decades. The aim of this chapter is to discuss the basic and ethical considerations involved in keeping these spiders in captivity (whether for research or as an enthusiast), as well as being aware of the origin and conservation status of the most common commercial species. As more has been learned about tarantula biology, there has been greater interest in how to breed them in captivity. However, few studies have addressed the reproductive biology of tarantulas. Despite this, many species are propagated successfully by enthusiasts, and the conditions for their reproduction are empirically known. We approach this chapter by dividing it into five sections: (1) natural history; (2) keeping and breeding tarantulas in captivity; (3) common ailments; (4) tarantulas’ popularity as pets and their husbandry; and (5) traffic, endangered species and responsible breeding facilities.
... The sperm charged during one sperm induction probably is not enough to inseminate several females what could occur when the sex ratio is biased toward females, or maybe there is some selective pressure to avoid old sperm in the palps (Costa and Pérez-Miles 2002). The first interpretation seems to be the more adequate since it was observed in Eupalaestrus weijenberghi that one sperm induction is enough for at least two copulations and copulating males recharge palpal organs after mating and more frequently than males that do not copulate (Pérez-Miles et al. 2007). ...
... This behavior has been reported in species of the genera Acanthoscurria Ausserer 1871, Aphonopelma Pocock 1901, Avicularia Lamarck 1818, Eupalaestrus Pocock 1901, Grammostola Simon 1892, Homoeomma Ausserer 1871, and Sickius Soares and Camargo 1948. Females usually respond to male courtship by tapping with forelegs and palps against the substrate indicating a sexually receptive state (Stradling 1994;Quirici and Costa 2005;Pérez-Miles et al. 2007;Copperi et al. 2012). Moreover, female sexual responses also help male orientation toward her location from long distances, for example, in species that inhabit crevices or under stones (Copperi et al. 2012). ...
... Moreover, female sexual responses also help male orientation toward her location from long distances, for example, in species that inhabit crevices or under stones (Copperi et al. 2012). Another female response to male courtship is called "piston" behavior (Costa and Pérez-Miles 2002;Quirici and Costa 2005;Pérez-Miles et al. 2007). This behavior comprises a ritualized agonistic response because after perceiving the signal the male immediately escapes. ...
Theraphosidae spiders (commonly known as tarantulas) comprise some of the largest known spiders. It is the most diverse family among Mygalomorphae and Theraphosinae, endemic to the Neotropics, is the richest subfamily. However, the knowledge on some aspects of their reproductive biology is still unknown. Usually, the sexual behavior of tarantulas has been considered as “simple,” that is, males just walk searching for females and when they randomly find one, the mating should occur. This point of view is changing as the number of studies has grown during the last 20 years, suggesting that the sexual behavior of Theraphosidae is far from simple. Such complexity may be represented by specific searching and courtship behavior of males and active roles of females, leading to an intricate intersexual communication before mating, the occurrence of male copulatory, and complex patterns of palpal insertions. This chapter describes the ways of communication of tarantulas mainly during the sexual encounters. The patterns of courtship and copulation of representatives of most subfamilies will be described based on a bibliographic review. Finally, some general strategies of mating and reproduction of tarantulas will be discussed and topics for future research are presented.
... These observations taken together suggest it is premature to preclude a role for sexual selection in the origin and evolution of blue tarantula coloration. Alternatively, given that upon maturity many male tarantulas will leave their retreats and wander in search of females [24][25][26], it is plausible that different selective pressures other than sexual selection could be driving sexual dimorphism. For instance, certain colours are either aposematic or cryptic under moonlight [27,28], and therefore useful to the wandering male but not to the fossorial female. ...
Tarantulas paradoxically exhibit a diverse palette of vivid coloration despite their crepuscular to nocturnal habits. The evolutionary origin and maintenance of these colours remains mysterious. In this study, we reconstructed the ancestral states of both blue and green coloration in tarantula setae, and tested how these colours correlate with presence of stridulation, urtication and arboreality. Green coloration has probably evolved at least eight times, and blue coloration is probably an ancestral condition that appears to be lost more frequently than gained. While our results indicate that neither colour correlates with the presence of stridulation or urtication, the evolution of green coloration appears to depend upon the presence of arboreality, suggesting that it ptobably originated for and functions in crypsis through substrate matching among leaves. We also constructed a network of opsin homologues across tarantula transcriptomes. Despite their crepuscular tendencies, tarantulas express a considerable diversity of opsin genes—a finding that contradicts current consensus that tarantulas have poor colour vision on the basis of low opsin diversity. Overall, our findings raise the possibility that blue coloration could have ultimately evolved via sexual selection and perhaps proximately be used in mate choice or predation avoidance due to possible sex differences in mate-searching.
... Females have a rather large life-spam, living up to 30 years and spending the major time of their life inside their burrows. Males live from months to a few years (Baerg, 1928;Millot, 1943;Stradling, 1994;Locht et al., 1999;Costa and Pérez-Miles, 2002;Pérez-Miles et al., 2005, 2007Schultz and Schultz, 2009) and after they reach adulthood they leave their burrows and start wandering, looking for females to court and copulate with (Costa and Pérez-Miles, 2002). Hence, while females and juveniles are mostly crepuscular (Álvarez et al., 2016), during the reproductive season males can be seen walking during the day and night (Pérez-Miles et al., 2005). ...
... Other potential functions of colours in tarantulas have not been discussed in the literature, but it seems plausible to consider that they might function in aposematism or crypsis, as is the case in several other taxa (Ruxton et al., 2004). However, with the exception of mature males who wander in search of females (Prentice, 1992;Pérez-Miles et al., 2007), most tarantulas will spend much of their lives in their burrows (Yáñez & Floater, 2000;Schultz & Schultz, 2009;. This largely solitary lifestyle adds yet another layer of intrigue to the story of functional colours. ...
... Alternatively, given that upon maturity many male tarantulas will leave their retreats and wander in search of females (Prentice, 1992;Pérez-Miles et al., 2007), it is plausible that different selective pressures other than sexual selection could be driving sexual dichromatism. For instance, certain colours are either aposematic or cryptic under moonlight, and therefore useful to the wandering male but not to the fossorial female. ...
... They are quite widespread and are found throughout the subtropical regions of every continent(Gallon, 2000; World Spider Catalog, 2019). However, while many mature male tarantulas are known to wander in search of females(Prentice, 1992;Pérez- Miles et al., 2007), most juvenile and female tarantulas rarely venture far from ...
Theraphosidae, commonly known as tarantulas, represent some of the most charismatic spiders on the planet. With almost 1000 described species, they have colonized the subtropics of every continent and have adapted to fill many of ecological niches. I address gaps in our understanding of the tarantula phylogeny with a view towards understanding the evolutionary patterns involved in generating the great diversity of tarantulas we see today. My thesis is hence focused into three main parts: (i) constructing the first robust subfamily-level phylogeny for tarantulas, (ii) time-calibrating this phylogeny to offer insights into their widespread distributions in tandem with biogeographic data, and (iii) estimating the ancestral histories of greenness, blueness, and other life history traits, with correlative tests to determine the functions of colouration in theraphosids.
... In spiders, polygyny is considered the most frequent mating system (Theraphosidae: Pérez-Miles et al. 2007;Agelenidae: Singer and Riechert 1995;Lycosidae: Norton and Uetz 2005;Jiao et al. 2011;Theridiidae: Modanu et al. 2013;Pisauridae: Anderson et al. 2018;Pholcidae: Cargnelutti F. unpub data). Although patterns of sperm transfer have been described in some groups (Snow and Andrade 2004;Ceballos et al. 2015), few studies have investigated the reproductive costs that they carry to males (Wedell et al. 2002), have quantified the sperm transferred to the female throughout successive matings (e.g. ...
... Female sexual receptivity and cannibalism of males with different mating histories During the courtship, we recorded the number of leg-tapping bouts (performed by females) as an indicator of receptivity (Aisenberg and Costa 2005;Pérez-Miles et al. 2007;González 2015). During the mating, we recorded the number of body shakings of the female (short, vigorous hops). ...
... Beyond the number of spermatozoa transferred, it has been shown that ejaculates can transfer nutrients used for the offspring or for the somatic maintenance of the females (Simmons 2002) and that their quantity and quality can decrease when increasing the frequency of matings (Jiao et al. 2011). Thus, females that mate with males already mated may suffer a reduction in fertility (Jones 2001;Jones et al. 2006;Lauwers and Van Dyck 2006) Female sexual receptivity and cannibalism of males with different mating histories Female leg tapping ('call') is considered a good indicator of sexual receptivity in other spiders (Aisenberg and Costa 2005;Pérez-Miles et al. 2007). However, unlike what we expected, the females performed a similar number of leg-tapping bouts to males with different mating histories. ...
Polygynous males increase their reproductive success by fertilizing as many females as possible. However, this strategy can lead to costs for the males. This study focused on an atypical wolf spider that lives in webs, Aglaoctenus lagotis. Previous studies report polyandrous females, but little is known about the mating strategy of males and its potential associated costs. Our goals were to determine the potential polygyny and the changes in sexual behaviour, body condition and physiology of males throughout successive matings. Males were expected to mate with multiple females; males’ body condition was expected to decrease and male mating performance, including sperm transfer, was expected to decrease over successive matings. Males were exposed to successive virgin females every 3 days until the male did not court, was cannibalized or died of natural causes. Agreeing with our predictions, males were capable of multiple matings, showing an average of 5 ± 2 matings (range 3–11). Their mating performance decreased in successive matings and, although no changes were found in the behavioural patterns during the courtship over successive matings, the number of palpal insertions decreased. Unexpectedly, overall body condition did not decrease and males did not deplete their sperm supply. We found that 44% of the males were victims of sexual cannibalism after their third mating. The females that attacked or cannibalized males had less sperm stored in their spermathecae than those that did not. We discuss hypotheses that may clarify this scenario and the role of the cryptic female choice mechanism.
... Females continue to molt even in their adult stage. Therefore old spermathecae and remaining sperm are lost during molting, consequently female, from an operational and sperm storage point of view, which have mated previously become "virginal" again after each molt (Foelix, 2011;Pérez-Miles et al., 2007). ...
... Similarly, in some araneomorphs, males show preference for courting unmated females over mated females (Baruffaldi and Costa, 2010;Riechert and Singer, 1995;Scott et al., 2018;Stoltz et al., 2007;Tuni and Berger-Tal, 2012) and use silk-based signals to discriminate their reproductive status (Baruffaldi and Costa, 2010;Riechert and Singer, 1995;Stoltz et al., 2007;Tuni and Berger-Tal, 2012). Preference for unmated females implies important benefits for males, such as lower rejection rates, less sperm competition and increased paternity success (Aisenberg and Costa, 2005;Baruffaldi and Costa, 2014;Bonduriansky, 2001;Pérez-Miles et al., 2007;Wedell et al., 2002). ...
In spiders, pheromones are known to be responsible for attracting the opposite sex, eliciting male searching and courtship behaviors, as well as for synchronizing potential mates in space and time. Most spiders are cannibalistic and aggressive. Thus, early recognition of a female as a possible mate is essential for males, who may suffer high energetic or reproductive costs to the extreme of losing all fitness opportunities. In Acanthogonatus centralis Goloboff 1995, a mygalomorph spider, what female signs might be triggering male courtship behavior remain unknown, as well as whether males can discriminate between females. The aims of the present work were (1) establishing whether males can detect the presence of females using airborne and silk-borne signals and (2) determining whether males can discriminate the reproductive status and body condition of females. We found no evidence that airborne pheromones play a role in the sexual communication of A. centralis, but silk-bound contact signals function as a female advertisement. Also, this is the first study that demonstrates that male mygalomorph spiders can discriminate between different signals on silk through direct contact, showing a preference for unmated females.
... However, polyandry is common in the majority of the animals (Arnqvist and Nilsson 2000; Boulton and Shuker 2013;Taylor et al. 2014), and spiders are no exception. Indeed, polyandry seems to be the most 1 3 frequent mating system in Araneae (Huber 2005), although some cases of monandry and monogyny have been reported (Pérez-Miles et al. 2007), principally associated with the occurrence of mating plugs and sexual cannibalism (Hosken et al. 2009;Kuntner et al. 2009;Nakata 2016). Among the benefits of polyandry for females are ensuring sufficient sperm to fertilize all of their eggs, receiving direct benefits such as nuptial gifts or, more indirectly, avoiding inbreeding and increasing the genetic diversity of the offspring (Eberhard 1996;Maklakov and Lubin 2006;Peretti and Aisenberg 2015). ...
Populations of a species may show variation in mating systems, especially when the species is widely distributed. Aglaoctenus lagotis is a funnel-web wolf spider distributed in South America and with a ‘central Argentina form’ (CA) and a ‘southern Uruguay form’ (SU). Both forms differ in sexual behaviour, population density and copulatory season. This study evaluates the potential level of polyandry of both forms, sequentially exposing females to different males of their form under laboratory conditions. The number of copulations each female accepted and the characteristics of these sexual encounters were registered. CA females accepted more re-copulations than SU females and seemed to maintain more sexual attractiveness after the first copulation. In neither form was female re-copulation influenced by body characteristics, duration of the first copulation, ejaculation frequency or copulatory body shaking of females. Additionally, the PCA showed that both forms could be separated by their copulation behaviours. The higher level of polyandry in the CA form compared to the SU form suggested in our results adds another difference between these forms, currently under study to determine whether they are different species. This study is the first on mating systems in funnel-web wolf spiders, adding knowledge to the discussion about the evolution of sexual strategies in this group.
... The number of palpal insertions varies between one to sixteen, depending on the species, and most of them are characterized by a mating system with polyandry and polygyny (Costa and Pérez-Miles 2002;Ferretti et al. 2013). However, recently a case of monandry and polygyny was reported in the tarantula species Eupalaestrus weijenberghi (Thorell, 1894), in which males perform just one palpal insertion during each mating (Pérez-Miles et al. 2007). Finally, although earlier studies proposed sexual cannibalism as a rule for theraphosids, current studies indicate that post-mating attacks are only occasional (Costa and Pérez-Miles 2002;Ferretti et al. 2013) (See Chap. ...
Spiders have long been noted as classic examples of sexual behavior among arachnids, including extreme sexual dimorphism in some groups, and behavioral adaptations to diverse mating patterns. In recent decades, studies on the biology of Neotropical spiders have offered novel information on processes related to reproductive biology, including sexual selection. The present chapter synthesizes the large amount of knowledge on sexual selection and associated subjects in spiders from the Neotropics. Some of the groups considered in this review are mygalomorphs, lycosids and related, orb-weaving species, tetragnathids, social species, pholcids, and oonopids, among others. Concepts, patterns, mechanisms, and prospects on different areas of sexual selection are shown in detail for all these groups. In particular, here we highlight selected examples of the different contexts in which male–female interactions occur, such as mate choice, sexual cannibalism, sperm competition, and cryptic female choice. We outline the potential evolutionary consequences according to those contexts, with a final selection of model groups for specific experimental and comparative investigations.
