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Ghislandi P.G.,University of Aarhus | Albo M.J.,University of Aarhus | Albo M.J.,Laboratorio Of Etologia | Tuni C.,University of Aarhus | Bilde T.,University of Aarhus
Current Zoology | Year: 2014

Males of the nursery web spider Pisaura mirabilis usually offer an insect prey wrapped in white silk as a nuptial gift to facilitate copulation. Males exploit female foraging preferences in a sexual context as females feed on the gift during copulation. It is possible for males to copulate without a gift, however strong female preference for the gift leads to dramatically higher mating success for gift-giving males. Females are polyandrous, and gift-giving males achieve higher mating success, longer copulations, and increased sperm transfer that confer advantages in sperm competition. Intriguingly, field studies show that approximately one third of males carry a worthless gift consisting of dry and empty insect exoskeletons or plant fragments wrapped in white silk. Silk wrapping disguises gift content and females are able to disclose gift content only after accepting and feeding on the gift, meanwhile males succeed in transferring sperm. The evolution of deceit by worthless gift donation may be favoured by strong intra-sexual competition and costs of gift-construction including prey capture, lost foraging opportunities and investment in silk wrapping. Females that receive empty worthless gifts terminate copulation sooner, which reduces sperm transfer and likely disadvantages males in sperm competition. The gift-giving trait may thus become a target of sexually antagonistic co-evolution, where deceit by worthless gifts leads to female resistance to the trait. We discuss factors such as female mating rate and intensity of sperm competition that may shape the evolution of male deception, and how ecological factors may influence the evolution and maintenance of worthless gifts as an evolutionarily stable alternative mating strategy by frequency dependent selection. © 2014 Current Zoology. Source


Albo M.J.,Laboratorio Of Etologia | Peretti A.V.,National University of Cordoba
PLoS ONE | Year: 2015

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 of experiments to examine whether females can select sperm based only on gift presence. This time we interrupted matings after the first pedipalp insertion, thus matching number of insertions and mating duration for males that: offered and did not offer gift. Our results showed that the amount of sperm stored is positive related to mating duration in all groups, except in matings with worthless gifts. Gift presence itself did not affect the sperm stored by females, while they store similar number of sperm in matings with males offering either nutritive or worthless gifts. We discuss whether females prefer males with gifts regardless, if content, because it represents an attractive and/or reliable signal. Or alternatively, they prefer nutritive nuptial gifts, as they are an important source of food supply and/or signal of male donor ability. Copyright © 2015 Albo, Peretti. Source


Montes de Oca L.,Laboratorio Of Etologia | D'Elia G.,Austral University of Chile | Perez-Miles F.,University of the Republic of Uruguay
Zoologica Scripta | Year: 2015

The mygalomorph genus Grammostola (family Theraphosidae) is endemic to South America. The species Grammostola anthracina is one of the largest spiders in Uruguay and reputed to be the longest lived tarantula in the world. This nominal species has two distinct colour morphs comprising black and reddish-brown forms with controversial taxonomic status. Here, we present a phylogenetic study based on molecular characters (cytochrome c oxidase subunit I) of haplotypes of G. anthracina and closely related species. Our analysis together with new morphological data and biogeographical information indicates that the two morphs of G. anthracina constitute different species that are not sister to each other. Consequently, a new species, Grammostola quirogai is described, diagnosed and illustrated to encompass the black morph. Phylogenetic relationships and new taxonomic characters for Grammostola species included in this study are discussed. © 2015 Royal Swedish Academy of Sciences. Source


Ghione S.,Laboratorio Of Etologia | Simo M.,University of the Republic of Uruguay | Aisenberg A.,Laboratorio Of Etologia | Costa F.G.,Laboratorio Of Etologia
Arachnology | Year: 2013

Predators such as spiders are particularly vulnerable to habitat fragmentation and are considered good bio-indicators of nature conservation or habitat degradation. As occurs all around the globe, the Uruguayan coastal sand dunes have been drastically diminished and fragmented, and seriously affected by human modifications such as urbanization, tourism, and introduction of exotic species. The objectives of the present study were to identify the indicator species of two adjacent areas of the sandy coastline of Uruguay (Marindia, Canelones) and, specifically, to confirm whether Allocosa brasiliensis can be considered a biological indicator of the open dunes with scarce psammophile vegetation in this locality. We used the IndVal method which quantifies the indicator value of each species. Allocosa brasiliensis had the highest indicator value for open dunes fixed with psammophilic native vegetation, reflecting its greatest specificity and fidelity to this environment. Source


Perez-Miles F.,Seccion Entomologia | Perez-Miles F.,Laboratorio Of Etologia | Costa F.G.,Laboratorio Of Etologia | Montes de Oca L.,Seccion Entomologia | Montes de Oca L.,Laboratorio Of Etologia
Journal of Natural History | Year: 2014

A new genus and species of a mygalomorph nemesiid spider collected in a hill of Northern Uruguay and in Araucaria forest at Southern Brazil is diagnosed, described and illustrated. A remarkable characteristic of the new genus is its dense body pubescence, unusual in most Nemesiidae. Also genital and somatic characters led to differentiate it from related genera. The habitat is characterized by a tubular burrow followed by an aerial tubular portion made with silk and vegetation. The sexual behaviour is briefly described from a copula between the types, observed in the laboratory.LSID: zoobank.org:pub: D5A6D7EA-19DD-4427-E6A41162EE4E. © 2014 © 2014 Taylor & Francis. Source

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