Kvadráty: 7166 7267 7367
  Nálezy podle období
Gnaphosidae 0-19001901-19501951-20002001-2018
Micaria sociabilis Kulczyński, 1897 Kriticky ohrožený 1x 10x 11x

Micaria sociabilis Kulczyński, 1897

České jménomikarie pospolitá
Stupeň ohroženíKriticky ohrožený
Nálezy11 nálezů, 3 kvadrátů
Poslední nález 2019 , Radek Šich


© Oto Zimmermann
In visual Batesian mimicry, the mimic acquires protection from predators by imitating visual signals of the model. It has not been known whether the occurrence of mimics among models is a result of selection by predators or an active choice by the mimics. Here, the occurrence of an ant-like spider, Micaria sociabilis Kulczyński, 1897, which occurs on tree trunks and visually imitates arboricolous Liometopum microcephalum (Panzer, 1798) ants, was studied. The fauna of arboricolous ant species was surveyed together with six tree characteristics in order to find which variables determined the occurrence and abundance of Micaria sociabilis. It was found that Micaria sociabilis occurred exclusively on trees where L. microcephalum ants occurred. The effect of any tree variable was not significant. The abundance of Micaria sociabilis increased positively with the abundance of L. microcephalum. Then, experiments using an olfactometer and Y-maze with volatile and contact cues obtained from the two most abundant ant species, L. microcephalum and Lasius fuliginosus
(Latreille, 1798), were performed to find whether Micaria preferred any cue. Micaria sociabilis did not respond to volatile cues obtained from the gaster of the two ant species. In contrast, it avoided contact cues from L. fuliginosus and was attracted to contact cues from L. microcephalum ants and its gaster extract in hexane. The results thus show that Micaria sociabilis associates exclusively with L. microcephalum and is attracted to contact cues from this ant while avoiding cues from the competing ant. This study reveals that Batesian mimics may use kairomones to associate with visual models.

Background: Sperm competition imposes a strong selective pressure on males, leading to the evolution of various physiological, morphological and behavioral traits. Sperm competition can be prevented by blocking or impeding the access to female genitalia by means of a mating plug. We investigated the factors responsible for plug production and function in the promiscuous female-cannibalistic spider Micaria sociabilis (Gnaphosidae).

Results: We performed mating trials using females with and without a plug that consists of an amorphous mass. The mating trials demonstrated that the probability of male plugging increased non-linearly with the duration of copulation. Copulation duration and plug production seem to be controlled by the female. We found that females terminated matings later if males were fast at genital coupling. Whereas incomplete plugs had disappeared on the day following copulation, complete plugs persisted (40%). In matings with females with complete plugs, only a small proportion of males (7%) were able to remove the plug, indicating the high effectiveness of plugging. Moreover, males ceased attempts to copulate with plugged females with higher probability. 3D X-ray microscopy of the female and male genitalia showed that the plug material can extend far into the female genital tract and that the plug material is produced by a massive gland inside the palpal organ of the modified male pedipalps.

Conclusions: Our study demonstrates that the mating plug in Micaria sociabilis constitutes an effective male strategy to avoid sperm competition that seems to be under female control.

Keywords: Secretory plugs, Sperm competition, Cryptic female choice, Multiple mating, X-ray microscopy

© Ondřej Machač
Female mate choice is regarded as a strong selective force that significantly affects male mating success. In extreme cases,mate rejection can result in sexual cannibalism. However, males may choose between their partners as well. The killing of potential female mates, i.e. reversed form of sexual cannibalism, may be related to male mate choice. We examined male mate choice in the spider Micaria sociabilis, focusing on the roles of female mating status (virgin/mated), size and age. Reversed cannibalism reached its highest frequency in the period of generation overlap, i.e. when young males from the summer generation met old(er) females from the spring generation. These results suggest discrimination against old(er) females. The frequency of cannibalism was not affected by female mating status or female size. However, larger males from the summer generation were more cannibalistic than smaller males from the spring generation. We conclude that reversed sexual cannibalism might be an adaptive mate choice mechanism and can be explained in the context of the aggressive spillover hypothesis.



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Micaria sociabilis Kulczyński, 1897 CRSamciSamiceMláďataNálezy
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Micaria sociabilis Kulczyński, 1897 CRSamciSamiceMláďataNálezy
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