Comparative analysis of passive defences in spiders (Araneae)

Abstract

Summary1. Being frequent prey of many predators, including especially wasps and birds, spiders have evolved a variety of defence mechanisms. Here I studied patterns of passive defences, namely anachoresis, crypsis, masquerade, aposematism and Batesian mimicry, in spiders. 2. Using published information pertaining more than 1000 spider species, the phylogenetic pattern of different passive defences (i.e. defences that decrease the risk of an encounter with the predator) was investigated. Furthermore, I studied the effect of foraging guild, geographical distribution and diel activity on the frequency of defences as these determine the predators diversity, presence and perception. 3. I found that crypsis (background matching) combined with anachoresis (hiding) was the most frequent defence confined mainly to families/genera at the base of the tree. Aposematism (warning coloration) and Batesian mimicry (imitation of noxious/dangerous model) were found in taxa that branched later in the tree, and masquerade (imitation of inedible objects) was confined to families at intermediate positions of the tree. Aposematism and Batesian mimicry were restricted to a few lineages. 4. Masquerade was used particularly by web-building species with nocturnal activity. Aposematism was rare but mainly used by web-building diurnal species. Batesian mimicry was frequently observed in cursorial species with diurnal activity. Cryptic species were more common in temperate zones, whereas aposematic and mimetic species were more common in the tropics. 5. Here I show that the evolution of passive defences in spiders was influenced by the ecology of species. Then, I discuss the evolutionary significance of the particularly defences.

Is inaccurate mimicry ancestral to accurate in myrmecomorphic spiders (Araneae)?

“…Estimation of ancestral defensive strategies at nodes that include species using myrmecomorphy and other defence strategies can reveal whether there is a similar ancestral defensive state for all myrmecomorphs (Pekár, ). The sister lineages to myrmecomorphs in Eresidae, Linyphiidae, Salticidae, Theridiidae, and Zodariidae use crypsis (i.e.…”

“…imitation of inedible objects) (Preston‐Mafham & Preston‐Mafham, ). Myrmecomorphy thus seems to evolve from crypsis and masquerade (Pekár, ).…”

Disentangling the Size and Shape Components of Sexual Dimorphism

“…1), their abdominal morphological modifications presumably enhancing female survival, e.g. through leaf-or twig-mimicry (Poltys, Deinopis, Arachnura) or spinal adornments (Micrathena, Gasteracantha, Poltys and others) (Elgar and Jebb 1999;Pekár 2014). These highly modified female spider morphologies may be accompanied by extreme SSD, but comparative research has never tested for a direct connection between SSD and SShD.…”

Human–Spider Entanglements: Understanding and Managing the Good, the Bad, and the Venomous

“…Early medical reports of human envenomation by Redback spiders often involved external toilets, and bites often occurred on the genitalia or buttocks. As indoor plumbing increased, the incidences of bites shifted from these sensitive areas to the limbs, as bites occur when people reach under objects where the spider is hiding or when people put on clothing, gloves, or shoes harboring the spider (Vetter and Visscher 1998;Pekár 2014). Several deaths have been attributed to Redback spider bites in Australia, but there have been no deaths since the introduction of an antivenom.…”