Post-copulation mate guarding in the sexually cannibalistic St Andrew's Cross spider (Araneae Araneidae)

Schneider

Harmer

et al. 2010

J Ethol

Female St Andrew's Cross spiders control copulation duration by timing sexual cannibalism and may thereby control paternity if cannibalism affects sperm transfer. We have investigated the effect of copulation duration on sperm transfer and documented sperm storage patterns when we experimentally reduced the ability of females to attack and cannibalise the male. Virgin males and females were paired and randomly allocated either to a control treatment, where females were allowed to attack and cannibalise the male during copulation, or to an experimental treatment, where females were unable to cannibalise the male. The latter was achieved by placing a paintbrush against her chelicerae during copulation. Our experimental manipulation did not affect copulation duration or sperm storage. However, the number of sperm stored by the female increased with copulation duration only if the male was cannibalised, suggesting that cannibalism increases relative paternity not only through prolonged copulation duration following a fair raffle model but also through the cannibalism act itself. Future studies should explore whether cannibalised males ejaculate more sperm or whether females selectively store the sperm of cannibalised males.

Section: Introductionmentioning

confidence: 96%

Sperm storage and copulation duration in a sexually cannibalistic spider

Schneider

Harmer

et al. 2010

J Ethol

“…In N. plumipes, males are monogynous due to a high frequency of fatal sexual cannibalism (;60%), a high injury rate while mating (Elgar and Fahey 1996, and a 76% mortality rate during mate searching (Kasumovic et al 2007). As a result, we predict that males should develop a phenotype that maximizes fitness for the single mating opportunity they are likely to Elgar and Fahey (1996), Herberstein et al (2005a) obtain after they mature. Male mating success is dependent upon outcompeting up to five rival males for access to the female (Vollrath 1980, Elgar andFahey 1996) and males attempt to mate guard if they survive their mating .…”

Section: Introductionmentioning

confidence: 99%

Evidence for developmental plasticity in response to demographic variation in nature

Kasumovic

Bruce

et al. 2009

Ecology

Adaptive developmental plasticity has been demonstrated across a number of taxa in response to variables such as photoperiod, resource abundance, and predator presence. Demographics also vary temporally and spatially within populations, but few studies have examined the possibility that developmental plasticity in response to changes in these variables can alter phenotypic distributions. Plastic responses to variable population density and sex ratio may play an important role in explaining phenotypic variation in nature. In this study, we examine two species of spiders (Nephila plumipes and Argiope keyserlingi) to examine whether there is evidence that males alter their development in response to demographics in natural populations. We studied spiders in which developing males can use pheromones as a cue of the density of conspecific males and females. We used published information about the mating systems and life history of each species to make predictions about expected patterns of plasticity in development time and correlated changes in adult body size in response to demographic variation. Within each species, male size and mass were positively correlated with the density of males but negatively correlated with the density of females, and as predicted, this was true only when calculated at spatial scales relevant to selection in each species. In contrast, seasonal variation in photoperiod could not explain measured variance in male size. Our results support the idea that developmental plasticity in response to demographics has a significant effect on phenotypic distributions in natural populations. Our results suggest that a proportion of variation in male phenotypes could be explained as a plasticity-mediated evolutionary response to variation in population demographics rather than as a physiological response to resource abundance and/or photoperiod.

“…For example, A. keyserlingi males appear to never mate twice with the same female but guard the female after copulation and then leave to search for a second mating option (Herberstein et al 2005a;Zimmer et al 2014). Other species apparently flip between both strategies.…”

Section: Male Mating Rates: Monogyny and Bigynymentioning

confidence: 94%

“…The most important variables are (i) a high variation in female quality, and (ii) seasonal as well as (iii) spatial differences in selection regimes. The model further revealed that bigyny alone can also be stable under a restricted set of conditions, and it remains to be seen whether the theoretical assumptions capture the biology of the Australian A. keyserlingi with a bigynous mating system (Herberstein et al 2005a). …”

Section: Male Mating Rates: Monogyny and Bigynymentioning

confidence: 97%

Cryptic Female Choice Within the Genus Argiope: A Comparative Approach

Schneider¹,

Uhl

Cryptic Female Choice in Arthropods

2015

The orb-web spider genus Argiope (Araneae) offers an excellent opportunity to detect cryptic female choice and to identify the species-specific traits that might lead to its evolution and maintenance. All studied species of the genus Argiope are characterized by low male mating rates. While males of some species are strictly mono-or bigynous, others plastically switch between these two strategies. All studied species show sexual cannibalism during copulation. Generally, males die after their second copulation, but the probability of surviving the first copulation differs considerably between species and so does copulation duration. Males of most species break off pieces of their genitalia during copulation that act as mating plugs, but how often this occurs and how effective these plugs are is highly variable. Females that mate multiply can influence the relative paternity success of males through their partial control of copulation duration and their likely control of sperm storage. There is evidence that females cryptically favor small males over large ones, unrelated males over siblings, and males that courted over those that do not. We will sketch variation within and between species in mating systems and related traits, and we will discuss how this relates to cryptic female choice. We will review the existing evidence for cryptic female choice and suggest future avenues in elucidating possible mechanisms that facilitate cryptic female choice and the cues that females may base their choices on.