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Discussion question:

Do female redbacks benefit from being monopolized by the male? What are the costs and benefits of polyandry in this situation?

Sexual cannibalism and sexual selection

Though these economic models are enticingly straightforward, they still do not explain all incidences of sexual cannibalism. Sexual size dimorphic species (prominently spiders) pose a problem when males are not complicit. Because their males are too small to provide a nutritionally substantive meal for females, these species elude the foraging strategy hypothesis. Consuming diminutive males may even be costly to the female if she neglects hunting larger food items while busy consuming her tiny mate (Elgar 1991). Since many male spiders are not willing self-sacrificers like the redback, cannibalism appears to be unfavorable to male fitness as well (Wilder and Rypstra 2008). How can non-complicit sexual cannibalism in mate size dimorphic couples be considered adaptive?

Relationship between sexual cannibalism incidence, sexual size dimorphism, and fecundity in arachnid and mantis species (modified from Barry et al. 2008).
chart 2

One hypothesis for this quandary claims that the cannibalistic behavior is an extreme form of mate selection, in which females reject miniscule, undesirable males by consuming them. According to the sexual selection hypothesis, the female is not driven to cannibalism by a proximate, nutrition-related cause, but instead by the function of ultimately beneficial sexual selection. Females may prefer larger males because body size reflects foraging skill: males who are able to obtain higher mass may be more capable of constructing and placing their webs, as well as capturing trapped prey (Wilder and Rypstra 2008b). If foraging abilities are heritable, then females can use male size as an indicator of the fitness of her offspring. Though sexual size dimorphic females may not obtain survival benefit from cannibalism, they use is as a mechanism of choosing males to sire fitter sons. This strategy is only costly if females are too selective and cannibalize all potential mates.

Testing the sexual selection hypothesis

In order for the argument to be supported, pre-insemination (non-mating) cannibalism in sexual size dimorphic species should target smaller males (Elgar and Nash 1999). One means of testing the hypothesis is through observation within a species , wherein researchers observe mating interactions involving same-species males with different levels of secondary sexual characteristics . Wilder and Rypstra monitored Hogna helluo (wolf spider) males in 90-minute mating trials within a laboratory setting, and found that larger male Hogna helluo were less frequent victims of sexual cannibalism (Wilder and Rypstra 2008b). In another investigation, Araneus diadematus females (1.89 female/male body length ratio) preferred to mate with, not consume, larger males (Elgar and Nash 1999). Furthermore, Schizocoas ocreata virgin females (1.26 female/male body length ratio) attacked smaller males of poorer body condition that displayed small, asymmetrical tufts of bristles, as opposed to voluminous tufts (Persons and Uetz 2005). Experimental evidence has consistently suggested that, in species with high sexual size dimorphism, predatory mating behavior targets smaller males. Thus, sexual cannibalism may indeed serve as a mechanism of sexual selection favoring larger males.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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