<< Chapter < Page Chapter >> Page >

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

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Berger describes sociologists as concerned with
Mueller Reply
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Mockingbird tales: readings in animal behavior' conversation and receive update notifications?