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Does a male ever really present himself to be eaten? In fact, such complicity is blatantly displayed in Australian redback spider mating, wherein the male grabs the female and somersaults directly into her mouthparts (move this up to the non compliance section). Without halting his acrobatics, the redback transfers his sperm into female storage organs by inserting one or both emboli into her (Andrade 1996). As a result, 65% of redback mating interactions end in sexual cannibalism (Andrade 2003). The male Australian redback’s biomass is miniscule, so his sacrifice has no apparent impact on the female spider’s reproductive output.

Discussion question:

Why could males have evolved such exaggerated willingness for self-sacrifice?

The tradeoffs: economic models for sexual cannibalism

In an attempt to develop an adaptionist description of sexual cannibalism, several researchers have devised mathematical cost-benefit models that address both the foraging strategy hypothesis and observations of redback self-sacrifice.

The male perspective

Male complicity in sexual cannibalism is interpreted by the economic model of Buskirk et al. Buskirk posits that a male should permit himself to be eaten only if he increases his inclusive fitness more in that manner than by surviving to inseminate other females (Buskirk et al. 1984). Two factors impact the male’s inclusive fitness in sexual cannibalism: the number of times a male may be expected to mate during his lifetime and the proportional increase in the male’s offspring resulting from self-sacrifice. The first factor is based on several conditions, including the ability of males to locate other females (often through the use of pheromones), as well as the time and effort required to court and defend the female. Other constraints are posed by male morphology, such as the length of reproductive lifetime, the time and energy needed to produce sperm, and (in spiders) the detrimental loss of pedipalpal tips to previous mates (Schneider and Lubin 1998). The second factor, offspring increase, is dependent on the female’s food supply and the male’s confidence of paternity . In turn, confidence of paternity is contingent on the extent of a female’s polyandrous behavior, as well as copulation duration, sperm storage methods, and the nearness of copulation to oviposition ( [link] ) (Buskirk et al. 1984).

Based on these parameters, the adaptive value of cannibalism for males can be mathematically modeled ( [link] ).

graph showing the evolution of sexual cannibalism
Buskirk et al.’s model for the evolution of sexual cannibalism, based on the mathematical formula A P > E NC 1 - 1 - C ENC - 1 C
This theoretical graph shows the relationship of A/P to C for different values ENC. For organism X, C=0.5 and A/P=2.5, and ENC=4. That is, if a male has a 50% chance of being cannibalized and can produce 2.5 times more offspring by being cannibalized than not, then self-sacrifice is advantageous until the male’s expected number of lifetime matings exceeds four (in other words, until being cannibalized causes him to forgo three or more matings). The graph suggests that, as the number of expected matings increases, male self-sacrifice must greatly enhance his mate’s fecundity in order to offset his cost of neglecting future mates (Buskirk et al. 1984).

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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