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Economic models are also readily applied to the behavior of Australian redback spiders. Experiments consistently show that when a male somersaults into the female’s mouth (thus inducing cannibalism), the length of the copulation period doubles (Andrade 2003). Male redbacks, like many organisms, can sexually function long after females start to consume them. While females are occupied with their meal, the male profits from 15-20 minutes extra insemination time. Studies show that cannibalized males usually insert emboli twice, and in one experiment, self-sacrificing redbacks fertilized twice the number of eggs as non-eaten males (Andrade 1996). Self-sacrifice also gives males an advantage in terms of sperm competition , because females tend to spurn other males directly after they copulate with, and cannibalize, their first mate (Andrade 2003). In economic terms, the male redback reaps high paternity benefit from increasing the proportion of offspring he sires in the female’s brood. Meanwhile, the cost inherent in redback self-sacrifice is extremely low, because males live in a hostile environment that often precludes them from second matings. In fact, there is an 85% mortality rate for males after they leave natal webs [Chart 1], so each male is destined to encounter very few females during his lifetime (Andrade 2003). Therefore, the fitness benefit to post-copulation survivorship is low (Andrade 1997). Based on economic models, male complicity in redbacks makes sense.

Weight and size values are mean. n represents total number of organisms monitored in given trial. “Residuals from a regression of male weight on size. Weight/size regressions were highly significant ( p 0.001 ) (Andrade 2003)
Success at finding a mate in male australian redback spiders: surviving versus perishing on trip to find mate (modified from andrade 2003).

Economic models are further verified by evidence from the orb-weaving spider. Males of the genus Argiope often die directly after copulation, regardless of female cannibalism (Sasaki and Iwahashi 1995). In the species Argiope aurantia , mating triggers the inflation of the male’s second palp when increased haemolymph pressure causes its distal bulb to expand. Palp swelling catalyzes a cascade of reactions that culminates in the male’s death 15 minutes later (Foellmer and Fairbairn 2003). Since the male willingly engages in mating and evolution has not selected against the spontaneous death mechanism, terminal reproductive investment appears ultimately beneficial. It is unusual to think of dying as a prime fitness strategy, but two morbid processes actually benefit males. The first is familiar: the male soma provides nutrients to the female and increases the quantity and quality of her offspring. Additionally, the dead male can prevent female polyandry. Several male spiders often wrestle vigorously for access to a mate, and even try to dislodge males already in the copulatory position. If the mating male’s pedipalp is in the inflated state, he is more difficult to remove, so his corpse serves as a genital plug to block his rivals’ access to the female (Foellmer and Fairbairn 2003). Thus, evidence from the orb-weaving spider indicates that the costs of foregoing future mating opportunities can be overcome by the direct benefit of increased female nutrition and the male’s confidence in paternity .

Questions & Answers

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.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
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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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