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Mating interactions are prime arenas for adaptation/counteradaptation, since they often involve a conflict of interest between the sexes. Males evolve traits that promote their confidence in paternity and sperm viability, while females develop mechanisms for selecting only optimum sperm (sexual selection)(Siller 2001). While sexual selection is easily recognized before mating (females choose to mate with males who display attractive characteristics and/or fitness indicators), it can also occur post-insemination through sperm ejection or a mechanism called cryptic female choice-the differential selection at the hidden level of the gamete(Eberhard 2000). Cryptic female choice can be passive, as when eggs are fertilized by sperm that win the “race” to the gamete. Or, the choice can be active: a female’s sperm storage system can be designed to give priority to the last sperm she receives, allowing her to annul the representation of previous mates if she meets a superior male (Eberhard 2004).

One intriguing example of cryptic female choice exists in Australian redback spiders. The female redback has developed multiple sperm storage sites, which promote post-copulatory sperm management by the female. The male has two palpal emboli, so he could potentially inseminate both sites (the fitness optimizing strategy for males), but the larger female can physically control where the male injects sperm (in one or two sites, or in an empty site versus one occupied by previous males’ sperm) (Andrade and Snow 2005).

The male redback thus appears at a disadvantage for two reasons. Firstly, if he manages the rare deal of finding a mate, his control over paternity is minimal. Also, if takes more time to inseminate two sites as opposed to one, and females usually cannibalize doubly inserting males before copulation is complete (Andrade and Snow 2005). Thus, the male redback has developed an important counteradaptation: a constriction of the abdominal exoskeleton during mating that protects male organs from wounds inflicted by the female mandible. In one study, males displaying constriction had improved survival, heightened physical endurance, and greater mating success with new males (Andrade and Snow 2005). Multiple sperm storage units in females and the constriction mechanism in males illustrate how mating interactions can disproportionately benefit a single sex, driving a progression of counteradaptations.

The question of female fecundity benefit

Even a conflict of interest hypothesis, a claim that females gain disproportionate benefits from eating males, is insufficient to explain the majority of sexual cannibalism cases. The behavior is prominently observed in spider species that are highly sexual size dimorphic , such as wolf spiders. In contrast with mantises, male spiders are frequently diminutive compared to females. The consumption of male bodies can contribute little substance to the mother’s nutrient store, so cannibalism does not measurably increase female body condition or ootheca mass (Wilder and Rypstra 2008). If female fecundity does not increase from sexual cannibalism (which obviously precludes the male from gaining fitness), then how can this behavior have evolved? Perhaps there is a context in which males alone profit from their own self-sacrifice.

Questions & Answers

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?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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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