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Proximate reasons for mate choice

Testosterone was positively associated with forced copulations in mallards, greater time spent near females, increased mate guarding, and mating success (Davis 2002). Females choose mates in the autumn that they can accurately predict will have higher levels of testosterone come breeding season, and the females that had mates with higher testosterone also had fewer lost feathers due to forced copulation, presumably because the mate was a better defender (Davis 2002). This may provide direct benefits that complement the good genes hypothesis (same as mate-choice hypothesis for indirect benefits). However, research also shows that increased testosterone increases the FEPCs that drakes perform, so it may just be that the females that chose the most aggressive drakes do not have to deal with FEPCs (Davis 2002).

How successful is it?

As a reproductive tactic, the success of the insemination matters greatly to unpaired males and slightly to paired ones. The action itself would not be worthwhile if it failed each time. The data for this are mixed. Brennan claims that successful forced copulations are rare and successfully blocked by the female hens’ elaborate vaginas (2007). However, other studies show successful forced copulation rates of up to 50% (McKinney and Evarts 1998). Depending on the study, success rates vary; however, in general, it seems that forced copulations are successful enough to remain a viable reproductive tactic.

Why have unconditional resistance?

three drakes pinning a female mallard duck down and performing the act of copulation.
Forced copulation in mallards. The female here has been caught by at least three persistent drakes that are pushing to mount her and shaking her by the scruff of her neck

However, as mentioned above, the hens have an uncanny desire it seems to remain faithful to their chosen mates (Adler 2010). The hen’s struggles often attract groups of other drakes who will follow after her, see [link] (Goodburn 1984). The hen’s resistance is unusual as the cost of it is so high. In their excitement, males continually pile themselves on top of hens and grasp at their neck feathers to better position themselves for entry. This, along with her resistance, frequently causes injuries ranging from lost feathers to scratches, ruptured organs, and even drowning (Adler 2010). Many times it may be better to avoid this damage by accepting the forced extra-pair copulation (FEPC) as other species do. There are several hypotheses for this. The resistance may be related to maintenance of the pair-bond to assure that the mate will continue to guard the hen since he needs assurance of his reproductive success. It may be the good genes hypothesis , to ensure the best chicks survive as stated above. However, if this were the sole reason, then hens should engage in some extra-pair copulations (EPCs) with dominant males that have better genes which it is never seen doing.

Instead, Adler suggests that in spite of the high costs of resisting, the hen is filtering out the weak drakes that attempt FEPCs in favor of the fittest individuals (2010). She does clarify however, that this is to make the best of a bad situation, not to have a net benefit. In other words, this behavior is has the byproduct of selecting for forced copulation and complex phalluses to stay in the pool. Thus, the resistance provides indirect mate choice making it more likely that the male with the most adaptive genitals, that can bypass the vaginal labyrinth, would succeed. To clarify, the hen is not calculating the fitness profits and deficits from her actions, but gradual evolution has resulted in these behaviors being selected and working together optimally. This furthers the co-evolution of the two genitalia in a constant arms race as the fit males would be able to reproduce with greater success and the females should also evolve more elaborate vaginas that only the fittest could inseminate forcibly (Adler 2010).

Questions & Answers

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..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
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.
yes that's correct
I think
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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
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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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