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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

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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.
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?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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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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