I am just replying to the opening poster and will therefore repeat without acknowledging specifically what has been mentioned in part by others in the thread.
Sexy genes theory
Attractive offspring more likely to pass on genes, it is good if the children are sexy. Aims: Sexy sons – more likely to be chosen, and sexy daughters that prefer the sexy trait in males and will chose a sexy male, leading to further sexy offspring. Sexy trait/genes more likely to be passed on.
Which trait?
1/ original arbitrary trait can become the sexy one, once critical mass reached.
Or 2/ the trait may have originally been beneficial for survival but then it became important purely for sexy reasons, leading to runaway model already mentioned in the thread.
Or 3/ the females already had a predisposition for a specific colour that then appeared by random mutation making the mutant sexy and it gets hold, critical mass reached.
In the case of 2, it had originally been linked to survival and for 3 a predisposition would have to exist perhaps in a large portion of the pop. when the mutation occurred. In the case of 1, I suppose in would be a numbers game, yes most would be eliminated but once the critical mass is reached at some stage, the new sexy individual is established on a more “permanent” basis. It is a good question. Ofcourse there is no such thing as a starting point, it’s a slow process of mutation and selection for small changes from 1 generation to the next. And it is a mixmash at any one time of multiple traits, no one trait dominates completely. To explain the theories, its simplest to paint the pic of a simple isolated process creating the ultimate sexy individual, that is however far from an appropriate description of reality.
Its important to realise that the decision of the individual is conscious, but what is sexy in a population is not, it’s a matter of survival and reproductive output. Therefore natural selection and survival are not separate processes here, natural selection can counter sexual selection and will influence what is sexy by selecting against very sexy individuals if the traits they have are very poor in ensuring survival. It can be a trade off.
I also have to ask Why? Perhaps you are applying to much credit here by labelling the word precise on it, and assuming what you perceive as chaotic or uniform to be simple. Either way the point is that there is consistent process in action, that of sexual selection and the choices of each individual bird. The pay off is the production of sexy children who are more likely to reproduce, which results in the passing on of such sexy traits. All this happens by slight changes generation to generation.
Incidentally there are other theories than just the sexy genes and fishers runaway model which don’t apply in every situation and imo the other models/theories are often the most plausible in many specific cases regarding birds and colouration et al., and some of these sexual selection theories are more closely linked to survival. It’s all damn fascinating if you ask me.
Sexy genes theory
Attractive offspring more likely to pass on genes, it is good if the children are sexy. Aims: Sexy sons – more likely to be chosen, and sexy daughters that prefer the sexy trait in males and will chose a sexy male, leading to further sexy offspring. Sexy trait/genes more likely to be passed on.
Which trait?
1/ original arbitrary trait can become the sexy one, once critical mass reached.
Or 2/ the trait may have originally been beneficial for survival but then it became important purely for sexy reasons, leading to runaway model already mentioned in the thread.
Or 3/ the females already had a predisposition for a specific colour that then appeared by random mutation making the mutant sexy and it gets hold, critical mass reached.
In the case of 2, it had originally been linked to survival and for 3 a predisposition would have to exist perhaps in a large portion of the pop. when the mutation occurred. In the case of 1, I suppose in would be a numbers game, yes most would be eliminated but once the critical mass is reached at some stage, the new sexy individual is established on a more “permanent” basis. It is a good question. Ofcourse there is no such thing as a starting point, it’s a slow process of mutation and selection for small changes from 1 generation to the next. And it is a mixmash at any one time of multiple traits, no one trait dominates completely. To explain the theories, its simplest to paint the pic of a simple isolated process creating the ultimate sexy individual, that is however far from an appropriate description of reality.
Its important to realise that the decision of the individual is conscious, but what is sexy in a population is not, it’s a matter of survival and reproductive output. Therefore natural selection and survival are not separate processes here, natural selection can counter sexual selection and will influence what is sexy by selecting against very sexy individuals if the traits they have are very poor in ensuring survival. It can be a trade off.
I also have to ask Why? Perhaps you are applying to much credit here by labelling the word precise on it, and assuming what you perceive as chaotic or uniform to be simple. Either way the point is that there is consistent process in action, that of sexual selection and the choices of each individual bird. The pay off is the production of sexy children who are more likely to reproduce, which results in the passing on of such sexy traits. All this happens by slight changes generation to generation.
Incidentally there are other theories than just the sexy genes and fishers runaway model which don’t apply in every situation and imo the other models/theories are often the most plausible in many specific cases regarding birds and colouration et al., and some of these sexual selection theories are more closely linked to survival. It’s all damn fascinating if you ask me.