Question

Study Questions

Why would organisms lose obviously advantageous traits? For example, primates have a greatly reduced olfactory system compared to their ancient ancestors, even though a keen sense of smell is an obviously advantageous trait under almost any condition. Why would evolutionary processes select against such traits? Why would we not retain them even if they were not absolutely necessary for our survival?

How is behaviour affected by evolutionary processes? Can behaviour still be subject to natural selection if it is not genetically determined? How would this work? Use examples to support and illustrate your views.

Answer 1

organisms sometimes looses the obviously advantageous traits like olfaction in primates. This type of selection of trait is actually realted to the order of importance and vitality. The role of smell is found to be of secondary importance in comparison to that of auditory, tactile, and visual senses. for ex- In humans and other arboreal vertebrates the development of higher neural senses like auditiory and visual sense are of more importancw than that of olfaction.

The evolutionary process generally select against those traits acccording to their need and viability This can be seen in case of aquatic lifeforms. As, smell is not so important so, whales and dolphins have reduced sense of olfaction. But, again in tetrapods rhe sense of olfaction returned back strongly as they are much needed in terrestrial lifeforms.

They don't  retain them even if they were not absolutely necessary for their survival beacuse they need to pave way for new changes new anatomical physiological and genetic cahnges are required for evolution of new developed characteristics. But, some times they are also not completely lost, but stay in reduced less efficient forms.

For ex- The diversity of smelling genes present in humans are the result of multiple rounds of mutations that have occurred throughout vertebrate evolution. In every organisms repeated rounds of gene duplication, deletion, and pseudogene evolution contribute to the variety of Olfactory receptor gene number which plays an important role in the olfaction sense.

yes, behaviours are affected by evolutionary processes. The nature adapts and selects the behaviour which is advantageous to the population. yes, it is a subject of natural selection irrespective of that it is genetically determined or not because the evolution is the result of many factors need, importance, ecology, environmental conditions , behaviour etc. Behavioral evolution may change the sensory systems in the brain or anatomical changes in the structures used to carry out a behavior. for ex- schooling differences between marine and freshwater sticklebacks shows multiple distinct behavioral modules that had evolved reduced schooling in freshwater sticklebacks.