Sexual selection and the roles of males and females

So far we have learned how natural selection impacts various things in the environment. However, there are certain environmental aspects that natural selection cannot explain. Sexual dimorphism is the difference in the males and females of a species. Natural selection cannot explain these differences between sexes and Darwin was puzzled by the occurrence. Sexual dimorphism can be the difference in size, coloring, or body structure between the sexes. One example is the cardinal. The females are a dull brownish color, while their male counterparts are a vibrant red. Male birds of paradise, on the other hand, are known for their elaborate feathers and strange mating dances. Females are much less ornate and do not perform these elaborate dances. Males and females play different roles in taking care of the offspring. This is otherwise known as parental investment. Parental investment is the time and energy spent to take care of the offspring as well as to create the actual offspring. A trade off is seen when comparing parental investment techniques. The more energy and time the parent spends on the offspring the higher potential for reproductive success it has. However, the more time spent on the offspring, the parent’s remaining reproductive success decreases. Many species have zero parental care and they produce mass amounts of offspring to better the chance that some will survive to reproduce. Females, in the majority of the species, are the ones that expend the most energy to take care of the offspring. Comparing male to female potential reproductive success vary from species to species. Species either have high parental care and few offspring or many offspring with little parental care. Mammals usually care for their offspring for many months while many insects just produce mass amounts of offspring with no parental care.

http://quantumbiologist.wordpress.com/page/2/

For More Information:

http://www.nature.com/scitable/knowledge/library/sexual-selection-13255240

http://beheco.oxfordjournals.org/content/11/2/161.full