Question

6. What evidence (data/graphs) from the example of marine iguanas (Ch. 11) demonstrates sexual dimorphism and what data or graphs demonstrate the difference between sexual and natural selection on females and males?

Answer 1

Sexual dimorphisam by considering example of marine iguanas ,is a condition where 2 sexes of same species exihibit different characterstics beyond differences in their sexual organs. sex biased mortality was the result sex diamorphism in them.Maine iguana populsation exhibits 10 fold differences in body mass betwween island populations .Large body size less favoured by fertility selection in females than large size in males .Resulting from these different selection pressures on males and female size, sexual dimorphism was mechanistically caused by the fact that females are matured at an early age than males,whereafter they constantly allocated resources into eggs whic slowed growth.Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring.Sxual selection is also a natural selection arising through preferences by one sex from certain characterstics in individuals of other sex,but same happens in between same sexes.Example is in priming of genetila for sexual intercourse and a stereotypical position assumed while having sex.