Question

Explain what is meant by "life history characteristics", including a summary of the most important ones. Discuss how ecological, genetic and evolutionary properties and processes interact and contribute to variation in life history characteristics.

Answer 1

The evolution of life histories involves the shape and size of the body with the rapid availability of resources for survival rather than the level of resource demand. Survival and reproduction rates are correlated. It is divided into fast life history with fast reproduction and a slow life history with slower reproduction. There is a trade-off between life-history and reproduction which slowers the rate of production of the offspring with decrease in the reproduction rate. LIfe histories are different in rats as compared to animals like elephants. It depends upon a number of factors like metabolism, mortality rates, fertility rates and fecundity of specific species of animals. There are various effects of predation and competition which decides the life history of organisms. Reproduction rate is high when there are ample amounts of resources present for giving birth to the offspring. There are various fitness traits which define the life history characteristics of a species of organsims. The method of dwelling of organisms is also an important factor for determining the life style like burrowing and living in holes by rates, shrews, living on trees by birds. It decides and prevents the attacks from predators and increases their chance of living in the eocsystem and habitat. The other parameters like genetic, environmental and ecological for defining the lifestyle history of organisms include:

• heritability factor.
• genetic variance.
• phenotypic variance.
• mutation selection.
• environmental factors.
• resources and food items available.
• space and amount of competition for living and survival.
• effect of predators.
• effect of destruction of environment ane effects of harmful chemicals on plants and animals.
• mass of living species.
• shape, structure and amount of consumption of food by the living organisms.
• linkage disequilibrium.
• survival of fitter species and death of weak species.
• changes in temperature which effects the sizes of drosophila.
• number of offspring and clutch size.
• migration, inbreeding and heterozygosity traits affect the life style history of organisms.
• high adult mortality treatment and low adult mortality treatment in drosophila with variation in the number of eggs layed and life span in drosophila and guppies under various harsh environmental conditions.