Life History Patterns

Development  At different stages of development, species require different resources  Also, they can be more at risk during different stages of life  Each species has a life history pattern: ◦-

Life Tables  Investigators focus on a cohort, focusing on their time of birth until the last one dies  -  Predicts how changes in the environment affects the species’ numbers  Human life tables are based on current conditions and focus on hypothetical situations

Survivorship Curves  A line graph that emerges when you plot a cohort’s age-specific survival in its habitat  Three types of survivorship curves are common in nature:  Type I  Survivorship is high until late in life  Large animals that have on to few offspring at a time, typical human populations with good health care fall in type I  Type II  Death rates do not vary much with age  Lizards, small animals, big birds die the same at young and old ages  Type III  Death rate peaks at an early age  Species that produce many offspring at birth with little to no parental care  Common for marine animals

Survivorship Curves

Reproductive Strategies  Some species reproduce only once and die after reproduction, others reproduce many times throughout life  -  The two types of reproductive strategies are known as:  -

Human Population Growth  The human population, like populations of other organisms, tends to increase. The rate of that increase has changed overtime.  Estimated average rate of increase for the human population was 1.16% per year.  What factors have contributed to the human population growth?  -  Plowing and Irrigation  -

Human Population Growth

Thomas Malthus  Stated that Human populations could be limited by…  -  Malthus’s work was important to Charles Darwin’s development of his Theory of Evolution

Fertility Rates and Age Structure  Governments recognize that populations growth, resource depletion, pollution, and quality of life are interconnected.  -  Food production will increase, more energy and fresh water to meet basic needs, and utilizing natural resources will intensify pollution.  Most growth will be seen in: India, China, Pakistan, Nigeria, Bangladesh, and Indonesia.

Age Structure Graph

Total Fertility Rate  The average number of children born to the women of a population during their reproductive years  1950 TFR was averaged at 6.5 worldwide  -

Demographic Transition  Describes how the population growth rate changes as a country becomes more developed  Four stages:  -– before technological and medical advances spread  Growth is low  Transitional Stage – -  Growth is increasing  -– Growth slows  Cities filled with employment opportunities, family size declines  We are currently in this stage  -  Population slowly decreases

Demographic Transition Graph

Demographic Transition  -  Predict why some countries have high growth rates and others have slow growth:  Birthrates  Death rates  Age structure

Resource Consumption  Industrialized nations use the most resources  -  “For everyone now alive to have a lifestyle like an average American would require 4x the resources present on Earth.”  If the human population keeps on increasing as predicted, what will happen to the human race?  Can we survive?

Rising Seniors  -  Predicted by 2030 more than 20% of our population will be over the age of 65.  million Americans will be over the age 65.  Social implications:  -