Age Structure graphs of Populations

POPULATION ECOLOGY This is the study of how and why populations change and grow. Ecologists try to identify the factors limiting population growth; understanding this helps predict future growth. For populations to survive, many different factors must stay in balance.

How do we show populations? In a GRAPH!! What are some factors to compare about populations? Total number of individuals during any year Number of women vs number of men Number of individuals that are young, middle aged, or old HOW do we get all this info on 1 graph???

Compare number of females at different ages- how does this change Compare number of females at different ages- how does this change? How many pre-adolescent? Adolescent into 30’s? How many over 40? Why discuss these age groups?

How about male population How about male population? Compare different age groups- how do they differ? What could be significance of different ages?

Compare Females and Males- are there differences in the 2 populations at any age groups? Do you think this population is increasing? Decreasing? Stable?

Which parts of the population INCREASE the size of the population? Which part of the poulation DECREASES the size of the population?

Graph the information on the sheet! Pick up the worksheet, and draw 2 age structure graphs Remember to put age groups in the MIDDLE of the graph (central Y-axis) Number of individuals on the X-axis

Compare the 2 populations! How do these 2 populations differ?

Discuss what factors will have affected these 2 populations Which is the developed nation and developing nation? What types of technology are important to a population? What will be overall effect on population when there are different levels of medical care (vaccination/preventative med, acute care, chronic disease treatment, etc) or water & sewage treatment? What impact does availability of education have on population? Access to birth control? Cultural impact on population numbers?

HW: Analyze the 2 graphs you made. List 2 differences between the 2 population profiles. Are there any similarities in the 2 populations? What technologies do you think are available to population A? What technologies do you think are available to population B?

Quick Quiz: 8 pts 1. Explain what a population pyramid/age structure graph shows. (think x and y axis). 2. How is it able to predict how a population will change over time? 3. Look at the graph of Mexico: Is Mexico stable, increasing or decreasing in the future? How do you know?