BIOL 180 Chapter Notes - Chapter 54: Life Table, Net Reproduction Rate, Exponential Growth

• School: UW
• Department: Biology
• Course: BIOL 180
• Professor: Freeman Scott

Document Summary

Population"s growth rate is change in number of individuals ( n) per unit time ( t: n/ t = growth rate. If no immigration/emigration is occurring, population growth rate = # of individuals (n) x birthrate (b) - death rate (d: no immigration/emigration: n/ t = n(b-d) Exponential population growth - occurs when r does not change over time. Key point about exponential growth is that the growth rate does not depend on the number of individuals in the population: this type of population growth is density independent. Example: r of 0. 02 per year in a population of 1 billion adds over 20 million individuals per year: same growth rate in a population of 100 adds just over 2 individuals per year. Not possible for exponential growth to continue indefinitely. When population density gets very high, population"s per capita birth rate decreases and death rate increases = r declines: growth is often density dependent.