Post on 22-Feb-2016
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Populations chapter 5 in text
3 factors affecting population size
• Births• Deaths• Immigration and Emigration
Growth without limiting factors
Growth without limiting factors
• Under ideal conditions a population will show exponential growth – What are ideal conditions?
Limiting factors can be density-dependent or density-independent
• Density-dependent factors are limiting factors that depend on population size– Examples of density-dependent factors:
– Examples of density-independent factors:
Density-dependentor
Density-independent?
Density-dependentor
Density-independent?
Density-dependentor
Density-independent?
Growth with limiting factors• Under such circumstances a population show
an s-shaped curve, indicating logistic growth
What is “K”?• “K” stands for a concept called carrying capacity,
which is the largest number of individuals with in a species that the environment can support.
What is shape of global human growth?
What is shape of global human growth?
What is shape of global human growth?
r-selected vs. K-selected species
Characteristics of r- and K-selected organismsr-organisms K-organisms
short-lived long-lived
small large
weak strong or well-protected
waste a lot of enrgey energy efficient
less intelligent more intelligent
have large litters have small litters
reproduce at an early age reproduce at a late age
fast maturation slow maturation
little care for offspring much care for offspring
strong sex drive weak sex drive
small size at birth large size at birth
What are your demographics?• Demographics: the statistical data of a population,
especially those showing average age, income, education, etc.
Age-structure diagrams predict future population size, looking at age, gender
• Match the countries: US, Germany, Kenya, Italy
Age-structure diagrams predict future population size
• Match the countries: US, Germany, Kenya, Italy