Measuring Populations Flashcards
Distribution of species
the geographical area in which species is found
Types of distribution
regular
random
cluster
Regular distribution
occurs due to interactions with other individuals
An organism in regular distribution
cresote bushes
Random distribution
no pattern of interaction
rare in nature
Organism in random distribution
stingless bee
Cluster distribution
interaction with others/environment
most common type
Organisms in cluster distribution
herds of large mammals
social insects
migrating waterfowl
schools of fish
Types of population pyramids
expansive
constructive
stationary
Expansive population pyramid
high fertility rates
lower than average life expectancy
3rd world countries and Latin America
Constructive population pyramid
longer percentages of young people
United States
Stationary population pyramid
equal percentages of all age groups
European countries
Natural selection
mechanism of evolution
Types of natural selection
stabilizing selection
disruptive selection
directional selection
What happens to genetic diversity in stabilizing selection
genetic diversity decreases
Examples of organisms with stabilizing selection
medium-sized spiders
medium-sized mice
What traits in a population are selected for in stabilizing selection
normal traits
In stabilizing selection gene frequencies are kept……
constant
In disruptive selection either…… in a population is selected for
extreme
Disruptive selection eliminates ……..
intermediate traits
What changes cause disruptive selection
disease
new predator
climate change
What is a population distribution of age and gender graph
a back-to-back graph
What does population distribution of age and gender show
number of males and females and age group pf each gender
Directional selection
extreme variation of a trait within a population
