Chapter 52 Test

the study of populations and interactions with their environment

• Birth Rate
• Death Rate
• Age Structure
• Sex Ratios
• Density

# of births/individuals born/unit time

• # deaths/ #individuals/year
• Mortality rate is the number of individuals in a population dying during any given time interval divided by the number alive at the beggining of the time interval

# individuals/unit area

increase populations

decrease populations

number of offspring/female/year or per 100 females/year

factor that takes a varying % of the population depending on the density of the population (competition, predation, crowding, parasites, disease)

factor that takes a constant % of the population independent of pupulation density (climate and weather, shortage of resources-nest sites, den sites, etc, non infections diseases, pollution)

growth under no environmental resistance or limiting factors

competition and its effects of food, cover, space and water resources, predation (interspecific competition), disease, starvation, etc

that there are no limits such as predation, diseases, etc

• population grows at increasing rates
• "j curve" depicts population growth at increasing rates

• usually no, environment is not constant and resources are limited
• birth rates will decline, death rates will increase, or both to even out once K is reached

• biotic potential of the population is held in check or limited by environmental resistance
• biotic potential is synonymous with reproductive potential, maimum rate of population increase under ideal conditions

• environmental resistance dictates the carrying capacity of the area or habitat
• there is an S curve graph

the number of animasl an area can support over a period of time without damage to that habitat

• the more energy spent on reproduction, the less energy it can distribute for growth and maintenence
• investment includes not only the production of offspring but also care and nourishment
• species in different environments will differ in life history traits such as size, productivity, age at first reporduction, # of reproductive events during lifetime, and total life span
• r and k selection

• selection under low population densities
• many offspring
• favors high reproductive rates under conditions of low competition
• fish, bugs, etc

• variable climate
• density independent mortality
• variable pop size
• short life span
• rapid development
• high rate of increase
• early reproduction

selection under carrying capacity conditions and a high level of competition

• stable climate
• density dependent
• constant pop size
• long life span (>1year)
• little offspring
• reproduce less often
• slow development
• low rate of increase
• larger offspring

• clumped together populations
• most common type of dispersion
• ex: packs of wolves, elephants, etc

evenly spread out, very specific

• random spacing and distribution
• ex: flower pollen, tree seeds, etc

• dN/dt= riN
• =N(m-b)

• N- number of individuals
• ri- max growth rate, intrinsic growth rate
• t- time
• d- rate of change
• b- birth rate
• m-mortality rate

• survivorship curves are graphs showing the survival and reproduction of populations
• Types 1,2, and 3

• like k selection
• few offspring, but live long time
• high mortality rate towards post reproduction years
• ex: humans

• constant mortality rate throughout life
• ex: Hydra

• like r selection
• many offspring, but many die close to birth
• few lucky ones survive a longer time
• high mortality rate at pre reproduction years

• Reproduces once before death
• k selected
• ex: bears

• reproduce ofthen througought life
• r selected
• ex:fish

limited resources can cause the pop to decrease and the fit survive and trade offs have organisms with low survival rate produce many offspring for a chance and organisms with a higher survival rate produce fewer organisms

dN/dt=rN

dN/dt=rN x (k-n)/k