Post on 31-Dec-2015
transcript
Levels of Study
• Population• Individuals of the same species living in the same area
• All the turtles of the same species
Levels of Study
• Community• All the organisms living in an area
• All the turtles, plants, insects, algae, bacteria
Levels of Study
• Ecosystem• All the organisms and all the abiotic factors
• All the organisms & the soil, water, gases, minerals
Biomes
• Savannas• Tropical• Grasslands• Scattered trees• High temperature
• Less rainfall than tropical rain forest
Biomes
• Temperate grasslands
• Grasses• Seasonal droughts• Occasional fires• Lower temperature & less rainfall than savannas
Biomes
• Deciduous forests• Deciduous trees• Oak, maple• Warm summers• Cold winters• Moderate rainfall
Population Characteristics• Dispersal Patterns
• Spacing between individuals
• Clumped• Uniform• Random
Population Characteristics• Demographics• Study of vital statistics
• Age structure– Groupings by age– Graphed
• Sex ratio– % of females compared to males
Limiting Factors
• Prevent population from reaching biotic potential
• Types– Density dependent– Density independent
Limiting Factors
• Density dependent• Effect becomes more intense with increased density
• Examples– Parasites & diseases– Competition for resources– Toxic effect of waste products– Predation
Limiting Factors
• Density independent• Occur independently of density• Examples:
– Natural disasters– Climate extremes
Population Growth Models• Exponential Growth• Change in # of individuals (N) over time (t) is equal to the growth rate (r) times the number of individuals (N)
rNt
N=
Population Growth Models• Logistic Growth• When limiting factors restrict size of population to carrying capacity
• Carrying capacity (K) = max. # of individuals of a population that can be sustained by the habitat ⎟
⎠
⎞⎜⎝
⎛ −=
K
NKrN
t
N
Life-History Strategies
• r-selected species• Exhibit rapid growth (J-curve)• Examples – grasses, insects• Characterized by opportunistic species
– Quickly invade habitat– Quickly reproduce– Then die
• Produce many offspring that are small, mature quickly, require little parental care
Life-History Strategies
• k-selected species• Population size remains relatively constant
• Example - humans• Produce small number of relatively large offspring that require extensive parental care
• Reproduction occurs repeatedly during lifetime
Community Interactions
• Interspecific Competition• Competition between different species• When 2 species compete for same resources one will be more successful
• To survive, the less successful species– Must use slightly different resources
– Must use resources during different time of day
Community Interactions
• Predation• Any animal that totally or partly consumes a plant or animal
• True predator kills and eats another animal
• Parasite lives in and off a host• Herbivore is an animal that eats plants
Community Interactions
• Symbiosis• Two species that live together in close contact
• Types– Mutualism– Commensalism– Parasitism
Community Interactions
• Mutualism• Both species benefit from relationship
• Examples– Bacteria in root nodules– Lichens – algae & fungus living together
Community Interactions
• Commensalism• One species benefits while the other is neither harmed nor helped
• Examples– Birds building nests in trees
– Egrets that eat insects around cattle
Community Interactions
• Parasitism• One species benefits while the other is harmed
• Examples– Tapeworm inside animal– Ticks on dog
Ecosystems – Pyramids
• 10% rule• Only 10% of energy available at each trophic level is converted into new biomass at the next level