ecology part 2
DESCRIPTION
Ecology Part 2. Honors Biology. Population Dynamics. Population Dynamics. Population: all the individuals of a species that live together in an area Demography: statistical study of populations, make predictions about how a population will change. Population Dynamics. - PowerPoint PPT PresentationTRANSCRIPT
EcologyEcologyPart 2Part 2
Honors Biology
Population DynamicsPopulation Dynamics
Population: all the individuals of a species that live together in an area
Demography: statistical study of populations, make predictions about how a population will change
Population DynamicsPopulation Dynamics
Three Key Features of Populations
•Size
•Density
•Dispersion
• (clumped, even/uniform, random)
Population DynamicsPopulation Dynamics
#1: Size
Growth Rate: Birth Rate (natality) - Death Rate (mortality)
How many individuals are born vs. how many die
Birth rate (b) − death rate (d) = rate of natural increase (r).
Three Key Features of Populations
PRE-REPRODUCTIVE
REPRODUCTIVE
POST-REPRODUCTIVE
Population of a Stable Country
US Baby BoomUS Baby Boom
19701970 19851985
Time unit Births DeathsNatural
increase
Year 130,013,274 56,130,242
73,883,032
Month 10,834,440 4,677,520 6,156,919
Day 356,201 153,781
202,419
Hour 14,842 6,408 8,434
Minute 247
107 141
Second 4.1
1.8 2.3
Three Key Features of PopulationsThree Key Features of Populations
#2: Density:
Number of individuals ÷ Unit of space
ex: 50 mice/square mile
1. 1. Immigration-Immigration- movement of movement of individuals into a populationindividuals into a population
2. 2. Emigration-Emigration- movement of movement of individuals out of a populationindividuals out of a population
4 Factors that affect density4 Factors that affect density
4 Factors that affect density4 Factors that affect density
3. 3. Density-dependent factors-Density-dependent factors- Biotic Biotic factors in the environment that have an factors in the environment that have an increasing effect as population size increasing effect as population size increasesincreases
Ex.Ex. diseasedisease
competitioncompetition
parasitesparasites
4. 4. Density-independent factors-Density-independent factors- Abiotic factors in the environment that Abiotic factors in the environment that affect populations regardless of their affect populations regardless of their densitydensity
Ex.Ex. temperature temperature
stormsstorms
habitat destructionhabitat destruction
droughtdrought
4 Factors that affect density4 Factors that affect density
Immigration
Emigration
Natality MortalityPopulation+
+
-
-
Factors That Affect Future Population Growth
Three Key Features of PopulationsThree Key Features of Populations
#3: Dispersion: describes organisms’ spacing
• even or uniform
• clumped
• random
clumped
even (uniform)
random
Population Dispersion
Other factors that affect population growthOther factors that affect population growth
Limiting factor-Limiting factor- any biotic or any biotic or abiotic factor that restricts the abiotic factor that restricts the existence of organisms in a existence of organisms in a specific environment.specific environment. EX.-EX.- Amount of waterAmount of water
Amount of foodAmount of foodTemperatureTemperature
Carrying Capacity- the maximum population size that can be supported by the available resources
Other factors that affect population growthOther factors that affect population growth
Carrying CapacityCarrying Capacity
Carrying Capacity (k)
Nu
m
b
e
r
Time
J-shaped curve (exponential growth)
S-shaped curve (logistic growth)
2 Life History Patterns2 Life History Patterns
1. R Strategists1. R Strategists short life span short life span small body sizesmall body size reproduce quickly reproduce quickly have many young have many young little parental care little parental care Ex: cockroaches, Ex: cockroaches,
weeds, bacteria weeds, bacteria
2 Life History Patterns2 Life History Patterns
2. K Strategists long life span large body size reproduce slowly have few young provides parental
care Ex: humans,
elephants
Squid vs. Sperm WhaleSquid vs. Sperm Whale Lives 1 yearLives 1 year Lays up to 9,000 eggsLays up to 9,000 eggs Length 20 cmLength 20 cm Embryos develop ~ 1 monthEmbryos develop ~ 1 month No care for offspringNo care for offspring Safety in numbers (mating Safety in numbers (mating
and eggs)and eggs) Dramatic population Dramatic population
fluctuations between years.fluctuations between years. Can quickly repopulate new/ Can quickly repopulate new/
unstable environmentsunstable environments
Lives 70 yearsLives 70 years Length 18 meters Length 18 meters
(male)(male) Gestation – 15 monthsGestation – 15 months Calf nurses ~ 2 yearsCalf nurses ~ 2 years Female calves every 4 Female calves every 4
years (max)years (max) Invest energy into Invest energy into
individual offspring.individual offspring. Best in stable/ Best in stable/
established established environmentsenvironments
Human Population GrowthHuman Population Growth
Human Population GrowthHuman Population Growth
World BiomesWorld Biomes
Succession in Succession in EcosystemsEcosystems
SuccessionSuccession--
a series of changes in a community a series of changes in a community in which new populations of in which new populations of organisms gradually replace organisms gradually replace existing ones existing ones
Primary successionPrimary succession--
colonization of new sites by colonization of new sites by communities of organisms communities of organisms – takes – takes place on bare rockplace on bare rock
Primary successionPrimary succession--
New bare rock comes from 2 New bare rock comes from 2 sources:sources: 1. volcanic lava flow cools and 1. volcanic lava flow cools and
forms rockforms rock
Primary successionPrimary succession--
New bare rock comes from 2 New bare rock comes from 2 sources:sources: 2. Glaciers retreat and expose 2. Glaciers retreat and expose
rockrock
Pioneer organisms-Pioneer organisms-
the first organisms to colonize a the first organisms to colonize a newnew site site Ex: lichens are the first to colonize Ex: lichens are the first to colonize
lava rocks lava rocks
Primary SuccessionPrimary Succession--
Rock
Climax community-Climax community-
a stable, mature community that a stable, mature community that undergoes little or no successionundergoes little or no succession
Climax community-Climax community-
Ex: In most of Virginia, the climax Ex: In most of Virginia, the climax community would be acommunity would be a deciduous deciduous oak–hickory forest oak–hickory forest
Primary succession-
Secondary succession-Secondary succession-
sequence of community changes sequence of community changes that takes place when a that takes place when a community is disrupted by natural community is disrupted by natural disaster or human actions disaster or human actions – takes – takes place on existing soilplace on existing soil
Secondary succession-Secondary succession-
Ex: Ex: A fire levels A fire levels
portions of a portions of a forestforest
Secondary succession-Secondary succession-
Ex: Ex: A farmer A farmer
plows his plows his fieldfield
Secondary succession-
Secondary succession-
Pond SuccessionPond Succession
A newly formed pond near the beach has sandy borders bare of vegetation
After two years such a pond is ringed by low vegetation including cottonwood saplings.
A 50-yr old pond is bordered by mature cottonwood trees. Such much sediment is produced by organisms growing in the pond that only a small area of water, choked with weeds, remains.
After 150-250 years the area has become a meadow.
Pond SuccessionPond Succession
Write the letters of the ponds in order from the youngest, to the oldest
Pond SuccessionPond Succession