LIFE HISTORY STRATEGY

Life History Strategy

A suite of traits that improve an individual's chances of surviving and

reproducing in a particular environment

1. Energy commited to one function is not available for others.

2. Every evolutionary ‘choice’ has costs and benefits

3. Every organism represents a compromise of a number of evolutionary ‘choices’

COST/BENEFIT ANALYSIS

Macarthur and Wilson (‘70’s) - Theory of Island Biogeography

r strategists K strategists

Equilibrium-slower colonizing, slow growth

Opportunistic-rapidly colonizing, fast growth

r - selected K - selected

Climate

Mortality

Population Size

Community Characteristics

Lifespan

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality

Population Size

Community Characteristics

Lifespan

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size

Community Characteristics

Lifespan

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community Characteristics

Lifespan

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan Short Long

Individual Attributes

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan Short Long

Individual AttributesRapid development, early reproduction, high rate of increase, small body size

Slow development, late reproduction, low rate of increase, larger body size

Allocation of Energy

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan Short Long

Individual AttributesRapid development, early reproduction, high rate of increase, small body size

Slow development, late reproduction, low rate of increase, larger body size

Allocation of Energy Greater % to reproductionGreater % to growth and

maintenance

Attributes of r and K - selected organisms

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival Density dependent,

uncertain juvenile survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan Short Long

Individual AttributesRapid development, early reproduction, high rate of increase, small body size

Slow development, late reproduction, low rate of increase, larger body size

Allocation of EnergyGreater % to reproduction

Greater % to growth and maintenance

Attributes of r and K - selected organisms

Productivity

r - selected K - selected

Climate Variable, unpredictible Consistent, predictible

Mortality Density independent,

uncertain adult survival

Density dependent, uncertain juvenile

survival

Population Size Variable, below K Consistent

Community CharacteristicsFew species,

recolonizationMore species, no

recolonization

Lifespan Short Long

Individual AttributesRapid development, early reproduction, high rate of increase, small body size

Slow development, late reproduction, low rate of increase, larger body size

Allocation of EnergyGreater % to reproduction

Greater % to growth and maintenance

Attributes of r and K - selected organisms

Productivity Efficiency

r-strategist K-strategist

r - K continuum

r-strategist K-strategist

Frequent disturbance Less frequent disturbance

r - K continuum

Death

recruitment

Aclonal Life History

Sexual reproduction

Death

recruitment

Clonal Life History

FissionFissionFission

Sexual reproduction

Fertilization Patterns

1. External (no copulation)

Fertilization Patterns

1. External (no copulation)

Problems

Gamete output

Synchrony

Gamete dispersal

Gamete dilution

Fertilization Patterns

1. External (no copulation)

Problems

Gamete output

Synchrony

Gamete dispersal

Gamete dilution

% success

Distance between individuals

0.5 m

100

Fertilization Patterns

1. External (no copulation)

Allee Effect

Reproductiverate

Number or Density

Fertilization Patterns

2. Internal (no copulation)

For oyster spawning video: www.umces.edu/ 2002Session/oyster.html

Fertilization Patterns

2. Internal (copulation)