Life Histories Flashcards
Life histories
The sequence and timing of events that occur between birth and death
Iteroparous discrete breeding
Iteroparous continuous breeding
Semelparous (monocarpic, univoltine)
Short juvenile phase, multiple moderate producing reproductive phases
Short juvenile phase, continuous low producing reproductive phase
Long juvenile phase, short lived by highly successful producing reproductive phase
Unitary individual
Structural units=genetic units
-determinate form and development
Modular individuals
Unpredictable form/development
-structure units are not genetic units
-Ramets
-genets
Ramets
Structural units, separate modules (tillers, bulbs from same rhizome)
Genets
Any collection of Ramets that originated from the same zygote
Fecundity
The number of offspring produced by an organism per reproductive episode
Parity
The number of reproductive episodes an organism experiences
Fast life history
-greater number of offspring
-shorter life span
-faster growth
-earlier reproduction
-earlier sexual maturity
-smaller parental investment
Ex: rat, fruit fly
Slow life history
-fewer offspring
-longer life span
-slower growth
-delayed reproduction
Later sexual maturation
-greater parental investment
Ex: elephant, oak tree
Do all animals fit into fast or slow life histories?
No, some have traits from both
Combinations of life history in plants represented by triangle of environmental conditions
stress tolerator
Competitors
Ruderals
Stress tolerators
-can survive and reproduce under extreme environmental conditions such as low water availability, very cold temperatures, or high salt concentrations.
-slow growth rate
-late sexual maturity
-low energy proportion to make seeds
-frequently important vegetative reproduction
Vegetative reproduction
Form of asexual reproduction in which new plants develop from the roots and stems of existing plants
Competitor plants
Environment less stressful, less disturbances
-grow quick
-achieve sexual maturity early
-devote small amount of energy to seeds
-often vegetative reproduction
-grow to large sizes
-exhibit long life spans
Ruderals
Low stress, high frequency of disturbance
-fast growth
-early maturation
-use high proportion of energy to make seeds
-reproduce quickly
Include weeds
Principle of allocation
The observation that when resources are devoted to one body structure, physiological function, or behaviour, they cannot be allocated to another
Plants that produce more seeds produce ______ seeds
Smaller
The more offspring an organism has…..the ______ time there is to spend with the offspring
Less
Tropical birds have ______ growth in their early nesting life than temperature birds. However tropical birds had _____ growth later in their nesting life
Slower
Faster
Tropical birds produce fewer higher quality offspring to increase survival rates
Temperature birds produce more nestlings at the cost of each nestling being in lower fitness
Increasing number of offspring provides what effect to parents
Diminishing fitness
More adult Mortality
Determinate growth
A growth pattern in which an individual does not grow any more once if initiated reproduction
Most birds and mammals
Indeterminate growth
A growth pattern in which an individual continues to grow after it initiated reproduction
Amphibians, fish, reptiles
Do endothermic or ectothermic organisms grow more rapidly
Endothermic
Annual
Perennial
An organism that has a life span of one year
An organism that has a life span of more than one year
Semelparity appears to arise when there is a
Massive amount of energy required for reproduction such as long migration or giant flowering stalks
-makes it difficult to survive after reproductive event
Salmon, agave, cicadas
Senescence
A gradual decrease in fecundity and an increase in the probability of mortality
Photoperiod
The amount of light that occurs each day
Embryos and embryo predator detection
Embryos can speed up their hatching to avoid being eaten if they sense a predator
Growth and reproduction timing
Some species delay their growth to start reproducing quicker if threatened. However, their smaller body size can only produce smaller amounts of offspring
Flower times and average annual temperature
With global warmings effects, some plants are flowering earlier, in connection with their preferred temperatures
Types of annuals
-facultative annuals: not necessarily 1 year life, may live to second
-ephemerals: short life span during favourable conditions
-supra annuals: love for long time then semelparous; biennials (1 year to grow, 1 to reproduce)
Trade offs in life histories
-more offspring=smaller egg size
-more seeds=less seed mass
-small seeds=small plants
-more seedling dry mass=more seed mass
-# of propagules = more weight of propagules per stem
Is r or k selection better
Neither better
Just different ways
R selected traits
-high reproductive potential (intrinsic rate of increase)
-not strongly favoured competitively
-rapid development
-early reproduction
-small body size
-single reproduction event (selemparous)
-many small offspring
K selected traits
-low reproductive potential
-competitive ability favoured
-slow development
-late reproduction
-large body size
-many reproductive events (Iteroparous)
-large offspring
Natural selection favours the pattern of resource allocation that yields the
Highest fitness
R and k fits which area of triangle
K for competition and stress tolerators
R for ruderals
Ruderals, competitive and stress tolerant main factors
R: Rapid growth, many seeds, short life
S: slow growth, evergreen, conserve resources, unpalatable
C: Intermediate? Plants grow well where disturbances and stress are low. Become good competitors that are efficient at appropriating resources
