Evo-eco 1: Life history traits Flashcards
The relationship between vital rates and life history traits/ overview
Vital rates can be scaled up to life history traits and strategies when considering the effect of the duration, intensity, timing, and frequency of the vital rates and how this shapes life history traits and strategies.
Vital rates:
- reproduction
- survival
- development
Modulations of vital rates:
- Frequency
- intensity
- duration
- timing
The state of the environment affects these factors of vital rates and can, therefore, shape life history traits and strategies.
Modulations in vital rates (impacted by environment) give life history traits.
Considering the vital rates in terms of the modulations: Survival
1) Survival in terms of duration = Longevity
2) Survival in terms of timing= Changing vitality/ survival thorugh time
-> Deaths early in life: Increasing vitality due to negative sentence (Tree- slower growth rates, reduced ability to absorb nutrients, damage)
-> Deaths constantly throughout life: Constant vitality due to negligible senescence (Eagle- few risk factors e.g. fly above storm)
-> Deaths late in life: Reducing vitality due to positive sensence (Gorilla)
Survival in stochastic environments:
-> shorter life spans (e.g. develope meant period in drosophila proportional to adult survival -> shorter life span if stochastic-> increase development rate giving larvae edge)
-> faster sensensence
Considering the vital rates in terms of the modulations: Reproduction
1) Reproduction in terms of time= Age of reproduction
2) Reproduction in terms of frequency= frequency strategy (semelparous vs iteroparous)
For semelparous species, there is a trade between reproducing now or later in terms of size and probability of survival.
Reproduction in stochastic environments:
-> Early maturation and reproduction
-> Annual semelparous species
-> Sychronised reproduction (masting- oak tree)
-> more offspring per reproductive event
But then this leads to trade of between early reproduction and reproduction of many offspring -> good solution is for it be be indeterminant
Example: chinook salmon
- reproduce once and their age of reproduction varies depending on the environment
- variable maturation selected for in stochastic environment
Considering the vital rates in terms of the modulations: Developement
Development in terms of time= time of maturation
Determinant species: they stop developing once they reach adulthood
Indeterminant species: they continue developing throughout life
Investment can also be plastic
example: Marine iguanas reducing in size to fit into gaps and eat algae (up to 20%)
Example: cindera capable of reversing developement to return to juvenile stage so that they can disperse to favourable conditions.
Example: chanook plastic maturation
Example: overall body shrinkage in response to warming
- limitation of oxygen and other resources
- shorter development as increased mortality
- body size fluctuation seen in the canook salmon -> global warming increasing water temperature limiting upwelling’s
Development in stochastic environments:
-> Smaller size
-> body fluctuations (e.g. marine iguanas)
Stochastic environments
Stochastic environments shape the vital rates (reproduction, development and survival) and therefore shape the life history traits
Key features
Reproduction:
-> Early maturation and reproduction
-> Annual semelparous species
-> Sychronised reproduction (masting)
-> more offspring per reproductive event
Survival:
-> shorter life spand
-> faster sensensence
Development:
-> Smaller size
-> body fluctuations (e.g. marine iguanas)
Modelling using vital rates
When you know the vital rates models can be made to predict key life history traits
Development has a gaussian distribution and reproduction/ survival has a binomial distribution
Integral projection models can then be used to combine these vital rates and predict the life history traits.
Example: Canuus natuans
- The optimal age of reproduction was calculated by looking at key vital rates
- Prediction was too late
- Modelling was repeated for a stochastic environment and it was accurate
Example of life history trait as a result of stochastic environment: Masting
When the environment is unpredictable, plants will wait for a favourable year and then all produce their seeds at the same time (synchronised).
This may also be a predator avoidance strategy.
Autocorrelated patterns and life history
Species adapt their life histories to positively autocorrelated seasonal fluctuations (e.g. coastal upwellings) - schedule reproduction, growth and migration
Environment tend to remain close to what they were in the previous year
Example: chinook salmon
- they have indeterminant maturation that varies depending on environment
- delay maturation if environment if favourable environment
- chinook salmon maturation and reproduction is dependent on costal upwelling -> more food, grow larger, reproduce later, more offspring
- good strategy for a stochastic environment
Larger upwelling = more food
Evolution of life history in guppies
With predators - early maturation and short life span
Without - later maturation and longer life span
