Lecture 16: Life History Flashcards
What is life history, from a biological perspective?
Defined as the sequence of anatomical, physiological, and behavioral changes and events that an organism experiences over the course of its lifetime
What are the 6 primary stages that the life of a mammal can be divided into?
1) fetal (gestation)
2) infancy
3) juvenile
4) subadult
5) adult
6) post-reproductive (female)
How does the variation of the 6 primary stages of life define a life history?
Variation in the length of these stages along with the way a species allocates resources to each phase defines a life history
How did the phases of life history change with primates (especially apes and humans)?
In general, we have extended each phase of life history
There is a relationship between the amount of energy that a species invests in growth and development and what?
The number of offspring produced
What is an R strategist?
Minimal investment in individual growth with a high reproductive output
What does “R” in R strategist stand for?
Rate of increase in population
What is a K strategist?
Maximum investment in individual growth and low reproductive output
What does “K” in K strategist stand for?
Carrying capacity of environment (max sustainable population size)
What is the logistical population growth model?
- When N (population size) is very small, effect of limited resources is negligible
- As N approaches K (carrying capacity), rate of population increase declines
- When N=K, there is no population growth
- When N>K, the population Celine’s because demand exceeds available resources
R strategy populations tend to have what type of enervironment? What about K strategy pops?
R=highly variable and unpredictable
K=stable, predictable environments
Which strategy (R or K or both) has a density dependent mortality rate?
K strategy= density dependent mortality
R=density independent
Does K or R strategy show faster growing populations?
R
Which strategy (R or K) has a variable population size and where do they fall in relation to carrying capacitys?
R= variable population size and below carrying capacity K= stable population and near K
How do R strategy populations compete vs K strategy?
R= compete by having high reproductive output and colonizing of new areas
K=compete by exploiting available resources
What does the species success for both R and K strategy populations rely on?
R= habitat change and chance
K=quality of offspring
What does high resource allocation go to in R strategy vs K strategy?
R=to reproduction
K= to growth and maintenance
What is the parental investment in offspring for R strategy vs K strategy?
R= low parental investment
K=large parental investment
How does the offspring birthweight and development compare between R and K strategy?
R= small/low birth weight and rapidly developing K= offspring large/high birth weight, slow developing
How does offspring mortality, life span and gestation compare between R and K strategy?
R= high offspring mortality, short life span, short gestation K= low offspring mortality, long life span, long gestation
How does weaning occur in R strategy vs K?
R= early weaning K= Late weaning
Why are oysters a good example of a very r-strategy?
They produce 500 million fertilized eggs per year and provide no parental care
Why are great apes a good example of a very k-strategy?
They produce one infant every 5 or 6 years and provide extensive parental care
What are indicators of K selection?
Increase in animal body size and complexity over time. Larger size and great complexity=K
