Lecture 31: Ecology I Flashcards
What are demographics?
The vital statistic of a population over time
What is survivorship curve?
Plot of numbers/proportions in a cohort still alive at each age
What is a cohort?
A group of individuals at the same age
What are type I curves?
Large animals. They have low mortality in early/mid life and have high mortality in late life. They produce few offspring but care for children until adulthood.
What are type II curves?
Small animals. They have constant mortality rates regardless of age. They also have to face constant predation
What is type III curve?
High fecundity(lots of offspring). They have high mortality in early life. They have lower mortality at mid life and late life. They also produce many offspring but provide little to no care.
What is population growth?
Number of individuals over time
What is population size?
Births + immigrants-deaths-emigrants
What is exponential growth?
Have J shaped curve that where it grows faster when there is a large population. High birth/low death make the curve sharp. It assumes unlimited resources and continues to grow if the population has abundant food and is free to reproduce.
What is logistic growth?
Realistic curve where it assumes the earth is finite. It is more S shaped.
What is carrying capacity(K)?
Maximum population size the environment can sustain. Where as the population increases then the resources decreases
What are factors that reduce population growth?
- competition for resources
- accumulation of toxic waste
- predation
- disease
What happens when population overshoots?
It can damage the environment and many die causing the curve to fall lower
What is life history?
The schedule of reproduction and survival such when reproduction begins, how often they reproduce, how many offsprings are produced each time
What is semelparity?
It means once to beget. Organisms reproduce once in their lifetime and die after. Examples, such as salmon and agave
What is k selection?
Density dependent selection. This is because as population increases the population growth decreases, environment is at carrying capacity, high competition, stable environment. It is also the best chance to make few high investment offsprings and give them a better chance to survive. It is best to prioritize survival over reproduction. Some examples are trees.
What is iteroparity?
It means “repeat to beget”. Organisms reproduce many times and produce fewer offspring. Offsprings are larger and better provisioned to survive. Examples are mice and humans.
What is r selection?
Density independent selection. This is because population density has no effect on growth. In addition, competition is low, high level disturbance, no guarantee for survival. It is best to make many low investment offspring and prioritize reproduction over survival. Some examples of this is dandelions.
What are some evolutionary trade off?
- r selection
- k selection
What are population dynamics?
The long term fluctuations in population size
What is population cycle?
Population fluctuations at regular intervals
What are humans experiencing?
Exponential growth
where,
1650~ 500 mil
1850 ~ 1bil
1930 ~ 2 bil
1975 ~ 4 bil
2020~ 7.8 bil
Is there a carrying capacity for humans?
Not sure. Since there is evidence for low birth rates and limited resources
What is ecological footprint?
The summary of land/water resources required to sustain the activities for each person
What is the average world wide footprint vs US footprint?
1 hectare vs 10 hectare
In short, we use a lot of energy and if everyone ate like us, then only half of the population can be supported and would overshoot carrying capacity.
