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
