Lecture 4: Evolution, Biodiversity and population ecology
Natural selection
Based on 4 main observations
Limits on population growth
Differential reproductive success
Adaptive trait
Adaption
Heritable (genetic) Variation
High reproductive capacity (best will survive)
Different types of selection (directional, Stabilizing, Disruptive) see slide for diagram
Logic of natural selection
E.g. Darwins finches
Artificial Selection
Biological Diversity
Speciation
Allopatirc
Sympatric
Tree of life
Phylogenetic tree see slides for diagrams
Extinction
Background extinction: Normal species loss, Result of natural selection
Mass extinction: Atypical species loss, Sudden catastrophic loss of large numbers of species see table on slides
Endangered and threatened species
The march toward extinction
Endangered species: species that faces threat that might cause extinction within a short period
Threatened species: Species whose population has declined to a point that it may be at risk of extinction
Species At Risk Act (SARA)
slides 1-2.5
Ecological organization
On a scale of atoms to organisms, the closer something is to an organism, the more relevance to environmental science or ecology
Habitat/ Ecological Niche see slides for more info
Population ecology: How populations of organism respond to their environment
See slides for diagrams
Populations
Population size
Population density
Population distribution
Random
Uniform
Clumped
Reproductive strategies:
Resource limitations: Scarcity/ abundance of resources restricts population
Populations of species can effect other species population size
Sex ratio, age structure and birth/death rate: type 1,2, or 3 (types of reproduction/ upbringing see slide 12 for diagram
R vs K reproductive strategies