Origin of Species• The term species refers to individuals in a population that are free to

breed and that produce viable offspring, without outside intervention, that can carry on the lineage. Speciation, or how species arise, can be further broken down using the concepts of micro and macroevolution.– microevolution - species arise through a divergence of breeding populations

that subsequently change the gene frequencies in a gene pool – macroevolution - evolutionary change above the species level such as the

evolution of birds from dinosaurs

Evolutionary Factors

• Catastrophes, competition, and changes in the environment drive evolution

• Evolution can be separated into 3 major divisions.– Divergent, parallel, & convergent

Factors that lead to speciation

• Convergent Evolution– 2 different unrelated

species that start to exhibit similar phenotypes due to having habitats with similar ecological pressures

Factors that lead to speciation

• Coevolution (parallel)– 2 different species tied together in

the same ecosystem evolve together• Flowers and the bees that pollinate

them• Disease and host resistance• Predator and prey

Factors that lead to speciation• Divergent Evolution

– Starting from the same species two breeding populations are exposed to different ecological pressures• Adaptive radiation - the evolution of

many diversely adapted species from a common ancestor upon introduction to a new environment

- Geographical isolation (founder effect)… Ex: HI islands and introductions of species.

- Mechanical or behavioral isolation- changing food source or environment

Changes that lead to Macroevolution.

• shows model of punctuated equilibrium - new species is formed from parent then is stable (stasis) for many years – Following mass extinction ecological

niches open up freeing resources– Assumes low competition & stable

environment