Chapter 8 Biological Evolution

Biodiversity The variation among organisms in an ecosystem Kinds of Biodiversity Ecosystem diversity – variety of ecosystems available Species diversity – the number of different species of organisms Genetic diversity – distinguishes among individuals within a species.

Genetic Diversity Evolution – when new species evolve from preexisting species over long periods of time. Adaptation – a change in structure of function that allows an organism to be more successful. Extinction – the condition where there are no living representatives of an organism.

Eubacteria Archaebacteria Fungi Plantae

The Fossil Record Fossil – the remains or body impressions of an organism that lived in the past. Fossil record – all the fossils that have been found since the study of fossils began. Index fossils – fossils recognized as unique to certain time periods.

How old is a fossil? Carbon dating – type of dating which uses the rate of radioactive decay of isotopes (Carbon-14) to determine that age of rocks and fossils.

Origin of the Species 2 Theories Special Creation or Intelligent Design – the belief that every organism is created by God. Evolution – the belief that organisms go through a process of change over time and develop new species from preexisting species.

Charles Darwin Theory of Natural Selection – organisms best suited to the environment are the ones most likely to survive and reproduce.

Mechanisms of Evolution 1. Environment and Variations 2. Mutations 3. Gene Flow 4. Genetic Drift

Environment and Variation Natural variation within a population allows for some individuals to survive over other individuals in a changing environment. This natural variation can lead to the formation of new species, which is called speciation.

Mutations Mutations are random changes in DNA that act as another mechanism for evolution.

Gene Flow Gene Flow is the change in the occurence of genes in a population. Immigration – can bring new genes into a population Emmigration – can take genes out of a population and can lead to the formation of new species.

Genetic Drift Genetic drift provides random changes in the occurrence of genes through chance events. When a few individuals of a population break off from the original group and start their own population is called th founder effect. Bottlenecking occurs when a large number of the population is killed because of disease, starvation, change in natural environment, or a natural disaster. Inbreeding between few individuals leads to populations that have very few genetic differences which make them more susceptible to disease.

Patterns of Evolution 1. Convergent evolution 2. Divergent evolution 3. Adaptive radiation 4. Co-evolution 5. speciation

Convergent Evolution Convergent evolution occurs when unrelated species can develop similar characteristics. Ex: Shark and Porpoise

Divergent Evolution Divergent evolution occurs when many species develop from a common ancestor

Adaptive Radiation Adaptive radiation occurs when many species evolve from a single ancestral species after entering a new environment.

Co-evolution Co-evolution occurs when two or more organisms in an ecosystem evolve in response to each other.

Speciation Speciation is the development of a new species. Allopatric speciation occurs when a population becomes geographically divided. Sympatric speciation exists when differences in habitat, sexual production, or heredity isolate members of a population from one another.