Biology IB: evolution

Biological evolution

A change in the allele frequency of a population’s gene pool over successive generations

Cumulative change

Small changes upon small changes over many generations occur

Heritable factors

Gene-controlled factors

The fossil record

The sum of all discovered and undiscovered fossils and their relative placement in rock

Direct fossils

Body fossils such as teeth, bones, shells, etc

Indirect fossils

Trace fossils such as footprints, tooth marks, tracks

How is selective breeding evidence for evolution?

Domestic animal breeds show far greater variation than wild animal species that are subject only to natural selection. Artificial selection can accelerate evolution.

Homologous structures

Those structures similar in shape in different types of organisms

Example of homologous structures

Humans, cats, whales and bats all have pentadactyl limbs with five phalanges (in humans they are fingers)

Adaptive radiation

the diversification of a group of organisms into forms filling different ecological niches.

Vestigial structures

An organ or part of the body that has become defunct in the process of evolution but remains (eg. the appendix)

Comparative DNA

Phylogenetic tree

AKA evolutionary tree. A graphical representation which shows the evolutionary history between a set of species or taxa during a specific time

What is the difference between a phylogram and a cladogram?