Evidence of Evolution
• Fossil Records
• Geographic distribution of living things
• Homologous structures of organisms
• Similarities in early development
• Darwin proposed that Earth was millions of years old, not thousands.
• During those millions of years, many different forms of species appeared, lived for a time, and then vanished leaving behind remains, or fossils.
• One can examine fossils and view the changes of each one; observe the changes in offspring.
• Each species is slightly different on Island A. Far away, on Island B, the species were also slightly different.
• The species had changed over time as the populations in different places adapted to local environments.
• The species had descended with modifications from a mainland ancestor – when Island A and Island B were combined as a contiguous land mass.
• Different species exist on Island C and Island D. Similar structure and behavior were found in different animals which roamed similar environments.
• As a result, one can conclude that the species now living on different islands had descended from different ancestors.
• Some species, however, are similar because they were
Fitness is a result of adaptation; adaptation is any inherited characteristic that increases an organism"tms chance of survival. Descent with modification implies that all living organisms are related to one another. MacroevolutionFive important patterns of macroevolution are mass extinctions, adaptive radiation, convergent evolution, coevolution, and punctuated equilibrium. Survival of the FittestThe ability of an individual to survive and reproduce is fitness - how well suited an organism is to its environment. Let"tms take birds and bats for example. Sometimes organisms that are closely connected to one another by ecological interactions evolve together. In order to prove evolution of a species, there must be enough inheritable variation in those traits to provide raw material for natural selection. -Behavioral isolation occurs when two populations are capable of interbreeding but have differences in courtship rituals or other type of behavior; like mating calls or songs-Geographic isolation is when two populations are separated by geographic barriers, like a river or lake. If three similar species of flowers were to release pollen on different days, they cannot pollinate another. Compare the front limbs, and one can observe that all bird wings are more similar to one another than any of them to bat wings. -Temporal Isolation takes place when two or more species reproduce at different times; like a flower releasing pollen. In natural selection, only certain individuals of a population reproduce new individuals. Microevolution is a minor change within a species or small group of organisms in a short period of time. -One must record variation; which organisms had lived and which had died, which had succeeded in breeding and which had not. This process, by which unrelated organisms come to resemble one another, is called convergent evolution.