2Evolutionary biology addresses fundamental questions Why are there so many different kinds of organisms?Why are organisms so proficient at life tasks: finding food, acquiring mates, fighting disease, and avoiding predators?
3OVERVIEW: Four Main Points to the Theory of Evolution. Variation exists within populations.Some individuals of a population are better suited to their environment.Over time, traits that make certain individuals of a population able to survive and reproduce tend to spread in that population.There is clear proof from fossils and many other sources that living species evolved from organisms that are now extinct.
4Does Variation Exist Within the Genes of every population or species (the result of random mutations)?
6Natural Selection Acts on These Heritable Variations of Traits. Working definition of Natural Selection:Natural Selection is the process by which populations change in response to their environment. Individuals better adapted to the environment leave more offspring than those individuals not suited to the environment.
7HOW ABOUT A REAL LIFE EXAMPLE, BEYOND THE CARTOONS. Do individuals who are better suited to their environment really leave more offspring than others?HOW ABOUT A REAL LIFE EXAMPLE, BEYOND THE CARTOONS.DayDayDay
8Real Life Examples of Evolution Natural Selection in Action
11A hypothesis for the explaining the increase in dark moths was formed using Darwin’s theory of evolution by natural selection.Hypothesis: The dark variety was camouflaged on the soot-darkened bark and so are not eaten by birds.
12The ExperimentPopulations of light and dark peppered moths were raised in the laboratory.Moths were marked so they could be identified laterMoths were released into two separate wooded areas.Birmingham= Heavily pollutedDorset = unpolluted
14Overcoming Misconceptions The darkened trees did not cause the darker variant of moth to appear.The darker characteristic was already present in the population.The “new” environment merely favored the survival of the darker moths.
15Beyond the Fossil Record Evidence of EvolutionBeyond the Fossil Record
16How Does Anatomy and Structure Show Evidence of Ancestry? Comparing the anatomy of different types of organisms often reveals basic similarities in body structures, even though their functions may be very different.
17Common AncestorA Species from which two or more species have diverged.
23Vestigial StructuresVestigial structures are anatomical structures of organisms in a species, which have lost much or all of their original function.Structures that are considered to be evidence for an organisms evolutionary past.
32How are Biological Molecules a Record of Evolution? Species that share common ancestry more closely, have more amino acid sequence in common.Species that have diverged from a distant common ancestor have more differences in amino acid sequences.
47Is the Fossil Record Complete? No, it most certainly isn’t.
48The probability that any particular organism that once existed, is part of the fossil record today is rare.For Three Good Reasons. . .Fossil formation is a rare eventFossils survival is a rare eventAn exceedingly small fraction of surviving fossils will ever be found