Maddie Fox

Charles Darwin Born in England Received his B.A. from Cambridge Darwin serves as ship naturalist on the HMS Beagle Wrote essay on the origin of species and natural selection, but was reluctant to publish, wanted more evidence Read Alfred Russel Wallace’s manuscript containing a theory on natural selection 1859-Published On the Origin of Species by Means of Natural Selection

The Origin of Species 1. Today’s organisms descended from ancestral species that were different from modern species. 2. Natural selection provided a mechanism for this evolutionary change  The basic idea of natural selection is that a population can change over time if individuals that posses certain heritable traits leave more offspring than other individuals.  Natural selection results in evolutionary adaption, an accumulation of inherited characteristics that increase the ability of an organism to survive and reproduce in its environment.

Jean-Baptiste de Lamark Two Main Concepts  Use and Disuse: Idea that body parts that are used extensively become longer and stronger, while those that are not used deteriorate.  Inheritance of Acquired Characteristics: Modifications that are acquired during the life of an organism could be passed on to offspring.

Origin of Life: Problems For spontaneous origin of life on earth to occur, four specific processes would have been needed. 1. Synthesis of organic molecules 2. Synthesis of polymers from organic molecules 3. Mechanisms for the self-replication of organic molecules 4. Packaging of these molecules inside of membranes.

Origin of Life: Solutions Organic compounds could have been formed or delivered from:  Space, delivered by comets  Intertidal zones  Near volcanoes  Deep-sea hydrothermal vents

Speciation Speciation is the formation of a new species and is initiated when a single gene pool is separated by various kinds of barriers. Barriers could include:  Geographic isolation  Hybrid infertility  Temporal isolation  Behavioral isolation

Terms of Speciation  Allopatric speciation: Geographic separation  Sympatric speciation: Same geographic area  Adaptive radiation: Development of many species from a common ancestor  Divergent evolution: Species evolve to become increasingly dissimilar  Convergent evolution: Species evolve to become more alike

Half-Life Radioisotopes are often used to identify the age of rocks and fossils. Half-life is the time it takes for half of a radioactive isotope to decay. An object that contains a radioactive isotope will give off half of its radioactivity after one half life had passed. # of half-lives elapsed Fractions remaining Percentage remaining 01/ /250 21/425 31/ / / n1/2ⁿ100(1/2ⁿ)