On the Origin of Species Darwin’s 5-year voyage began Dec. 1831 He formulated the theory of how species evolved and wrote a 231 page outline in 1844 He continued to gather evidence for another 15 years to support his theory

Alfred Russel Wallace (1823-1913)

A.R. Wallace A British naturalist, evolutionist, geographer, anthropologist He spent many years, from 1848, studying organisms in the Amazon and Rio Negro regions of South America In 1854 he began his studies in the Indonesian region, collecting 125,600, and discovering more than a thousand new species He wrote an essay entitled “On the Tendency of Varieties to Depart Indefinitely from the Original Type” and sent it to Darwin

Darwin gave the essay to Charles Lyell (geologist) and Joseph Hooker (botanist) to present at the meeting of the Linnaean Society, along with some of his own writings This prompted Darwin to quickly finish his book 1859 On the Origin of Species was published

Natural Selection The basic premise behind Darwin’s work is that species evolved by the process of natural selection; i.e., the way individuals in an environment are able to survive to reproduce over those individuals who cannot Traits that lead to characteristics favouring survival and ability to reproduce would be passed on to the next generation

Herbert Spencer (1820-1903) Was a sociologist, philosopher, biologist (i.e., polymath) who coined the phrase “survival of the fittest” to describe natural selection

More Terms to Know Adaption = a characteristic that makes a species better suited to survive and reproduce in an environment Evolution = the result of natural selection, occurring over many years

Consolidate the Concepts Read pages 304 – 307 Do questions on page 307 #1-5, 7, 8

Modern Evolutionary Synthesis This is the field of evolutionary biology studied today Takes into consideration genetics, botany, entomology, cellular biology, molecular biology, and more Darwin’s theory focused on the inherited traits of a species over time Modern scientists focus their work on changes in the gene pool over time

Radiometric Dating A process of determining the age of rocks from the decay of their radioactive elements An isotope of an atom contains the same number of protons as the atom but different numbers of neutrons, hence has a different atomic mass A radioisotope is an atom with an unstable nucleus

Half-Life Radioisotopes decay at a unique and constant rate Rate at which decay occurs is counted in half lifes Half-life = the amount of time it takes a substance to decay to half its original mass Half-life of 14C is 5730 years Half-life of 10Be is 1.5 million years and the radiogenic daughter isotope is 10B

Fig 1. pg 308

Carbon Dating Radioactive carbon-14 has 6 protons and 8 neutrons A high-energy particle is released changing a neutron into a proton Daughter isotope is nitrogen (7 protons and 7 neutrons), which is a stable atom The age of organic material can be determined using carbon dating

More About Mutations Mutations can create new or altered traits Misalignment during cross-over in prophase 1 of meiosis

Misalignment of Genes Mutation from misalignment can result in extra copies of genes or missing genes If there’s a mutation on the extra gene, it could result in new trait, and still be able to make the protein from the other gene copy Gametes containing missing genes may not produce a viable zygote

Homologous Genes Closely related species inherit homologous genes – genes with the same nucleotide sequences Shows there is a common ancestor The more unrelated the species are, the bigger the difference in nucleotide sequences

Homologous Genes

Pseudogenes Vestigial genes that no longer code for a functioning protein Further evidence of a shared common ancestor If pseudogenes mutate, no harm is done to the organism

Paleontology The investigation of prehistoric life through the study of fossils The distribution of fossils helped Darwin formulate his theory of evolution The location of similar fossils from disparate regions posed a problem until the theory of continental drift, proposed by Alfred Wegener in 1912

Plate Tectonics This is the modern version of continental drift, developed from the 1950s through to the 1970s The Earth’s outer shell is divided into plates that glide over the mantle (the rocky inner layer above the core)

Consolidate the Concepts Read pages 308-313 Do questions on page 313, #1-9