Evolution Types of Evolution Microevolution evolution within a

Evolution

Types of Evolution • Microevolution- evolution within a species • Macroevolution- evolution that produces a new species • Origins of life according to evolution

Evolution by Natural Selection • Mechanism of evolution- evolution is what happens, natural selection is how it happens • Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to have more offspring than other individuals which leads to the accumulation of favorable traits in a population over generations

Evolution by Natural Selection • Traits must be genetically based • Genes must lead to a reproductive advantage • Causes the allele frequency in the population to change • Takes many generations • Remember: favorable traits are based on the environment

• Evolution- change in allele frequency in a population over time (decent with modification) • Population- Group of individuals of a single species that occupy the same general area • Allele- an alternative version of a gene • Gene- a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA, codes for a protein that leads to a physical characteristic

Lamarckian Evolution Lamarck’s theory is incorrect 3 concepts • Theory of need • Theory of use and disuse • Theory of inheritance of acquired characteristics

Charles Darwin Naturalist on the HMS Beagle Surveying ship 5 year voyage beginning in 1831 Made observations and collected specimens along the way, many from the Galapagos Islands • Returned to England began to develop his theory of Evolution • •

• Galapagos finches that Darwin observed have different beaks based on the food that they eat • Darwin believed the differences in their beaks were due to evolution • He believed the different species of finches adapted to different environments at different times, so they could get the food that was available there • Darwin believed they evolved from a common ancestor

Charles Darwin • Published “On the Origin of Species by Means of Natural Selection” in 1859 • Published “The Descent of Man” in 1871

Artificial Selection Species definitely have the ability to change over time to become very different than what they once were. In artificial selection we select what alleles we want to be passed to the next generation over others.

Survival of the fittest • Somewhat misleading • Does not necessarily mean physical strength • It means better adapted to the current environment

What leads to Evolution? • There must be genetic variation within the population – Mutation- altering of the nucleotide sequence can make a gene more advantageous. • Environmental change- an allele that was once not an advantage becomes an advantage because the environment is different. • Immigration (gene flow)- individuals with more advantageous genes join a population. • Genetic drift- random selection of a gene because of an event that significantly decreases population size and eliminates all or most individuals with a particular gene.

The evolution of organisms is constrained. 1. Selection can act only on existing variations. New, advantageous alleles do not arise on demand. 2. Evolution is limited by historical constraints. Evolution co-opts existing structures and adapts them to new situations. 3. Adaptations are often compromises. The same structure often performs many functions. 4. Chance, natural selection, and the environment interact. Environments often change unpredictably.

Microevolution • Pests and pesticides • Bacterial resistance to antibiotics • Selection to avoid predation Microevolution- evolution within a species

Evidence

Macroevolution • Macroevolution- evolution that produces a new species • What is a species?

Species • A species according to the biological species concept is a group of populations whose members have the potential to interbreed in nature and produce fertile offspring

Reproductive Barriers Prezygotic Barriers • Habitat isolation- species live in different habitats within the same area and rarely meet • Temporal isolation- breeding occurs at different times of the day or different seasons • Behavioral isolation- different courtship rituals or other behaviors prevent mate recognition between species • Mechanical isolation- differences in physical structures prevent successful mating • Gametic isolation- male and female gametes of different species fail to unite Birds of Paradise – Mating Dance https: //www. youtube. com/watch? v=W 7 QZnw. Kqopo

Reproductive Barriers Postzygotic Barriers • Reduced hybrid viability- the development or survival of hybrids is impaired • Reduced hybrid fertility- hybrids fail to produce functional gametes • Hybrid breakdown- offspring of hybrids are feeble or infertile

Figure 14. 3 G Horse Donkey Mule

Macroevolution Allopatric Speciation 1. Geographic barrier splits a population 2. Microevolution occurs separately in the populations 3. Some kind of reproductive barrier evolves so that even if the populations were brought back together, individuals from the 2 populations could not produce fertile offspring and they would be considered two different species

Figure 15. 7 B Zones of violent tectonic activity Direction of movement North American Plate Juan de Fuca Plate Eurasian Plate Caribbean Plate Arabian Plate Cocos Plate Pacific Plate Nazca Plate Philippine Plate South American Plate Scotia Plate Indian Plate African Plate Antarctic Plate Australian Plate

Figure 15. 8 Pacific Plate North American Plate San Francisco San Andreas Fault Los Angeles California

Origins of Life

Creation/Evolution • We are going to look at theory for how all life could have evolved from a common ancestor through natural processes. • We want to look at the evidence for this part of evolution. • Some use theories as a way to justify their atheism. • I believe God was involved in some way. • Even if you don’t agree with any of the origins of life theory, it is important to understand it so you can explain why your theory is better.

Creation/Evolution • There are different theories for how creation and evolution can coexist. • We will look at these in more detail later. Christian organizations that agree with much of evolution: • Reasons to Believe • Bio. Logos

Origin of Life According to Evolution • Abiotic synthesis of monomers – Miller/Urey experiment 1953 - mixed gases that simulated the early atmosphere, according to theory at that time. Used an electric spark to simulate a lighting strike that could have provided the energy to rearrange the atoms. Some amino acids and hydrocarbons formed. – Whether or not Miller/Urey’s mixture of gases accurately simulated the early atmosphere is debated • Monomers spontaneously join to form polymers • Protocells form- membrane enclosed droplets that can maintain an internal chemistry different than the surrounding environment

Origin of Life According to Evolution • Self-replicating molecules form – Complimentary pairing of RNA nucleotides – Later DNA replaced RNA as the primary genetic material

Figure 15. 3 B_s 1 C G A G C G U A C 1 A Collection of monomers G

Figure 15. 3 B_s 2 C G A G C G U A C 1 A Collection of monomers U A A C U G C G U G C A U G G C 2 U U U Formation of short RNA polymers: simple “genes”

Figure 15. 3 B_s 3 C G A G C G U A C 1 A Collection of monomers U A A C G U A C U G C A G U G C A U G G C 2 U U U Formation of short RNA polymers: simple “genes” 3 Assembly of a complementary RNA chain, the first step in the replication of the original “gene”

Origin of Life According to Evolution • Prokaryotes – Stromatolites are believed to be some of the earliest fossils. They are layered rock columns formed by photosynthetic prokaryotes. Still built today

Origin of Life According to Evolution • Single celled eukaryotes – Endosymbiont theory- mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells – These organelles have their own DNA • Multicellular eukaryotes

Evidence • Fossils- any direct or indirect evidence of a once-living organism • Definitely there were things that were different than the things that are alive today, and some appear to be intermediates, like Archaeopteryx, which is somewhat bird-like and reptile-like

Evidence • Biogeography- many fossils and organisms are more alike when they are closer geographically. • The earth is changing – Tectonic activity- Earth’s crust is divided into plates that move – Earthquakes, volcanoes

Cenozoic Present 4 65. 5 3 ca eri m h. A rt No Eurasia Africa South America India Madagascar Laurasia 135 2 Mesozoic Gondwana Pangaea 251 1 Paleozoic Millions of years ago Antarctica a rali st Au

Evidence • Comparative Anatomy- mainly deals with similarities in bone structure and stages of embryological development. • Homologous structures- parts in different species that are structurally similar, but serve different functions

Evidence • Molecular Biology- common genetic “language”, which is DNA and RNA.

Table 15. 6