EVOLUTION

Charles Darwin

Voyage of the Beagle

The Galapagos Islands Dates: Left England in 1831, Galapagos in Islands: each with a different climate and ecosystem Darwin Collected Fossils & live organisms from each island: – Tortoises: variations in shell – Finch Birds: variations in beak and color – Blue-Footed Boobies – Marine Iguanas

Animals

Darwin’s Conclusion Variation: Individual organisms in a species look different from one another Hypothesis: New species could appear gradually due to small changes in an original species – Cannot see the changes occur, so looked to BREEDING

Natural Selection vs. Artificial Selection Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful. – Ex. BREEDING

Evolution by Natural Selection “Nature Selects” The Struggle for Existence: – members of each species have to compete for food, shelter, other life necessities “Survival of the Fittest”: – Some individuals better suited for the environment due to physical traits – Allows them to REPRODUCE & pass on genetic traits

Struggle For Existence & Survival of The Fittest

Natural Selection Four Principles of Natural Selection – Individuals in a population show differences, or VARIATIONS – Variations are INHERTIED (genes) – Organisms have more offspring than available resources – Any variations that increase survival are passed on to future generations

Types of Natural Selection “Fur color” Directional Selection (Dark OR Light) Stabilizing Selection (Medium) Disruptive Selection (Dark AND Light

Darwin’s Theory of Evolution Published a book, On the Origin of Species by Means of Natural Selection, in 1858 Used the term “evolution” on the LAST PAGE! Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. Evolution

Evidence of Evolution The Fossil Record Geographic Distribution of Living Things Comparative Anatomy Similarities in Embryology Biochemistry discoveries/videos/evolution.htm discoveries/videos/evolution.htm

Evidence for Evolution The Fossil Record- Layers in Earth’s crust show change The deeper the fossil, the older it is Compare old and new fossils

Evidence of Evolution Geographic Distribution of Living Things: Organisms that live in similar environments have similar characteristics, even if far apart

Evidence of Evolution Comparative Anatomy – Homologous Structures: anatomically similar structures inherited from a common ancestor – Analogous Structures: structures that are anatomically different, but have the same purpose, came from different ancestor – Vestigial Organs: organs that do not serve a purpose, lost through evolution and mutation (ex. Appendix, tail

Evidence for Evolution Comparative Embryology: embryos of different organisms are similar, came from common ancestor

Adaptation Basis of Natural Selection Organisms CANNOT choose to have an adaptation…controlled by DNA Adaptation increases FITNESS: ability to survive and reproduce

Types of Adaptation Camouflage: ability to blend with environment Mimicry: ability to resemble another species m/category/endangered-species

Mary River Turtle

Skull Caterpillar (Australia)

Glauert's seadragon

Human Ancestors 99% identical DNA between Humans and Apes Australopithecus africanus: small brain, big teeth, walked on all 4 limbs Australopithecus africanus Homo habilis: larger brain, 1 st to use tools, smaller molars Homo erectus: first to always stand completely upright, most “human” like qualities Homo neaderthalensis: unsimilar mitochondrial DNA and Y-chromosome material, scientists think they were separate species, no our ancestors! Homo sapien : US

“Finding Lucy” 8dM 8dM

“Ardi” Ardipithecus ramidus – 1992 – 50kg Female – Missing “step” between chimp and human; had both sets of characteristics – Bipedal on land, Quadruped in trees

EVOLUTION FUN FACTS… Homo sapiens is still evolving rapidly. Homo sapiens has only had a culture for less than 50,000 years. The human population crashed about 80,000 years ago. Humans have incredibly low genetic diversity. We Share 70% of our DNA with a Slug.

Causes of Evolution If alleles in a population remain the same, evolution will remain at EQUILIBRIUM; no change. Disruptions of Equilibrium: – Mutations (changes in DNA) – Natural selection (change in environment causes certain traits to be more favorable) – Random mating (mating outside of the population) – Genetic Drift – Gene Flow

Genetic Drift Change in allele frequency Founder Effect: small group of organism settle in an area separated from population – Ex. Amish People Bottleneck Effect: population declines in size, then rebounds – Ex. Northern Elephant Seals – Humans hunted them, population decreased, now less variation in current populatioin

Gene Flow Genes/traits in a population remain the same until new organisms enter or leave the population

Speciation Formation of a new species Allopatric – Creation of a new species due to a physical barrier – Ex. Grand Canyon; Kaibab vs Abert Squirrel Sympatric – Creation of a new species without a physical barrier – Ex. Several insects and plants, change in chromosome number

Patterns of Evolution Adaptive Radiation – Aka Divergent Evolution – Species diverged from a single ancestor – Usually due to different environments Coevolution – Species evolve in close relationship with other species Convergent Evolution – Unrelated species evolve to form similar adaptations, due to living in similar environments

Coevolution of Humans & Dogs!

Evolution video shorts le-people-flores.html evolution of …HOBBITS?! le-people-flores.html coding-neanderthals.html decoding neanderthals coding-neanderthals.html hat-makes-us-human-pro.html becoming human hat-makes-us-human-pro.html

Hmm…Ha Ha Ha! Are humans the only species that can laugh? Why do we laugh? Does the ability to laugh help organisms to survive? tion-laughter.html evolution of laughter! tion-laughter.html