Evolution and Mechanisms of Change

Evolution and Mechanisms of Change

• Evolution is the process of different living organisms developing and diversifying.
• Artificial selection is a process where humans breed organisms for specific traits.
• Natural selection is where organisms with traits suitable for their environment are more likely to survive and reproduce. Peppered moths are an example of natural selection, where moths adapt their coloration to evade predators.
• Genetic drift is a random change in allele frequencies within a population.
  • Bottleneck effect: A natural disaster drastically reduces population size, significantly impacting genetic diversity.
  • Founder effect: A small group of individuals starts a new population, also leading to a reduction in genetic diversity.
• Mutations are random changes in DNA, creating new traits. Sickle cell trait is an example of a mutation providing resistance to malaria.
• Recombination is the exchange of genetic material during sexual reproduction, creating new combinations of genes.

Patterns of Descent with Modification

• The Tree of Life illustrates the diverging paths of life forms over time.
• Descent with modification is the gradual accumulation of small changes in successive generations, leading to variations within species.
• Homologous structures indicate common ancestry in organisms: Similar body parts with a similar structure suggest common evolutionary origins.
• Australian marsupials, carrying young in a pouch, illustrate a specific evolutionary adaptation.

Speciation

• Allopatric speciation occurs when a population is geographically isolated, leading to the formation of a new species.
• Peripatric speciation involves small groups of individuals breaking off from a larger group, leading to isolation and speciation.
• Sympatric speciation occurs when individuals within the same area develop reproductive isolation and eventually new species.
• Reproductive isolation prevents successful interbreeding between populations. Examples include geographic isolation (physical barriers), behavioral isolation (different mating calls or rituals), and temporal isolation (reproduction at different times).

Precambrian

• Precambrian covers 88% of Earth's history, from 4.54 billion years ago to the Cambrian period (about 542 million years ago).
• The Hadean Eon spans 4.6 billion years ago, representing a time when rocks formed from cooling lava.
• The Archean Eon represents the ancient era, beginning a billion years after the Earth's formation.
• The Proterozoic Era is the longest geologic eon, marked by the Great Oxygenation Event and the formation of supercontinents.

Key Geological Events (Cambrian to Cenozoic)

• Cambrian Explosion: Rapid diversification of life, including the rise of complex organisms.
• Ordovician Period: Continental drift, sea level changes, and climate events.
• Silurian period: Gondwana(South), Devonian Period - Laurentia & Baltica = Euramerica
• Carboniferous & Permian periods: Vast swamp forests and the origination of new species.
• Mesozoic Era (Age of Reptiles): Dominance of dinosaurs, and Triassic-Jurassic extinction event.
• Cretaceous period: Dominance of dinosaurs and flowering plants.
• Cenozoic Era (Age of Mammals): Introduction of mammals, Quaternary Period - current geological era, diversifying mammals and birds, paleogene marking the evolution of mammals and birds.