Abiogenesis and Origin of Life

• Abiogenesis is a theory regarding the origin of life on Earth
• Abiogenesis theorizes that life evolved from inanimate objects

Evolutionary Biology

• Evolutionary biologists aim to understand the causes of evolution and the history and relatedness of all life forms on Earth

Cellular Complexity

• All living things are composed of one or more complex and organized cells enclosed within membranes

Paleontological Evidence

• Modern humans may have evolved from Homo erectus approximately 250,000 years ago

Early Earth

• Around 4.6 to 3.8 billion years ago, debris from the forming solar system crashed into the early Earth, keeping its surface burning hot

Oldest Geological Evidence

• The oldest geological evidence of life comes from sedimentary rock formations, called stromatolites, dating back approximately 3.5 billion years

Cyanobacteria

• Around 3.0 billion years ago, cyanobacteria produced oxygen, transforming Earth's atmosphere and paving the way for biodiversity

Growth and Development

• Growth and development involves metabolizing compounds through cellular respiration or photosynthesis, proceeding systematically from birth to maturity

Reproduction

• Life continues and traits are passed on from generation to generation through reproduction

Irritability

• Irritability is the capacity to respond to stimuli. All organisms are sensitive to environmental or physiological changes

Homeostasis

• Living things maintain relatively constant internal conditions that differ from their external environment

First Eukaryotes

• Around 2.0 billion years ago, geological evidence indicates that life was only composed of prokaryotes

Multicellular Organisms

• Around 1.2 billion years ago, some hypothesize that multicellularity resulted from symbiotic relationships between similar or different cells, eventually leading to interdependency

Cambrian Explosion

• Approximately 500 million years ago, fossil records show a drastic increase in the diversity of complex faunal species during a relatively short time span, leading to the appearance of major animal phyla

Panspermia

• Microscopic life forms survived space and became trapped in debris expelled after a strong collision between planets

Lamarck's Theory of Adaptation

• Jean Baptiste de Lamarck (1744-1829) was an early proponent of evolution

Natural Selection

• Natural selection can lead to speciation, where one species gives rise to a new and distinctly different species
• Individuals with adaptive traits are more likely to survive and reproduce

Natural Selection Explanation

• It explains life forms evolved from a single common ancestor and that phenotypes can give advantages or disadvantages

Alfred Russel Wallace

• Alfred Russel Wallace, the Father of Biogeography, wanted to demonstrate evolution by showing how geography influenced the current distribution of species

Darwin's Evolutionary History

• Darwin proposed the evolutionary history of life forms a branching tree with many levels, tracing all species back to an ancient common ancestor

Tree Model

• More closely related groups of species have more recent common ancestors and share features from their last common ancestor

Molecular Biology

• At the most basic level, all living organisms share the same
  • genetic material (DNA)
  • genetic codes
  • basic process of gene expression (transcription and translation)
  • molecular building blocks, such as amino acids

Biogeography

• The geographic distribution of organisms on Earth follows patterns explained by evolution and the movement of tectonic plates over geological time
• The evolution of unique species on islands is another example of how evolution and geography intersect

Erasmus Darwin

• Believed in the concept of single origin and changes in species

Gregor Mendel

• Gregor Mendel (1822-1884) carried out experiments that would finally prove Darwin's concepts of natural selection
• Investigated how characteristics like pod shape, seed shape, and flower colors are inherited

Fossils

• Fossils are the preserved remains or traces of previously living organisms
• The fossil record is incomplete and most organisms never fossilize
• Fossils are often contained in rocks in layers called strata

Charles Darwin

• In 1859, Charles Darwin brought the idea of natural selection to the world's attention in his book "On the Origin of Species"

Mutation

• Mutation is a source of new alleles in a population and a change in the DNA sequence of the gene

Genetic Drift

• Genetic drift is a mechanism of evolution that refers to random changes in the frequency of alleles in a population over time

Artificial Selection

• Artificial selection is the process by which humans choose individual organisms with certain phenotypic trait values for breeding
• If there is additive genetic variance for the selected trait, it will respond to the selection, that is, the trait will evolve

Evolution

• Evolution explains the major principles in biology. All living things are descendants of organisms that lived more than 2 billion years ago
• Evolution is a dynamic and multifaceted area of research
• Comprehensively understand what causes evolution and explain the history of all life forms on Earth

Anatomy

• Anatomy is the study of the structure of living things, including plants, animals, and humans
• It examines how the body's cells, tissues, and organs are organized

Embryology

• Embryology is the study of how an organism develops from a fertilized egg into an adult

Mechanisms of Evolution

• Natural Selection
• Genetic Drift
• Gene flow
• Mutation