Evolution, phylogenetics, origin (1)

Quote by Theodosius Dobzhansky: "Nothing in biology makes sense except in the light of evolution."

Evolution explains the origin of biological diversity.
Key questions:
- Where does diversity in biology come from?
- How do new species form?
- When do we classify a species as diverging?
- Are species always in competition?
- What causes species extinction?
Example: Evolution of the genus Homo (Homo habilis, Homo erectus, Homo neanderthalensis, Homo sapiens)

Evolution: A process resulting in changes in the genetic content of populations over time, detailing inherited trait changes through generations.
Misconceptions: Evolution does not aim towards a specific goal or endpoint.

Changes at or below species level.
Involves variation in traits and frequencies among population members due to ecological shifts, environmental changes, and interspecies interactions.
May lead to new species over time but often results in fluctuating trait frequencies based on selective pressures.

Changes occurring above the species level.
Macroevolutionary changes typically observed over long time scales and inferred from fossil records, phylogenetic studies, and microevolution patterns.
Helps address present ecological phenomena, such as climate impacts on species survival.

Origin of Species by Charles Darwin outlines key evolutionary theories:
1. Evolution as such: Constant change in the world; organisms evolve over time.
2. Common descent: All organisms share a common ancestor.
3. Multiplication of species: Species diversify through splitting and budding.
4. Gradualism: Evolution occurs gradually, not through sudden changes.
5. Natural Selection: Adapted traits enhance survival and reproduction across generations.

All organisms trace back to a single origin:
- Example: Evolution of whales showcases transitional forms over millions of years.

Geographic isolation leads to new species formation, illustrated by different finch species in Hawaii.

Evolutionary change is a slow, consistent process rather than bursts of new forms.

Variations arise from mutations; survival favoring well-adapted individuals leads to population changes over time.
Key Concepts: Variation, Inheritance, Selection, Time, and Adaptation (VISTA).

Importance: Understanding evolutionary relationships, classification, forensics, and conservation efforts.
Phylogenetic Trees: Represents evolutionary relationships.

Topology: Indicates how organisms are related.
Branches: Represent genetic change; longer branches indicate more divergence.
Nodes: Points of evolutionary history.
Root: Most recent common ancestor of taxa, demonstrating evolutionary direction.
Outgroup rooting: Utilizes distantly related sequences for accurate tree rooting.

Proposed theories include:
- Panspermia: Life or its building blocks came from space.
- Spontaneous Generation: Disproven idea that life arose from non-living matter.
- Chemical Evolution: Suggests that life originated from simple chemical processes leading to complexity.
Urey-Miller Experiment: Demonstrated that organic compounds can form under prebiotic conditions.

Characteristics include cell structure, metabolism, and reproduction capabilities.

Hypothetical ancestor linking abiotic Earth and early life forms, thought to be a complex community rather than a simple organism.
Predicted properties: unicellular, RNA as genetic material, adaptability to extreme environments.

Developed by Theodor Schwann and Matthias Jakob Schleiden:
1. All organisms are made of cells.
2. Cells are the structural and functional units of life.
3. Cells arise from pre-existing cells.
Modern interpretation includes that cellular activity depends on independent cell activities.

Characteristics: Smaller in size, unicellular, no nucleus, circular DNA, lack membrane-bound organelles.
Domains: Bacteria and Archaea.

Characteristics: Larger, more complex, nuclei present, linear DNA, membrane-bound organelles.
Examples include plant and animal cells.

Key structures: capsule, cell wall, plasma membrane.
Cell Wall Variability:
- Gram-positive vs. Gram-negative bacteria, different structure and staining properties.

Distinct from bacteria, live in extreme environments, possess unique biochemical and genetic traits.
Cell walls composed of pseudopeptidoglycan, can utilize diverse energy sources.