Subject: Biology II: Evolution by Natural Selection
Instructor: Dr. Tarushika Vasanthan
Department: Chemistry & Biology
Darwin's Definition of Evolution:
Descent with modification: Change over time leads to modern species from ancestral species.
Predictions of Natural Selection:
Species change over time.
Species are related through common ancestry.
Fossils: Traces of organisms from the past constitute the fossil record.
Fossil Organization:
Fossils organized by relative age in sedimentary rocks.
Younger layers sit atop older layers.
Geologic Time Scale: Divided into eons, eras, periods, and epochs, indicating the Earth is over 6000 years old.
Absolute Dating: Employs radioactive decay to assign precise ages.
Extinction Evidence:
Fossils provide evidence for extinct species; species are dynamic and change over time.
Over 99% of all species are extinct.
Extinctions have occurred continuously throughout Earth's history.
Law of Succession: Similarity between fossil and living species supports species change over time.
Transitional Features:
Traits in fossils that are intermediate between ancestral and derived species, strong evidence of evolutionary change.
Example: Gradual transition from aquatic fins to terrestrial limbs.
Definition: Reduced or incompletely developed structures that have no or reduced function.
Significance: Inconsistent with special creation; evidence species have changed over time.
Documented changes:
Bacteria evolving drug resistance.
Insects developing pesticide resistance.
Plant adaptation to herbicides and climate-related changes.
Evolution continues in real-time.
Evidence Against Immutability: Fossil records and current species indicate relatedness.
Island Species: Striking similarities among species in the same geographic area.
Mockingbirds' Example: Darwin's hypothesis of common ancestry supported by DNA analyses.
Phylogenetic Tree: Illustrates ancestor-descendant relationships.
Homology Defined: Similarity in species descended from a common ancestor, studied at three levels:
Genetic
Developmental
Structural
Similarity in DNA or protein sequences (e.g., eyeless gene in fruit flies vs. Aniridia gene in humans).
Similar embryos across species (e.g., tails and gill pouches in various vertebrates).
Similar adult structures (e.g., common limb bone arrangement in vertebrates).
Hypotheses can be tested, such as gene transfer experiments leading to functional changes in different organisms.
Non-static Nature of Species:
Fossil records indicate species change over time; transitional and vestigial traits are common.
Species Relatedness: Geographic similarities and homologous traits exist at genetic, developmental, and structural levels.
Consistency of data from independent sources supports evolutionary theory (e.g., cetacean evolution).
Relative and absolute dating consistently supports evolutionary trends.
DNA analysis strengthens the close relationship between hippos and cetaceans.
**Misconceptions about Natural Selection: **
Individuals do not change; populations evolve.
Natural selection is not goal-directed and does not result in "higher" organisms.
Fitness Trade-Offs: Adaptations come at a cost; traits may be compromised for efficiency.
Genetic Constraining and Historical Constraints: Traits evolve from pre-existing structures; adaptive evolution is influenced by historical factors.
Define evolution, fitness, and adaptation biologically.
Assess Darwin's postulates and apply examples in real scenarios.
BLG144_Week 1_Jan 13
Subject: Biology II: Evolution by Natural Selection
Instructor: Dr. Tarushika Vasanthan
Department: Chemistry & Biology
Darwin's Definition of Evolution:
Descent with modification: Change over time leads to modern species from ancestral species.
Predictions of Natural Selection:
Species change over time.
Species are related through common ancestry.
Fossils: Traces of organisms from the past constitute the fossil record.
Fossil Organization:
Fossils organized by relative age in sedimentary rocks.
Younger layers sit atop older layers.
Geologic Time Scale: Divided into eons, eras, periods, and epochs, indicating the Earth is over 6000 years old.
Absolute Dating: Employs radioactive decay to assign precise ages.
Extinction Evidence:
Fossils provide evidence for extinct species; species are dynamic and change over time.
Over 99% of all species are extinct.
Extinctions have occurred continuously throughout Earth's history.
Law of Succession: Similarity between fossil and living species supports species change over time.
Transitional Features:
Traits in fossils that are intermediate between ancestral and derived species, strong evidence of evolutionary change.
Example: Gradual transition from aquatic fins to terrestrial limbs.
Definition: Reduced or incompletely developed structures that have no or reduced function.
Significance: Inconsistent with special creation; evidence species have changed over time.
Documented changes:
Bacteria evolving drug resistance.
Insects developing pesticide resistance.
Plant adaptation to herbicides and climate-related changes.
Evolution continues in real-time.
Evidence Against Immutability: Fossil records and current species indicate relatedness.
Island Species: Striking similarities among species in the same geographic area.
Mockingbirds' Example: Darwin's hypothesis of common ancestry supported by DNA analyses.
Phylogenetic Tree: Illustrates ancestor-descendant relationships.
Homology Defined: Similarity in species descended from a common ancestor, studied at three levels:
Genetic
Developmental
Structural
Similarity in DNA or protein sequences (e.g., eyeless gene in fruit flies vs. Aniridia gene in humans).
Similar embryos across species (e.g., tails and gill pouches in various vertebrates).
Similar adult structures (e.g., common limb bone arrangement in vertebrates).
Hypotheses can be tested, such as gene transfer experiments leading to functional changes in different organisms.
Non-static Nature of Species:
Fossil records indicate species change over time; transitional and vestigial traits are common.
Species Relatedness: Geographic similarities and homologous traits exist at genetic, developmental, and structural levels.
Consistency of data from independent sources supports evolutionary theory (e.g., cetacean evolution).
Relative and absolute dating consistently supports evolutionary trends.
DNA analysis strengthens the close relationship between hippos and cetaceans.
**Misconceptions about Natural Selection: **
Individuals do not change; populations evolve.
Natural selection is not goal-directed and does not result in "higher" organisms.
Fitness Trade-Offs: Adaptations come at a cost; traits may be compromised for efficiency.
Genetic Constraining and Historical Constraints: Traits evolve from pre-existing structures; adaptive evolution is influenced by historical factors.
Define evolution, fitness, and adaptation biologically.
Assess Darwin's postulates and apply examples in real scenarios.