Evolutionary Biology: Key Concepts and Theories
Key Concepts in Evolutionary Biology
PUNT (Punctuated Equilibrium): The theory suggests that there are certain periods of intense speciation which interrupt the equilibrium of normal adaptation.
Fixism: Upholds the idea that species on Earth were created by God.
Catastrophism: Proposed by Cuvier, it maintained that fossils were the remains of extinct species that had died out as a result of catastrophes.
Evolution: Maintains that species undergo a process of transformation which results in the appearance of new species.
Actualism: Held that events in Earth’s distant past were caused by the action of forces identical to those operating today.
Homologous Structures: Same origin and same basic structure, although their shape is different.
Analogous Structures: Different origin, similar shape.
Adaptation Types
Adaptation Types:
- Structural: Affects the organs. Extremities of vertebrates adapted to swim.
- Physiological: Function of organisms, e.g., dromedaries.
- Behavioral: Reproduction, food, etc., e.g., migrations.
Miller-Urey Experiment
Miller-Urey Experiment:
- They introduced gases.
- Then, they ran electricity currents through it to simulate energy from lightning.
- The products created that took place in the chamber collected in a container.
- When they extract the liquid, they analyze the biomolecules.
Biological Evolution
Biological Evolution: Refers to the process that led protocells to become different types of cells, and resulted in all the different organisms ever to have inhabited the Earth.
Endosymbiotic Theory
Endosymbiotic Theory:
- A primitive prokaryotic cell folds its membrane and creates a cell nucleus.
- The cell engulfs other prokaryotic cells.
- A prokaryotic cell creates the mitochondria.
- A prokaryotic cell creates the flagellum.
- A prokaryotic cell creates the chloroplast.
Embryological Evidence
Embryological Evidence: During the 19th century, Haeckel suggested that the different shapes that an organism’s embryo shows during development reflect the different shapes that its ancestors had during the evolutionary process. When studying the development of the embryos of some of the vertebrate species, we see something that can only be explained if all vertebrates had a common ancestor. They exhibit many similarities; embryos disappear as they develop further and begin to acquire the different traits that evolution has provided them.
Darwin’s Hypothesis
Darwin’s Hypothesis: The world is not static. The process of change is gradual and continuous. A common ancestor exists. Evolutionary changes are responsible for natural selection.
Natural Selection
Natural Selection: Process that favors the individuals in populations that are best adapted to the environment and which, over time, will lead to the appearance of new species.
Neo-Darwinism
Neo-Darwinism: Is a revised version of the theory of natural selection enriched by contributions from studies.
Embryological Evidence
Embryological Evidence: During the 19th century, Haeckel suggested that the different shapes that an organism’s embryo shows during development reflect the different shapes that its ancestors had during the evolutionary process. When studying the development of the embryos of some of the vertebrate species, we see something that can only be explained if all vertebrates had a common ancestor. They exhibit many similarities; embryos disappear as they develop further and begin to acquire the different traits that evolution has provided them.
Darwin’s Hypothesis
Darwin’s Hypothesis: The world is not static. The process of change is gradual and continuous. A common ancestor exists. Evolutionary changes are responsible for natural selection.
Natural Selection
Natural Selection: Process that favors the individuals in populations that are best adapted to the environment and which, over time, will lead to the appearance of new species.
Neo-Darwinism
Neo-Darwinism: Is a revised version of the theory of natural selection enriched by contributions from studies.
Embryological Evidence
Embryological Evidence: During the 19th century, Haeckel suggested that the different shapes that an organism’s embryo shows during development reflect the different shapes that its ancestors had during the evolutionary process. When studying the development of the embryos of some of the vertebrate species, we see something that can only be explained if all vertebrates had a common ancestor. They exhibit many similarities; embryos disappear as they develop further and begin to acquire the different traits that evolution has provided them.