AP Bio Unit 7 Evolutionary Theories

Darwin and Evolution

• Charles Darwin was a 19th-century naturalist known for his studies aboard the HMS Beagle.
• Proposed that species are related through common descent with natural variation leading to adaptation and diversity.

Lamarck's Ideas

• Jean-Baptiste Lamarck was the first scientist to advocate for the theory of evolution.
• Believed complex organisms evolved from simpler ones and introduced the concept of inheritance of acquired characteristics.

Structural Comparison

• Homologous structures are anatomical features that share a common ancestry despite possible functional differences.
• Analogous structures have similar functions but do not share a common ancestor.

Vestigial Structures

• Vestigial structures are remnants of organs or genes that no longer serve a functional purpose.
• Provide evidence of common ancestry as these structures were once functional in ancestral species.

Selection Mechanisms

• Artificial selection refers to the human-directed breeding of organisms for desired traits.
• Natural selection involves variations within species, competition, differential fitness, and adaptation to environments.

Hardy-Weinberg Equilibrium

• Hardy-Weinberg principle states allele frequencies remain constant in a population under specific conditions: no mutations, extensive gene flow, random mating, no genetic drift, and no selection.

Limitations of Darwin's Work

• Darwin could not consider molecular evidence for evolution due to the lack of technology for analyzing amino acid differences.

Natural Selection

• Defined as "survival of the fittest," it favors organisms best adapted to their environment.

Fossil Evidence

• Biochemical evidence, such as comparing amino acid sequences, can be utilized to ascertain relatedness between similar but not identical fossils.

Biogeography

• The study of the geographical distribution and range of species, providing insights into evolutionary relationships.

Transitional Forms

• Archaeopteryx serves as a transitional fossil linking dinosaurs to birds, illustrating the evolution of species.

Cuvier and Comparative Anatomy

• Georges Cuvier was a 19th-century zoologist and the founder of paleontology, advocating catastrophism as an explanation for the sudden appearance of new species in the fossil record.

Inheritance of Traits

• The idea that cutting off mice tails could lead to shorter tails in offspring stems from Lamarck's theory, which is now known to be incorrect.

Selection Types

• Directional selection favors extreme phenotypes, shifting population traits in that direction.
• Stabilizing selection favors intermediate phenotypes, leading to less variation.
• Disruptive selection favors two or more extreme phenotypes over intermediates.

Population Genetics

• A gene pool consists of all the genes and alleles present in a population.
• Genetic drift describes fluctuations in allele frequencies resulting from random sampling effects.

Gene Flow

• Involves the transfer of alleles into or out of a population, often through migration.

Founder Effect

• Occurs when a small group establishes a new population, leading to reduced genetic diversity and prevalence of certain alleles.

Microevolution

• Refers to small evolutionary changes within a population, often in contrast to the expectations set by Hardy-Weinberg equilibrium.

Speciation

• Speciation is the formation of new species due to reproductive isolation.
• Allopatric speciation results from geographic isolation, while sympatric speciation occurs without physical barriers.

This quiz covers key figures in evolutionary biology, including Charles Darwin and Jean-Baptiste Lamarck. It explores their contributions to the understanding of evolution and the mechanisms behind it. Use this study guide to prepare for your AP Biology exam and strengthen your grasp of evolutionary concepts.