Evolution, Speciation, and Animal Behavior: Exam 2 Study Guide for General Biology

Lecture 5: History of Life on Earth; Evolutionary Processes I

Appreciate How Long Earth Has Existed

The history of life on Earth spans billions of years, with major evolutionary events shaping the diversity of organisms we see today.

• Earth's Age: Earth is approximately 4.6 billion years old.

• Major Life Forms: Life began with simple prokaryotes, followed by the evolution of eukaryotes, multicellular organisms, and eventually animals and plants.

• Comparative Evolution: Dinosaurs, mammals, and other groups appeared at different times in Earth's history.

Recognize and Explain the Four Conditions Necessary for Evolution by Natural Selection

Natural selection is a key mechanism of evolution, requiring specific conditions to operate.

• Variation: Individuals in a population vary in their traits.

• Inheritance: Some of these traits are heritable and passed to offspring.

• Overproduction: More offspring are produced than can survive.

• Differential Survival and Reproduction: Individuals with advantageous traits are more likely to survive and reproduce.

Artificial Selection: The process by which humans select for desirable traits in organisms, such as crops or pets, which is similar to but directed by humans rather than nature.

Adaptation: A trait that increases an organism's fitness in a particular environment.

Example: Darwin's finches on the Galápagos Islands evolved different beak shapes to exploit different food sources.

Lecture 6: Evolutionary Processes II

Other Processes That Can Cause Microevolution

Microevolution refers to changes in allele frequencies within a population over time, driven by several mechanisms.

• Mutation: Random changes in DNA that introduce new genetic variation.

• Gene Flow: Movement of alleles between populations through migration.

• Genetic Drift: Random changes in allele frequencies, especially in small populations.

• Bottleneck Effect: A sharp reduction in population size leading to loss of genetic diversity.

• Founder Effect: When a new population is established by a small number of individuals, leading to different allele frequencies.

Hardy-Weinberg Equilibrium

The Hardy-Weinberg principle provides a mathematical model to study genetic variation in populations.

• Allele Frequency: The proportion of a specific allele among all alleles in a population.

• Genotype Frequency: The proportion of a specific genotype among all individuals in a population.

• Equation:

$p^2 + 2pq + q^2 = 1$

where p and q are the frequencies of two alleles at a locus.

• Conditions: No mutation, random mating, no gene flow, infinite population size, and no selection.

Example: If the frequency of allele A is 0.7 and allele a is 0.3, the expected genotype frequencies are AA: 0.49, Aa: 0.42, aa: 0.09.

Lecture 7: Species and Speciation

How Earth Has Changed Over Time

Earth's environment and life forms have changed dramatically over geological time.

• Continental Drift: Movement of continents has influenced the distribution and evolution of species.

• Extinction Events: Mass extinctions have periodically reshaped biodiversity.

• Atmospheric Changes: Oxygenation of the atmosphere enabled the evolution of aerobic organisms.

Defining Species and Speciation

Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.

• Biological Species Concept: Defines species based on the ability to interbreed and produce fertile offspring.

• Other Concepts: Morphological, ecological, and phylogenetic species concepts.

• Speciation: The process by which new species arise, often through reproductive isolation.

• Allopatric Speciation: Occurs when populations are geographically separated.

• Sympatric Speciation: Occurs without geographic separation, often through polyploidy or behavioral changes.

Reproductive Isolation Mechanisms

• Prezygotic Barriers: Prevent mating or fertilization (e.g., habitat, temporal, behavioral, mechanical, and gametic isolation).

• Postzygotic Barriers: Prevent hybrid offspring from surviving or reproducing (e.g., hybrid inviability, hybrid sterility, hybrid breakdown).

Example: Mules are sterile hybrids of horses and donkeys.

Lecture 8: Phylogenetics

Interpreting Phylogenetic Trees

Phylogenetic trees depict evolutionary relationships among species or groups.

• Clade: A group consisting of an ancestor and all its descendants.

• Monophyletic Group: Includes a common ancestor and all its descendants.

• Paraphyletic Group: Includes a common ancestor and some, but not all, descendants.

• Polyphyletic Group: Does not include the most recent common ancestor of all members.

Using Phylogenetic Trees

• Character Matrix: A table showing the presence or absence of traits among taxa.

• Outgroup: A taxon outside the group of interest, used to root the tree.

• Synapomorphy: A shared derived trait that defines a clade.

Example Table: Character Matrix

Species	Trait 1	Trait 2	Trait 3
Species A	1	0	1
Species B	1	1	0
Species C	0	1	1

Lecture 9: Animal Behavior

How Behavior Develops in Organisms (Nature vs. Nurture)

Animal behavior is influenced by both genetic (innate) and environmental (learned) factors.

• Innate Behavior: Behaviors that are genetically programmed and performed without prior experience.

• Learned Behavior: Behaviors acquired through experience.

• Imprinting: A rapid form of learning occurring at a specific life stage.

• Critical Period: A specific time during development when certain behaviors can be learned.

Example: Konrad Lorenz's experiments with geese demonstrated imprinting.

Evolution of Behavior and Survival

• Natural Selection and Behavior: Behaviors that increase survival and reproduction are favored.

• Altruism: Behavior that benefits others at a cost to oneself, explained by kin selection and inclusive fitness.

• Mating Systems: Patterns of mating in animal populations, such as monogamy, polygyny, and polyandry.

Social and Mating Behavior in Animals

• Social Behavior: Interactions among individuals, including cooperation, competition, and communication.

• Mating Systems: Strategies for reproduction, including monogamy (one mate), polygyny (one male, multiple females), and polyandry (one female, multiple males).

Vocabulary List

Be able to define the following terms:

• Strata

• Radiometric dating

• Fitness

• Adaptation

• Gene flow

• Genetic drift

• Bottleneck effect

• Founder effect

• Allele frequency

• Genotype frequency

• Hardy-Weinberg equilibrium

• Mutation

• Nonrandom mating

• Assortative mating

• Dissortative mating

• Phenotype

• Reproductive isolating mechanisms

• Prezygotic and postzygotic isolation

• Allopatric and sympatric speciation

• Phylogeny

• Clade

• Monophyletic, paraphyletic, polyphyletic

• Character matrix

• Innate and learned behavior

• Altruism

• Kin selection

• Monogamous, polygynous, polyandrous, polygynandrous

• Circadian rhythm

Additional info: This study guide covers key concepts in evolution, speciation, phylogenetics, and animal behavior, providing a comprehensive overview for exam preparation in a General Biology course.