General Biology Exam 1 Study Guide: Evolution, Genetics, Speciation, and Bioskills

Doing Biology

Characteristics and Methods in Biology

Biology is the study of living organisms and their interactions with the environment. Understanding the scientific method and the organization of life is foundational for all biological sciences.

• Characteristics of Living Things: Living organisms share traits such as cellular organization, metabolism, growth, reproduction, response to stimuli, and adaptation.

• Scientific Hypotheses and Theory: A hypothesis is a testable statement about the natural world; a scientific theory is a well-substantiated explanation based on evidence.

• Experimental Design: Key components include control, replication, variables (independent and dependent), treatment, and falsifiability.

• Ranks of Biological Hierarchy: Life is organized into levels: domain, kingdom, phylum, class, order, family, genus, species.

• Scientific Nomenclature: The use of binomial names (e.g., Homo sapiens) for species identification.

The Rise of Evolutionary Thought (Chapter 22)

Historical Context and Theories of Evolution

The development of evolutionary theory involved contributions from many scientists, culminating in Darwin and Wallace's theory of evolution by natural selection.

• Darwin and Wallace: Proposed evolution by natural selection, emphasizing variation and differential survival.

• Aristotle and Plato: Early philosophers who influenced later evolutionary thought; Plato emphasized ideal forms, Aristotle the "Great Chain of Being."

• Catastrophism vs. Uniformitarianism: Catastrophism suggests sudden events shape Earth; Uniformitarianism (Lyell) argues for gradual processes.

• Special Creation: The belief that species are individually created and immutable; contrasted with evolution.

• Lamarckian Evolution: Lamarck proposed inheritance of acquired traits, differing from Darwin's natural selection.

• Influence of Charles Lyell, Erasmus Darwin, James Hutton, Georges Cuvier: These scientists contributed to the understanding of Earth's age, fossil record, and gradual change.

Evidence and Principles of Evolution

• Geological Principles: Fossil evidence and Earth's age support gradual change.

• Law of Succession: Fossil species are succeeded by similar living species in the same region.

• Extinct vs. Extant: Extinct species no longer exist; extant species are currently living.

• Types of Evidence: Direct observations, biogeography, homology (similarity due to shared ancestry), analogy (similarity due to convergent evolution).

The Theory of Natural Selection (Chapter 22)

Postulates and Mechanisms

Natural selection is the process by which organisms better adapted to their environment tend to survive and reproduce. Darwin's theory is based on several key postulates.

• Four Postulates of Natural Selection:

  1. Variation exists among individuals in a population.

  2. Some variation is heritable.

  3. More offspring are produced than can survive.

  4. Survival and reproduction are not random; individuals with advantageous traits are more likely to survive and reproduce.

• Antibiotic Resistance: Example of natural selection in action; bacteria with resistance genes survive and proliferate.

• Galápagos Finches: Variation in beak size and shape demonstrates adaptation to different food sources.

• Misconceptions: Natural selection does not "aim" for perfection; it acts on existing variation.

• Fitness: The ability to survive and reproduce; measured by reproductive success.

• Constraint: Limitations on evolution due to genetic, developmental, or environmental factors.

Evolutionary Processes (Chapter 23)

Mendelian Genetics; Population Genetics; Mechanisms of Evolution

Evolutionary processes include genetic variation, inheritance, and changes in allele frequencies within populations.

• Mendelian Genetics: Gregor Mendel's work established the principles of inheritance (dominant and recessive alleles).

• Genotype and Phenotype: Genotype is the genetic makeup; phenotype is the observable trait.

• Hardy-Weinberg Principle: Describes allele and genotype frequencies in a non-evolving population. Equation: $p^2 + 2pq + q^2 = 1$ (where p and q are allele frequencies)

• Mechanisms of Evolution:

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

  • Gene Flow: Movement of alleles between populations.

  • Mutation: Source of new genetic variation.

  • Natural Selection: Differential survival and reproduction.

• Founder Effect and Bottleneck: Special cases of genetic drift where population size is drastically reduced.

• Patterns of Natural Selection: Directional, stabilizing, disruptive, and balancing selection.

• Sexual Selection: Selection for traits that increase mating success; includes intersexual (mate choice) and intrasexual (competition).

• Batesman–Trivers Hypothesis: Explains differences in reproductive investment between sexes.

• Honest Signals: Traits that reliably indicate fitness.

Speciation (Chapter 24)

Processes and Types of Speciation

Speciation is the formation of new species through evolutionary processes. It can occur via several mechanisms.

• Species Concepts: Biological, morphological, and phylogenetic species concepts are used to define species.

• Reproductive Isolation: Prezygotic (before fertilization) and postzygotic (after fertilization) barriers prevent gene flow between species.

• Allopatric Speciation: Occurs when populations are geographically separated.

• Sympatric Speciation: Occurs without geographic separation, often via polyploidy or disruptive selection.

• Polyploidy: The condition of having more than two sets of chromosomes; common in plants.

Phylogenies (Chapter 25)

Understanding Evolutionary Relationships

Phylogenetic trees represent evolutionary relationships among species. They are constructed using morphological and genetic data.

• Parts of a Phylogenetic Tree: Node (common ancestor), branch (lineage), root (ancestral lineage).

• Monophyletic Clade: Group containing an ancestor and all its descendants.

• Building Trees: Use of parsimony (simplest explanation) and different methods (e.g., maximum likelihood).

• Interpreting Trees: Nucleotide change or time can be plotted on the x-axis.

• Common Misconceptions: Trees do not imply "progress" or "higher" forms.

Bioskills

Experimental Design and Data Analysis

Bioskills are essential for interpreting scientific data and designing experiments.

• Dependent vs. Independent Variables: Independent variable is manipulated; dependent variable is measured.

• Graph Types: Choose appropriate graphs (bar, line, scatter) for data representation.

• Standard Error Bar: Indicates variability in data; helps assess reliability.

• p-value: Probability that observed results are due to chance; lower p-values indicate stronger evidence against the null hypothesis.

• Causation vs. Correlation: Causation implies one variable affects another; correlation indicates a relationship but not necessarily causation.

• Statistical Tools: Use error bars, statistical tests, and p-values to interpret data.

• Probability Rules: "Both-And" and "Either-Or" rules for calculating probabilities.

• Visual Models: Use diagrams and models to study complex concepts.

• Latin and Greek Roots: Biological terms often derive from these languages; understanding roots aids in comprehension.

• Multiple Meanings: Words like "theory" and "fitness" have specific scientific meanings.

• Goal-Oriented and Human-Centered Thinking: Avoid anthropocentric interpretations in biology.

Sample Table: Mechanisms of Evolution

Mechanism	Description	Effect on Genetic Variation
Natural Selection	Non-random survival and reproduction based on traits	Can increase or decrease variation
Genetic Drift	Random changes in allele frequencies	Reduces variation, especially in small populations
Gene Flow	Movement of alleles between populations	Increases variation within populations
Mutation	Introduction of new alleles	Increases variation

Additional info:

• Some content was expanded for clarity and completeness, such as definitions and examples.

• Equations and table entries were inferred from standard biology curriculum.