bio notes

Key Concepts: Natural selection is a fundamental mechanism of evolution addressing how populations adapt and change over time.
AP Weighting: 13-20%.

Jean-Baptiste Lamarck: Proposed an early, incorrect model of evolution.
- Main Idea: "Use it or lose it" concept, which suggests that body parts that are used grow stronger, while those that are not used deteriorate.
- Example: Giraffes evolving from a short-necked species through the stretching of their necks.
Critique: His theories lacked empirical support and were ultimately superseded by Darwin's work.

Charles Darwin: His theory revolves around "descent with modification" based on empirical observations, particularly from the Galapagos Islands.
Observations made by Darwin:
- Variation exists among individuals in a population with heritable traits.
- Species produce more offspring than their environment can sustain; many offspring die young.
- Individuals that survive tend to pass on advantageous traits to their offspring.
Natural vs. Artificial Selection:
- Natural Selection: Driven by environmental pressures (predators, diseases).
- Artificial Selection: Driven by human choices (e.g., breeding of crops and livestock).

Definition: Process of human-directed breeding to promote specific traits in organisms.
Applications:
- Breeding crops for desirable traits (size, growth rate, pest resistance).
- Development of diverse domestic dog breeds from wolves through selective pressure.

Definition: Study of genetic composition of populations and how it changes over time.
Microevolution: Minor changes in allele frequencies within a population over short timescales.
Macroevolution: Larger evolutionary changes that occur over longer periods.

Discrete Characteristics: Clear categorizable traits, e.g., eye color, blood type (either-or traits).
Quantitative Characteristics: Traits that exist on a spectrum, influenced by multiple genes/environmental factors.

Directional Selection: Favors individuals at one end of the phenotypic spectrum.
Disruptive Selection: Favors individuals at both extremes, against the average phenotype.
Stabilizing Selection: Favors average phenotypes, reducing variance in the population.

Definition: A model that describes a theoretical population that is not evolving; used as a null hypothesis for evolutionary biology.
Five Conditions for Equilibrium:
1. Large population size to prevent genetic drift.
2. No migrations (gene flow).
3. No net mutations.
4. Random mating (no selection pressures).
5. No natural selection.
Equations:
- Allele frequency: $p + q = 1$
- Genotype frequency: $p^2 + 2pq + q^2 = 1$

Homologous Structures: Shared anatomical features between species that have evolved from a common ancestor (e.g., bones in whale flippers and human arms).
Analogous Structures: Similar function, but different evolutionary origins (e.g., wings of bats vs. wings of birds, resulting from convergent evolution).
Vestigial Structures: Reduced or non-functional features that were important in the organism's ancestors (e.g., human appendix, snakes' pelvis).

Concept emphasizing that many species arise from shared ancestors, leading to shared anatomical structures and genetic traits.

Ongoing evolutionary changes influenced by environmental pressures, mutations, and genetic drift.

Definition: The evolutionary history and development of a group of organisms.
Phylogenetic Trees: Visual representations of evolutionary relationships among various biological species based on similarities and differences in their physical and/or genetic characteristics.
- Key Components:
- Branches: Represent the evolutionary lineages.
- Tips (leaves): Represent the current species.
- Nodes (ancestors): Points where lineages diverge.

Knowledge of how to read and interpret these trees is crucial for understanding evolutionary relationships and history.

The process by which new species arise, typically through mechanisms such as allopatric and sympatric speciation.

Loss of entire species, often as a result of environmental changes, human impact, and evolutionary pressures.

Importance of genetic diversity and variations within populations to ensure resilience to changes and survival through adaptation.

Discusses hypotheses surrounding the emergence of life from simple organic compounds, including conditions on early Earth that facilitated this process.