bio EVOLUTION

Antibiotic-resistance

random mutations make some resistant and those reproduce (natural selection)

Homology vs. analogy

Homologous structures: same origin, different function
Analogous structures: different origin, same function

Comparative biochemistry vs. comparative morphology vs. comparative embryology

• Biochemistry: DNA/protein similarities

• Morphology: body structures

• Embryology: early development similarities

Vestigial organs

Structures with little/no function today

Definition of a population

A group of the same species living + breeding in one area

Hardy-Weinberg Purpose

Tells you if a population is evolving or not

Genetic Drift vs. Gene Flow

• Genetic drift: random change (small populations)

• Gene flow: movement of genes between populations

Biological Species Concept

Species = organisms that can mate and produce fertile offspring

Prezygotic Barriers (before fertilization)

• Temporal (different times)

• Mechanical (don’t fit)

• Behavioral (different mating signals)

• Gametic (sperm can’t fertilize egg)

• Habitat isolation

Postzygotic Barriers (after fertilization)

• Hybrid inviability (dies early)

• Hybrid sterility (mule)

• Hybrid breakdown (weak offspring later)

Geographic Isolation

Physical separation (river, mountain)

Allopatric vs. Sympatric Speciation

• Allopatric: separated physically

• Sympatric: same area (genetic changes)

Adaptive Radiation

One species → many species (different niches)

Punctuated Equilibrium vs. Gradualism

• Punctuated: fast changes + long stability

• Gradualism: slow, steady change

Classification

• Binomial: Genus species (Homo sapiens)

• Hierarchy: Kingdom → Species

Cladistics

Classifies organisms by common ancestry (evolutionary relationships)

Hardy-Weinberg Conditions

• No mutations

• Random mating

• No natural selection

• Large population

• No gene flow

Convergent evolution

Species from different evolutionary branches may come to resemble one another if they have similar ecological roles

and natural selection has shaped analogous adaptations.

order of the catagories

Kingdom → Phylum → Class → Order → Family → Genus → Species

hardy weinberg equation

p² +2pq +q²=1

p+q=1

• p² = homozygous dominant

• 2pq = heterozygous

• q² = homozygous recessive

practice frq ex

To determine the frequency of each genotype in the population, the Hardy-Weinberg equation (p² + 2pq + q² = 1) is used. First, the frequency of the recessive phenotype (q²) is identified from the data. Taking the square root of this value gives q, the frequency of the recessive allele. Then, p is calculated by subtracting q from 1 (p = 1 − q). Using these values, the frequencies of the genotypes can be calculated: p² represents homozygous dominant individuals, 2pq represents heterozygous individuals, and q² represents homozygous recessive individuals. The frequency of the dominant phenotype is found by adding p² and 2pq, since both genotypes express the dominant trait.

A population is considered to be in Hardy-Weinberg equilibrium only if five conditions are met: there must be no mutations, random mating must occur, the population must be very large, there must be no natural selection, and there must be no gene flow. These conditions ensure that allele frequencies remain constant over time. To determine whether a population is evolving, the observed genotype frequencies are compared to the expected frequencies calculated using the Hardy-Weinberg equation. If there is a significant difference between the observed and expected values, then the population is not in equilibrium and is therefore evolving.

An environmental change can disrupt Hardy-Weinberg equilibrium by affecting one or more of its conditions. For example, the introduction of a new predator could increase selective pressure on the population, favoring individuals with traits that improve survival. As a result, the frequency of certain alleles would increase over time, while others would decrease. This violates the condition of no natural selection and causes the population to evolve. This process demonstrates how external factors can influence allele frequencies and lead to evolutionary change over time, showing that equilibrium is often transitory in real-world populations.