Evolution Flashcards
What is evolution?
Evolution is the change in allele frequencies in a population over time.
What are the three main arguments for evolution?
- Species vary locally
- Species vary globally
- Species vary through time
What is biogeography?
The study of how species are distributed across the planet and how geography affects evolution.
What is comparative morphology?
The study of structural similarities and differences in organisms to determine evolutionary relationships.
What are homologous structures?
Structures that share a common origin but may have different functions (e.g., human arm and whale flipper).
What are analogous structures?
Structures with similar functions but different evolutionary origins (e.g., bird wings vs. butterfly wings).
What are vestigial structures?
Body parts that have lost their original function through evolution (e.g., human tailbone).
Why is the fossil record incomplete?
Many organisms do not fossilize due to decay, lack of sedimentation, or destruction over time.
What counts as a fossil?
Any preserved remains, impressions, or traces of ancient organisms.
How do fossils help us understand evolution?
They provide physical evidence of past life forms and show changes over time.
What was the significance of Darwin’s trip on the Beagle?
It allowed him to observe species variations, leading to his theory of natural selection.
Why are the Galápagos Islands important in evolution?
They were home to unique species that helped Darwin develop his ideas on adaptation.
What did Darwin’s finches demonstrate?
Adaptive radiation—different beak shapes evolved to match available food sources.
How does natural selection work?
It leads to changes in allele frequencies as advantageous traits become more common.
Who else contributed to evolutionary theory?
Alfred Russel Wallace independently conceived the theory of natural selection.
What is radiometric dating?
A method that uses radioactive isotopes to determine the age of fossils and rocks.
What is half-life?
The time it takes for half of a radioactive isotope to decay.
What was Pangea?
A supercontinent that existed before plate tectonic movements separated landmasses.
What is plate tectonic theory?
The idea that Earth’s crust is divided into plates that move, affecting evolution and species distribution.
How do mutations contribute to evolution?
They introduce new alleles into a population
What are the three types of mutations?
Beneficial, harmful, and neutral
What is immigration in evolutionary terms?
Movement of individuals into a population, introducing new alleles.
What is emigration?
Movement of individuals out of a population, reducing genetic diversity.
What is genetic equilibrium?
A state where allele frequencies in a population remain constant over generations.
What is random mating?
When individuals pair by chance rather than by selective traits.
What is sexual selection?
When certain traits increase reproductive success, leading to non-random mating.
What is directional selection?
Favors one extreme trait (e.g., giraffes with longer necks).
What is allopatric speciation?
New species form due to geographic isolation.
What is the founder effect?
A small group starts a new population with limited genetic variation.
What is the bottleneck effect?
A sharp population reduction due to an event, reducing genetic diversity.
What are postzygotic isolating mechanisms?
Barriers that prevent viable, fertile offspring
What defines a species?
A group of organisms that can interbreed and produce fertile offspring.
What is speciation?
The formation of new species when populations become reproductively isolated.
How do geographic barriers affect speciation?
They prevent gene flow, leading to genetic divergence.
What is Linnaean taxonomy?
A classification system based on hierarchical categories (Kingdom, Phylum, etc.).
What is the phylogenetic system of classification?
A system based on evolutionary relationships and common ancestry.
What are master genes?
Genes that control major developmental processes (e.g., Hox genes in limb formation).
What is the Big Bang Theory?
The scientific theory explaining the origin of the universe.
How did oxygen levels change early Earth?
Early Earth had little oxygen; photosynthetic organisms later increased atmospheric oxygen.
How did amino acids develop on early Earth?
Possibly through chemical reactions in Earth’s primitive atmosphere or from meteorites.
What were the first cells like?
Anaerobic (did not need oxygen); later evolved into aerobic cells as oxygen increased.
How did early photosynthesis impact evolution?
It produced oxygen, allowing for aerobic respiration and more complex life forms.
What is the endosymbiotic theory?
The idea that mitochondria and chloroplasts originated as symbiotic bacteria.
What did the Miller-Urey experiment demonstrate?
That organic molecules (amino acids) could form under early Earth conditions.
What is the Hardy-Weinberg Principle?
A mathematical model predicting allele frequencies in a non-evolving population.
What is the Hardy-Weinberg equation?
p² + 2pq + q² = 1, where p and q represent allele frequencies.
What are the advantages of asexual reproduction?
• Fast reproduction
• Requires only one parent
• No need for complex mating behaviors
How does sexual reproduction increase genetic variation?
• Crossing over during meiosis
• Independent assortment of chromosomes
• Random fertilization
What is the difference between asexual and sexual reproduction?
• Asexual: One parent, identical offspring.
• Sexual: Two parents, genetic variation.
Explain two advantages of asexual reproduction.
• Fast reproduction – No mate needed.
• Energy-efficient – Saves resources.
Explain how sexual reproduction creates genetic variability.
Crossing over, independent assortment, and random fertilization shuffle genes.
Two prezygotic mechanisms?
• Temporal isolation – Different mating times.
• Behavioral isolation – Different courtship behaviors.
Mutation
Source of new alleles
Crossing over at Meiosis 1
Introduces new combinations
of alleles into chromosomes
Independent Assortment at Meiosis 1
Mixes maternal and paternal chromosomes
Fertilization
Combines alleles from two parents
Change in chromosome number or structure
Transposition, duplication, or loss of chromosomes
Order
Species- Genus- Family- Order- Class- Phylum- Kingdom- Domain
SGFOCPKD
Master Genes
• Hox genes: Control body plan and segment identity.
• Dlx genes: Regulate limb and skull development.
