evolution notes

What are the two types of fossils?

Fossils include actual remains and ichnofossils (e.g. footprints, nests).

What is petrification?

Minerals replace organic material, turning remains into rock.

What does biogeography show?

Species evolved separately after Pangaea split due to isolation.

Example of biogeographic isolation?

Penguins (South Pole), polar bears (North Pole).

What does similar embryonic development indicate?

Common ancestry.

Example of embryological evidence?

Gill slits in chordate embryos.

What are homologous structures?

Same origin, different function (e.g. human arm & whale fin).

What are analogous structures?

Same function, different origin (e.g. bat & butterfly wing).

What are vestigial structures?

No current function (e.g. ostrich wings).

What is biochemical evidence of evolution?

Shared DNA, RNA, or proteins across species.

Example of biochemical similarity?

Humans and chimps share ~98% DNA.

Who proposed catastrophism?

Baron Cuvier.

What is catastrophism?

Sudden disasters shape species and fossil patterns.

Who proposed the theory of acquired traits?

Lamarck.

What is use and disuse?

More use leads to more development (Lamarck's idea).

What is inheritance of acquired traits?

Traits gained in life are passed on (Lamarck, incorrect).

Who proposed natural selection?

Charles Darwin.

Who influenced Darwin’s theory?

Malthus (population > resources → struggle).

What is natural selection?

Gradual, non-random change in allele frequencies.

What is fitness in evolution?

Ability to survive and reproduce.

What does "survival of the fittest" mean?

Traits that increase survival and reproduction get passed on.

Requirement 1 of natural selection?

More demand than supply (competition).

Requirement 2 of natural selection?

Variation in fitness among individuals.

Requirement 3 of natural selection?

Traits must be heritable.

Requirement 4 of natural selection?

Traits must affect survival or reproduction.

What is stabilizing selection?

Favors average traits (e.g. human birth weight).

What is directional selection?

Favors one extreme (e.g. dark-colored moths).

What is disruptive selection?

Favors both extremes (e.g. snails in different environments).

What is sexual selection?

Traits increase mating success.

What is artificial selection?

Human-driven breeding (e.g. dog breeding).

What is Hardy-Weinberg equilibrium?

No evolution, allele frequencies stay constant.

Hardy-Weinberg equation (alleles)?

p + q = 1

Hardy-Weinberg equation (genotypes)?

p² + 2pq + q² = 1

Hardy-Weinberg conditions?

Large population, Random mating, No mutation, No natural selection, No migration.

What is microevolution?

Change in allele frequencies within a population.

Sources of genetic variation?

Mutations, sexual reproduction, balanced polymorphism, polyploidy.

What is genetic drift?

Random changes in allele frequencies, common in small populations.

What is the bottleneck effect?

Most of population dies off, reducing genetic diversity.

What is the founder effect?

Small group migrates and forms a new gene pool.

What is non-random mating?

Choosing mates based on traits.

How do mutations contribute to evolution?

Introduce new alleles (if non-fatal).

What is gene flow?

Migration of individuals and alleles between populations.

What is macroevolution?

Evolution above species level, leading to speciation.

What causes speciation?

Reproductive isolation.

Prezygotic isolation types?

Habitat, temporal, behavioral, mechanical, gametic.

Postzygotic isolation types?

Hybrid mortality, hybrid sterility, hybrid breakdown.

Allopatric speciation?

Geographic barrier leads to new species (e.g. Grand Canyon squirrels).

Sympatric speciation?

Occurs without geographic barrier.

Sympatric speciation via balanced polymorphism?

Traits give advantage in specific environments.

Sympatric speciation via polyploidy?

Chromosome duplication, especially in plants.

Sympatric speciation via hybridization?

Two species mate and produce a hybrid.

What is phyletic gradualism?

Slow, steady evolution over time.

What is punctuated equilibrium?

Short bursts of evolution followed by long stasis.

What is divergent evolution?

Species evolve from common ancestor into different forms.

What is convergent evolution?

Different ancestors evolve similar traits.

What is parallel evolution?

Similar traits evolve independently in related species.

What is coevolution?

Two species evolve in response to each other.

What is camouflage (crypsis)?

Organism conceals itself with its surroundings.

What is aposematic coloration?

Bright colors warn predators of toxicity.

What is Batesian mimicry?

Harmless species mimics harmful one.

What is Mullerian mimicry?

Two harmful species resemble each other.

What is a phylogenetic tree?

Diagram showing evolutionary relationships.

What is a clade?

Ancestor and all its descendants.

What is a paraphyletic group?

Ancestor and some (not all) descendants.

What does parsimony mean in phylogenetics?

Simplest explanation with least evolutionary changes is preferred.

What is homoplasy?

Similar traits evolved independently (e.g. convergent evolution).

What is gene flow?

Movement of alleles between populations through migration.

What is genetic drift?

Random shifts in gene frequencies, more impactful in small populations.

What is adaptive radiation?

One species rapidly evolves into many to fill different niches.