evolution 2.0

Who proposed the incorrect theory that organisms acquire traits during their lifetime and pass them to offspring?

Jean-Baptiste Lamarck

What was Lamarck’s example involving giraffes?

Giraffes stretched to reach leaves, which lengthened their necks and passed it to offspring.

Who proposed the correct theory of evolution by natural selection?

Charles Darwin and Alfred Wallace

What was the name of Darwin’s book?

The Origin of Species by Means of Natural Selection

What is a gene pool?

All the genes/alleles present within a particular population

What is allele frequency?

The proportion/percentage of a certain allele in a gene pool

What three agents can cause changes to allele frequencies?

Natural selection, gene flow, and chance events (genetic drift)

What causes the introduction of new alleles into a population?

Random genetic mutations

What is population in a biological context?

A group of individuals of the same species living in the same location

What is fitness?

The phenotype that confers the greatest advantage to an individual

What is a selection pressure?

A factor that affects the reproductive success of an organism

What happens to phenotypes with higher fitness?

They survive more and reproduce more

What is the result of natural selection?

Populations adapt and become better suited to their environment

What are structural adaptations?

Physical differences (e.g. giraffe neck length)

What are behavioural adaptations?

Activity differences (e.g. playing dead)

What are physiological adaptations?

Internal differences (e.g. homeothermy)

What happened to the peppered moth population during industrialisation?

Dark-coloured moths had higher survival due to pollution

What is gene flow?

Movement of genes from one population to another

How does gene flow affect allele frequencies?

Introduces new alleles quickly and changes variation

What is genetic drift?

Random change in allele frequencies, especially in small populations

What is the founder effect?

A small group establishes a new population with less genetic variation

What is a population bottleneck?

A large reduction in population size that reduces genetic diversity

What is artificial selection?

Humans selecting traits through breeding

What are consequences of artificial selection?

Desired traits increase; may reduce fitness or diversity

What is speciation?

Formation of a new species through reproductive isolation

What causes reproductive isolation?

Physical barriers, different mating behaviours, mechanical differences

What is an example of speciation from the Galapagos?

Finches developing different beaks for different foods

What defines a species?

Ability to produce viable, fertile offspring; similar DNA and traits

What are hybrids?

Offspring of two species, often sterile or unfit

What are races/breeds/subspecies?

Genetically distinct populations within a species

What is biogeography?

Study of organism distribution as evidence for evolution

What does continental drift show about evolution?

Species evolved in isolation as land masses separated

What evidence does embryology provide for evolution?

Similarities like gill slits and tails suggest common ancestors

What does comparative biochemistry examine?

DNA and protein similarities to show relatedness

What is comparative morphology?

Study of structural similarities/differences in organisms

What are homologous structures?

Same structure, different function; evidence of common ancestry

What are vestigial structures?

Non-functional remnants (e.g. whale pelvis, wisdom teeth)

What are analogous structures?

Different structure, same function; no recent common ancestor

What is a fossil?

Preserved remains, impression, or trace of past organisms

What conditions favour fossilisation?

Hard parts, rapid burial, low oxygen, fine sediment

What are trace fossils?

Indirect evidence like footprints or burrows

What does stratigraphy say about fossil age?

Lower rock layers are older

What is an index fossil?

Used to identify geological time periods

What are requirements for index fossils?

Widespread, abundant, short-lived, easily recognisable

What is a transitional fossil?

Fossil showing features of both ancestral and descendant groups

What is an example of a transitional fossil?

Archaeopteryx (bird with dinosaur features)

What are hominins?

Modern humans and their extinct ancestors

What distinguishes hominins from hominoids?

Bipedalism

What skeletal traits support bipedalism?

S-shaped spine, foramen magnum under skull, longer legs

What was Homo habilis?

2.4–1.4 mya, tool users with ~640ml brain and possible meat diet

What was Homo erectus?

1.8–0.3 mya, first to use fire and leave Africa; ~1000ml brain

What is Homo floresiensis?

A small hominin (~1m tall) with a small brain, lived ~100,000 years ago

What is the Out of Africa theory?

Modern humans migrated out of Africa 50,000–65,000 years ago