EVOLUTION

Lamarck’s theory: Organisms acquire traits during their lifetime through use/disuse (e.g. giraffe necks growing longer from stretching), which are passed to offspring — now known to be incorrect.

Darwin’s theory: Evolution occurs by Natural Selection — organisms with advantageous traits survive and reproduce more successfully. Published in On the Origin of Species (1859).

Population: A group of individuals of the same species living in the same location.

Gene pool: All the genes/alleles present in a population.

Allele frequency: The proportion or percentage of a specific allele in a gene pool.

Factors causing allele frequency change: Natural selection, gene flow (migration), genetic drift (chance events).0

Fitness: The phenotype that provides the greatest advantage in survival and reproduction.

Selection pressure/agent: An environmental factor (biotic or abiotic) that affects an organism’s reproductive success.

Reproductive success: Organisms with advantageous alleles survive, reproduce, and increase allele frequency in the population.

Natural Selection: Individuals with advantageous phenotypes survive longer and reproduce more; over generations, the gene pool shifts toward those traits.

Adaptations from natural selection:

* Structural (e.g. long neck)

* Behavioural (e.g. playing dead)

* Physiological (e.g. temperature regulation)

Peppered moth example: Dark moths increased in polluted environments due to camouflage advantage — a classic case of natural selection in response to environmental change.

Gene flow: The movement of alleles from one population to another through migration. Can quickly alter allele frequencies.

Genetic drift: Random change in allele frequencies, especially in small populations. Not based on fitness.

Founder effect: A few individuals form a new population with reduced genetic variation, different from original population.

Population bottleneck: A large population is drastically reduced due to events (e.g. disaster), decreasing genetic diversity and potentially leading to extinction.

Artificial selection: Humans select parents with desired traits to produce offspring (e.g. dog breeds, muscular cows).

Artificial selection effects: Can increase frequency of desired alleles, but may reduce genetic diversity and fitness in wild conditions.

Speciation: Formation of new species through:

* Geographic isolation (no gene flow)

* Exposure to different selection pressures

* Accumulated genetic differences

* Reproductive isolation

Reproductive isolation: Prevents interbreeding through:

* Physical barriers

* Different courtship rituals

* Different breeding seasons

* Mechanical incompatibility

Species: Organisms that can produce fertile offspring.

Hybrid animals: Offspring of different species; often sterile or unfit.

Race/breed/subspecies: Genetic variations within the same species capable of interbreeding.

Biogeography: Study of species distribution. Explains evolution via geographic isolation (e.g. marsupials in Australia vs placentals in Asia).

Ratite birds example: Similar flightless birds on separated continents suggest common ancestry and continental drift.

DNA and protein similarities: Organisms with similar DNA/amino acid sequences are more closely related (e.g. cytochrome-C).

Embryology: Similarities in embryos (e.g. gill slits, tails) indicate shared ancestry.

Comparative morphology: Study of structures to determine relatedness.

Homologous structures: Same structure, different function — evidence of divergent evolution (e.g. pentadactyl limb in mammals).

Vestigial structures: Reduced or non-functional remnants of structures from ancestors (e.g. whale pelvis, human wisdom teeth).

Analogous structures: Different structures, same function — evidence of convergent evolution (e.g. bird wings vs insect wings).

Fossil: Preserved remains or traces of past life (e.g. bones, shells, impressions).

Fossilisation requirements: Rapid burial, sediment layers, mineralisation or preservation.

Strata: Layers of rock. Older fossils are found in lower layers.

Index fossils: Common, widespread, and existed for a short geologic time — help date rock layers.

Transitional fossils: Show features of both ancestral and modern species (e.g. Archaeopteryx between reptiles and birds).

Hominin: Humans and their extinct ancestors.

Skull features for age:

* Cranial capacity (brain size)

* Eyebrow ridge size

* Teeth size

* Foramen magnum position (spine connection)

Bipedalism traits:

* Inferior foramen magnum

* S-shaped spine

* Shorter arms, longer legs

* Broad pelvis

Early hominins:

* Australopithecus afarensis (Lucy): 400mL brain, bipedal, 3.9–2.9 mya

* Homo habilis (Twiggy): 640mL brain, tool use, 2.4–1.4 mya

* Homo erectus: 1000mL brain, used fire, migrated from Africa, 1.8–0.3 mya

Human evolutionary trends:

* Larger brain

* Shorter arms

* Flatter face

* More central foramen magnum

Migration out of Africa:

* Homo sapiens left Africa 50,000–60,000 years ago

* Reached Australia via Sahul (land bridge)

* Evidence: Lake Mungo remains (42,000 yrs), Juukan Gorge artefacts

Connection to Country (Indigenous knowledge):

* “Country” = land, spirit, and cultural identity

* Aboriginal and Torres Strait Islander peoples adapted uniquely to Australian environments through long-term occupation and limited gene flow