NCEA Level 3 Biology: Biogeography, Speciation, and Evolution

Vocabulary practice flashcards covering New Zealand biogeography, mechanisms of sympatric speciation and polyploidy, patterns of evolution, and macroevolutionary models based on NCEA Level 3 Biology lecture notes.

Gondwanaland

The southern supercontinent of which New Zealand was a part approximately 200 million years ago.

Oligocene Drowning

A geological event around 25 million years ago where rising sea levels and subsiding land reduced New Zealand to about 20% of its present land area, resulting in population bottlenecks and genetic divergence.

Kaikoura Orogeny

A period of mountain building caused by tectonic plate convergence beginning about 5 million years ago, which uplifted the Southern Alps and created a new alpine environment.

Glacial Period

A cooler climatic phase in which water becomes locked up in ice, lowering sea levels (up to approximately $100\,m$ lower than today during the last glacial maximum) and connecting land areas to facilitate gene flow.

Interglacial Period

A warmer climatic phase during which ice melts and sea levels rise, isolating landmasses and populations, thereby restricting gene flow.

Sympatric Speciation

The formation of new species from an ancestral population living in the same geographical area, where gene flow is halted by non-geographical barriers such as ecological or behavioural isolation.

Allopatric Speciation

Speciation that initiates when a physical geographical barrier separates populations and stops gene flow between them.

Instant Speciation

The rapid formation of a new species in a single generation, typically occurring through polyploidy which immediately establishes reproductive isolation.

Polyploidy

The condition of possessing three or more complete sets of chromosomes (such as $3n$ or $4n$), rather than the usual two sets ($2n$); common in plants but rare in animals.

Non-disjunction

An error during meiosis wherein homologous chromosomes or sister chromatids fail to separate properly, producing unreduced diploid ($2n$) gametes instead of haploid ($n$) gametes.

Triploid Organism

An organism with three sets of chromosomes ($3n$) that is typically infertile because three sets cannot pair and segregate evenly during meiosis, preventing the formation of viable, balanced gametes.

Tetraploid Organism

An organism with four sets of chromosomes ($4n$) formed by the fusion of two unreduced diploid ($2n$) gametes; capable of fertility because the four sets form homologous pairs during meiosis.

Autopolyploidy

A form of polyploidy where all chromosome sets originate from the same single species, often through meiotic non-disjunction or somatic chromosome doubling.

Somatic Chromosome Doubling

A process where a diploid cell replicates its chromosomes but fails to divide during mitosis, resulting in a tetraploid ($4n$) cell that can develop into a polyploid individual in plants.

Allopolyploidy

A form of polyploidy where chromosome sets are derived from different species, typically following hybridisation between two distinct species.

Hybrid Vigour

An advantage observed in polyploids where combining useful genetic traits from parental lineages leads to increased size, growth rate, yield, or disease resistance.

Convergent Evolution

An evolutionary pattern where unrelated species independently evolve similar anatomical or physiological traits due to experiencing similar selection pressures or occupying similar niches.

Divergent Evolution

An evolutionary process where populations sharing a common ancestor accumulate genetic differences over time through mutation, selection, and drift, becoming increasingly distinct.

Adaptive Radiation

A rapid form of divergent evolution where many species evolve from a single common ancestor over a relatively short period, with each adapting to a different, often unoccupied ecological niche.

Homologous Structures

Anatomical features in different species that share a common evolutionary origin and underlying structural plan, though they may have been modified to serve different functions.

Analogous Structures

Structures that perform similar functions but lack a shared evolutionary origin or underlying anatomical plan, arising independently due to convergent evolution.

Coevolution

A reciprocal evolutionary process in which two closely interacting species exert selective pressures on each other, driving mutual evolutionary changes.

Tetrodotoxin (TTX)

A potent neurotoxin produced by rough-skinned newts that acts as a chemical defence by killing or deterring predators.

Nav1.4 Gene

The specific gene in garter snakes where resistance-conferring mutations occur, enabling them to consume toxic rough-skinned newts without succumbing to paralysis or death.

Gradualism

A model proposing that evolutionary change proceeds slowly, steadily, and continuously through the gradual accumulation of small genetic variations over extended geological timescales.

Punctuated Equilibrium

A model proposing that species undergo prolonged periods of evolutionary stability and minimal change (stasis), interrupted by brief, rapid bursts of speciation and significant evolutionary change.