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Bio L3 Speciation

NCEA Level 3 Biology Processes Leading to Speciation AS 91605

TermDefinition
adaptation An inherited structural, behavioural or physiological trait which increases an organism’s fitness
adaptive radiation Relatively sudden appearance of new forms from single ancestral type to fill a variety of niches.
allele One of the two (or more) forms of a gene for a trait.
allele frequency The proportion of a particular allele in the gene pool of a population (as a %).
allopatric speciation Speciation involving a period of geographic separation.
allopolyploidy Polyploidy involving the hybrid offspring of two species.
amphiploidy When a fertile individual results from chromosome doubling in the hybrid offspring of two different species.
analogous structures Structures which are used for the same purpose, but which have a different structure and origin; e.g. wings of insects and birds (contrast: homologous structures).
autopolyploidy Polyploidy involving a single species.
behavioural barrier Differences in courtship behaviour, causing reproductive isolation.
biogeography The study of the geographical distribution of living things.
bottleneck effect A reduction in genetic diversity in a gene pool when a population is reduced to small number of individuals.
chromosome mutation A mutation which involves multiple genes on a chromosome (by duplication, deletion, insertion or translocation of a chromosome section)
cline A gradual change in the traits of a species over a geographical gradient.
co-evolution When two species influence each other’s evolution. A change in one species acts as a strong selection pressure for change in the other species.
common ancestor Original species from which others develop through divergent evolution
competition When organisms living in the same location require the same (finite) resource.
continental drift The gradual movement and formation of continents, resulting from the movement of tectonic plates.
convergent evolution Occurs when similar features evolve in unrelated species as a result of similar selection pressures e.g. streamlined body shape in dolphins and fish
deme A local interbreeding population of a species.
directional selection Selection in which organisms in one end of the range of variation are favoured.
disruptive selection Selection in which organisms at both ends of the range of variation are favoured.
divergent evolution When one species evolves into two.
ecological barrier Differences in habitat that prevent different species interbreeding.
endemic species Species restricted to one area only (e.g. endemic to N.Z.)
evolution Changes in a gene pool over successive generations.
extinction Occurs when all members of a species die out.
fitness The relative ability of an individual to survive and reproduce in an environment.
fossil record All fossils and their relative locations in layers of rock. Provides useful information about evolution.
fossils Preserved remains or traces of organisms which lived in the past.
founder effect Random changes to a gene pool resulting from a small number of individuals establishing a new population.
frameshift When an insertion or deletion changes the ‘reading frame’ of triplets in a DNA sequence (changing the amino acids coded for)
gene flow Exchange of alleles between populations by immigration and emigration.
gene mutation A change to the base sequence within a gene (by insertion, deletion or substitution)
gene pool The collective alleles of all members of a population.
genetic drift Random changes in the allele frequencies. The effects are greatest in small populations.
genetic equilibrium The allele frequencies in a population are static over time because the evolutionary forces acting upon the alleles are equal (this is very rare!)
geographic barrier A physical barrier that isolates populations and prevents gene flow.
glacial period Cooler period in which sea water becomes ‘locked up’ as ice and sea levels fall, exposing new areas of land.
Gondwana The southern super-continent which existed from about 180 mya and from which NZ separated about 80 mya
gradualism When the accumulation of changes resulting in speciation occurs slowly and steadily (contrast: punctuated equilibrium).
homologous structures Structures which have the same origin, but different functions (contrast: analogous structures).
hybrid The offspring from a cross between two different species.
hybrid breakdown The first generation (hybrid) may be fertile, but the second generation are infertile or not viable.
hybrid inviability A sperm and egg from different species fuse, but the resulting hybrid individual does not develop successfully.
hybrid sterility The hybrid is sterile (cannot reproduce).
Interglacial period Warmer period in which rising temperatures melt ice and sea levels rise, isolating areas of land as islands
introduced species A species that does not naturally occur in a given area, but has been introduced to it by humans.
macroevolution Large changes in a gene pool over a long period of time; e.g. the formation of a new species, extinction, adaptive radiation, etc
mass extinction When a large number of species and major groups of organisms disappear over a relatively short time.
microevolution Changes in the allele frequencies a gene pool over successive generations.
molecular biology The branch of biology that involves or applies the study of DNA, RNA and proteins.
mutation A sudden, permanent change in the DNA of an organism (could affect a gene, chromosome or sets of chromosomes).
native species A species that naturally occurs in a given area.
natural selection The process in which individuals in a population which are best suited to the environment are more likely to survive and produce offspring.
niche The role of a species in its habitat (remember FAHA!).
non-disjunction The failure of chromosomes to separate normally during the process meiosis. Leads to gametes and offspring with chromosome numbers different to those of the parents.
parallel evolution The development of similar characteristics in separate but related evolutionary lineages through the action of similar selection pressures.
plate tectonics The large-scale movement of tectonic plates, which contributes to continental drift.
polyploidy Having three or more complete sets of chromosomes. The major types are allopolyploidy and autopolyploidy.
population A group of organisms of the same species living in the same location.
post-zygotic isolating mechanism Reproductive isolation after successful development of a zygote (fertilisation).
pre-zygotic isolating mechanism Reproductive isolation prior to fertilisation.
punctuated equilibrium When there are long periods of little change in a species, punctuated (i.e. interrupted) by short bursts of rapid change usually associated with speciation (contrast: gradualism)
reproductive isolating mechanism (RIM) Any factor which prevents breeding between groups of individuals
ring species A special type of cline where the demes (local populations) are arranged in a circle across the species range, and the demes at the ends, although adjacent, may be unable to interbreed.
selection pressure The strength of natural selection for or against a particular trait.
sequential evolution When a species changes so much over time that is classified as a new species (no divergence has occured)
speciation The process of forming distinct new biological species.
species A group of organisms that normally interbreed in nature to produce fertile offspring.
stabilising selection Selection against organisms at the extreme ends of the range of variation.
stasis A period of little or no evolutionary change in a species
structural barrier Differences between the reproductive structures of different groups or species which prevent sperm transfer.
subspecies Populations of a species which are genetically different but capable of interbreeding successfully where their ranges overlap.
sympatric speciation Speciation not involving a period of geographical separation.
temporal barrier Two species are active or reproduce at different times, preventing mating.
variation Differences between individuals (e.g. in phenotypes). The raw material on which selection acts.
vestigial organ An organ that was once useful in an animal’s evolutionary past, but now has no apparent function e.g. wings on many flightless birds.
Created by: nztcowen