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Bio L3 Speciation
NCEA Level 3 Biology Processes Leading to Speciation AS 91605
| Term | Definition |
|---|---|
| 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. |
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