biology level 3 ncea speciation

Adaptive radiation

The evolution of several different species of plant or animal from one ancestral species, in a  short amount of time due to vacant niche

Allopatric speciation

Speciation occurring resulting after gene flow between populations was stopped originally  due to a geographical barrier

Allopolyploidy

A type of polyploidy in which there is more than two copies, of chromosomes derived from  different species. It occurs when two species mate to produce a hybrid species.

Analogous structures

Structures that are superficially similar due to similar selection pressures but have different  genetic origins as the species are not from a recent common ancestor.

Autopolyploidy

A type of polyploidy where the multiple sets of chromosomes are all derived from the same  species.

Biogeography

the study of the distribution of species and ecosystems in geographic space  and through geological time.

Cline

A gradual variation in the characteristics of a species or population over its geographical  range.

Coevolution

occurs when two or more species reciprocally affect each other's evolution. aka  are each others selection pressure.

Convergent evolution

The development of superficially similar structures (analogous structures) in unrelated  organisms, usually because the organisms live in the same kind of environment with similar  selection pressures

Deme

Is a population of organisms within which the exchange of genes is completely random; i.e.,  all mating combinations between individuals of opposite sexes have the same probability of  occurrence.

Divergent evolution

An accumulation of changes in the gene pools of two (or more) populations, leading to the  formation of sub-species, species etc.

Evolution

The gradual process by which the present diversity of plants and animals arose from the  earliest and most primitive organisms.

Fossil record

History of life as documented by fossils, the remains or imprints of the organisms from  earlier geological periods preserved in sedimentary rock. Can be used to show evolution.

Founder effect

When a new population is established by a very small number of individuals that have  become isolated from a larger population.

Gene pool

Refers to the total number of genes of every individual in a population.

Gene flow

The movement and exchange of genes or alleles from one population of a species to  another.

Genetic drift

Is the change in the frequency of an existing gene variant (allele) in a population due to  random chance alone and not natural selection.

Geographical isolation

Is a term that refers to a population’s organisms that are physically separated from  exchanging genetic material with other organisms of the same species.

Geological record

Fossils preserved in sedimentary rock layers that can be used to trace the evolutionary  history of a species.

Gradualism

Idea that evolution proceeds by imperceptibly small, cumulative steps over long periods of  time rather than by abrupt, major changes. Due to mutations still occurring but as selection  pressures remain similar the morphology selected for is similar.

Homologous structures

Structures that have a similar evolutionary history[ recent common ancestor] but have  developed to suit different functions.

Hybrid

The offspring of a mating where the parents differ in at least one characteristic. The term is  usually applied to offspring of widely different parents, e.g. different varieties/species.

Hybridisation

Is the offspring resulting from combining the qualities of two organisms of different breeds,  varieties, species or genera through sexual reproduction.

Instant speciation

The formation of a new species through polyploidy . Because the chromosome numbers of  the new ‘instant’ species do not match that of the original species they cannot interbreed as  they don’t have homologous chromosome

Macro-evolution

The formation of a completely new species, genera, etc.

Micro-evolution

The accumulation of (through mutation) of new characteristics in a species.

mtDNA

Is the DNA located in mitochondria, mtDNA is inherited from the mother (maternally  inherited). This can be used to trace maternal lineage far back in time. It has a region of non-coding and therefore can accumulate mutations that arise at a known rate, can work  out time from common ancestor.

Mutation

A permanent change in the bases on the DNA. It is the only way of creating new alleles.

Natural selection

The process by which individuals have differential reproductive success due to the  environment influence. These aspects are called selection pressures and can be biotic and  abiotic.

Nondisjunction

Is the failure of homologous chromosomes or sister chromatids to separate properly during  cell division resulting in cells with more than two copies of each chromosome e.g. 3n, 4n.

Polyploidy

The polyploid cell or organism has three or more times the haploid chromosome number.  Polyploidy arises as the result of total nondisjunction of chromosomes during mitosis or  meiosis.

Population bottleneck

Is an event that drastically reduces the size of a population, may be caused by various  events, such as an environmental disaster. The population bottleneck produces a decrease  in the gene pool of the population because many alleles, or gene variants, that were  present in the original population are lost.

Postzygotic isolating  mechanism

Reproductive isolation is a mechanism that keeps species from mating with others.  Postzygotic isolation prevents the formation of fertile offspring. Postzygotic  mechanisms include hybrid inviability, hybrid sterility and hybrid "breakdown."

Prezygotic isolating  mechanism

A mechanism that keeps species from mating with others, prevents the fertilization of  eggs e.g. spatial isolation, temporal isolation, mechanical isolation, gametic isolation  and behavioural isolation.

Punctuated equilibrium

Theory that states that evolution occurs primarily through short bursts of intense  speciation due to major environmental/selection change followed by lengthy periods  of being in statis or little change / equilibrium. Mutations of course happen randomly  at all times.

Reproductive isolation

When breeding is no longer possible to get fertile offspring.

Ring species

Two apparently distinct species that are connected by a series of intermediate  geographical and structural subspecies between which interbreeding can occur.

Sexual selection

Sexual selection acts on an organism's ability to obtain or successfully copulate with a  mate. Sexual selection is often powerful enough to produce features that are harmful to  the individual's survival. For example, extravagant and colourful tail feathers or fins are  likely to attract predators as well as interested members of the opposite sex.

Selection pressure

The extent to which organisms possessing a particular characteristic are either selected  for or against by environmental demands.

Speciation

The development of one or more species from an existing species. It occurs when  sympatric or allopatric populations diverge so much from the parent population that  interbreeding cannot occur.

Species

A category used in the classification of organisms that consists of a group of organisms  that can usually breed together and produce fertile offspring.

Sub-species

A group of individuals within a species that breed more freely among themselves than  with other members of the species and resemble each other in more characteristics.

Sympatric speciation

Speciation occurring where organisms living within the same area are theoretically  capable of interbreeding, but cannot because of difference in behaviour, flowering time.

Sympatry

Describes groups of organisms that live in the same geographical area.

Temporal isolation

Temporal isolation means 'isolated in time,' so this is a mechanism that prevents species from mating because they breed at different times. These differences can  be time of day, season, or even different years.

Vestigial structures

A structure in an organism that has lost all or most of its original function in the  course of evolution, such as human appendixes.

Y Chromosomes

The Y chromosome is one of two sex chromosomes (allosomes) in mammals. The Y  chromosome is passed only from father to son and can be used to demonstrate  relatedness

Populations

 groups of individuals belonging to the same  

species that live in the same region at the same time. Each  

individual in a population carries its own unique combination of  

alleles (genotype).

Mutations

Any permanent change in the nucleotide sequence of DNA. This plays a very  important part in increasing genetic diversity by creating new alleles.