Speciation

• zeitgeber: the environmental agent that resets the biological clock
• Founder Effect: a small number of individuals emigrate from a population, or become geographically isolated from their original population
• Gene Flow: occurs when individuals more into (immigrate) or move out of (emigrate) a population
• Gene Pool: the total stock of different genes in an interbreeding population.
• Genetic Drift: the process of change in the genetic composition of a population due to random events rather than by natural selection
• Genetic Variation: the differences in alleles in the gene pool of a population
• Mutation: a permanent change in the nucleotide sequence of DNA
• Natural Selection: the process whereby organisms better adapted to their environment tend to survive and produce more offspring
• Population Bottleneck: a sharp reduction in the size of a population due to environmental events or human activities
• Sexual selection: a type of natural selection where members of one sex choose mates of the other sex to mate with based on phenotypical features
• adaptive radiation: the evolution of several different species of plant or animal from one ancestral species
• Allopatric Speciation: speciation occurring where organisms are initially capable of interbreeding but cannot because they are geographically separated.
• Allopolyploid: a type of polyploidy in which the chromosome complement consists of 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 but have evolved in different ways
• 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.
• Coevolution: occurs when two or more species reciprocally affect each other's evolution.
• Convergent Evolution: the development of superficially similar structures (analogous structures) in unrelated organisms, usually because the organisms live in the same kind of environment.
• Divergent Evolution: an accumulation of changes in the gene pools of two (or more) populations, leading to the formation of races, 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.
• Gene Flow: refers to the total number of genes of every individual in a population.
• Geographical Isolation: is a term that refers to a population of organisms that are physically separated from exchanging genetic material with other organisms of the same species.
• Gradualism: the view that evolution proceeds by imperceptibly small, cumulative steps over long periods of time rather than by abrupt, major changes.
• Homologous structures: structures that have similar evolutionary history but have developed to suit different functions
• mutation: a permanent change in the bases of the DNA. it is the only way of creating new alleles
• Natural Selection: the process that brings about new species by eliminating individuals that are less well adapted to their current environment from a population showing variation, allowing mainly individuals with advantageous adaptations to survive and reproduce.
• non-disjunction" 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
• parallel evolution: the development of related organisms along similar evolutionary paths due to strong selection pressures acting on all of them in the same way
• polyploidy: the polyploid cell organism has three or more ties to the haploid chromosome number. arises as the result of total non-disjunction of chromosomes during mitosis or meiosis.
• population bottleneck: 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, this prevents the formation of fertile offspring. this includes hybrid sterility, hybrid inviability, and hybrid breakdown.
• prezygotic isolating mechanism: that keeps secies from mating with others. it prevents that fertilization of eggs
• punctuated equilibrium: a theory that states that evolution occurs primarily through short bursts of intense speciation followed by lengthy periods of being in stasis or little change/equilibrium.
• reproductive isolation: a barrier to breeding that exists due to differences in mating season or mating organs
• ring species: two apparently distant species that are connected by a series of intermediate geographical and structural subspecies between which interbreeding can occur.
• sexual selection: acts on the ability of an organism 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.
• selection pressure: to the extent to which organisms possessing a particular characteristic are either eliminated or favoured 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.
• Sympatry: groups of organisms that live in the same geographical area.