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Population Genetics and Evolution (Convergent Evolution (Chemosynthesis…
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- is the study of genetic variation within populations, and involves the examination and modelling of changes in the frequencies of genes and alleles in populations over space and time.
- is the collection of different genes within an interbreeding population. The concept of a gene pool usually refers to the sum of all the alleles at all of the loci within the genes of a population of a single species. It includes both genes that are expressed, and those that are not.
- is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people.
- is the intentional reproduction of individuals in a population that have desirable traits. In organisms that reproduce sexually, two adults that possess a desired trait — such as two parent plants that are tall — are bred together.
- the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.
- the formation of new and distinct species in the course of evolution. Speciation involves the splitting of a single evolutionary lineage into two or more genetically independent lineages.
- Phyletic gradualism is a model of evolution which theorizes that most speciation is slow, uniform and gradual. When evolution occurs in this mode, it is usually by the steady transformation of a whole species into a new one.
- Divergent evolution is a pattern of evolution in which one species gives rise to many, it is also when a number of different species move away from a common ancestor.
- (also known as gene migration or allele flow) is the transfer of genetic variation from one population to another.
- Pollination is the transfer of pollen from a stamen to a pistil. Pollination starts the production of seeds.
- Seed dispersal is the movement, spread or transport of seeds away from the parent plant. Plants have very limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic vectors such as the wind and living vectors like birds.
- is a form of asexual reproduction of a plant. Only one plant is involved and the offspring is the result of one parent. The new plant is genetically identical to the parent.
- The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile.
- Any physical, nonliving feature that prevents two populations from exchanging genes.
- Allopatric speciation, also referred to as geographic speciation, vicariant speciation, or its earlier name, the dumbbell model, is a mode of speciation that occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with gene flow
- can be either prezygotic (barriers that prevent fertilization ) or postzygotic (barriers that occur after zygote formation such as organisms that die as embryos or those that are born sterile).
- Sympatric speciation is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.
- can be temporal, behavioural, geographic / ecological or mechanical; whereas postzygotic isolation barriers include the inviability, infertility or breakdown of hybrid organisms
- Hybrid inviability is a post-zygotic barrier, which reduces a hybrid's capacity to mature into a healthy, fit adult. The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species.
- is a post-zygotic barrier, which reduces a hybrid's capacity to mature into a healthy, fit adult. The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species.
- In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
- Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces.
- is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
- the synthesis of organic compounds by bacteria or other living organisms using energy derived from reactions involving inorganic chemicals, typically in the absence of sunlight.
- was generated by gases that had been trapped within the rocks making up the body of the planet, but escaped due to volcanic activity, a process known as "outgassing". The components of this atmosphere were primarily carbon dioxide, water, and lesser amounts of nitrogen.
- A reducing atmosphere is an atmospheric condition in which oxidation is prevented by removal of oxygen and other oxidizing gases or vapours, and which may contain actively reducing gases such as hydrogen, carbon monoxide, and gases such as hydrogen sulphide that would be oxidized by any present oxygen.
- a colorless, odorless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air.
- is a (planetary) atmosphere which oxidizes immersed (surface) compounds. It sometimes refers to an O2-rich atmosphere, for example the atmosphere of modern Earth.
