Keywords
Definition
Adaptive radiation
A rapid evolutionary diversification of descendents from a single ancestry.
Allele Frequency
Proportion of different alleles within a population.
Allopatric speciation
Speciation where populations are physically isolated by physical barrier and evolve intrinsic isolation. When species into new environments, they are faced with intense competition, and gene flow is not common. Different selection pressure like disease lead to rise of an advantageous characteristic. Later the separated populations will undergo changes in their genetic makeup as well as their behaviour patterns. The example is adaptive radiation of Galapagos finches.
Analogous
Structure in organisms that look the same with similar purposes but with different origin. One example is the eye. Mammalian eye and octopus eye have similar appearances and same function but have different origins.
Balanced polymorphism
Balanced is when different phenotypes coexist in the population. E.g. Sickle Cell Allele
Clade
A group of organisms consisting of a single common ancestor and all descendants of that ancestor.
Cladistics
A method of classification of living organisms using cladograms.
Convergent evolution
Evolution where species may resemble each other if they occupy similar ecological roles and go through natural selection.
Divergent evolution
The evolution that involves diversification of an ancestral group into number of different species in various habitats.
Endosymbiotic theory
This theory explains the origin of chloroplasts and mitochondria. It is thought that eukaryotic cells were formed by large prokaryotic cells ingesting other free-floating prokaryotic cells.
Eukaryote
A type of cell containing specialized organisms and an elaborate system of cell division.
Evolution
Accumulative change
Gene pool
The sum total of alleles in a population where organisms can interbreed.
Gradualism
The characteristics change due to selective pressures and accumulated, causing the populations to slowly diverge.
Half-life
Half-life is an amount of time the atoms take to fall to half its original quantity.
Hardy-weinberg
An equation used to predict the frequency of dominant and recessive alleles and phenotypes in a population. We assume the allele frequency will remain the same over time. This assumption draws other implications: 1) the population is large. 2) No change in allele frequency = no mutation or gene flow.
Homo spp.
Genus that includes modern humans as well.
Homologous
Structure that looks different and serves different function but diverged from a common ancestry. One example of homologous feature is pentadactyl limb in vertebrate. It is found in human arm, bat wing and whale front fin in similar structure but serves different functions.
Panspermia
Theory that life exists and is distributed throughout the universe in the form of germs or spores that develop in the right environment.
Phylogeny
the evolutionary history of a group of organisms, depicted in a family tree.
Polymorphism
Refers to the occurrence of two or more phenotypes
