The study of organism divergence, , and adaptation.
See evolution as well as evolutionary ecology and .
The differs in his method and in the problems in which he is interested. His basic question is "Why?" When we say "why" we must always be aware of the of this term. It may mean "how come?," but it may also mean the "what for?" It is obvious that the evolutionist has in mind the historical "how come?" when he asks "why?" Every organism, whether or species, is the product of a long history, a history which in- deed dates back more than 2000 mil- lion years. As
has said, "a mature , acquainting himself for the first time with the problems of biology, is puzzled by the circumstance that there are no 'absolute phenomena' in biology. Everything is time-bound and space-bound. The animal or plant or microorganism he is working with is but a link in an of changing forms, none of which has any permanent validity." There is hardly any structure or function in an organism that can be fully understood unless it is studied against this historical background. To find the causes for the existing characteristics, and particularly adaptations, of organisms is the main preoccupation of the evolutionary biologist. He is impressed by the enormous diversity of the organic world. He wants to know the reasons for this diversity as well as the pathway by which it has been achieved. He studies the forces that bring about changes in and (as in part documented by paleontology), and he studies the steps by which have evolved the miraculous adaptations so characteristic of every aspect of the organic world.
We can use the language of to attempt still another characterization of these two fields of biology. The functional biologist deals with all aspects of the decoding of the programmed information contained in the of the fertilized zygote. The evolutionary biologist, on the other hand, is interested in the history of these codes of information and in the laws that control the changes of these codes from generation to generation. In other words, he is interested in the causes of these changes.
It is evident that the functional biologist would be concerned with analysis of the proximate causes, while the evolutionary biologist would be concerned with analysis of the ultimate causes. This is the case with almost any biological phenomenon we might want to study. There is always a proximate set of causes and an ultimate set of causes; both have to be explained and interpreted for a complete understanding of the given phenomenon.
Evolutionary terms and concepts include the following:
Absolute fitness, Adaptability, Adaptation, Adaptive landscape, Adaptive radiation, Adaptive zone, Allele, Allele frequency, Allele-neutral, Allopatric speciation, Anagenesis, Analogy, Ancestor, Ancestor species, Antagonistic pleiotropy, Altering gene number, Artificial selection, Assortative mating, Average heterozygosity, Balanced mutation, Balanced polymorphism, Balancing selection, Biased reproductive success, Biological species concept, Biogeography, Bottleneck (genetic), Breakdown of reproductive barriers, Cladogenesis, Clonal expansion, Clonal interference, Coefficient of relatedness, Common ancestor, Convergent evolution, Differential success, Darwinian evolution, Darwinian fitness, Darwinism, Deleterious allele, Derived, Descendant species, Descent with modification, Detrimental allele, Directional selection, Disruptive selection, Disruptive frequency-dependent selection, Divergent evolution, Diversifying selection, Ecological species concept, Endosymbiotic theory, Evolution, Evolutionary compromise, Evolutionary divergence, Evolutionary ecology, Evolution, Existing variation, Extant, Fit, Fitness, Fixation, Founder effect, Frequency-dependent selection, Gametic isolation, Gene flow, Gene pool, Genetic bottlenecking, Genetic drift, Genetic drift: impact of population size, Genetic drift: impact on allele frequency, Genetic drift: impact on genetic variation, Genetic drift: impact on allele fixation, Genetic variation, Genetic structure, Genotype frequency, Geographic variation, Geographical barrier, Geographical isolation, Habitat isolation, Hard selection, Hamilton's rule, Hardy-Weinberg assumption # 1, Hardy-Weinberg assumption # 2, Hardy-Weinberg assumption # 3, Hardy-Weinberg assumption # 4, Hardy-Weinberg assumption # 5, Hardy-Weinberg equilibrium, Hardy-Weinberg theorem, Heterochrony, Heterozygous advantage, Hidden genetic variation, Hitchhiking (genetic), Homologous structure, Homology, Homoplasy, Horizontal gene transfer, Hybrid, Hybrid breakdown, Hybrid vigor, Hybrid zone, Hybridization, Identical by descent, Inclusive fitness, Intersexual selection, Intrasexual selection, Introgression, K selection, Kin selection, Lineage, Macroevolution, Mate choice, Mechanical isolation, Microevolution, Migration (genetic), Modern synthesis, Molecular evolution, Molecular homology, Monomorphic (locus), Morphological homology, Morphological species concept, Mosaic evolution, Muller's ratchet, Mutation, Natural selection, Negative selection, Neutral allele, Neutral theory, Neutral variation, New alleles, Non-Darwinian evolution, Nonrandom mating, Orthologous genes, Paedomorphosis, Panmixis, Paralogous genes, Parapatric speciation, Peripatric speciation, Peripheral isolates, Phyletic gradualism, Phylogenetic species concept, Pluralistic species concept, Polymorphism, Population biology, Population genetics, Postzygotic barrier, Prezygotic barrier, Punctuated equilibrium, r selection, Random mating, Rapid reproduction, Reinforcement, Relative, Relative fitness, Reproductive barriers, Reproductive isolating mechanism, Reproductive isolation, Reduced hybrid fertility, Reduced hybrid viability, Secondary endosymbiosis, Selection, Selection for reproductive isolation, Selective sweep, Serial endosymbiosis, Sexual selection, Shared ancestral character, Shared character, Shared derived character, Speciation, Species concepts, Species selection, Stabilizing frequency-dependent selection, Stabilizing selection, Sympatric speciation, Temporal isolation, Tradeoffs, Ultimate causation, Universal tree, Vertical gene transfer, Vestigial structure