Anagenesis
When a species forms without branching into multiple species from one primary ancestor
Cladogenesis
Speciation via evolutionary divergence from a parent population
Speciation
Speciation is a lineage-splitting event that produces two or more separate species, it is the formation of new and distinct species via evolution
Adaptive Radiation
the diversification of a group of organisms into forms that fill different ecological niches
Biostratiagraphy
determining the age of a region using fossils found in rock layers
Biogeography
biology that deals with the geographical distribution of plants in animals
Transitional Forms
fossils and organism that show intermediate states between the structure of an ancestral species and its descendants
Phylogeny/Phylogenesis
the evolutionary development & diversification of a species, group, or particular feature of an organism
Allopatric
speciation that takes place while geographically isolated from the parent population
Sympatric
speciation that takes place while intermingled the parent population but distinct due to genetic mutation
Convergent Evolution
when analogous structures are formed by genetically distinct groups to counter the same environmental pressures
Divergent Evolution
when species sharing common ancestor undergo cladogenesis and fill entirely different ecological niches while maintaining common/homologous structures
Gradualism
selection and variation within a species that occurs gradually and consistently with no sudden changes
Punctuated Equilibrium
selection and variation within a species that occurs in spurts, with periods of equilibrium and periods of rapid change
Coevolution
when two species evolve in response to changes in each other over time
Cladogram
a branching diagram that shows common ancestors and diverging species
Genetic Drift
Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
In small populations, random changes to allele frequency can have a dramatic ef
Phenotype
the appearance of an organism based on its genotype and its environment
Genotype
the genetic makeup of an organism, often responsible for its phenotype
Macroevolution
This is a change that occurs at or above the species level, resulting to a new species.
Microevolution
This is when a change occurs in the allele frequencies of a population; it causes new varieties within a species but no new species is produced, only variations.
Polyploidy
The presence of extra sets of chromosomes due to accidents during cell division. A polyploidy is when the number of chromosomes in an organism's cell doubles. This would mean that the organisms that have more chromosomes than other individuals of the same
Endosymbiosis
symbiosis in which one organism lives within the other
Derived character
a character that sets members of a line apart from other species descended from the same ancestor
Fossils
Records allow us to date events that occurred in history and match layers of rock across continents with the use of the organisms remnants to provide the evidence. It outlines the development of organisms driven by the environment at a given time and loca
Alleles
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Homologous Structures
These are traits/structures inherited from a common ancestor, even though they may not have similar functions. Many aspects would have changed size or shape as they have adapted to new environments and this supports the idea that a common ancestor created
Analogous Structures
These are structures/traits that have different anatomies but a similar function. They are seen in organisms that are not necessarily closely related but do live in very similar environments, having the similar adaptations. The same selective and evolutio
Vestigial Structures
They are anatomical remnants that were important in the organism's ancestors but are no longer used in the same way. However, because there is no incentive to get rid of them, they remain and this shows that the relics of ancestors demonstrates the evolut
Natural Selection
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.
Diff
Artificial Selection
The breeding of plants and animals to produce desirable traits. Organisms with the desired traits, such as size or taste, are artificially mated or cross-pollinated with organisms with similar desired traits.
Selective Advantage
The characteristic of an organism that enables it to survive and reproduce better than other organisms in a population in a given environment; the basis for evolution by natural selection.
Descent with Modification
The evolutionary term descent with modification is most often associated with human evolution, but it is actually a more general term than that would suggest. Simply put, descent with modification means that traits are passed down from generation to gener
Mutation
Changes in the DNA sequence causing new genes and alleles to arise, creating new phenotypes that are visible in the population
Gene Flow
Genetic additions or subtractions from a population, resulting from movement of fertile individuals or gametes.
Ontogeny
Ontogeny (also ontogenesis or morphogenesis) is the origination and development of an organism, usually from the time of fertilization of the egg to the organism's mature form. Yet, the term can be used to refer to the study of the entirety of an organism
Heterozygous
An organism that has two different alleles for a particular gene. For example, a heterozygous garden pea plant for the characteristic of flower colour will have a genotype of Pp (one allele for a purple flower, one allele for a white flower).
Homozygous
An organism that has two identical alleles for a particular gene. In the case of the garden pea plant for the characteristic of flower colour, it will be homozygous if both parents give a white flower allele, or if both parents give a purple flower allele
Fitness
This is affected by differences between various alleles of a given gene, contributing to reproductive success. It is interpreted as "survival of the form (phenotypic or genotypic) that will leave the most copies of itself in successive generations.
Adaptation
A change or the process of change by which an organism or species becomes better suited to its environment.
Allele Sequence
The sequence of nucleotides on a DNA molecule that constitutes the form of a gene at a specific spot or a chromosome. There can be several variations of this sequence, and each of these is called an allele.
Evolutionary (selection) Pressure
Selective pressures are environmental factors which may reduce reproductive success in a population and thus contribute to evolutionary change or extinction through the process of natural selection. Examples of selective pressures include: competition. pr
Hybrids
This is a blurry line as to whether they are a new species. It is hard to know when to draw the line, separating similar organisms as different species. An example is with hooded crows and carrion crows. They look very different but a large part mate with
Ring Species
Species with a geographic distribution that forms a ring and overlaps at the end. Most of them interbreed with their immediate neighbours so are they a different species?
Chronospecies
These are different stages in the same evolving lineage and have existed a different points in time. This is hard to differ for species since we would not know if, for example, a trilobite from 300 million years ago would have interbred with its ancestors
Phylogenetic
The concept of a species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining or derived traits.
Morphological
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Paleontological
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Ecological Species
This is a concept where a species is a set organisms adapted to a particular set of resources, called a niche, in the environment.
Biological Species
This is a concept where a species is a set of organisms that don't necessarily appear to look the same but do interbreed in nature.
The biological species concept defines a species as members of populations that actually or potentially interbreed in natur
Teleological/Creationist
Belief in or the perception of purposeful development toward an end, as in history.
Phenetic
An attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation.
Recognition
The ability of one molecule to attach itself to another molecule having a complementary shape, as in enzyme-substrate and antibody-antigen interactions.
Directional Selection
Directional selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.
Disruptive/Divergent Selection
describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.
Stabilizing Selection
a type of natural selection in which genetic diversity decreases and the population mean stabilizes on a particular trait value.
Apostatic Selection
This is the frequency dependent selection where the most common phenotype is selected against (e.g. predation)
Heterzygote Advantage
Where a heterozygous individual is more fit than a homozygous individual. It guarantees that there will be both alleles in subsequent generations.
Random Mating
Random mating is a factor assumed in the Hardy-Weinberg principle and is distinct from lack of natural selection: in viability selection for instance, selection occurs before mating.
Pre-zygotic Barriers
Reproductive isolation can be either prezygotic (barriers that prevent fertilization)
Post-zygotic Barriers
postzygotic (barriers that occur after zygote formation such as organisms that die as embryos or those that are born sterile).
Habitat
Two species encounter each other rarely, or not at all, because they occupy different habitats (even though the isolation might not be physical)
Temporal
Species that breed at different times of day, different seasons or different years cannot mix their gametes
Behavioral
Courtship rituals and other behaviours unique to a species are effective barriers
Mechanical
Morphological difference can prevent successful mating, this is the method in which they mate where they have different mechanisms (e.g. shape and size of pollen)
Gametic
Sperm of one species may not be able to fertilize eggs of another species
Hybrid Viability
Genes of the different parent species may interact and impair the hybrids development
Hybrid Fertility
Even if hybrids are vigorous, they might be sterile
Hybrid Breakdown
Some first generation hybrids are fertile but when they mate with another species or with either parent species; offspring of the next generation are feeble or sterile
Autopolyploidy
The evolution of some plant species such as autopolyploid (oats, potatoes and cotton) that have 2 chromosomes sets derived from one species
Allopolyploidy
For allopolyploid (wheat) where species have multiple sets of chromosomes with different sets.)
Adaptive Evolution
A dynamic, ongoing, life-sustaining process by which living organisms adjust to environmental changes.
Parallel Evolution
the independent development of closely corresponding adaptive features in two or more groups of organisms that evolved in different but equivalent habitats.
Co-evolution
The influence of closely associated species on each other in their evolution.
Padeomorphosis
The resemblance of adult animals to the young of their ancestors: seen in the evolution of modern man, who shows resemblances to the young stages of australopithecines
Sexual Selection
The process in nature by which individuals with certain traits, especially secondary sex characteristics such as colorful plumage and large antlers, are chosen more often for mating and thus pass those traits on to their offspring.
Apomorphy
This is a derived trait that is a novel and new evolutionary trait that is unique to a particular species and all its descendants and which can be used as a defining character for a species/group in phylogenetic terms.
Plesiomorphy
This is an ancestral trait that is one that links to other taxa that have an earlier last common ancestor with the taxa under consideration.
Synapomorphy
An ancestral trait that has been passed down to two or more separate taxa
Phylogeny
his references the species' evolutionary history.
Phylogenetic trees
Also known as an evolutionary tree, it is a branching diagram showing the inferred evolutionary relationships among various biological species (their phylogeny) based upon similarities and differences in their physical/genetic characteristics.
Molecular phylogeny
This is the branch of phylogeny that analyses hereditary molecular differences, mainly DNA sequences, to gain information on an organism's evolutionary relationships. The rest are in a phylogenetic tree.
Alignment
DNA sequences are arranged through alignment to identify the regions of similarity that may be a consequence of functional, structural or evolutionary relationships between the sequences.
Interpretation
This is the process to interpret and identify the DNA sequences.
Bottleneck Effect
When there is a random disaster that reduces a population to a smaller size, which may not represent the actual genetic makeup of the initial population. This leave less variation among the surviving individuals.
Founder Effect
This occurs when a new population is established with a very small number of individuals from a larger population, resulting to the loss of genetic variation.
Sexual Dimorphism
This is the differences in appearance between males and females of the same species (in colour, shape, size and structure) and are caused by the inheritance of one or the other sexual pattern in the genetic material.
Inter Sexual Selection
This influences the evolution of secondary sexual characteristics that determine the relative "attractiveness" of members of one sex to the other. Examples are courtship displays for peacocks in their plumage. The impacts of mate choice seem to be subtle
Intra Sexual Selection
This involves traits which affect the outcome of competition among members of one sex for access to members of the other. For example, this would operate on physical and behavioral features that help to determine the outcome of aggressive encounters among
Frequency Dependent selection
This is where the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population. In a positive scenario, the fitness of a phenotype increases as it becomes more common.