Module 4.2
Fundamental aspects of evolution
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Macroevolution: The change that occurs at or above the level of species over long periods of
time. It includes the transformations in evolution such as the origin of mammals and radiation of
flowering plants
Microevolution: The chances within a species or a population
Phylogeny: The scientific study of evolutionary relationships among species (can be
represented in a phylogenetic tree)
Phylogenetics: The study of evolutionary relationships among groups of organisms which have
been discovered through the lines of evidence mentioned earlier
Cladogenesis: An evolutionary splitting even where a parent species splits into two distinct
species forming a clade
A clade: A life-form group consisting of a common ancestor and all its descendants
representing a single branch on the tree of life
Adaptive radiation: The burst of divergence from a single lineage to give rise to many new
species from a single ancestor
Natural selection: A process by which nature selects for survival, the individuals which are best
adapted to environmental conditions and as a result, they will produce the most offspring
Germ-line: In the eggs
Polyploidy: The doubling or even trebling of the two basic sets of chromosomes
Gene flow: The movement of genes between populations
Genetic drift: The process that produces a random change in the frequency of characteristics
in a population
Artificial selection: The process of selecting and breeding organisms with desirable traits to
produce offspring with those traits that will be of some use to humans
Inbreeding: Mating of closely related individuals
Outbreeding: Mating of individuals not closely related
Wild plants: Plants that grow without the help of humans
Cultigens: Plants that are dependent on cultivation
Some patterns that are repeated in the tree of life:
, 1. Stasis/equilibrium
● Many lineages (branches) exhibit stasis which means that they don't change
much for a long time
● Some species change so little that they are called living fossils such as the
coelacanths:
○ Until 1983 it was thought to have gone extinct 80 mya
2. Lineage-splitting (or speciation)
● Patterns/times of specification can be identified by constructing and examining a
phylogeny (ie: the evolutionary history of a species or group especially in
reference to lines of descent and relationships among other groups of organisms)
● Phylogeny might show cladogenesis or anagenesis
● Cladogenesis is an evolutionary splitting even where a parent species splits into
two distinct species forming a clade
● A clade is a life-form group consisting of a common ancestor and all its
descendants representing a single branch on the tree of life
Clades
Cladogenesis
● Anagenesis when the ancestral species gradually accumulates changes and
eventually, when enough is accumulated the species is sufficiently distinct and
different enough from its original starting form that it can be labelled as a new
species
Fundamental aspects of evolution
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Macroevolution: The change that occurs at or above the level of species over long periods of
time. It includes the transformations in evolution such as the origin of mammals and radiation of
flowering plants
Microevolution: The chances within a species or a population
Phylogeny: The scientific study of evolutionary relationships among species (can be
represented in a phylogenetic tree)
Phylogenetics: The study of evolutionary relationships among groups of organisms which have
been discovered through the lines of evidence mentioned earlier
Cladogenesis: An evolutionary splitting even where a parent species splits into two distinct
species forming a clade
A clade: A life-form group consisting of a common ancestor and all its descendants
representing a single branch on the tree of life
Adaptive radiation: The burst of divergence from a single lineage to give rise to many new
species from a single ancestor
Natural selection: A process by which nature selects for survival, the individuals which are best
adapted to environmental conditions and as a result, they will produce the most offspring
Germ-line: In the eggs
Polyploidy: The doubling or even trebling of the two basic sets of chromosomes
Gene flow: The movement of genes between populations
Genetic drift: The process that produces a random change in the frequency of characteristics
in a population
Artificial selection: The process of selecting and breeding organisms with desirable traits to
produce offspring with those traits that will be of some use to humans
Inbreeding: Mating of closely related individuals
Outbreeding: Mating of individuals not closely related
Wild plants: Plants that grow without the help of humans
Cultigens: Plants that are dependent on cultivation
Some patterns that are repeated in the tree of life:
, 1. Stasis/equilibrium
● Many lineages (branches) exhibit stasis which means that they don't change
much for a long time
● Some species change so little that they are called living fossils such as the
coelacanths:
○ Until 1983 it was thought to have gone extinct 80 mya
2. Lineage-splitting (or speciation)
● Patterns/times of specification can be identified by constructing and examining a
phylogeny (ie: the evolutionary history of a species or group especially in
reference to lines of descent and relationships among other groups of organisms)
● Phylogeny might show cladogenesis or anagenesis
● Cladogenesis is an evolutionary splitting even where a parent species splits into
two distinct species forming a clade
● A clade is a life-form group consisting of a common ancestor and all its
descendants representing a single branch on the tree of life
Clades
Cladogenesis
● Anagenesis when the ancestral species gradually accumulates changes and
eventually, when enough is accumulated the species is sufficiently distinct and
different enough from its original starting form that it can be labelled as a new
species
