Taneil Thompson
4.2. Fundamental aspects of evolution
PLEASE NOTE THAT I HAVE SIFTED THROUGH THE IEB FINAL PAPERS FROM 2011 TO 2018 AND ADDED
SOME INFORMATION THAT KEPT COMING UP. THIS INFORMATION IS IN PINK. I HAVE ALSO CHECKED
THROUGH THE SAGS DOCUMENT TO MAKE SURE THAT ALL THE RELEVANT INFORMATION IS HERE. J
Macroevolution:
- Change that occurs at or above the level of species over long periods of time
- Phylogeny: scientific study of evolutionary relationships among species
- Phylogenetics: study of evolutionary relationships among groups of organisms
- Phylogenetic Tree Plan:
1. Equilibrium or stasis is when a line on the tree does not branch or change for a long time showing
that no evolution has occurred
2. Lineage-splitting or speciation is when a single line branches into several. Cladogenesis is when the
parents species splits into two DISTINCT species and form a clade (a life-form group consisting of
a common ancestor and all its descendants.
SAHETI School, 2019
, Taneil Thompson
Anagenesis: gradual change occurs in a species and the lineage in the
tree does not split. This is known as micro-evolution.
*Cladogenesis is macro-evolution*
3. Adaptive radiation is a burst of divergence from one ancestor
(a lot of lines of lineage from one common ancestor) that
occurs when one species goes extinct (dinosaurs) and new
species emerge to fill the empty ecological niches (birds)
4. Extinction occurs when a lineage seizes to exist (line does not
continue)
Trends in macro-evolution:
1. Increase in complexity
2. Increase in body size
3. Evolving from marine life to terrestrial life and then to the ability to fly
SAHETI School, 2019
4.2. Fundamental aspects of evolution
PLEASE NOTE THAT I HAVE SIFTED THROUGH THE IEB FINAL PAPERS FROM 2011 TO 2018 AND ADDED
SOME INFORMATION THAT KEPT COMING UP. THIS INFORMATION IS IN PINK. I HAVE ALSO CHECKED
THROUGH THE SAGS DOCUMENT TO MAKE SURE THAT ALL THE RELEVANT INFORMATION IS HERE. J
Macroevolution:
- Change that occurs at or above the level of species over long periods of time
- Phylogeny: scientific study of evolutionary relationships among species
- Phylogenetics: study of evolutionary relationships among groups of organisms
- Phylogenetic Tree Plan:
1. Equilibrium or stasis is when a line on the tree does not branch or change for a long time showing
that no evolution has occurred
2. Lineage-splitting or speciation is when a single line branches into several. Cladogenesis is when the
parents species splits into two DISTINCT species and form a clade (a life-form group consisting of
a common ancestor and all its descendants.
SAHETI School, 2019
, Taneil Thompson
Anagenesis: gradual change occurs in a species and the lineage in the
tree does not split. This is known as micro-evolution.
*Cladogenesis is macro-evolution*
3. Adaptive radiation is a burst of divergence from one ancestor
(a lot of lines of lineage from one common ancestor) that
occurs when one species goes extinct (dinosaurs) and new
species emerge to fill the empty ecological niches (birds)
4. Extinction occurs when a lineage seizes to exist (line does not
continue)
Trends in macro-evolution:
1. Increase in complexity
2. Increase in body size
3. Evolving from marine life to terrestrial life and then to the ability to fly
SAHETI School, 2019
