Patterns in the Tree of Life

Question 1

What are some patterns that are repeated in the tree of life?

Answer 1

1. Stasis/equilibrium
2. Lineage-splitting (or speciation)
3. Adaptive radiation
4. Extinction

Question 2

What is stasis/equilibrium in evolution?

Answer 2

• the quality of lineages not changing much for long periods of time

Question 3

What is cladogenesis?

Answer 3

• an evolutionary splitting event where a parent species splits into two distinct species, forming a clade

Question 4

What is a clade?

Answer 4

• a life-form group consisting of a common ancestor and all its descendants

Question 5

What is anagenesis?

Answer 5

• when the ancestral species gradually accumulates changes, and eventually the species is sufficiently distinct and different enough from its original starting form that it can be labelled as a new form, a new species

Question 6

What is adaptive radiation?

Answer 6

• the burst of divergence from a single lineage to give rise to many new species from a single ancestor

Question 7

What are some trends that appear in macroevolution?

Answer 7

• increased complexity (prokaryotes to eukaryotes)
• increasing body size
• evolving from marine habitats, then to terrestrial habitats, before evolving the ability to fly