Week 1 Flashcards
Fossil records
is where ancestors are
Three main paradigms in reconstructing evolutionary trees
- origen of species through modification from a common ancestor
-One ancestral species is the ancestor of one or more species in a particular - there will be several ancestors in a particular tree
Phylogenies
History of branches between species
How to reconstruct tree of life
By comparing DNA sequences between species
Derived characteristics of
No vascular tissue
Spores
Sporangia
No vascular tissue -> vascular tissue
Spores -> seeds
Sporangia -> flowers or cones
Derived characteristics
Similarity that is inherited from the most recent common ancestor of an entire group
Ancestral characteristics
Similarity that arose prior to the common ancestor of the group
Ancestral characteristics of
Vascular tissue
Seeds
Flowers or cones
No vascular tissue
Spores
Sporangia
Synapomorphies
Shared derived characters that are considered informative about evolutionary relationships
Clades
Organisms that share common ancestor
Sporophyllis
Ancestor
leaves of plants that bear “spores”
Gymnosperms
Plants with cones
Oldest ancestor: cycads - have cones, in cones there are seeds
Females and males
Oldest have leaves with seeds in them - compressing leaves with seeds in them makes cones
Sporophyllis facts
- scales are modified Sporophyllis
- Sporophyllis (seeds) make fruit:
- folds over (like avocado) | compress into scales
^ - modified leaves
Cladistics
The study of evolutionary trees
Group of organisms that share a common ancestor
Cladogram, phylogenics, clades
Angiosperms and Gymnosperm
Direct ancestor of seeds
Cladogram
Depicts a hypothesis of evolutionary relationships and are composed of clades
Sister species
Pair that share the same direct common ancestor
- organisms that share a trait don’t always share a common ancestor
