Phylogenetic Trees and Geologic Time Flashcards
Tree of Life
branching evolutionary pattern that relates organisms (living and extinct)
Phylogenetic Tree
visual representation of the relationship between different organisms through evolutionary time from a common ancestor to descendants
- speciation is the starting point for biological diversity
- the endpoint is extinction
Taxa / Taxon
one or more populations of organisms that form an evolutionary unit
Branches
lineage of ancestors
Nodes
representation of a speciation event from a common ancestor
Root Node
represents the most common ancestor of all the taxa represented on the tree
Clade
group of taxa that includes a common ancestor and all its descendants (aka a MONOPHYLETIC GROUP)
Outgroup
least related taxon in a tree of that phylogeny due to contrasting characteristics
Synapomorphy
a characteristic present in an ancestral species and shared exclusively by its evolutionary descendants (homologous trait specific to that group)
Building Phylogenetic Trees
Phylogenetic trees represent a hypothesis about homology, using this data:
- Morphological (structural features, organs, skeletal arrangements)
- Genetic (mitochondrial DNA, ribosomal RNA, genomic genes)
Homology
similarity due to common ancestry
Parisomy
the idea that the most likely branching pattern in the evolutionary hypothesis is the pattern that requires the fewest changes (still applies to convergent evolution)
Monophyletic Group
one or more organism(s) that have a shared, homologous, shared trait from a common ancestor
- includes the organism(s) and the common ancestor
Derived Trait
a trait that first appeared in the most recent common ancestor
Adaptive Radiations
periods of increasing biodiversity and RAPID SPECIATION in geologic time that can caused by:
1. New ecological niches becoming available, like after major climate events or mass extinctions
2. Key “evolutionary innovations”, which is a new derived adaptation trait in the environment (opens up new resources to organisms)
