Flashcards in Evolution- Phylogeny Deck (21)
What is systematics?
An analytical approach to understanding diversity and relationships of organisms both extant and extinct
What are the categories of classification?
Domain, kingdom, phylum, class, order, family, genus, and species
What is a taxon?
The taxonomic unit at any level
What is a phylogenetic tree?
A hypothesis about evolutionary relationships
What are sister taxa?
Groups that share an immediate ancestor
What is a polytomy?
A branch from which more than 2 groups emerge
What don't phylogenetic trees do?
They don't show patterns of descent and they don't indicate when species evolved or how much change has occurred
What is convergent evolution?
Similar environmental pressure and natural selection produce similar adaptation in organisms for different evolutionary lineages
What are non-homologous traits and what is another word for them?
Structures or molecular sequences that evolved independently. Another word is homoplasy
What is a cladogram?
A hypothesis depicting patterns of shared characters among taxa
What is a clade?
It is within a cladogram. It is a group of species that includes ancestral species and all its descendants
What does a paraphyletic group consist of?
An ancestral species and some, but not all, of the descendants
What does a polyphyletic group consist of?
Various species that lack a common ancestor
What is the difference between shared ancestral and shared derived characters?
Shared ancestral characters originate in an ancestor of a taxon. Shared derived characters is unique to a particular clade
What are the two things the length of a branch can represent in phylogenetic trees?
1. Reflect the number of genetic changes that have taken place in a particular DNA sequence in that lineage
2. Reflect chronological time
What are molecular clocks?
They uses constant rates of evolutions in some genes to estimate the absolute time of evolutionary genes
What are some difficulties with molecular clocks?
- Not as smooth as neutral theory predicts
- Some DNA changes are favoured over others
- Estimates of evolutionary divergences older than the fossil record have a high degree of uncertainty
What are the 3 domains?
Bacteria, Archaea, and Eukarya
What does the tree of life suggest and what is is based on?
Eukaryotes and Archaea are more closely related to each other. It is based largely on rRNA genes that have evolved slowly
Who is Doolittle?
First to show importance of horizontal gene transfer