Chapter 26 Flashcards
Phylogeny
The evolutionary history of a species or group of related species
Systematics
Scientific discipline focused in classifying organisms and determining their evolutionary relationships
Classification system (high to low)
Domain, kingdom, phylum, class, order, family, genus, species
Taxon
Named group at any level of the hierarchy
Evolutionary lineage
Sequence of ancestral organisms leading to a particular taxon
Sister taxa
Groups of organisms that share an immediate common ancestor not shared by other groups (EX: humans and chimps)
Basal taxon
A lineage that diverges from the other members of group early in group history
3 things to remember when looking at phylogenetic trees
1) they show patterns of descent not phenotypic similarity
2) we cannot infer ages of taxa or branch points
3) we cannot assume taxon evolved from the taxon next to it
Homology
Similarity in characteristics resulting in shared ancestry
Analogy
Similarities due to convergent evolution, not descent from common ancestor
Convergent evolution occurs when…
Similar environmental pressures/natural selection produce similar looking adaptations in organisms
Cladistics
Approach to systematics where organisms are put into groups called “clades” based on common descent
Monophyletic
A group of taxa that consist of a common ancestor and all it’s descendants, equivalent to a clade
Paraphyletic
Group of taxa that consist of common ancestor and some, not all, descendants
Polyphyletic
Group of taxa that included distantly related organisms but doesn’t include most recent common ancestor
Shared ancestral character
A trait shared by members of a particular clade that originated in an ancestor not from that clade
Shared derived character
Evolutionary novelty that is unique particular clade
Outgroup
Species from an evolutionary lineage that diverged before the lineage that contains the group being studied (closely related to group being studied)
Ingroup
Group who’s evolutionary relationships are being analyzed
Maximum parsimony
Principal when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with facts
Maximum likelihood
Principal that states when one is considering multiple phylogenetic hypotheses, one should take into account the most likely sequence of evolutionary events
Orthologous genes
Homologous genes found in different species bc of speciation
Paralogous genes
Homologous genes found in same genome bc of gene duplication
Molecular clock
Method for estimating time required for a given amount of evolutionary change
Horizontal gene transfer
Transfer of genes from one genome to another through mechanisms such as transposable elements, plasma exchange, viral activity or fusions
