CH 20 Phylogenies and the history of life

Estimates for diversity of life

1.5-2.3 million species cataloged

Systematics

studies the kind and diversity of organisms and their relationships

Phylogeny

evolutionary history and relationships of an organism or group of organisms, depicted as a phylogenetic tree

Taxon/Taxa

groups of organisms

Clade

a group of organisms believed to comprise all the evolutionary descendants of a common ancestor

Nodes are

the most recent common ancestor

Taxonomy

theory and practice of identifying, naming and classifying organisms into taxa

Binomial Nomenclature

2 worded scientific name (ex: Homo Sapiens)

Homologous Characteristics

similar due to evolutionary origin (having a common ancestor)

Analogous Characteristics

similar in function, but are unrelated (ex: bat wings and birds wings)

Evolutionary reversal

similar, analogous characters that may cause taxa to appear related (ex: dolphin and cheetah, both mammals)

Horizontal Gene Transfer (HGT)

transfer of genetic material between unrelated species (more common in prokaryotes)

Transformation

naked DNA uptake by bacteria

Transduction

genes transferred by virus

Conjugation

genes transferred between bacteria via a sector

Theory for endosymbiosis for origin of a eukaryotic cell

mitochondria and chloroplasts originated by the engulfment of free living prokaryotic cells by an ancestral cell