The Tree of Life and The History of Life Flashcards
Tree of Life
-phylogenies show evolutionary relationships
-phylogenies are inferred from morphological and molecular data
-shared characters are used to construct phylogenetic trees
History of Life
-conditions on early earth made the origin of life possible
-the fossil record documents the history of life
-key events in life’s history: the origin of unicellular and multicellular life, and the colonization of land
-the rise and fall of major groups of organisms are caused by extinction and radiation
Phylogenetic tree
branching diagram that represents a hypothesis about the evolutionary history of a group of organisms
Root
represents ancestral lineage
Branch tips
represents the most recent descendants of that ancestor
Evolutionary lineage
a sequence of ancestral organisms leading to a particular descendant taxon
Branch point (node)
represents a common ancestor and the divergence of two evolutionary lineages from that common ancestor
Common ancestor
an ancestral population that gave rise to two or more descendant lineages
Most recent common ancestor
youngest relative from which all the linages in the group are directly descended
Clade
a grouping that includes a common ancestor and all the descendants of that ancestor; also called monophyletic groups
Paraphyletic group
consists of some but not all of the descendants of an ancestral species
Polyphyletic group
includes distantly related species but does not include their most recent common ancestor
Sister taxa
groups that share a common ancestor that is not shared by any other group; more closely related to each other than any other taxon
Systematics
a discipline focused on classifying organisms and determining their evolutionary relationships
Organisms have to have what to be more closely related?
Similar phenotypes or similar DNA sequences
