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
Characters
phenotypic traits
Shared ancestral character
a character that originated in an ancestor of the taxon
Shared derived character
an evolutionary novelty unique to a particular clade
Homology
shared ancestry
Analogy
similar through convergent evolution
Outgroup
a species or group of species closely related to, but not part of the group of species being studied
Ingroup
the group of species being studied
An ancestral character is present in…
both the outgroup and the ingroup
A derived character is present in…
only the ingroup
Maximum parismony
assumes that the most likely tree is the one that requires the fewest evolutionary events (appearances of shared derived characters)
Extant
still in existence; surviving
Convergent evolution
evolution of similar features in independent evolutionary lineages
