Phylogenetics Flashcards
What is descent with modification?
All species, living and extinct, had descended without interruption, from one or a few original forms of life
What is something that all life on Earth shares?
a common ancestor (descent with modification = diversity today)
What are the 8 (or 9) taxons?
(Life)
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Who is the father of modern taxonomy and systematics?
Carolus Linnaeus
What is binomial nomenclature?
every organism is given a 2-part Latine name 1) a generic name (=genus, which is capitalised) and 2) a specific name (=species which is lower case)
e.g. Homo sapiens (Humans)
What is a genus?
A group of one or more species related by common descent from a recent ancestor and sharing similar traits
What is a species?
a group within a genus whose members share the same set of structural traits and can successfully interbreed with one another to produce fertile offspring
What is hierarchical classification?
a filing system for grouping species into a hierarchy of general categories. (nested pattern of similarities among species)
What is a polymorphic species?
the occurrence of two or more different forms of individuals of the same species
What is a cryptic species?
two or more morphologically identical species
What is the biological species concept?
organisms are members of the same species if they can mate with each other when they encounter each other in nature and produce fertile, viable hybrids
What are systematics?
field of biology that recpnstructs the evolutionary history (pyllogeny) and studies the patterns of relationships among organisms (taxa): visualised as evolutionary trees
What are phylogenetic trees?
genealogies for organisms
is a hypothesis regarding the evolutionary history for a group of organisms
how is closeness of relationships determined in a phylogenetic tree?
by looking to see how recently two groups shares a common ancestor
in phylogenetic trees, what is the order of branches (nodes) mean?
the sequence of events in time
on a phylogenetic tree what are sister groups?
groups more closely related to one another than any other group
what are clades?
a group of organisms that represent a common ancestor and all the descendants of the ancestor
what is a taxon?
a group of organisms that is given a name, which ideally share a common ancestor
what are natural taxa?
when clades (monophyletic groups) and taxa are consistent with common ancestry
what is a monophyletic group?
taxa that encompass an ancestor and all its descendants (also called a clade), members bound together by common ancestry not shared wuith other taxa
What is a paraphyletic group?
a taxon that includes an ancestor, but not all of the descendants of that ancestor (artificial taxa)
What is a polyphyletic group?
a taxon that has at least two separate evolutionary origins from unrelated ancestors
What is homology?
likeness among groups of organisms due to shared ancestry
What is convergent evolution?
species from different evolutionary linmeages may come to resemble one another if they have similar ecological roles and natural selection generates analogous adaptation (homoplasy)
what are plesiomorphic (or ancestral) characters?
characteristics shared by all members of the group including the most recent common ancestor
What are apomorphic (or derived) characters?
Homologous characters that have evolved more recently 9after divergence from the common ancestor) and therefore only occur among certain taxa when building a phylogeny
What is an Ingroup taxa?
any group of theoretically related organisms
What is an Outgroup taxa?
a group or taxon used for comparative purposees in a phylogenetic analysis: related to the ingroup but presumed to have diverged before the ingroup diversifies
what is parsimony?
the most plausible explanation of an occurrence or phenomenon is often the simplest, involving the fewest assumptions or evolutionary changes
