theme 5ab- Evolutionary Patterns, Phylogeny and Macroevolution Flashcards
what are the two patterns produced by evolution?
- nested similarities found among extant species
- historical pattern recorded by fossils
what is phylogeny?
a branching diagram that shows the relationships between species according to the time since a common ancestor?
what does phylogeny do?
organize our knowledge of biodiversity
what does phylogeny provide a hypotheses for?
evolutionary relationship
what is a phylogram?
a phylogenic tree where the branch lengths represent the amount of inferred evolutionary change/time
what is a cladogram?
a phylogenic tree where all branches are of equal length
what are sister groups?
two species that share a common ancestor not shared by any other species or group
how can different trees be equivalent?
nodes can be rotated without changing evolutionary relationships
what are shared characters?
characters that are shared between species and have a genetic basis (morphological, chromosomal, molecular)
what does morphological characters refer to?
observable traits of the whole organism
what are homologous characters (homologies)
similar due to common ancestry, has shared sncestral and derived characters
what are analogous characters (homoplasies)?
similarity in appearance but not in origin , shared due to convergent evolution
what are the two reasons character states can be similar?
- amniotic egg (homology)
- wings (analagous)
how did characters evolve from homology?
something evolved once in the common ancestor
how did characters evolve from analagy?
something evolved independantly (ancestor didnt have wings)
how are homologies recognized?
structural similiarity
relations between parts
embryonic development
what are synapomorphies?
homologies shared by some but not all
what are shared derived characters?
unique character states uniformative for sister group
what is the strongest hypothesis of evolutionary relationships?
the tree with the fewest number of change required
why is the tree with less changes the strongest hypothesis for evolutionary relationships?
because it minimizes the total number of independant origins of character states
when given options of possible phylogenic trees which is most likely true?
the one with the fewest number of changes
which phylogenic tree is often favoured?
the simplest
what is the principle of parsimony?
the phylogeny requiring the fewest evolutionary change is the best estimate of the true phylogeny is the most parsimonious
what is the molecular data complement comparative morphology?
-each nucleaotide in the dna sequence can act as a trait
-amino acid sequence of proteins act as traits
-underlying logic of phylogenetic inference is identical for morphological and molecular characters
