Ch 3 - Patterns of evolution Flashcards
Cladogenesis
Starting a new branch (Gould)
Anagenesis
Slow gradual change of one particular feature within a certain lineage (Darwin)
Punctuated equilibrium
SJ Gould: majority of change occurs at a speciation event, little change otherwise
Protostome and deuterstome
the first opening (the blastopore) becomes the anus, while in protostomes it becomes the mouth.
Rise of HIV from phylogenetic tree
HIV-1 developed from chimpanzee SIV, HIV-2 from mangabey; multiple independent origins and transfers to humans;
Monophyletic, para- and poly-
Mono- group including all descendants of a certain ancestor; para- only a few of them (ie the reptiles, excludes birds); poly- includes descendants of two of more ancestors but not all of their descendants
Determining homology
Many features are modified from pre-existing ones from common ancestor; same genetic and developmental basis but CAN differ!
Compare differences in humerus, radius and ulna, and metacarpals
Very different! Porpoise has really small, horse metacarpals are massive, bats have extended fingers
Convergence
Independent evolution of similar states usually in widely separated taxa
Parallelism
Independent evolution of similar states but similar genes/development (usually in more closely related species)
Reversals
Independent evolution of similar states but change back to ancestral condition
Mimicry
Aposematic: warning colouration; Batesian (“safe” animal resembling a dangerous species) and Mullerian (two dangerous species are alike); example of convergence.
Rates of character change
Organisms are mosaics - gradualism (Darwin) and saltations (Gould)
Individualization
A feature becomes more specialized (ie teeth - once were all similar shape, now many are diverse)
Heterochrony
Evolutionary change in timing of developmental processes (ie stop of brain growth in chimps is sooner than humans)
Neotony
Type of heterochrony where sexual maturation is complete before other characters have reached the mature state.
Allometry
Differing growth rates from different parts of body (y=bx^a, a describes relative growth rate, x and y are the measurements in question), ex. head vs legs
Heterotopy
Different place of expression for a certain tissue; eg Lianas - really long roots exposed from canopy to floor, or development of sesamoid bones
Paedomorphosis
Organism takes on some maturity characteristics early while retaining many juvenile ones into adulthood
Paralogy
Genes that are related through duplications in a common ancestor (ie A into A and B)
Orthology
homologous gene found in two different lineages, related via speciation
