Rates of Evolution

Question 1

what was darwis view?

Answer 1

that evolution proceeds gradually

Question 2

what did the discovery of mendelian genetics show?

Answer 2

discrete units of hereditry were inconsistent with continuous range of variation seen in nature - big changes should be more common

Question 3

what was the modern synthesis?

Answer 3

evolution framed as ‘changes in allele frequencies w/in pops’

Question 4

the four forces of evolution?

Answer 4

drift, gene flow, mutations, ns

Question 5

what did darwins original ideas see?

Answer 5

extinction events, diversification, stasis, new species/types/clades

Question 6

what was the general overview? darwin and neo?

Answer 6

rate was - gradual morphological change over time

neo - same - gradual change in gene frequencies

Question 7

what is macroevolution?

Answer 7

origin of major changes in morphology or body plan

Question 8

what was the decision in the 1980’s?

Answer 8

neo-darwinism is wrong and evolution is not characterised by gradual anagenesis

Question 9

what is anagenesis?

Answer 9

gradual change within a lineage

Question 10

what is cladogenesis?

Answer 10

when one lineage splits in two

Question 11

what is phylogenetic gradualism and what was the verdict on it?

Answer 11

it was rejected

the pattern of gradual change over time, such that trait morphology change is not associated with cladogenesis

Question 12

what is punctuated equilibrium?

Answer 12

abrupt changes, most frequent pattern in the fossil record

Question 13

what are the implications of punctuated equlibrium?

Answer 13

new species suddenly appear
intermediates rarely found
macroevolution

Question 14

how does PE imply macroevolution occurs?

Answer 14

lineage splitting
rapidly  
lineages stable between changes
in small geographically isolated populations 
changes in few key loci

Question 15

evidence for PE?

Answer 15

molluscs - speciation in Cenazoic
claimed to have punctuated diversification in two time periods - not gradualistic

bryozoans - found not much change within species but sudden appearance of new species - was persistance of ancestor species

Question 16

counter evidence for PE/

Answer 16

trilobites
found 8 lineages w/ changes in the number of pygidial ridges w/ time
‘end’ members had previously been assigned to a different species

Question 17

what did JBS Haldane do?

Answer 17

came up with an equation that expressed morphological change in darwins
commonly used in studies of fossil record
can compare rates of evolution that occured over different time periods in different lineages - for a single trait

Question 18

what did Gingerich do?

Answer 18

looked at rates of morphological evolution, scale to look at variability in rates
I - v high - lab selection experiments
II - high - adaptive radiation
III - moderate - faunal changes since glaciation
IV - low - fossil record

Question 19

when will negeative relationships between evolutionary rate and time interval be found?

Answer 19

if the direction of evolution fluctuates over time

Question 20

is PE a problem for neo-darwinism?

Answer 20

abrupt morphological change likely not a characteristic of how evolution proceeds

Question 21

is stasis a problem for neo-darwinism?

Answer 21

stasis does not mean evolution has stopped, its not a result of reduced genetic variation

Question 22

what is the debate in the molecular era?

Answer 22

want to map genotypes to phenotypes to find loci that matter for evolution

Question 23

why do we look for QTL?

Answer 23

its the region of chromosome that correlates with phenotypic variation - so we assume we should find few large QTL and that they’re sometimes hard to find

Question 24

what do we expect if evolution proceeds by phyletic gradualism?

Answer 24

that we won’t find few loci of large effect