5.4 cladistics

Question 1

what are analogous traits

Answer 1

structures that evolve separately, through convergent evolution, from different ancestral features but have a similar function
(often due to similar selection pressures)

Question 2

what are homologous traits

Answer 2

structures that are similar because of shared ancestry, but that may have different functions due to divergent evolution

Question 3

what is convergent evolution

Answer 3

independent evolution of similar features in species of different lineages

Question 4

what is divergent evolution

Answer 4

process whereby groups from common ancestor evolve and accumulate differences → formation of new species

Question 5

relationship between DNA sequences of two species and recency of divergence?

Answer 5

the more similarities existing between DNA/protein seq of two species → closer rs and more recently these species diverged from each other

Question 6

what information can be gathered from the gradual accumulation of DNA mutations

Answer 6

an INDICATION of how much time has passed since the two species diverged from a common ancestor

(positive correlation)

Question 7

what is the molecular clock?

Answer 7

technique using mutation rate of biomolecules when two or more life forms diverged

Question 8

how does the molecular clock work?

Answer 8

if DNA mutates at a predictable rate like a molecular clock, valuable tool for estimating dates when two species split from common ancestry + how ancient species is

Question 9

which section of DNA is analysed? (and why)

Answer 9

non-coding parts of DNA provide most information for analysis as they are highly repetitive sequences and mutations will occur more frequently in these sections of DNA

coding sequences and AA sequences not usually analysed when two species are suspected to be closely related as mutations in these sections of DNA occur at much slower pace

Question 10

what is a clade

Answer 10

a group of organisms that have evolved from a common ancestor

Question 11

what are cladistics

Answer 11

a system of classifying organisms according to shared characteristics based on ancestry

Question 12

what is a cladogram

Answer 12

a diagram that shows the evolutionary relationship of a group of organisms

Question 13

in cladogram, what is the part where the clade branches off called?

Answer 13

node

Question 14

analysis of cladograms rely on some assumptions, what is assumed when there are more nodes between species

Answer 14

more nodes between species → more distant their relationship

Question 15

analysis of cladograms rely on some assumptions, what is assumed about the rate of mutations at DNA and protein level

Answer 15

mutations at DNA and protein level assumed to occur at CONSTANT RATE

Question 16

analysis of cladograms rely on some assumptions, what is assumed about branching pattern

Answer 16

branching pattern is assumed to represent the evolutionary relationship between the species

Question 17

analysis of cladograms rely on some assumptions, what is assumed when extinct species is included

Answer 17

if extinct species incl, info must be given on whether cladogram based on morphology only because DNA generally not available for the analysis
(with some exceptions)

Question 18

what does the ROOT on the cladogram represent

Answer 18

the common ancestor

Question 19

what is the outgroup on a cladogram

Answer 19

most distantly related organism

Question 20

cladograms with time scales are called ____

Answer 20

phylogenetic trees