Lab 2: Origin of Species

Question 1

What does a branch represent in a phylogenetic tree?

Answer 1

it represents a speciation event

Question 2

What are character states?

Answer 2

they are morphological properties of an animal

Question 3

what is a clade?

Answer 3

a set of species with the same common ancestor

Question 4

what is gene flow?

Answer 4

its a mechanism of evolution involving transfer of alleles or genes from one population to another (i.e. if a part of the population moves away or migrates)

Question 5

what is genetic drift?

Answer 5

It is another mechanism of evolution involving decrease in genetic diversity in populations. It is common after a population bottle necks or founder effects.

Question 6

what is a genotype?

Answer 6

its the genetic traits of an individual

Question 7

what is the molecular clock hypothesis?

Answer 7

it is figuring out when a species diverged from its ancestors by looking at the rate of mutation occurring (i.e. looking at strata and seeing the time periods between a fossil of the same species and seeing what changed). By looking at the continuous accumulation of mutations, we can use them to estimate how long ago the ancestors of currently living species split into different lineages.

Question 8

what is the most recent common ancestor of a species?

Answer 8

it is usually a species that looks similar to the new one but has some changes

Question 9

what is natural selection?

Answer 9

it is the process of evolution by which the organisms that are better adapted to their environment tend to reproduce and be more fit and survive

Question 10

what is a node?

Answer 10

it is a branch point in a phylogenetic tree that represents an area of speciation

Question 11

what is an outgrip?

Answer 11

it is a group similar to the species being observed but different (it evolved from the same common ancestor)

Question 12

what is a phenotype?

Answer 12

a phenotype is genetic expression through how an individual LOOKS

Question 13

what is a phylogenetic tree?

Answer 13

a phylogenetic tree is mapping relatedness among species and it is a hypothesis

Question 14

what is a single-base substitution?

Answer 14

when one nucleotide base replaces another aka frameshift substitutions when one base replaces another

Question 15

what is speciation?

Answer 15

when a new species is formed as a result of branching out from its common ancestor

Question 16

what is a phylogeny/phylogenetics?

Answer 16

it is using complex algorithms to reconstruct evolutionary relationships among groups of organisms using molecular (DNA) or morphological (looks) data

Question 17

what are species?

Answer 17

organisms that are formed as a result of speciation

Question 18

what is a taxa?

Answer 18

a taxa is a taxonomic group of any rank, such as species, class or family

Question 19

how often does a single-base substitution mutation occur?

Answer 19

it occurs 1 time for every half billion bases copied

Question 20

How do we know how fast a particular DNA sequence is changing?

Answer 20

the fossil record tells us divergence times, providing a calibration point.

• finding a fossil of ancestral species for your phylogenetic tree can be helpful to base the mutations from afterwards, and you can assign a rate of mutation and make a phylogenetic tree from it

Question 21

Discuss how you could use the necklaces to construct a reasonable approximation of the group’s history, including divergence times. how many necklaces could you compare at once?

Answer 21

you could compare 2 necklaces at once and see where most of the mutation lies and then base the rest off of the mutations there