Lecture #12 - Evolution

Question 1

“Ctenophora-sister” hypothesis

Answer 1

implies that eumetazoan-specific traits either evolved once along the metazoan stem lineage and became lost in sponges and placozoans, or evolved at least twice independently in ctenophoroa and in cnidaria and bilateria

Question 2

Gene linkage

Answer 2

closer they are, more often they are inherited together because recombination depends on distance

Question 3

is the mitochondrial linked?

Answer 3

yes it is 100% linked because there is NO recombination

Question 4

Cambrian Explosion

Answer 4

the sudden appearance in the fossil record of complex animals w/ mineralized skeletal remains; 542 mya

Question 5

evolution

Answer 5

change w/ time; occurs through natural selection and neutral processes

Question 6

Evolutionary fitness

Answer 6

the number of viable offspring an individual has

Question 7

Evolution by natural selection requires

Answer 7

heritable variation that impacts evolutionary fitness

Question 8

mutations are

Answer 8

random DNA changes

Question 9

mutations provide a source of

Answer 9

variation

Question 10

mutations within what are inheritable?

Answer 10

gametes

Question 11

Selection advantage

Answer 11

only effective if it is more than ½ Ne (effective population size) → larger than the inverse of 2x the population size

Question 12

neutral processes

Answer 12

Populations can experience genetic “drift” in which they develop different genotypes over time

Question 13

Neutral theory

Answer 13

great majority of substitutions are caused by random fixation by sampling of selectively equivalent alleles

Question 14

why does population size matter?

Answer 14

Small populations quickly lose the alternative allele and thus have less genetic variation

Question 15

where do adaptive genes come from?

Answer 15

Likely the standing genetic variation within a population (the variation that is already present)

Question 16

most major taxonomic groups are old, BUT

Answer 16

the species in these groups can be relatively young

Question 17

what does neutral theory suggest?

Answer 17

adaptive differences are rare, but not totally absent

Question 18

first step of selection

Answer 18

Genetic variability that affects a trait exists in a population

Question 19

second step of selection

Answer 19

Environmental factors favor survival of individuals w/ some heritable traits over others → adaptive heritable traits

Question 20

third step of selection

Answer 20

Heritable adaptive traits may lead to differential reproduction, allowing individuals w/ the adaptation to produce more offspring