C&C Ch.2

Question 1

a simple definition of adaptation

Answer 1

the fit of structure to function

Question 2

what did 18th Century British theologians do?

Answer 2

they introduced the term adaptation to argue that the appearance of design in the features of living creatures proves the existence of a supernatural designer

Question 3

biological evolution involves

Answer 3

changes over time in the characteristics of populations of living organisms

Question 4

give an example of how evolution can be studied during a human lifetime

Answer 4

when changes occur in a single character - eg the increase in the frequency of strains of bacteria resistant to penicillin within a few years of the widespread medical use of penicillin.

Question 5

give an example of evolution which may take millions of years

Answer 5

the emergence of a major new design of organisms - eg the transition from reptiles to mammals

Question 6

state a key insight of the founders of evolutionary theory, Charles Darwin and Alfred Russel Wallace

Answer 6

• changes at all levels are likely to involve the same types of processes
• major evolutionary changes largely reflect changes of the same type as more minor events, accumulated over longer time periods

Question 7

what does evolutionary change rely on?

Answer 7

the appearance of new variant forms of organisms: mutations

Question 8

what are mutations caused by?

Answer 8

stable changes in the genetic material that can be transmitted from parent to offspring.

Question 9

give 3 different degrees of effects of mutations

Answer 9

• no detectable effect
• relatively small effects on a simple trait (change in eye colour, acquisition of antibiotic resistance, alteration of no of bristles on the side of a fruitfully)
• drastic effects on development(eg mutation of D. melanogaster that causes a leg to grow on the fly’s head in place of its antenna)

Question 10

how often does the appearance of any particular kind of new mutation occur?

Answer 10

very rarely, with a frequency of around one per 100,000 individuals per generations or less.

Question 11

describe the theory of evolution by natural selection by Darwin and Wallace

Answer 11

• more individuals of a species are born that can normally live to maturity and breed successfully, so there is a struggle for existence
• there is individual variation in many characteristics of the population, some of which affect an individual’s ability to survive and reproduce. successful parents of a generation may differ from the population as a whole
• there is likely to be a hereditary component to much of this variation, so that the characteristics of the offspring of the successful parents will differ from the characteristics of the previous generation in a similar way to their parents

Question 12

if the process of evolution by natural selection continues from generation to generation, there will be

Answer 12

a gradual transformation of the population, such that the frequencies of characteristics associated with greater survival ability or reproductive success increase over time

Question 13

describe most mutations

Answer 13

• mutations affecting a particular trait arise all the time regardless of whether or not they are favoured by selection
• most mutations either have no effects on the organic or reduce its ability to survive/reproduce

Question 14

when is the process of change especially likely?

Answer 14

if a population is exposed to a changed environment, where a different set of characteristics is favoured from those already established by selection

Question 15

subsistence

Answer 15

the action/fact of maintaining or supporting oneself at the minimum level

Question 16

describe selectively neutral variability

Answer 16

when the offspring generation differ slightly from the parental generation even though there are no differences in survival or fertility among individuals

Question 17

define genetic drift

Answer 17

the change in frequency of an existing gene variant in the population due to random chance

Question 18

why does genetic drift take place?

Answer 18

in the absence of selection, the genes in the population of offspring are a random sample of the genes present in the parental populations.

Question 19

what causes changes in the composition of a population, and, eventually, alters the population’s genetic makeup?

Answer 19

the combined effects of mutation, natural selection, and genetic drift.

Question 20

when are two populations different species?

Answer 20

if they cannot interbreed with each other, so that their evolutionary fates are totally independent.

Question 21

the formation of a new species must involve…

Answer 21

the evolution of barriers to interbreeding between related populations, which then diverge under mutation, selection, and genetic drift.