Evolution Chapter 3

Front 1

Natural selection is the logical outcome of four postulates, which Darwin laid out in his introduction to "On the origin of species by means of natural selection"

what are the four postulates?

Back 1

1) Individuals within species are variable

2) some of these variations are passed on to offspring

3) in every generation, more offspring are produced than can survive

4) the survival and reproduction of individuals are not random:

Individuals who survive and reproduce are those with the most FAVORABLE VARIATION. They are naturally selected

Front 2

what is the main consequence of the four postulates?

Back 2

the characteristics of populations change from one generation to the next.

*As a result the characteristics of the population will change slightly with each succeeding generation.

Front 3

What is Darwinian evolution?

Back 3

gradual change in populations over time

Front 4

Darwin referred to individuals who make up a greater percentage of the population in the next generation as ___ ____. In doing so he introduced the concept of ____.

Back 4

more fit

fitness

Front 5

What is Darwinian fitness?

Back 5

the ability of an individual to survive and reproduce in its environment.

Front 6

Biologists use the word ______ to refer to a trait or characteristic of an organism that increases its fitness relative to individuals without the trait.

Back 6

adaptation

Front 7

How many species of finches are in the Galapagos islands?

Two traits do show remarkable variation among these; what are they?

Back 7

14 species

the size and the shape of their beaks

Front 8

what does the enormous range of beak morphologies of the Galapagos finches reflect?

Back 8

the diversity of foods they eat

Front 9

The four postulates of Darwin were tested using data that the team of Grant and Grant have gathered on what type of finch?

Back 9

medium ground finch

Geospiza Fortis on isla Daphne Major

Front 10

Measurements of beak depth of G. fortis indicated that this character varies in the individuals of the Isla Daphne Major.

All the finch characteristics that the team of Grant and Grant measured clearly conform to Darwin's _____ postulate.

Back 10

first

Front 11

Within a population, individual finches could vary in beak depth because of two things. what are these

Back 11

because the environments they have experience are different or

because their genotypes are different

or both

Front 12

What is Heritability?

Back 12

the proportion of the variation observed IN A POPULATION that is due to the variation in the effects of genes.

Front 13

what does a value of zero mean for heritability

Back 13

all variation in this population is due to the ENVIRONMENT and therefore all the individuals of the population are genetically identical for a particular trait

Front 14

what does a value of 1 mean for heritability

Back 14

the levels of genetic variation for a particular trait in this population are so high that each individual has a different genotype for this trait.

Front 15

parents with deep beaks tend to have offspring with deep beaks, and parents with shallow beaks tend to have chicks with shallow beaks.

what evidence does this provide about the proportion of the observed variation in beak depth?

which postulate does this confirm?

Back 15

this is evidence that a large proportion of the observed variation in beak depth is GENETIC and can be transmitted to offspring

postulate #2

Front 16

in 1977 there was a severe drought at Isla Daphne Major, instead of the normal 130mm of rainfall only 24mm fell. 84% of medium ground finches disappeared.

this showed a correlation between...

Back 16

pollution size and seed availability

Front 17

In every natural population studied more offspring are produced each generation than ______

Back 17

survive to breed

Front 18

The biotic potential or _____of organisms is demonstrated in table 3.1

it has been shown that in most populations, some individuals are more successful at mating and producing offspring than others.

Variation in ______, represents an opportunity for selection, as does variation in ____.

Back 18

reproductive capacity

reproductive success

survival

Front 19

After a server drought of 1977 the team of Grant found that a distinct subset of the population had survived: those with....

Back 19

the deepest beaks

Front 20

after the drought of 1977 because the average survivor had a deeper beak than the average non survivor

what was the ultimate result of this?

Back 20

average bill size in the population changed

Front 21

before the drought in 1976 the number of all Daphne birds was 751 in 1978 is was

Back 21

90

Front 22

what was the name of the annual plant with the large and hard fruits that became a key food item after the drought?

why?

Back 22

Tribulus cistoides

during the drought the supply of soft seeds quickly became exhausted

Front 23

Only large birds with deep narrow beaks can crack and eat Tribulus fruits successfull.

because large size and deep beaks are ___ _____, the two traits _____

Back 23

positively correlated

the two traits responded to selection together.

Front 24

table 3.2 shows the data of the offspring of birds surviving the 1977 drought? what did the data illustrate?

Back 24

birds surviving the drought were significantly larger, on average, that the population that existed before the drought

Front 25

Natural selection acts on _____, but its consequences occur in ______

Back 25

individuals

populations

Front 26

what changed after the selection process?

Back 26

the characteristics of the population of virions and not finches, NOT the affected individuals themselves.

Front 27

Natural selection acts on ______, but evolution only consists of changes in ...

Back 27

population allele frequency for a particular population

Front 28

Each generation is a product of selection by the environment conditions that prevailed in

which generation?

Back 28

pass

in the generation before

Front 29

evolution is always a generation ____ any changes in the environment

Back 29

behind

Front 30

Natural slection can also lead to novel characteristics. this is possible because selection is able to "repurpose" existing behaviors, structures, or genes for new functions.

what is an example

Back 30

giant panda's thumb

anatomically the bone that forms the "thumb" is highly modified radial sesamoid, which in closely species is a component of the wrist

Front 31

A trait that is used in a novel way and is eventually elaborated by selection into a complete new structure, like the radial sesamoid of the ancestral panda, is known as a ______

Back 31

preadaptation

Front 32

natural selection does not optimize all of the trait involved.

Natural selection results in overall adaptation, not perfection

why?

Back 32

because of the genetic correlation among characters

example: beak width is positively correlated with beak depth and large body size. As a result large birds with deep beaks also tend to have wide beaks, which are less effective at cracking tribulus fruits.

Front 33

Natural selection is a progressive process true or false?

Back 33

false natural selection is nonrandom but it is NOT progressive

Front 34

Natural selection acts on
a. individuals
b. groups

Back 34

a individuals

Front 35

what were the two main problems with the theory formulated by Darwin?

Back 35

1. because Darwin know nothing about mutation, he had no idea how variability was generated in populations

2. because Darwin know nothing about genetics, he had no idea how variations are passed on to offspring

Front 36

Between ___ & ____ a series of landmark books was published that successfully integrated genetics with Darwin's four postulates and led to the reformation of the theory of Evolution. The restatement known as the __________, was a consensus grounded in two propositions.

Back 36

1932 and 1953

modern synthesis

Front 37

what were the two propositions of modern synthesis

Back 37

1. gradual evolution results from small genetic changes that are acted upon by natural selection

2 the origin of species and higher taxa, or macroevolution can be explained in terms of natural selection acting on individuals, or microevolution

Front 38

how where darwin's four postulates restated after synthesis

Back 38

1. as a result of
*mutation creating new alleles
*segregation
*independent assortment shuffling alleles into new combinations
individuals within populations are variable for nearly all traits

2 individuals pass their alleles on to their offspring intact

3 in most generations more offspring are produced than can survive

4 the individuals that survive and go on to reproduce, or who reproduce the most, are those with the alleles and allelic combinations that best adapt them to their environment