midterm 1

Question 1

what is evolution

Answer 1

change in form and/ or behavior of organisms between generations
- decent with modification in darwins terms

Question 2

what is natural selection

Answer 2

the process whereby some individuals contribute more offspring to the next generation as a consequence of their carrying a trait or traits favorable to survival or reproduction
IT OCCURS WHENEVER THERE IS…
-VARIANCE (Varity in some trait between individuals)
-SELECTION (individuals with some trait values are more likely to live and/ or reproduce)
-HERITABILITY (parents have offspring with similar trait values)

Question 3

Aristotle

Answer 3

Greek philosopher
divine order
“chain of being” (Scala naturae)
-hierarchical arrangement of forms
-species arranged linearly along a scale (God-man-mammals-egg laying animals-insects-plants-nonliving matter)
- formed the basis for the western belief in the fixity of species, each of which has a typical form

Question 4

Carlos Linnaeus

Answer 4

Classified organicism’s according to a binomial system, giving each a specific and a generic name
proposed a nested system of relationships
modernized Linnean system organisms into: Kingdom, Phylum, Class, Order, Family, Genus, Species
Recognized fundamental difference between interbreeding organisms (within a species) and non-interbreeding organisms (different species)
believed in balance of nature- each species has its place in a divine plan, species would not change or go extinct
eventually acknowledged limited formation of new species by hybridization

Question 5

Comte de Buffon

Answer 5

believed Linnean hierarchy reflected common descent (degeneration) with divergence over time
-physical environment (somehow) changes organic particles
-New species form when animals migrate
-new environment then causes change to the species
change only happens within families: each family conforms to an internal mold. Species can change over time but are limited to their original mold

Question 6

Erasmus Darwin

Answer 6

Charles Darwin grandfather
believed organisms constantly attempted to improve themselves by adapting to their environment (transformism or transmutation)
all of life consists of “one living filament” connecting all living forms to a common ancestor
didn’t know mechanism for transmutation

Question 7

Jean-Baptiste Lamarck

Answer 7

“Inheritance of acquired characters”
Theory of “transformism”
- organisms progress through a hierarchy of ever-more-advanced forms
- at the base of this hierarchy “simple” organisms constantly arise by
spontaneous generation and then evolve more complexity
suggested a mechanism for this organic progression
- First Law: use or disuse of a structure leads to its development or diminishment
- Second law: these acquired characters can be passed on to offspring

Question 8

Thomas Malthus

Answer 8

principle of overproduction
major influence on Darwin and Wallace
An Essay on the Principle of Population
-Most organisms produce far more offspring than can possibly survive
-even when resources are plentiful, populations tend to grow geometrically until they outstrip their food supply
-Poverty, disease and famine are inevitable, leading to a struggle for existence

Question 9

Charles Lyell

Answer 9

“uniformitarianism” - earth is subject to gradual, continuous change, but without progress or development earth remains a a steady sate

Believed earth is constantly changing
-Processes that molded earth’s surface can be understood by modern-day evens

Question 10

Charles Darwin

Answer 10

The Voyage of the Beagle
developed an appreciation of biogeographical patterns
Biogeography
Natural selection
- variability exists within species
- variant traits may be inherited (Darwin didn’t know how)
- Individuals slightly better suited to their environment must be more likely to survive therefore some variants will be preserved over time more than others. The composition of populations must change over time -> Evolution by natural selection

Question 11

Alfred R. Wallace

Answer 11

Natural selection co-discovered
English professional naturalist
independent discovery of natural selection

Question 12

If WA =Wa

Answer 12

allele A will stay constant in frequency (neutral)

Question 13

If WA >Wa

Answer 13

allele A will rise in frequency to fixation (p=1)

Question 14

If WA< Wa

Answer 14

allele A will decline in frequency to loss ( p= 0)

Question 15

describe the spread of a beneficial allele and why it is that way

Answer 15

Spread of a beneficial allele always follows an S-shaped curve, increasing slowly when the allele is rare and also when it is common.

Question 16

Weakly favored alleles take ____ to spread than strongly favored alleles

Answer 16

longer

Question 17

When selection (s) is ____ it takes about ____ times ____ to observe the same amount of frequency change

Answer 17

when selection (s) is 10 time weaker, it takes about 10 time longer to observe the same amount of frequency change.