Exam 3

Question 1

gene regulatory networks

Answer 1

biological circuits that respond to signals by activating genes during development, metabolisms and cell cycle, made up of interacting genes, transcription factors, promoters and RNA, allows for evolution of complexity by being expressed at different times or in different tissues

Question 2

gene duplication

Answer 2

can produce novel functions because one copy stays pristine due to purifying selection and duplicate can evolve new regulation and function

Question 3

Promiscuous protein

Answer 3

capable of carrying out two functions;
are especially likely to take on new functions if duplicated

Question 4

Gene recruitment

Answer 4

the co-option of a particular gene or
network for a totally different function as a result of a
mutation; the reorganization of a preexisting regulatory
network can be a major evolutionary event

Question 5

evolution by natural selection

Answer 5

individuals vary in some traits, some of the differences in traits are passed along to offspring through genes (must be heritable), different individuals produce different numbers of surviving offspring, the particular value of a trait is connected to the number of offspring produced (trait is connected to fitness)- Traits that allow for more offspring to be produced are said
to be “naturally selected”

Question 6

asexual individuals

Answer 6

should outcompete sexual individuals but exclusive asexuality is uncommon

Question 7

sex

Answer 7

combination and mixing of chromosomes, involves meiosis and fertilization (horizontal gene transfer is not)

Question 8

costs of sex

Answer 8

only females reproduce directly in 2 sex species, breaks down good gene combinations, meiosis takes longer than mitosis, if population density is low its more difficult to reproduce (search for partner), male-female cuts list of potential mates in half (indiscriminate sex does not exist), STDs, reduced relatedness to offspring than asexual reproduction

Question 9

benefits of sex

Answer 9

removes bad mutations and combines good ones through recombination that generates individuals with allele combos that exclude deleterious mutations-Mullet’s ratchet, increased genetic diversity leads to novelty and increase resistance to parasites (tangled bank hypothesis, red queen hypothesis)

Question 10

Mullet’s ratchet in asexuals

Answer 10

removing bad mutations and recombination of genes not possible in asexual, therefore greater fitness in sexual lines

Question 11

tangled bank hypothesis

Answer 11

sex allows for organisms to take advantage of diverse environments aka more adaptability

Question 12

red queen hypothesis

Answer 12

increased resistance to parasites, one step ahead of parasite coevolution of two

Question 13

gametic anisogamy- organelles theory

Answer 13

reproductive cells are of different sizes (males- small, abundant, motile; females- larger, fewer, non-motile), if both were same size and had sets of organelles, which organelles would be adopted would be a problem

Question 14

sex determination

Answer 14

mammalian model- not deterministic, lots of things need to be turned on, conversation between genes (genetic sex-> gonadal sex-> phenotypic sex), chicken model- sex chromosomes are associated with somatic cells (can get gynandromorphs) (soma->phenotype) but in mammals we don’t carry sex identity in our soma (start with undifferentiated model)

Question 15

intersexual selection

Answer 15

Members of the same sex compete for access to mates, often leads to the evolution of weapons and/or large body size

Question 16

mate choice

Answer 16

one of the sexes works to entice or seduce the other sex into mating- often manifests itself in showy traits such as colorful bird plumage (often males and females are choosy), females are not passively choosing: looking for mates, incite competition, being receptive to copulation (males can also be choosy)

Question 17

hypothesis: sensory exploitation by males

Answer 17

females not gaining benefit by choosing but drawn to certain males due to preexisting preferences- preference comes before male trait

Question 18

hypothesis: female seeks direct benefits

Answer 18

protection, more food, help with offspring, future mating insurance, secure fertilization, avoid parasites, sexual cannibalism in spiders (these males can only mate once so provide nutrition for eggs)
advantage for females for mating with many different males

Question 19

indirect benefits hypothesis

Answer 19

females choosing males with exaggerated traits (bigger cost of having large body so have better body condition so better quality males/genes for offspring), (however, not much evidence- null hypothesis)

Question 20

fisherian runaway

Answer 20

exaggerate traits bc preference and trait coevolve but no particular benefit, just will be passed on to offspring and allow them to be successful mating, can lead to exaggeration until halted by natural selection

Question 21

sexual conflict

Answer 21

one of the sexes tries to bypass the choice of the other sex, leads to evolution of antagonistic, harmful traits

Question 22

sexual selection

Answer 22

sex ratio should be 50:50, but if variance in reproductive success is greater in males than in females then sexual selection is stronger in males or vice versa

Question 23

post-copulatory sexual selection

Answer 23

cryptic female choice, sperm competition, sexual conflict over fertilization; more intense when females mate with more males and females store sperm

Question 24

hypotheses to explain diverse genitalia

Answer 24

natural selection- species isolation (lock and key- have to fit together, Genitalia evolved to be very different across species as a mechanism to avoid mating with the wrong species, Enforcing speciation and preventing hybridization), sexual selection- intrasexual (male-male competition), intersexual (female choice, sexual conflict)

Question 25

r-selected species

Answer 25

quickly reproduce, large number of offspring, quickly die, fluctuating population size

Question 26

k-selected species

Answer 26

stable population size, exponential growth until reach carrying capacity, less offspring and longer life

Question 27

type I survivorship

Answer 27

drop in survivorship later in life (humans)

Question 28

type II survivorship

Answer 28

constant mortality rate throughout life (rabbits)

Question 29

type III survivorship

Answer 29

huge dip at beginning of life (fish)

Question 30

tradeoffs between competing demands

Answer 30

reproduction and maintenance, both require energy, selection favors strategy that optimizes number of surviving offspring

Question 31

antagonistic pleiotropy

Answer 31

mutations that make you better early in life will accumulate even if they are bad for you when you are older because it is better if you do well when you are young when you are much more likely to be alive (ex. in high predator environment)

Question 32

parental investment

Answer 32

Absent in most organisms, Don’t buy into the females are more likely to be parental because they already made precious eggs (book). Sperm are precious too. Male parental care is very common! Insects, amphibians, fish. Most birds are biparental. Female only care is only typical of mammals and reptiles (though most reptiles do not offer care).