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evolution > envs lecture 10 > Flashcards

envs lecture 10 Flashcards

1
Q

sexual reproduction

A

two individuals fertilize each others sex cells and the process creates opportunities for genetic recombination to occur via meiosis

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2
Q

what does process of sexual reproduction do

A

creates opportunities for genetic recombination to occur via meiosis

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3
Q

what do some animals have besides sexual reproduction

A

internal fertilization

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4
Q

what else can some animals do besides sexual reproduction and internal fertilization

A

vectors

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5
Q

examples of vectors

A

wind, water (broadcast spawning), other animals

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6
Q

what do bacteria and fungi do

A

parasexuality/parasexual reproduction

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7
Q

what do bacteria and fungi have (w/r to recombination)

A

recombination in mitosis instead of meiosis

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8
Q

what is parasexuality

A

bacteria pass DNA b/w each other via conjugation

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9
Q

what is conjugation

A

involves transfer of plasmids, which sometimes carry genes for antibiotic resistance

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10
Q

how else can parasexuality occur (besides conjugation)

A

other bacteria are able to absorb naked DNA left in environment

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11
Q

basically what is conjugation

A

horizontal gene transfer; DNA transferred from donor to recipient bacterium via direct contact (or bridge-like connection), cell-cell contact

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12
Q

how do viruses reproduce

A

similarly; several viral particles infect the same host, progeny that are produced carry a mix of their genotypes

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13
Q

describe mating in frogs and toads

A

sexual reproduction –> recombination occurs via meiosis

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14
Q

describe reproduction in bacteria

A

parasexual reproduction –> thru conjugation

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15
Q

hermaphrodites

A

each individual has both male and female gonads

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16
Q

how do hermaphrodites mate

A

some mate w/ other individuals, others self fertilize

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17
Q

examples of hermaphroditic organisms that mate

A

earthworms, snails, slugs

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18
Q

example of hermaphroditic organisms that self-fertilize

A

plants

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19
Q

what is hermaphroditism a form of

A

reproductive assurance

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20
Q

reproductive assurance (hermaphroditism)

A

increases chances of reproduction when potential mates are scarce

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21
Q

what are clownfish

A

sequential hermaphrodites

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22
Q

describe how clownfish are sequential hermaphrodites

A

first male, then later changes to females

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23
Q

what is key difference b/w males and females

A

gametes come in two sizes

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24
Q

anisogamy

A

dimorphism in gamete size (males and females having two diff gamete sizes)

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25
Q

describe egg

A

large, immobile, provisioned

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26
Q

describe sperm

A

small, mobile, not well provisioned

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27
Q

what does well provisioned mean

A

inhibiting movement

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28
Q

when do gametes have high fitness

A

if large, well provisioned (inhibiting movement)

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29
Q

when else do gametes have high fitness

A

small, mobile so it can find and fertilize the egg

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30
Q

which gender makes more

A

females make fewer eggs than male (who make lots of sperm)

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31
Q

another word for egg

A

ovules

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32
Q

another word for sperm

A

pollen

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33
Q

what defines sexes

A

difference in gamete size

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34
Q

what do males make

A

small, less costly gametesw

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35
Q

what do females make

A

large, more costly gametes

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36
Q

what is another example of dimorphism

A

sexual dimorphism

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37
Q

what is sexual dimorphism

A

sexes of the same species exhibit diff morphological characteristics (not characteristics involved in reproduction)

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38
Q

what do anglerfishes have

A

extreme sexual dimorphism

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39
Q

what do male anglerfishes do

A

bite and attaches himself permanently to a female

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40
Q

what happens when male anglerfishes attaches to female

A

his body fuses with hers, his organs degenerate except for his testes, which grow to fill most of his body

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41
Q

how many mechanisms do animals have which determine an individual’s sex

A

a variety of mechanisms

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42
Q

what do all mammals have

A

XY system of sex determination

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43
Q

what is the XY system of sex determination

A

males are heterogametic sex (XY), females are homogametic (XX)

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44
Q

do all vertebrates have XY system of sex determination

A

nope

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45
Q

what system of sex determination do birds have

A

ZW; females are heterogametic (ZW), males are homogametic (ZZ)

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46
Q

what is most common sexual system in teleost fishes

A

hermaphroditism

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47
Q

what are hymenoptera

A

ants, bees, wasps, etc.

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48
Q

how do hymenoptera and acari (mites) determine sex

A

haploploidy

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49
Q

what is haploploidy

A

sex determination system where males develop from unfertilized eggs and are haploid; females develop from fertilized eggs, are diploid

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50
Q

describe males in haploploidy

A

develop from unfertilized eggs –> haploid

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51
Q

describe females in haploploidy

A

develop from fertilized eggs –> diploid

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52
Q

what are sex determination strategies in plants

A

2 major sex determination strategies: some plants are dioecious, others are monoecious

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53
Q

what are dioecious plants

A

(means 2 houses); individual plants are either male or female (and have either male or female flowers)

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54
Q

another definition of dioecious

A

male and female sex organs found in separate individuals

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55
Q

what are monoecious plants

A

hermaphroditisim; one house –> both male and female sex organs on the flowers

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56
Q

what have plants evolved

A

evolved dioecy (male/female sex organs on diff individuals) multiple times from monoecy (hermaphroditism)

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57
Q

what else have plants evolved

A

have evolved sex chromosomes multiple times

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58
Q

how is sex determined in turtles and crocodilians

A

environmental factors; environmental sex determination

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59
Q

what is environmental sex determination

A

sex is determined by temperature during egg developmnet

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60
Q

are the temperatures that alter sex ratios the same for all species

A

no; diff species have diff temps

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61
Q

how can the sex ratio evolve (for environmental sex determination)

A

by females changing where they lay their eggs / females evolving diff preferences for where they lay their eggs

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62
Q

what sex determination system do we see in ants, bees, waps

A

haplodiploid sex determination

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63
Q

what is haplodiploid sex determination for females

A

females are diploid, produce haploid eggs via meiosis

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64
Q

what is haplodiploid sex determination for males

A

males are haploid, produce haploid sperm without meiosis

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65
Q

what does fertilization do in haplodiploid sex determination

A

fertilization produces diploid female bees

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66
Q

what do unfertilized eggs do in haplodiploid sex determination

A

produce haploid male bees

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67
Q

how do females determine sex ratio in haplodiploid sex determination

A

by altering number of offspring resulting from fertilization

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68
Q

what ratio do we see in most species w/ separate sexes

A

1:1 sex ratio

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69
Q

what happens if one sex is rarer

A

newborns of that sex more likely to find mates than common sex

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70
Q

what happens to parents w/ genetic tendency to have offspring of rarer sex

A

will have more grandchildren than average

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71
Q

what happens to alleles for that tendency

A

alleles will spread, sex ratio will shift back to 1:1, where this tendency is no longer favor

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72
Q

what are other strategies besides 1:1

A

sequential hermaphrodites

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73
Q

describe uneven sex ratio

A

initially females produce more daughters than sones. then single female has a mutation causing her to produce only sons. mutation increases in frequency, spreads until equal sex ratio, 1:1 (equal numbers of males and females)

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74
Q

what happens to this mutation at equilibrium

A

mutation more common in males, because females w/ mutation produce only sons but males w/ mutation produce both sons and daughters that carry mutation

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75
Q

what traits evolved via sexual selection

A

traits not related to natural selection, maybe even inhibited survival and thus reproduction

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76
Q

what are two classes of sexual traits

A

primary and secondary sexual traits

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77
Q

what are primary traits

A

necessary for reproduction to occur

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78
Q

examples of primary traits

A

structures such as gonads and genitalia

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79
Q

what are secondary traits

A

strange, gaudy, increase the probability of mating

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80
Q

do secondary sexual traits play a role in reproduction

A

nope, only indirect role

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81
Q

example of secondary sexual traits

A

male peacock’s train

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82
Q

what are genitalia on slugs (what kind of trait)

A

primary sexual trait

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83
Q

what kinda trait is bright colored butt of male mandrill

A

secondary sexual trait

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84
Q

what did darwin propose about secondary sexual traits

A

evolved b/c of competition for mates among individuals of same sex or through mate choice (females preference for male secondary sexual traits)

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85
Q

describe secondary sexual traits evolving cuz of competition for mates among individuals of same sex

A

male-male competition; male prevents other males from mating and this helps him to leave more copies of his genes to the next generation

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86
Q

what is mate choice

A

female preference for male secondary sexual traits

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87
Q

who came up w/ idea of sexual selection

A

Darwin

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88
Q

what was Darwin’s idea of sexual selection

A

special case of natural selection

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89
Q

what do other scientists say about sexual selection w/r to natural selection

A

they say it is a separate force

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90
Q

what can sexual selection act on

A

primary or secondary sexual traits

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91
Q

how can traits evolve by sexual selection

A

if it increases overall fitness, even if it decreases survival

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92
Q

basically what is secondary selection

A

differential reproduction as a result of variation in the ability to obtain mates

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93
Q

another definition of sexual selection

A

mode of nat selection where members of one sex choose members of opposite sex to mate with, and compete with members of same sex for access

94
Q

2 examples of sexual selection

A

female choice, male-male competition

95
Q

experimental test of sexual selection

A

male long-tailed widowbirds have long tail feathers; shortened in one group and lengthened in another. long tailed males had greatest success

96
Q

do males and females in population have same average reproductive success

A

yes

97
Q

what do males and females differ in

A

reproductive variance among members of each sex

98
Q

what do differences in the selection gradient result in

A

sexual dimorphism

99
Q

what happens when males are subject to stronger sexual selection than females

A

males will evolve secondary sexual characters that result in marked differences b/w sexes

100
Q

what do male peacocks do

A

don’t provide parental care

101
Q

what leads to marked dimorphism in male peackocks

A

some males more successful than others who may never reproduce

102
Q

what happens when males contribute to offspring care

A

selection gradient is lower, sexes are monomorphic

103
Q

what species contributes to offspring care

A

male albatross

104
Q

what are many seabirds

A

monogamous, raise offspring together, and sexes are indistinguishable

105
Q

what happens when males provide all the parental care

A

selection gradient is reverse, and females compete for access to male

106
Q

what happens when gradient is reversed and females compete

A

reverse sexual dimorphism

107
Q

example of reversed sexual dimorphism

A

females are brightly colored

108
Q

what species provide all parental care, and females compete for access to males

A

red-necked phalaropes

109
Q

describe female red-necked phalaropes

A

females are larger and more aggressive; polyandrous, mate w/ many males

110
Q

what is trade-offs

A

selection favors display that maximizes a males lifetime fitness

111
Q

what are trade-offs a tug of war between

A

two fitness components: survival and mating success

112
Q

what does compromise ultimately maximize

A

a male’s lifetime fitness

113
Q

what is male survival maximized by

A

a tail length that optimizes aerodynamics, leading to stabilizing selection for tails of intermediate length

114
Q

what does male mating success depend on

A

mean female mating preference

115
Q

what happens if most females prefer long tails

A

males w/ long tails have greatest mating success [tails will evolve to an equilibrium that is longer than what maximizes survival]

116
Q

what happens if most females prefer short tails

A

tails will evolve to a length shorter than what maximizes survival

117
Q

when does the optimum shift

A

if strength of natural selection or sexual selection changes

118
Q

what did darwin say about exaggerated secondary sexual traits

A

decrease survival

119
Q

what else can calls attract besides mates

A

predators

120
Q

are signals always costly? what does this cause

A

tug of war between survival and mating success, between effects of secondary sexual traits on survival and mating success

121
Q

so are these signals always costly

A

maybe?

122
Q

what does rick prum argue

A

beauty evolves cuz of female choice, not necessarily costly or indicative of male fitness potential

123
Q

what is bateman’s principle asking

A

why do we usually see males w/ exaggerated secondary sexual traits?

124
Q

what 3 principles did bateman derive

A

males have greater variance in number of offspring (reproductive success), greater variance in number of sexual partners (mating success), AND stronger relationship b/w RS and MS in males

125
Q

why do we usually see males w/ exaggerated secondary sexual traits?

A

female can fertilize all eggs w/ single mating, so no fitness/selective advantage from a trait to increase number of mates

126
Q

another reason we see males w/ exaggerated secondary sexual traits

A

males produce lots of sperm. sexual selection can act more on males than females, because males gain from traits that increase mating success. [-Sexual selection can act more readily on males than females: because selection generally will act to increase the number of mates a male can acquire]

127
Q

what is operational sex ratio

A

relative number of males and females available to mate

128
Q

what is outcome of sexual selection influenced by

A

operational sex ratio

129
Q

when do we see sex role reversal

A

when more females are available, and they are not a limiting resource

130
Q

basically when do we see sex role reversal

A

most common sex must compete for access to less common sex

131
Q

what is this a case of

A

reversal of bateman’s principle

132
Q

example of reversal of bateman’s pirnicple

A

female red phalaropes fight over smaller duller plumaged male on breeding ground; females court males who care for young. AND. male australian seahorse giving birth from his pouch; males choose which courting females will lay eggs in their pouches

133
Q

what are 2 specific modes of Darwin’s sexual selection

A

intrasexual competition, intersexual selection

134
Q

intrasexual competition

A

male-male competition

135
Q

intersexual selection

A

female choice

136
Q

example of male-male competition

A

male bighorn sheep competing for access to females; male stag beetles fighting to defend sites where females lay eggs, and they mate w. females. male elephant seals guard harems of females w/ which they sire offspring

137
Q

how else do males compete

A

alternative mating strategies

138
Q

3 male strategies

A

alpha blocks entrance, beta male sneakily mimic females, gamma males sneak past alpha male

139
Q

what do alpha males do

A

large; guard harem of females by blocking the entrance

140
Q

what do beta males do

A

medium size; imitates females

141
Q

what do gamma males do

A

small size; try to reach females by slipping past alpha male

142
Q

how do beta male and gamma male gain access to females

A

by tricking alpha males

143
Q

how can males interfere w/ each others reproduction

A

sperm competition

144
Q

what is sperm competition a way for

A

males to interfere w/ each others reproduction

145
Q

how do damselflies mate

A

when they mate, claspers on male’s abdomen grasp female behind her head. she curls her abdomen so that opening of her oviduct makes contact w/ males penis.

146
Q

give the example of sperm competition in males

A

scoop like structure on male’s penis removes sperm of males that copulated w/ female. basically they use this structure to remove sperm of a female’s previous mates before depositing his own

147
Q

can sperm competition happen in mammals

A

yup

148
Q

describe how females of some primates mate w/ males

A

they mate w/ many males

149
Q

describe sperm competition in chimpanzees/primates

A

males have evolved large testicles to produce more sperm

150
Q

which chimpanzees produce most offspring

A

individuals w/ most sperm

151
Q

what can organisms optimize

A

copulation

152
Q

what does optimizing copulation do

A

optimizes fertilization

153
Q

how can we predict duration of copulation by male dungly

A

from proportion of eggs fertilized as a function of copulation time, and time it takes to search for and guard female

154
Q

what is another male strategy

A

infanticide

155
Q

where does infanticide occur

A

mammals, including lions

156
Q

describe infanticide in lions

A

male lion has killed a cub after displacing cub’s father and other adult males. females w/ cubs don’t go into heat. when new males takeover a pride they kill the young so that females in pride become fertile again, increasing male’s fitness.

157
Q

are extravagant male secondary sexual traits (like bright plumage) useful for male-male competition

A

nope

158
Q

what is the point of these extravagant secondary sexual traits

A

help attract females and persuading them to mate –> female choice

159
Q

describe evidence of sexual selection

A

simple nervous systems; don’t actually make a conscious choice

160
Q

what does ‘choice’ refer to

A

any phenotype of female that biases the type of male she will mate with

161
Q

what does female choice require

A

genetically based phenotypic variation in females and males

162
Q

can mating preferences evolve

A

yup

163
Q

what do females of closely related species have

A

innate preference for mating w/ their own species, which have evolved since divergence from most recent common ancestor

164
Q

what does avoiding mating with another species do

A

increases fitness

165
Q

why does avoiding mating w/ another species increase fitness

A

hybrids have low viability/fertility

166
Q

what is sexual selection the cause of

A

suite of crazy male secondary sexual traits (due to female choice)

167
Q

describe Leks

A

females visit lek, mate w/ male of their choice, rear offspring w/o help of males.

168
Q

what ways do females evolve preferences for male secondary sexual traits

A

direct benefits, pleiotropic effects, perceptual bias, good genes, fisher’s runaway

169
Q

what are direct benefits

A

sometimes males provide direct benefits to females; cricket places spermatophore which female eats, resources like food and care for young that increases female survival and reproductive success

170
Q

another example of direct benefits

A

some insects and spiders, male allows itself to be eaten by female after mating

171
Q

what is pleiotropy

A

single gene producing multiple effects

172
Q

what do female guppies prefer

A

females prefer males w/ more orange in their body

173
Q

what are guppies attracted to and why

A

small orange disks, because they feed on small orange fruits and this has translated to females preferring orange colored males

174
Q

what male guppies have higher fitness

A

males w/ more orange

175
Q

describe pleiotropic effect in guppies

A

guppies prefer orange males b/c they are also attracted to orange fruit for feeding

176
Q

what are perceptual biases

A

mating preferences caused by pleiotropic effects

177
Q

what can females be attracted to

A

signals that males of their species don’t make and are therefore a side effect of features of nervous system –> epiphenomenon

178
Q

what are some female mating prefernces

A

perceptual biases that evolved before origin of male trait on which they act

179
Q

describe trait evolving via a perceptual bias

A

male swordtails have dramatic swords that attract females. males of diff species lack the sword, but females prefer males w/ sword that has been surgically added.

180
Q

describe how the preference of sword evolved

A

preference for sword evolved before sword itself did

181
Q

what is good genes

A

a way that female choice might evolve

182
Q

define good genes

A

male traits are advertising to females that the male has good genes

183
Q

describe good genes in sticklebacks

A

percentage of sticklebacks that became infected when exposed to tapeworm declined w/ intensity of their father’s red coloration

184
Q

what do red male sticklebacks have

A

red males are attracted to females, have alleles that make them resistant to tapeworms and passed on to offspring

185
Q

describe its indirect effe t

A

the female preference allele is in linkage disequilibrium w/ alleles at other loci that are under direct selection (alleles related to tapeworm resistance)

186
Q

describe fisher’s runaway sexual selection model

A

females w/ preference for long tails mate w/ long tails. offspring have genes for long tail and for preference of long tail.

187
Q

what are genes for the male trait and female trait in

A

in linkage disequilbrium (statistically associated w/ each other)

188
Q

what does Fisher’s model say about these tails

A

can cause a feedback loop favoring longer and longer tails & preference for them

189
Q

is fisher’s model actually observed

A

no; nat selection would balance sexual selection at some point otherwise species would go extinct

190
Q

why do we see unique features in plants

A

they have passive fertilization via pollinators

191
Q

what are these unique features a result of

A

sexual selection

192
Q

what are most flowering plants

A

hermaphrodites

193
Q

describe operational sex ratio of flowering plants

A

biased towards males

194
Q

why is operational sex ratio of plants male biased

A

b/c after a plant’s ovules are fertilized, it keeps sending out pollen to other plnats

195
Q

what else do individual plants have

A

better floral displays

195
Q

why do individual plants have better floral displays

A

to compete for pollinators

195
Q

is having males in a species costly

A

it seems like it but not actually

195
Q

why do males seem costly

A

finding mates takes time & energy, increases risk of predation, parasitism, disease, injury, sex reproduction reduces avg fitness fo offspring, males don’t provide resources to next gen AND females invest half of their resources in producing males.

196
Q

when do we see male-male competition in plants

A

pollen grains racing to fertilize ovule (similar to sperm compmetition in animals)

196
Q

what is benefit to sexual reproduction

A

increases genetic variation through recombination, allows faster adaptation

197
Q

what is parthenogenesis

A

reproduction by making genetic clones of themselves

198
Q

why must sex have substantial advantage

A

because parthenogenesis is rare

199
Q

what is two-fold cost o fmales

A

males don’t give brith, so population growth rate is halved if there are males

200
Q

what happens in parthenogenesis

A

sexual individuals replace themselves, and asexual individuals double their reproduction (produce 2 offspring, 1 male and 1 female).

201
Q

what happens if there is a mutation that causes females to reproduce asexually

A

it will spread to fixation quickly

202
Q

what does the fact that asexuality is so rare suggest

A

there must be strong advantage for reproducing sexually to compensate for two-fold cost of producing males

203
Q

what does mutation encoding for asexual reproduction do

A

spreads to fixation in a few generations (so rarity of asexuality is notable)

204
Q

what is one advantage of sexual reproduction

A

recombination produces genotypes and phenotypes that may be better able to fend off pathogens

205
Q

what is red queen hypothesis

A

host must run constantly to stay in same place resect to its parasites

206
Q

basically what is red queen hypotehsis

A

evolutionary arms race b/w a host and its pathogens

207
Q

what is red queen hypothesis a metaphor for

A

evolutionary arms race (host-pathogen evolutionary arms race)

208
Q

what does red queen hypothesis explain

A

the evolution of sex in response to an arms race w/ pathogens

209
Q

basically what is red-queen hypothesis

A

organisms must continuously adapt and evolve to survive while pitted against ever-evolving opposing organisms in a constantly changing environment

210
Q

who came up w/ red queen hypothesis

A

leigh van halen

211
Q

what does red queen hypothesis predict

A

attacks by parasites give an evolutionary advantage to sexual reproduction

212
Q

why do sexual females in NZ mud snails have higher fitness

A

b/c lower rates of infection by parasites

213
Q

what do populations exposed to higher densities of parasites have

A

higher frequencies of sexually reproducing individuals

214
Q

who has higher fitness, sexual or asexual females

A

sexual femalse

215
Q

what happens to these snails (specifically sexual females)

A

overcome two-fold cost of producing males b/c sexual reproduction has an advantage w/r to arms race against pathogens

216
Q

what do attacks by parasites do

A

give evolutionary advantage fo sexual reproduction in NZ mud snail

217
Q

sexual reproduction allows

A

exchange of genetic material

218
Q

where is sexual reproduction found

A

most organisms

219
Q

what kinda gametes do males have (what size)

A

small gametes

220
Q

describe size of female gametes

A

larger

221
Q

what does this difference in size of gametes b/w males and females lead to

A

diff fitness strategies and sexual selection

222
Q

what is sexual selection (what types)

A

male-male competition or female choice

223
Q

can role reversals in sexual selection occur

A

yup

224
Q

what sex ratio is present in most species

A

1:2

225
Q

what does sex do to population growth

A

slows rate of population growth 2x

226
Q

so what must happen because sex is so common

A

must have strong benefits

227
Q

what does recombination allwo

A

allows much faster adaptation in changing environment (like evolutionary arms race w/ pathogens)

evolution (15 decks)

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