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
2
Q
what does process of sexual reproduction do
A
creates opportunities for genetic recombination to occur via meiosis
3
Q
what do some animals have besides sexual reproduction
A
internal fertilization
4
Q
what else can some animals do besides sexual reproduction and internal fertilization
A
vectors
5
Q
examples of vectors
A
wind, water (broadcast spawning), other animals
6
Q
what do bacteria and fungi do
A
parasexuality/parasexual reproduction
7
Q
what do bacteria and fungi have (w/r to recombination)
A
recombination in mitosis instead of meiosis
8
Q
what is parasexuality
A
bacteria pass DNA b/w each other via conjugation
9
Q
what is conjugation
A
involves transfer of plasmids, which sometimes carry genes for antibiotic resistance
10
Q
how else can parasexuality occur (besides conjugation)
A
other bacteria are able to absorb naked DNA left in environment
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
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
13
Q
describe mating in frogs and toads
A
sexual reproduction –> recombination occurs via meiosis
14
Q
describe reproduction in bacteria
A
parasexual reproduction –> thru conjugation
15
Q
hermaphrodites
A
each individual has both male and female gonads
16
Q
how do hermaphrodites mate
A
some mate w/ other individuals, others self fertilize
17
Q
examples of hermaphroditic organisms that mate
A
earthworms, snails, slugs
18
Q
example of hermaphroditic organisms that self-fertilize
A
plants
19
Q
what is hermaphroditism a form of
A
reproductive assurance
20
Q
reproductive assurance (hermaphroditism)
A
increases chances of reproduction when potential mates are scarce
21
Q
what are clownfish
A
sequential hermaphrodites
22
Q
describe how clownfish are sequential hermaphrodites
A
first male, then later changes to females
23
Q
what is key difference b/w males and females
A
gametes come in two sizes
24
Q
anisogamy
A
dimorphism in gamete size (males and females having two diff gamete sizes)
25
describe egg
large, immobile, provisioned
26
describe sperm
small, mobile, not well provisioned
27
what does well provisioned mean
inhibiting movement
28
when do gametes have high fitness
if large, well provisioned (inhibiting movement)
29
when else do gametes have high fitness
small, mobile so it can find and fertilize the egg
30
which gender makes more
females make fewer eggs than male (who make lots of sperm)
31
another word for egg
ovules
32
another word for sperm
pollen
33
what defines sexes
difference in gamete size
34
what do males make
small, less costly gametesw
35
what do females make
large, more costly gametes
36
what is another example of dimorphism
sexual dimorphism
37
what is sexual dimorphism
sexes of the same species exhibit diff morphological characteristics (not characteristics involved in reproduction)
38
what do anglerfishes have
extreme sexual dimorphism
39
what do male anglerfishes do
bite and attaches himself permanently to a female
40
what happens when male anglerfishes attaches to female
his body fuses with hers, his organs degenerate except for his testes, which grow to fill most of his body
41
how many mechanisms do animals have which determine an individual's sex
a variety of mechanisms
42
what do all mammals have
XY system of sex determination
43
what is the XY system of sex determination
males are heterogametic sex (XY), females are homogametic (XX)
44
do all vertebrates have XY system of sex determination
nope
45
what system of sex determination do birds have
ZW; females are heterogametic (ZW), males are homogametic (ZZ)
46
what is most common sexual system in teleost fishes
hermaphroditism
47
what are hymenoptera
ants, bees, wasps, etc.
48
how do hymenoptera and acari (mites) determine sex
haploploidy
49
what is haploploidy
sex determination system where males develop from unfertilized eggs and are haploid; females develop from fertilized eggs, are diploid
50
describe males in haploploidy
develop from unfertilized eggs --> haploid
51
describe females in haploploidy
develop from fertilized eggs --> diploid
52
what are sex determination strategies in plants
2 major sex determination strategies: some plants are dioecious, others are monoecious
53
what are dioecious plants
(means 2 houses); individual plants are either male or female (and have either male or female flowers)
54
another definition of dioecious
male and female sex organs found in separate individuals
55
what are monoecious plants
hermaphroditisim; one house --> both male and female sex organs on the flowers
56
what have plants evolved
evolved dioecy (male/female sex organs on diff individuals) multiple times from monoecy (hermaphroditism)
57
what else have plants evolved
have evolved sex chromosomes multiple times
58
how is sex determined in turtles and crocodilians
environmental factors; environmental sex determination
59
what is environmental sex determination
sex is determined by temperature during egg developmnet
60
are the temperatures that alter sex ratios the same for all species
no; diff species have diff temps
61
how can the sex ratio evolve (for environmental sex determination)
by females changing where they lay their eggs / females evolving diff preferences for where they lay their eggs
62
what sex determination system do we see in ants, bees, waps
haplodiploid sex determination
63
what is haplodiploid sex determination for females
females are diploid, produce haploid eggs via meiosis
64
what is haplodiploid sex determination for males
males are haploid, produce haploid sperm without meiosis
65
what does fertilization do in haplodiploid sex determination
fertilization produces diploid female bees
66
what do unfertilized eggs do in haplodiploid sex determination
produce haploid male bees
67
how do females determine sex ratio in haplodiploid sex determination
by altering number of offspring resulting from fertilization
68
what ratio do we see in most species w/ separate sexes
1:1 sex ratio
69
what happens if one sex is rarer
newborns of that sex more likely to find mates than common sex
70
what happens to parents w/ genetic tendency to have offspring of rarer sex
will have more grandchildren than average
71
what happens to alleles for that tendency
alleles will spread, sex ratio will shift back to 1:1, where this tendency is no longer favor
72
what are other strategies besides 1:1
sequential hermaphrodites
73
describe uneven sex ratio
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)
74
what happens to this mutation at equilibrium
mutation more common in males, because females w/ mutation produce only sons but males w/ mutation produce both sons and daughters that carry mutation
75
what traits evolved via sexual selection
traits not related to natural selection, maybe even inhibited survival and thus reproduction
76
what are two classes of sexual traits
primary and secondary sexual traits
77
what are primary traits
necessary for reproduction to occur
78
examples of primary traits
structures such as gonads and genitalia
79
what are secondary traits
strange, gaudy, increase the probability of mating
80
do secondary sexual traits play a role in reproduction
nope, only indirect role
81
example of secondary sexual traits
male peacock's train
82
what are genitalia on slugs (what kind of trait)
primary sexual trait
83
what kinda trait is bright colored butt of male mandrill
secondary sexual trait
84
what did darwin propose about secondary sexual traits
evolved b/c of competition for mates among individuals of same sex or through mate choice (females preference for male secondary sexual traits)
85
describe secondary sexual traits evolving cuz of competition for mates among individuals of same sex
male-male competition; male prevents other males from mating and this helps him to leave more copies of his genes to the next generation
86
what is mate choice
female preference for male secondary sexual traits
87
who came up w/ idea of sexual selection
Darwin
88
what was Darwin's idea of sexual selection
special case of natural selection
89
what do other scientists say about sexual selection w/r to natural selection
they say it is a separate force
90
what can sexual selection act on
primary or secondary sexual traits
91
how can traits evolve by sexual selection
if it increases overall fitness, even if it decreases survival
92
basically what is secondary selection
differential reproduction as a result of variation in the ability to obtain mates
93
another definition of sexual selection
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
2 examples of sexual selection
female choice, male-male competition
95
experimental test of sexual selection
male long-tailed widowbirds have long tail feathers; shortened in one group and lengthened in another. long tailed males had greatest success
96
do males and females in population have same average reproductive success
yes
97
what do males and females differ in
reproductive variance among members of each sex
98
what do differences in the selection gradient result in
sexual dimorphism
99
what happens when males are subject to stronger sexual selection than females
males will evolve secondary sexual characters that result in marked differences b/w sexes
100
what do male peacocks do
don't provide parental care
101
what leads to marked dimorphism in male peackocks
some males more successful than others who may never reproduce
102
what happens when males contribute to offspring care
selection gradient is lower, sexes are monomorphic
103
what species contributes to offspring care
male albatross
104
what are many seabirds
monogamous, raise offspring together, and sexes are indistinguishable
105
what happens when males provide all the parental care
selection gradient is reverse, and females compete for access to male
106
what happens when gradient is reversed and females compete
reverse sexual dimorphism
107
example of reversed sexual dimorphism
females are brightly colored
108
what species provide all parental care, and females compete for access to males
red-necked phalaropes
109
describe female red-necked phalaropes
females are larger and more aggressive; polyandrous, mate w/ many males
110
what is trade-offs
selection favors display that maximizes a males lifetime fitness
111
what are trade-offs a tug of war between
two fitness components: survival and mating success
112
what does compromise ultimately maximize
a male's lifetime fitness
113
what is male survival maximized by
a tail length that optimizes aerodynamics, leading to stabilizing selection for tails of intermediate length
114
what does male mating success depend on
mean female mating preference
115
what happens if most females prefer long tails
males w/ long tails have greatest mating success [tails will evolve to an equilibrium that is longer than what maximizes survival]
116
what happens if most females prefer short tails
tails will evolve to a length shorter than what maximizes survival
117
when does the optimum shift
if strength of natural selection or sexual selection changes
118
what did darwin say about exaggerated secondary sexual traits
decrease survival
119
what else can calls attract besides mates
predators
120
are signals always costly? what does this cause
tug of war between survival and mating success, between effects of secondary sexual traits on survival and mating success
121
so are these signals always costly
maybe?
122
what does rick prum argue
beauty evolves cuz of female choice, not necessarily costly or indicative of male fitness potential
123
what is bateman's principle asking
why do we usually see males w/ exaggerated secondary sexual traits?
124
what 3 principles did bateman derive
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
why do we usually see males w/ exaggerated secondary sexual traits?
female can fertilize all eggs w/ single mating, so no fitness/selective advantage from a trait to increase number of mates
126
another reason we see males w/ exaggerated secondary sexual traits
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
what is operational sex ratio
relative number of males and females available to mate
128
what is outcome of sexual selection influenced by
operational sex ratio
129
when do we see sex role reversal
when more females are available, and they are not a limiting resource
130
basically when do we see sex role reversal
most common sex must compete for access to less common sex
131
what is this a case of
reversal of bateman's principle
132
example of reversal of bateman's pirnicple
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
what are 2 specific modes of Darwin's sexual selection
intrasexual competition, intersexual selection
134
intrasexual competition
male-male competition
135
intersexual selection
female choice
136
example of male-male competition
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
how else do males compete
alternative mating strategies
138
3 male strategies
alpha blocks entrance, beta male sneakily mimic females, gamma males sneak past alpha male
139
what do alpha males do
large; guard harem of females by blocking the entrance
140
what do beta males do
medium size; imitates females
141
what do gamma males do
small size; try to reach females by slipping past alpha male
142
how do beta male and gamma male gain access to females
by tricking alpha males
143
how can males interfere w/ each others reproduction
sperm competition
144
what is sperm competition a way for
males to interfere w/ each others reproduction
145
how do damselflies mate
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
give the example of sperm competition in males
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
can sperm competition happen in mammals
yup
148
describe how females of some primates mate w/ males
they mate w/ many males
149
describe sperm competition in chimpanzees/primates
males have evolved large testicles to produce more sperm
150
which chimpanzees produce most offspring
individuals w/ most sperm
151
what can organisms optimize
copulation
152
what does optimizing copulation do
optimizes fertilization
153
how can we predict duration of copulation by male dungly
from proportion of eggs fertilized as a function of copulation time, and time it takes to search for and guard female
154
what is another male strategy
infanticide
155
where does infanticide occur
mammals, including lions
156
describe infanticide in lions
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
are extravagant male secondary sexual traits (like bright plumage) useful for male-male competition
nope
158
what is the point of these extravagant secondary sexual traits
help attract females and persuading them to mate --> female choice
159
describe evidence of sexual selection
simple nervous systems; don't actually make a conscious choice
160
what does 'choice' refer to
any phenotype of female that biases the type of male she will mate with
161
what does female choice require
genetically based phenotypic variation in females and males
162
can mating preferences evolve
yup
163
what do females of closely related species have
innate preference for mating w/ their own species, which have evolved since divergence from most recent common ancestor
164
what does avoiding mating with another species do
increases fitness
165
why does avoiding mating w/ another species increase fitness
hybrids have low viability/fertility
166
what is sexual selection the cause of
suite of crazy male secondary sexual traits (due to female choice)
167
describe Leks
females visit lek, mate w/ male of their choice, rear offspring w/o help of males.
168
what ways do females evolve preferences for male secondary sexual traits
direct benefits, pleiotropic effects, perceptual bias, good genes, fisher's runaway
169
what are direct benefits
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
another example of direct benefits
some insects and spiders, male allows itself to be eaten by female after mating
171
what is pleiotropy
single gene producing multiple effects
172
what do female guppies prefer
females prefer males w/ more orange in their body
173
what are guppies attracted to and why
small orange disks, because they feed on small orange fruits and this has translated to females preferring orange colored males
174
what male guppies have higher fitness
males w/ more orange
175
describe pleiotropic effect in guppies
guppies prefer orange males b/c they are also attracted to orange fruit for feeding
176
what are perceptual biases
mating preferences caused by pleiotropic effects
177
what can females be attracted to
signals that males of their species don't make and are therefore a side effect of features of nervous system --> epiphenomenon
178
what are some female mating prefernces
perceptual biases that evolved before origin of male trait on which they act
179
describe trait evolving via a perceptual bias
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
describe how the preference of sword evolved
preference for sword evolved before sword itself did
181
what is good genes
a way that female choice might evolve
182
define good genes
male traits are advertising to females that the male has good genes
183
describe good genes in sticklebacks
percentage of sticklebacks that became infected when exposed to tapeworm declined w/ intensity of their father's red coloration
184
what do red male sticklebacks have
red males are attracted to females, have alleles that make them resistant to tapeworms and passed on to offspring
185
describe its indirect effe t
the female preference allele is in linkage disequilibrium w/ alleles at other loci that are under direct selection (alleles related to tapeworm resistance)
186
describe fisher's runaway sexual selection model
females w/ preference for long tails mate w/ long tails. offspring have genes for long tail and for preference of long tail.
187
what are genes for the male trait and female trait in
in linkage disequilbrium (statistically associated w/ each other)
188
what does Fisher's model say about these tails
can cause a feedback loop favoring longer and longer tails & preference for them
189
is fisher's model actually observed
no; nat selection would balance sexual selection at some point otherwise species would go extinct
190
why do we see unique features in plants
they have passive fertilization via pollinators
191
what are these unique features a result of
sexual selection
192
what are most flowering plants
hermaphrodites
193
describe operational sex ratio of flowering plants
biased towards males
194
why is operational sex ratio of plants male biased
b/c after a plant's ovules are fertilized, it keeps sending out pollen to other plnats
195
what else do individual plants have
better floral displays
195
why do individual plants have better floral displays
to compete for pollinators
195
is having males in a species costly
it seems like it but not actually
195
why do males seem costly
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
when do we see male-male competition in plants
pollen grains racing to fertilize ovule (similar to sperm compmetition in animals)
196
what is benefit to sexual reproduction
increases genetic variation through recombination, allows faster adaptation
197
what is parthenogenesis
reproduction by making genetic clones of themselves
198
why must sex have substantial advantage
because parthenogenesis is rare
199
what is two-fold cost o fmales
males don't give brith, so population growth rate is halved if there are males
200
what happens in parthenogenesis
sexual individuals replace themselves, and asexual individuals double their reproduction (produce 2 offspring, 1 male and 1 female).
201
what happens if there is a mutation that causes females to reproduce asexually
it will spread to fixation quickly
202
what does the fact that asexuality is so rare suggest
there must be strong advantage for reproducing sexually to compensate for two-fold cost of producing males
203
what does mutation encoding for asexual reproduction do
spreads to fixation in a few generations (so rarity of asexuality is notable)
204
what is one advantage of sexual reproduction
recombination produces genotypes and phenotypes that may be better able to fend off pathogens
205
what is red queen hypothesis
host must run constantly to stay in same place resect to its parasites
206
basically what is red queen hypotehsis
evolutionary arms race b/w a host and its pathogens
207
what is red queen hypothesis a metaphor for
evolutionary arms race (host-pathogen evolutionary arms race)
208
what does red queen hypothesis explain
the evolution of sex in response to an arms race w/ pathogens
209
basically what is red-queen hypothesis
organisms must continuously adapt and evolve to survive while pitted against ever-evolving opposing organisms in a constantly changing environment
210
who came up w/ red queen hypothesis
leigh van halen
211
what does red queen hypothesis predict
attacks by parasites give an evolutionary advantage to sexual reproduction
212
why do sexual females in NZ mud snails have higher fitness
b/c lower rates of infection by parasites
213
what do populations exposed to higher densities of parasites have
higher frequencies of sexually reproducing individuals
214
who has higher fitness, sexual or asexual females
sexual femalse
215
what happens to these snails (specifically sexual females)
overcome two-fold cost of producing males b/c sexual reproduction has an advantage w/r to arms race against pathogens
216
what do attacks by parasites do
give evolutionary advantage fo sexual reproduction in NZ mud snail
217
sexual reproduction allows
exchange of genetic material
218
where is sexual reproduction found
most organisms
219
what kinda gametes do males have (what size)
small gametes
220
describe size of female gametes
larger
221
what does this difference in size of gametes b/w males and females lead to
diff fitness strategies and sexual selection
222
what is sexual selection (what types)
male-male competition or female choice
223
can role reversals in sexual selection occur
yup
224
what sex ratio is present in most species
1:2
225
what does sex do to population growth
slows rate of population growth 2x
226
so what must happen because sex is so common
must have strong benefits
227
what does recombination allwo
allows much faster adaptation in changing environment (like evolutionary arms race w/ pathogens)
