Exam 3 Flashcards
Who introduced the idea of sexual selection?
Charles Darwin in the book “on the origin of species”
Expanded on in “The Descent of Man and Selection in Relation to
Sex.”
what are the two methods of sexual selection according to Charles Darwin?
Intersexual Selection
Intrasexual Selection.
Members of the same gender competing to mate with the other gender?
Intrasexual selection
Members of one sex influence the characteristics of the opposite sex through sexual selection?
Intersexual Selection.
Done through “Mate Choice.”
In intersexual selection which gender is in demand? the one making choices or the sex being affected?
The one making choices.
Think Female Choosiness.
Who theorized that females will usually invest more energy into offspring than males and therefore be the limiting resource?
A.J. Bateman.
What did A.J. Bateman conduct studies on?
Drosophila
To test the reproductive success of fruit flies and found more variance between males, meaning that females reproductive success does not depend on number on mates as heavily.
What are two reasons that females tend to be the limiting reproductive resource?
Gametes are genetically more expensive and produce less.
Females tend to have more parental investment.
Male Seahorses are known to incubate the eggs the females produce, yet the males still compete with each other for females, why?
Intrasexual selection is happening because the energy the females put into producing the eggs is still more than the energy males spend incubating them. Females are still the limiting resource.
In general the fertility of a male or female will be more limited?
The female. This leads to females being much more “choosy/ coy” while males may have an indiscriminate eagerness.
Why is it that males are not totally indiscriminate in mate choosing?
Because the energy it costs to produce sperm may be cheap, but the amount produced makes up for this.
A packet of spermatozoa and proteins used to deliver to the female?
Spermatophore.
Who assumed that females were passive in reproduction?
Bateman.
What is special about bonobo mate selection?
They are a matriarchal species and the females generally will initiate contact with the males for mating.
Usually the number of mates will not increase a females reproductive success. Why, what may be evidence against this?
This is because females have a limited fecundity. Animals, usually insects, which produce a spermatophore may challenge this, as the spermatophore give the female nutrients as well, so the more spermatophores a female gets the higher her egg production/ reproductive success may be.
What type of sexual selection may lead to an increase in the males size Vs the females?
Usually intrasexual selection, bigger males have a greater chance of winning in competing for females.
What is a species that shows female dominance?
Wolves. The lead male and female both will dominate over their own sex in the pack.
Phenotypic difference between males and females of the same species?
Sexual Dimorphism.
What type of sexual selection is generally associated with sexual dimorphism of ornamentation?
Intersexual selection. This is because ornamented males are more likely to be chosen by females, but this may also be a part of intrasexual selection as well.
In horned beetles the females are choosy for bigger horns, but the horns also assist the males in fending off other males (Intrasexual.)
Why do African cichlids have one of the greatest size sexual dimorphisms?
This is due to intrasexual selection. The males mate by collecting shells for the females to lay eggs in. So the males must be big enough to carry and defend the eggs and the females must be small enough to fit in the shells.
Elephant seals exhibit what kind of sexual selection?
Intrasexual selection.
The males arrive to plots of land before the females and will defend their territory and then harem of females from other males. They will often go without food to ensure other seals do not get access to their females. The males fighting with each other is usually non-fatal and often is ending just through bluffing.
What are the alternative mating strategies used by non-dominant males?
Sneak/ Streak spawning, Satellite Male, and some just sit on the outside of a harem waiting.
What is called when a non-dominant males rushes up to a mating pair to attempt insertion of his sperm?
Sneak/ Streak spawning. This is common in reptiles, but also salmon where this male is called a Jack male.
What are the three color morphs of side blotched lizards? what do they mean?
Orange: Prime Dominant Male
Blue: Dominant enough for one female territory, over powered by orange, but easily fends off yellow.
Yellow: On the periphery to mate with the orange’s females while the orange is out- territory is large enough to not be seen at all times.
This is an example of sneak spawning.
Male that mimics a female to get access to breeding opportunities?
Satellite male. This is a sneaker fish that is too large to hide. They will get in-between a dominant courting male and female just as they spawn.
They may also use this to increase indirect fitness for a relative instead.
Bluegill sunfish do this.
What is the usual cause of a satellite male existing?
These males are usually younger and smaller therefore they cannot defend or claim their own females or territories. They also do not inout any parental investment.
What is Sperm competition?
The Competition between spermatozoa of two different males to fertilize an egg of one female.
What scenarios usually lead to sperm competition?
When females have many partners, while this may increase her reproductive success it usually lowers the chances for a male.
This is a sexual conflict of males and females.
What are the 6 defensive sperm competition methods?
- Mate guarding
- Mating plug
- Prolonged mating
- Releasing substances which make it less likely for the female to mate again.
- Breaking off the mating appendage within the female (Regenerative usually.)
- Sperm Partitioning.
What are three methods of offensive sperm competition?
- Increased Sperm Production
- Increased Sperm motility.
-Mechanisms to displace or inactivate competing sperm.
A male mates with a female and then defends other males from approaching her, what is this an example of?
This is an example of defensive sperm competition. This may occur pre or post copulatory.
A male guards a female only around the times she is fertile?
Strategic defensive sperm competition mate guarding, this allows the male to attempt extra pair paternity while painting intra pair paternity.
EX: Blue crabs- females can only mate right after molting so a male will mate with her and guard her only until her shell hardens.
When a male inserts a gelatinous substance that hardens/ interferes with another male mating directly after he has mated with a female?
Post-copulatory plug.
“Time-advantage.”
Found in many insects and may be used as part of a spermatophores. Also found in reptiles and some mammals such as rats.
Defensive sperm competition.
What is an advantage of post-copulatory plug Vs. Mate guarding?
The male that is guarding cannot further increase his fitness by mating with more females while the copulatory plug allows the male to leave immediately to find another female.
When a male does not release all of his sperm into one female?
Sperm partitioning, this allows the male to conserve more sperm to mate with more females, however it does leave the female with less sperm so possibly less chance of success with her individually.
Blue headed wrasse fish do this.
Defensive sperm competition.
What are the two advantages of prolonged mating?
This means other males are not mating with the female.
Allows the male to release even more sperm into the female. This is common in insects, but also dogs do this called “knotting”.
Defensive sore competition.
What are mating inhibitory secretions?
These are secretions of the male put onto the female that make her less receptive/ or less attractive to mating. These secretions may also stimulate ovulation and oogenesis.
Defensive sperm competition.
When a male has increased production of sperm for offensive sperm competition and the resulting cells are smaller due to the energy cost of so much sperm?
Anisogamy.
Gorillas have smaller testicle than bonobos, why?
Female Gorillas are relatively monogamous, while bonobos are very promiscuous, this means offensive increased production of sperm competition is more at play in bonobos, and larger testes can produce more sperm.
What is increased sperm motility?
an offensive sperm competition where some males will produce a normal amount of sperm but these sperm have more motility to reach the egg first.
Damselflies have an appendage before mating they use to remove previous ejaculate prior to mating, what is this an example of?
This is an offensive sperm competition by a mechanism to displace competing sperm.
Dunnock birds and crabs also do a form of this.
What is sperm heteromorphism?
when not all of the sperm produced into the ejaculate is meant for fertilization.
There will be eusperm (Normal) and parasperm (Usually has a purpose to displace or inactivate competing sperm.)
What is eusperm?
Normal sperm meant for fertilization.
What is parasperm?
Sperm not meant for fertilization, meant to displace or inactivate competing sperm.
Form a barrier to competing sperm
Attack/kill other sperm
Assist the eusperm.
This is a sperm heteromorphism.
Offensive sperm competition.
Any behavior which reduces a rivals reproductive fitness?
Sexual Interference.
Newts will clasp together to mate, when a male newts clasps another male it will clasp back to show it is also male. some male newts do not clasp back and allow the new to release it’s spermatophore, what is this an example of?
Pseudofemale behavior Sexual interference.
The males have a limited number of spermatophores and this one has now been wasted when it could’ve gone to a female.
What are the three tactics of sexual interference in newts?
- Pseudo-female behavior.
- Amplexus interference
- Spermatophore interference.
What is an amplexing male?
When the male is wrapped around the female to fertilize her eggs as she lays them.
When a male is amplexing a female another male shows up. this pauses the apmplexing male and he will now have to start again. What is this an example of?
Amplexus sexual interference The male starting all over again is wasting energy that could’ve been spent on more females.
A rival male inserts himself between an external mating couple and releases his spermatophore as well, what is this an example of?
Spermatophore sexual interference.
The female may use the rival males spermatophore, this would decrease the OG males reproductive success both directly and indirectly by way of a wasted spermatophore.
What are the four modes of sexual interference?
What kind of competition is this?
- Pseudo-female behavior.
- Amplexus interference
- Spermatophore interference.
- Infanticide.
This is intrasexual competition.
When a male kills the kids of his new harem. Benefits?
The kids are from previous male, this will make the female receptive to mater sooner and reduce intraspecific competition between his and the previous males offspring.
Since this means these new cubs have these genetics that improve their own reproductive success this behavior has stayed prevalent.
how do waterbeds participate in infanticide?
Although usually males commit infanticide, in water bugs males care for the larvae on their backs, this makes them a limiting resource and then females will stab the larvae if they cannot find a free male so that he can take care of her own eggs.
when the members of one gender influence the characteristics of the opposite gender through mate choice?
Intersexual selection.
Peacocks will display their feathers to the peahen. She will be choosy about the male ornamentation, what is predicted she is looking for?
Symmetry- Asymmetry may indicate poor health/ less offspring.
The vigor of presenting shows that male has enough nutrition to waste on display and may be a better provider.
What are Three criteria of choosy females selecting males?
- Sperm Production: female Stone crabs will prefer unmated larger male crabs= More sperm.
- Ability to provide resources:
- Ability to provide good genes.
What are the resources a male may provide to a female?
Short term gains: Nupital gifts: These can range from an eaten gift, spermatophore absorbed across cloacal mucosa & cannibalism.
Long Term gains: Territory & Parental investment.
When a male gives a female a courtship food gift?
Nupital gift by way of courtship feeding.
Shrike birds will place impaled prey on thorns and the female will choose the biggest prey.
Some spiders will give a wrapped food item.
Some insects give an edible spermatophores and will inseminate with another.
Scorpionflies gift a non-edible salivary gift, why might this be valuable to the female?
The salivary secretion shows the male has the energy and resources to have good genes. Males in poor condition will prolonger the precopulatory period so their gift is less likely to be rejected, while males with ample resources will have more gifts/ shorter precopulatory periods/ more mating opportunities.
This is a short term nupital gift gain.
What are the benefits of cannibalism?
The female gets nutrients and the male gets to increase his direct fitness.
House wrens will select a male based on the number of nesting sites within his territory, what is this an example of?
intersexual selection. The males with bigger territories will generally have a higher fitness. The females are selecting for a long term gain.
Male Calliope humming birds will bring many food gifts to the female during courtship, these birds also assist in parental investment. The male birds which bring more gifts are chosen. What is this an example of, what is the female selecting for?
This is intersexual selection, the female is selecting for long term gains of parental investment. The gifts show how well the male will provide to the offspring.
What are three factors which determine the quality of a males genes?
- Ability to dominate rivals
- Ability to produce and maintain showy displays.
- Ability to produce and maintain sexual ornamentation.
in mammals pheromones may indicate the reproductive health of the individual.
In peacock spiders the showier spiders get to mate with the female, what is this an examples of? what is the female choosing for?
Intersexual selection.
The female is choosing for better genes that show the spider is able to maintain sexual ornamentation.
The female will also eat him after so he may also be a post copulatory nupital gift.
Why do blue tits have sexual dimorphism?
The females are choosy towards males with more yellow plumage. The yellow plumage is associated with better ability to gain nutrition -the bugs contribute to feather color- more yellow birds will have better body condition. The females therefore are also selecting for better genes of the males and likely better parental investment.
What does the male king bird of paradise show in sexual selection?
intersexual selection, the females choose the males with a better mating dance that shows off his genes for strength.
What does the male bower bird of paradise show in sexual selection?
These male birds will build an elaborate nest, a bower, to attract a mate and also perform a mating dance, this shows off his resourceful and energetic genes. The male will also raise the young and so this may also show ability to commit to parental investment.
Who proposed the handicap principle?
Amotz Zahavi. Proposed the idea that a male which is able to survive with a “Handicap” will have better fit genes.
The handicap indicates and honest communicator that the male has good genes.
Who proposed the idea of runaway sexual selection?
Ronald Fischer.
The idea that a female preference may evolve and then her offspring males will have that trait and daughters will learn to prefer the trait?
Run away sexual selection proposed by Ronald Fischer. this will lead to extremes in male traits.
The males will become preferred and produce more offspring with the trait or the preference for that trait.
In betta fish, the male which have a dot at the their tail will have a better reproductive fitness. it has been found that the prey of these fish resemble this dot. What is this an example of?
Sensory bias. Because the females are already attracted to prey which look like the red dot they are more likely to approach these males.
Bower birds do this with color blue in their nests, the females prefer to eat blue grapes.
When females are able to store and preferentially choose sperm paternity?
Cryptic female choice.
Who defined sexual conflict?
Parker in 1979
An antagonistic co-evolution to a males sexual morphology which is deleterious to the female. this will evolve to the point of max reproductive success.
Sexual Conflict.
An example of this is in some bugs the males mating damages the health of the female, the females which develop traits which limit the number of copulations will live and produce offspring.
Males will then probably evolve some response to this and vice versa.
Who came up with idea that females almost always invest more into producing offspring than males, so they will almost always be the resources competed over?
A.J. Batman.
Who theorized that the gender which provides more parental investment will become the limiting resource?
R.A. Trivers.
Specific traits in a male that a female prefers snd serve as “good gene” models?
Indicator mechanism.
Any parental expenditure which benefits offsprings at a cost to the parents.
Parental investment.
What are the two decisions of parental investment?
- How much of their own resources should go towards reproduction Vs. Their own needs
- How those resources/ investments should be allocated among offspring.
Parental Behaviors which have an immediate physical effect on the offspring and their survival.
Direct Parental Care.
EX: Feeding, maintaining nest, caring for eggs.
Parental behaviors which do not have an immediate physical effect on the offspring.
Indirect Parental Care.
Usually done while parents are away from offspring or before offspring are born.
EX: Building nest, establishing territory, defending resources, defending young from predators, male caring for pregnant female.
What are the three evolutionary conflicts of parent investment between family members.
- Evolutionary interests between males and females.
- Intrabrood conflict (Within same brood.)
- Interbrood conflict (Members of different broods.)
Parental invest theory is a branch of what?
Life history Theory.
Who argued the parental investment between the sexes should be equal?
Fisher (1930).
Who expanded the concept of parental investment to include costs to any other component of parental fitness?
Clutton and brock.
Who’s idea was it that the sex which invests more time into parental investment will be more discriminating in mating and will be competed for?
Robert Trivers.
Intrabrood conflict AKA:
Sibling rivalry.
What is it called when intrabrood conflict reaches the level of murder?
Siblicide.
Nazca Boobies are known for what?
Obligate siblicide, when two eggs are laid the one which hatches first will push the other out of the nest. if they both hatch the older sibling will still do this.
What is it called when siblicide only occurs situationally?
Facultative siblicide.
How much resources should be invested into the current litter at the cost of providing for future litters is an example of what conflict?
Interbrood conflict.
Also includes when the lifetime reproductive success of the parents is lowered.
What is the conflict of Galapagos fur seals?
interbrood conflict. These seals pups may ween up to two years if environmental conditions are poor. Frequently ~23% of pups are born to a family with an already sucking pup. If conditions are good, the pup will likely wean and the new pup lives. If bad conditions then the new pup will be starved from suckling and many die within the first month.
How does life history affect the parental investment of broods?
In shorter lives species parents will put more investment into a singular brood as it may be the only one they have. In longer lived species they will likely partition their resources.
RV=?
Current reproduction + residual reproductive value.
RV= Total Reproductive value.
What is residual reproductive value?
The individuals future reproduction through its investment in growth and survivorship.
Over investment in current reproduction lowers what?
Residual reproductive value. AKA future ability to have more offspring and may lead to a shorter lifespan.
Male blue gill guard their young. How does this behavior change based on exposure to sneaker males?
Sneaker males may have affect paternity. Due to the un/ lack of certainty of paternity the blue gills with more exposure to sneaker males were found to be less aggressive guarding the young Vs. those with less exposure.
When parents have different investment for male Vs. Female offspring?
Sex Allocation.
What type of species in sex allocation limited to?
Dioecious Species (Those having only two consistent lifetime genders.)
What are the two means of sex allocation?
- Increased production of one gender.
- Increased parental investment in one gender.
Why do birds have such a high incidence of biparental care?
This is because once the egg is laid both the female or male can just as easily incubate the egg. The male participating in prenatal care makes them more likely to participate as a parent of the young.
Why do mammals have so much parental care only from the female species?
Since the mammals have pre-natal care in the womb there is not direct prenatal care from the male, therefore he is not likely to participate as a parent.
What two classes of animals have the highest incidence of no parental care?
Teleosts and anurans. This is likely because they practice external fertilization and neither parent does much towards prenatal care.
However this is not 100% chondrichythyes all practice internal fertilization, but show no parental care.
Population growth strategy where the species focuses on producing as many young as possible with little to no parental investment.
R-Selection.
Animals with a great deal of predation which would not be able to defend their young from predators are better off using which population growth tactic?
R-selection. Think sea turtles- they can’t fend off their young from their predators so they produce as many as possible with prenatal resources to be sufficient as birth with no parental investment. (Defense mechanisms would be wasted energy.)
Reproductive strategy where a species will have fewer young but higher parental investment leading to higher survivability and longer lifespan of young.
K-selection.
Species which are able to defend their young from predation will benefit from which reproductive strategy?
K-selection. Parental investment in successful defense of young will increase both the young and parent’s fitness level.
Who’s theory regarding the mate that does the parental investment will be the sought after mate is also open to role reversal?
Robert Trivers.
Robert Triver’s theory is that the mate which provides more parental investment will be less available to mating and therefore the “sought after” sex. What two scenarios does this lead?
- The operational sex ratio: The ratio of sexually active males to sexually available females.
- Potential reproductive rate: The maximum number of offspring a parent can produce per unit of time.
Bird which the male does majority of the parental investment and therefore is the “sought after” mate?
Northern Jacana.
The females will compete for mates, they will have defensive territories of harem males and will even practice infanticide when they take over another female jacana’s territory.
Manipulation of hosts individuals to raise and rear the young of the brood parasite.
Brood parasitism. May be either intra or inter specific.
What does brood parasitism reduce?
While is raise the fitness of the parasite it will decrease the reproductive fitness of the parents raising the parasite.
What is different about inter Vs intra specific brood parasites?
intraspecific brood parasites may build their own nest as well and rely more heavily on parasitism when nests are hard to obtain/ build.
Interspecific brood parasites are obligate parasites and are unable to build their own nests.
