PSYC 311: Exam 4
90 Cards in this Set
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Runaway Selection
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Exaggeration of a Trait- One "locus" houses alleles that code for male traits that females prefer. Other locus houses elleles that code for female preference.
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Epigamic selection and female choice
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very high female investment/ burden
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Western Whiptail Lizards
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Display typical lizard reproductive behavior, bite female's legs and tail(as foreplay), the mount
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Desert-grasslands whiptail
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No males, females only.
Asexual reproduction = cloning
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Argument Against Sex
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1. Cost of Meiosis
2.Cost of Recombination
3. cost of mating
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Asexual vs Sexual reproduction
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Asexual reproduces genes at least twice as fast
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Cost of Meiosis
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Cost of producing males
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Cost of Recombination
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Males and females are both successful survivors, therefore both must possess good gene combinations
recombination might delete good genes and advance bad genes
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cost of mating
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mates must be courted, secured, and protected, often means that one's positions in the dominance hierarchy must be maintained.
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how do we know that sexual union is with a member of one’s own species and not with a similar species?
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Pre-zygotic reproductive and Post-zygoticisolating mechanisms
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Post zygotic Isolating mechanisms:
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Cross breeding of species, when it occurs, is usually fraught with problems.
If a ‘viable’ offspring is produced, that offspring will typically be a sterile hybrid. Ex. Mules and Ligers
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Why Sex???The original was evidently successful and change is obviously costly.(and not asexual)
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1. Sexual populations evolve faster because of recombination
2. It has been pointed out that sexual reproduction provides resistance to the effects of mutations.
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Sexual populations can evolve faster
because of recombination.
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Genetic diversity within a species means that the species has a greater probability of being able to adapt to changes in evolutionary pressure.
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Epigamic element-
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refers to differences between males and females in terms of mate selection.
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2. It has been pointed out that sexual reproduction provides
resistance to the effects of mutations.
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Most mutations are deleterious and once embedded in asexual forms cannot be removed. The cumulative deleterious effects of these mutations are called the “Ratchet Effect”.
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With animals employing both sexual and asexual reproduction, such as aphids and hydras:
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Asexual reproduction is favored when the near-future environment is constant.
However:
Sexual reproduction is favored when environmental change is impending (onset of winter).
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Differential (disruptive) Selection
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Eventually results in different sexes
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EvolutionarySpeculation asto“WHY” this uneven burden? (females burden vs male burden)
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differential evolutionary pressure
At one time, sperm and ova were equal in size, but with ova, the bigger the ova, the greater the fitness; with sperm, the smaller (and faster), the fitter. So, evolution favors increased ova size and decreased sperm size.Again, this is an example of dis…
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Why wouldn't males have a greater investment?
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1.Cost/Benefit ratio of increasing investment for males is less...
Are the offspring his?
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1.Cost/Benefit ratio of increasing investment for males is less...
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There would be a decrease in the probability of passing on his own genes if his investment were equal to that of the female.
There would be little time for territorial defense, maintenance of position in the dominance hierarchy, pursuit of other females, competition with other …
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Are the offspring his?
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In general, females always know who the mother of their children is....
Males can never be sure!!
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Consequences of differential C/B ratio for males as compared to females:
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1. There is competition among males for females
So…. Males have a low threshold for sexual activities!
2.Mistakes are most costly for females so females have to be choosier
(thus, the female threshold should be higher).
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More specifically, evolutionary pressure has produced the following malebehaviors:
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1. There is competition to secure a female(s)
2. Competition to
Ensure:
1.Protection of Inseminated female
2. Being the last to copulate with female
3. Carrying the eggs (etc.)
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In general, epigamic selection for males results in:
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1. Use of strategies the help a male copulate successfully
2. Use of strategies the increase the P(fertilization)
3. Use of strategies that decrease the fitness of competitors
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More specifically, evolutionary pressure has produced the following malebehaviors:
A.There is competition to secure a female(s) resulting in:
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1. Low Threshold
2. Dominance behavior
3. Alternative Mating Strategies
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Competition for females may also result in: (for subordinates)
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(i.e., those lacking phenotypical magnificence), if they are to mate, genetic selection must result in more obsequious(i.e., sneaky), but very adaptive mating strategies.
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Alternative mating strategiesmeans that there must be selection for “other strategies” such as:
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1. Troops
2. Satellite Males
3. Mimicry of females
All 3 use sneak
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Evolutionary pressure has also produced the following male behaviors (continued…):
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Competition to Ensure:
1. Protection of Inseminated female
2. Being the last to copulate with female
3. Carrying the eggs (etc.)
4. The use of vaginal plugs (i.e., chastity belts)
5. One novel approach: pair bonding (in some cases, for life). This approach may have some merit.
Pair …
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C. Competition by decreasing the reproductive fitness of rival males.
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1. Sexual interference – disruption courting/copulations.
2. Kill or injure competition (this may include homosexual rape)
3. Reasserting dominance through threat and displays
4. Control and defense of territories
5. Faking of females (cloacal lizards) slightly different from previous…
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More specifically, evolutionary pressure has produced the following male behaviors:
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1. There is competition to secure a female(s) resulting in different mating strategies
2. Competition to Ensure insemination
3. Competition by decreasing the reproductive fitness of rival males.
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Bateman Principle:
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1. Females must be choosier than males because the cost of eggs, pregnancies, etc., and because a females’ potential reproductive success is limited as compared to males.
2. Females’ reproductive choosiness in mate selection should result in greater variability in the reproduct…
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Pre-reproductive isolating mechanisms
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Attire.... General appearance
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Monogamy
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one male for each female. Rare in mammals (16% in humans [origin of data unknown])
Seasonal vs. Serial… Social vs Genetic
Usually found where males are needed after fertilization.
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Polygamy
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more than one male or female for each male or female
Polygyny – more than one female per male (84 % of humans)
Polyandry – more than one male per female (rare; less than 1%)
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Polygynandry
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- several males share several females (and vice versa)
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Promiscuity
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multiple partners, little time spent with each...
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Monogamy
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Is monogamy adaptive? Seemingly not for Males!
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Are there circumstances where monogamy is adaptive for males?
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1. Mate guarding
2. Mate assistance
3. Female enforced monogamy
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Extra Pair Copulations (EPC)
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– found in 10 % of supposedly monogamous birds.
EPC are adaptive in that both males and females ensure that their offspring are more genetically diverse.
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EPC
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if females are engaged in EPC, then this may be the first step towards Polyandry.
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Polyandry
Why would females voluntarily mate with more than one male?
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A. Genetic benefits polyandry
B. Material benefits (Direct Benefits) polyandry
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Polygyny
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In polygynous mating systems, males compete with one another with the goal of acquiring many females.
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Types of Polygyny:
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1. Female defense polygyny
2. Resource defense polygyny
3. Lek polygyny
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Female Distribution Theory
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- female defense polygyny is found where females flock or herd groups together for foraging and protection from predators.
This grouping allows males to control the group.
From the female perspective, females benefit by better group defense created by the herd and by the phenotypica…
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Territorial quality is paramount
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a high quality territory is rich in food, water, and shelter from weather or predators. The battles between males are fiercest when high quality territories are involved.
Females’ perspective – Polygyny Threshold Model: females choose males based on the quality of resources. And, since t…
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Why Polygyny???
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Polygyny Threshold Model – when thequantity or quality of the resources controlled by males varies greatly, females joining already paired-up males on very rich, (or very safe), territories may have more surviving offspring than if they were paired with males that control resource-poor or…
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Scramble Competition Polygyny.
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If females are not clumped together in groups, or, if resources are widely scattered, then males may race to locate and mate with as many females as possible (to the point of exhaustion and death.... some rodents age 75% of their lifetime in a few days...)
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Explosive Breeding Assemblage
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females are clustered during a very brief breeding season (horseshoe crabs, grunion fish, squid, etc., or below, right, snakes)
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Lek polygyny
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a LEK is an courtship/display area.
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Why do females tend to mate with the same males at leks?
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Only 10 to 20 % of the males gathered at a lek actually mate.
The selected (chosen) males are evidentlyphenotypically superior
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Lek paradox
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females all select the same sort of male, which then decreases genetic diversity (which is bad)
As a check against this paradox, note that excellence is determined by more than one genetically diverse factors
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In general, offspring recognition is highly accurate in..?
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Colonial Animals, not so much in solitary nesters
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Why do colonials sometimes adopt genetic strangers?
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Recognition is not perfect.
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Colonials must balance accepting their own n rejecting strangers against rejecting their own and accepting strangers.
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Price of increasing accuracy in rejection is to erroneously reject a small percentage of one’s own offspring.
Price of decreasing accuracy in rejection is to not reject own but at the cost of erroneously accepting genetic strangers.
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Interspecies brood parasitism
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the eggs of a brood parasitic species (BPS) are placed into nest of host species. The host species (HS) then has the cost of raising another species offspring.
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How did cuckoos and cowbirds evolve to parasitize the broods of other birds?
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1. Gradual scenario-
2. Parasitizational exploitation from the start(not gradual)
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Gradual scenario-
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the parasitizing species initially parasitized other of their own species (this is seen in > 200 species of birds).
Then they shifted to other similar species then occurred, finally shifted to any other species which has occurred as in American cowbirds.
Coots- ‘floaters’ (those …
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Phenomena associated with BroodParasitization:
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1. Many parasitizing species choose smaller species
2. All birds have “larger eggs” and “larger hatching” preferences.
3. The eggs and hatchlings of parasitic species are larger than those of the host species.
4. Hatchlings of parasitic species often expel host bird eggs and…
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Why do host birds accept brood parasite eggs?
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The brood parasite’s egg is a larger mimic of the host’s egg, and for most birds, the larger the egg, the better.
Some host birds do throw out the parasite egg, but, unfortunately, also throw out some of their own.
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If the parasitic eggs or hatchlings are too big to remove, why doesn’t the host bird move to a new nest?
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High cost of finding new and more labor
Better to raise a mixed brood if at least some of the hatchlings are of the host species.
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Mafia Hypothesis
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Retaliation by the parasitic cuckoo if the host bird either destroys parasitic eggs/hatchlings or if the host species abandons the conflicted nest
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Can adoption benefit foster parents?
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Dilution of predation on true offspring since the adopted species increases the number of hatchlings.
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Evolution of Parental Favoritism
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Nurturance is provided to the offspring with the best probability of surviving to reproduce
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Siblicide...
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worse when resources are scarce
Parents of some species do nothing; other species do intercede and prevent siblicide.
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Advantages of of Social behaviors
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Protection against predators with Dilution, Defense, Detection.
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Pros of Social Behaviors
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1. Protection against predators
2. Care of young
3. Foraging efficiency (finding food)
4. other (thermoregulation, Grooming, migration, Social stimulation, etc.
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Cons of Social Behaviors
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1. Competition for resources
2. Increased problems with stress, disease n parasites
3. Energy spent on attending to the demands of the dominance hierarchy
4. Increased conspecific aggression. (aggression by adults to others offspring
5. Increase predator pressure
6. Inappropriate you…
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Calhoun
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Population density experiment
unlimited food and water provided but with high population densities cues associated with oldfactory became confused leading to abnormal sexual, social and reproductions behaviors
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Behavioral Sinks
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areas where animals clustered in great mass.... ex. Around feeding and watering areas.
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Mutualism
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when both helper and recipient have reproductive gains from their interaction.
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Goodall
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Chimp brothers cooperate to defeat Alpha Chimp
chimpanzees conduct war against neighboring groups of chimps, particularly along the border of territories.
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Manikins
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Two males display, dance, and perform flying gymnastics for her ladyship. If she is impressed, one manikin (b animal) leaves, the other (a animal) mates with female.
When a dies, the b becomes the a animal, and the next animal in the hierarchy becomes b.
(example of Mutualism)
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Cooperative behavior
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1. Mutualism
2. Reciprocal Altruism
3. Kin Selection
4. Group selection
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Reciprocal Altruism
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(a term coined by Trivers) – the animals that are “helped”, return the favor at a later date.
Sentry duty in Meercats – when a predator approaches, the sentry animal gives a warning cry, but at a personal cost.
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Dyadic Interactions
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two individuals cooperate
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Polyadic Interactions
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More than two cooperate
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Altruism
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where a helpful donor permanently loses reproductive opportunities by placing itself at risk in order to indirectly increase the reproductive fitness of others.
According to W.D. Hamilton – altruism will survive evolutionary criticism (i.e., altruism will work) if the donor, while at r…
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J.B.S. Haldane (1932)
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I would give my life for my identical twin...
I would give my life for two siblings...
I would give my life for eight cousins....
I would give my life for four nieces or nephews...
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Hamilton’s Rule
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If altruism is to spread, the loss of direct fitness has to be less than the gain in indirect fitness
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Evolution of Eusocial behavior
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Species that include non-reproductive working castes.
Worker bees, sister wasps, Soldier ants and termites, storage of food, environmental control workers, etc
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Darwin/ Hamilton
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Eusocial behavior can exist because workers share genes with the reproductive caste.
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Haploidiploidy
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species employing a Eusocial system
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Haploid
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having only one copy of each gene in one’s genotype as is characteristic of sperm and ova in diploid species
Non fertilized egg produces a male drone.
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Diploid
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– having two copies of each gene in one’s genotype.
Fertilized egg produces worker females.
Queen is also diploid
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E. O. Wilson
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many eusocial colonies can be considered as “single Super Organisms.”
Sociobiology- Concerned with the evolutionary analysis of human behavior
Wilson was severely criticized for his sociobiological viewpoints.
The criticisms focused upon objecting to the idea of Humans evolving trait…
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Locomotor Play
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physical activity that may be practice for behaviors required later in life.
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Sociobiology
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Concerned with the evolutionary analysis of human behavior
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Freud
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Totem and Taboo
Edicts at one point in human history were very adaptive but now may be antiquated and arbitrary
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Increased dexterity
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the distance between the thumb and other fingers of Australopithecus were shorter, more curved, and pointed. This made for better power and precision grips.
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Gender specific division of labor = GSDL).
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GSDL evolved since women nursed and cared for young, their bodies had to evolve in order to be able to give birth to the big CNS young… men evolved to hunt, defend hunting grounds, etc. Actually, women probably, through gathering of edibles, provided most of the food, but men were…
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PSYC 311: EXAM 2 PART 1