48 Cards in this Set
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Arguments Against Sex (3)
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1) Cost of Meiosis
2) Cost of Recombination
3) Cost of Mating
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Western Whiptail lizards (WWTL)
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example of typical lizard reproductive behavior i.e., they bite females legs and tails as foreplay and then mount
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Desert-Grasslands Whiptail (DGWTL)
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Example of lizards that reproduce via asexual reproduction (cloning); there are no males in the species, only females
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Cost of Meiosis
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It costs more to reproduce both your own genes and the males genes, DGWTLs can replicate their genes twice as fast as WWTLs
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Cost of Recombination
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Existing genes are already successful, and this could delete good genes and advance bad genes
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Cost of Mating
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Mates must be courted, secured, protected, and rituals may attract predators, requires maintaining dominance hierarchy, and mating may cause wounds (esp. to female)
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Pre-zygotic Reproductive Isolating Mechanisms
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Factors which cause species to mate with their own kind (includes temporal, ecological, behavioral, or mechanical isolation)
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Temporal isolation
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Individuals of different species do not mate because they are active at different times of day or in different seasons
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Ecological isolation
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Individuals mate in their preferred habitat, and therefore do not meet individuals of other species with different ecological preferences
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Behavioral isolation
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Potential mates meet, but choose members of their own species
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Mechanical isolation
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Copulation is attempted, but transfer of sperm does not take place
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Post-zygotic Isolating Mechanisms
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Cross-breeding of species leads to problems post reproduction such as gametic incompatibility, zygotic mortality, hybrid in-viability, hybrid sterility, or hybrid breakdown
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Arguments for Sex
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1) Genetic Diversity
2) Resistance to effects of mutations
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Genetic Diversity
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With more recombination,and therefore (term), the species has a greater probability of being able to adapt to changes in evolutionary pressure
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Ratchet Effect
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Mutations that are deleterious that cannot be removed through asexual reproduction--the cumulative effect of these is known as this term. Eventually, mutation induced liabilities cause the loss of vigor and maybe death
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Use of both Asexual and Sexual Reproduction
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Examples: aphids and hydras; asexual reproduction is favored if near-future environment is constant, sexual reproduction is favored when environmental change is impending
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Sperm Competition
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Over time, sperm has trimmed down to bare essentials because speed is crucial
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Sperm versus Ova size
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At one time, sperm and ova were equal in size, but with ova is more "fit" the bigger it is and sperm is more "fit" the faster it is, so evolution favors this (disruptive selection)
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Trivers' Conclusions
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1) Females have a greater parental investment than males
2) This "inequity" is obviously true both before and after birth
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Reasons for less male investment
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1) C/B of greater investment for males is less
2) No guarantee offspring are males
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Epigamic element
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Refers to the differences between males and females in terms of mate selection
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Consequences of differential C/B ratio for Males versus females
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1) There is competition among males for females
2) Mistakes are most costly for females so females have to be choosier
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Epigamic Selection for males
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1) Use of strategies that help a male copulate successfully
2) Use of strategies that increase the fertilization
3) Use of strategies that decrease the fitness of competitors
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Competition results in:
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1) Low threshold
2) Dominance behavior
3) Alternative Mating Strategies
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Alternative Mating Strategies
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1) Less dominate males may coordinate displays and sneak in to mate
2) Satellite Males
3) Mimicry of females
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Satellite Males
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Solitary males hang around periphery and, when possible, sneak copulations
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Mimicry of Females
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Allows them to mingle with females
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Competition Strategies used by males to ensure offspring
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1) Protection of inseminated female
2) Being the last to copulate with female
3) Carrying the eggs
4) The use of vaginal plugs
4) Pair bonding
5) Repugnant chemical on females
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Male Behaviors
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1) Competition
2) Competition to Ensure (Strategies)
3) Competition by decreasing reproductive fitness of rival males
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Behaviors to decrease reproductive fitness of rival males
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1) Sexual interference
2) Kill or injure
3) Reasserting dominance
4) Control and defense territories
5) faking of females
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Pretending to be Female
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Mimics females so that a male "presents" his cloaca (filled with sperm) before him so that the female ignores his competition, leaving him with the only available cloaca
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Questions Females must ask:
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1) Is the male the correct species?
2) Fitness of the male genes
3) Male Parental Investment Value
4)
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Indicators of fitness of male genes
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1) high rank in dominance hierarchy
2) superior phenotype
3) responses to females "compete for me" (wins the battle)
4) Old age or handicap (indicates survivability)
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Male Parental Investment Value
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1) quality of territory (food, predators, nesting sites and shelter)
2) willingness to share
3) protection of females and offspring
4) sharing parental obligations
5) Gifts presented to females
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Benefit of eating males
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Contributes the protein to the offspring
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Monogamy
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One male for each female (rare in mammals) and used when male is needed beyond fertilization
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Polygamy
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more than one male or female for each male or female
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Polygyny
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More than one female per male
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Polyandry
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More than one male per female
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Types of Polygamy
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Polygyny and Polyandry
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Polygynandry
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Several males share several females
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Promiscuity
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multiple partners, little time spent with each
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When monogamy is adaptive:
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1) Mate guarding
2) Mate assistance
3) female enforced monogamy
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Mate guarding
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Male may guard female especially if the female remains receptive after mating or if the females are dispersed
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Mate assistance
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When males aide with parental care of offspring, such as with male djungarian hamsters who act as midwives because females are sexually receptive immediately after birth
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Extra Pair Copulations (EPC)
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copulation with a male other than the bonded male
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Advantages of EPC
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1) ensures offspring are more genetically diverse
2) beneficial if female is monogamous for male
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end on slide 67
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...
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PSYC 311: EXAM 2 PART 1