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15 Dec 2010
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Lecture #4
Slide3:
-life history: is an organisms lifetime pattern of growth, development, and reproduction
involves adaptations ( physiological, morphological, adaptations to environment etc)
-an organisms decisions are going to be a balance between the costs and benefits
Slide 4:
-as soon as you put energy into one aspect, then it comes at a cost of putting energy into
another
e.g. putting energy into reproduction, cost is growth ( they are smaller) - why males are
usually bigger
Slide 5:
-sexual reproduction: fusion of haploid egg and sperm to form diploid zygote
major source of genetic variation due to the recombination of chromosomes during
gamete production
-asexual reproduction produces offspring without fusion of egg and gamete
Slide 6:
- modes of asexual reproduction
rhizomes: strawberry plants
splitting in two : paramecium
budding: hydra
parthenogenesis: aphids
-organisms that rely on heavily on asexual reproduction can revert to sexual reproduction
usually due to environmental change
e.g. hydra- sexual reprod
pg. 2
Slide 1:
Asexual reproduction:
-costs:
low genetic variability in the population
maybe unable to adapt to a change in environmental conditions
-benefits have to outweigh the costs
Slide 2:
Sexual Reproduction:
-costs:
parents only contribute one half of their genes
specialized reproductive organs
energetically expensive
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expense of reproduction not equally shared between parents
Slide3:
-hermaphroditic: organisms possess both male and female organs
Slide 5:
-advantage:
genetic variability
pg. 3
Slide 2:
-Parents cooperate to raise young
Increased survival of young and parents’ genes
-But…one of the parents may cheat
To increase fitness by producing more offspring
Slide3:
-Polygamy…. Two or more mates ( pair bonds exist)
Individual having multiple mates is generally not involved in caring for young
Slide 4:
-Sexual selection is a subset of natural selection
-Sexual dimorphism: two sexes differ in body size, ornamentation, and color
Slide 5:
-Intrasexual selection involves male to male competition
Large size, aggressiveness, antlers, horns
Pg. 4
Slide 1:
-What does tail size imply about the individual :
-Secondary…. Superiority
in choosing a mate with large tail feathers ( bright plumage), a female is choosing
the most fit
Slide 2: Female Choice
-The driving force…. Selection by females
-Proposed hypothesis: health vs. disease
Slide3:
- Male investment is elaborate …. E.g. foraging, defense
-Green sword tail ; some of them have really long swords
Slide 4:
-Females preferred males with longer swords ( conclude that long swords enhance
mating success increase in reproduction, & increase in fitness)
Slide 5:
-As the sword length increases, the time spent increases
Slide 6:
-In some cases, researchers experimented by shortening the sword
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Document Summary

Slide3: life history: is an organism"s lifetime pattern of growth, development, and reproduction. involves adaptations ( physiological, morphological, adaptations to environment etc) an organisms decisions are going to be a balance between the costs and benefits. Slide 5: sexual reproduction: fusion of haploid egg and sperm to form diploid zygote. major source of genetic variation due to the recombination of chromosomes during gamete production asexual reproduction produces offspring without fusion of egg and gamete. parthenogenesis: aphids organisms that rely on heavily on asexual reproduction can revert to sexual reproduction. maybe unable to adapt to a change in environmental conditions benefits have to outweigh the costs. parents only contribute one half of their genes. expense of reproduction not equally shared between parents. Slide3: hermaphroditic: organisms possess both male and female organs. increased survival of young and parents" genes. to increase fitness by producing more offspring. Two or more mates ( pair bonds exist)

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