Life History Patterns Ch.10

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Life History Patterns Ch.10

• Life history patterns how they reproduce
• Maturity age at first reproduction
• Parity of times an organism reproduces
• Fecundity offspring per reproduction
• Mortality death rate
• Parental care

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Inverse relationship between fecundity and
parental care
high
?
Parental care
low
high
low
fecundity
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Inverse relationship between fecundity and
parental care
high
Parental care
low
high
low
fecundity
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r vs. k selection
k-selected
r-selected
Fewer offspring Slow development Long lived Good
competitors Slow dispersers Much parental
care Examples?? Trees bears
Many small offspring Rapid development Short
lived Poor competitors Fast dispersers Little
parental care Examples?? Weeds ants
r-selected opportunistic
k-selected equilibrium
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altricial vs. precocial

• Altricial helpless and featherless
• 2-10 eggs per clutch
• Precocial ready to follow parents
• 8-20 eggs per clutch
• (clutch nest of eggs)

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Reproduction
Plants Annuals lives one year Perennials
live more than one year Semelparity one
reproductive effort per lifetime Also called big
bang reproduction, programmed death i.e. agave
(century plant), yucca, salmon Iteroparity
more than one reproductive effort per
lifetime Senescence age, causes decline in
fecundity
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Mating systems

• Monogamy pair bond between one male and one
  female
• Polygamy one individual forms pair bonds with
  many others
• Polygyny male mates with more than one female
• Polyandry female mates with more than one male
• Promiscuity mate with many, no pair bonds

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Monogamy
Rare in mammals Common in Birds
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Polygyny one male with many females Common in
mammals
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Polyandry one female with many males rare
female
Since females attract mate, they are larger And
more colorful than male Wilsons phalaropes
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Promiscuity no pair bonds Lek common mating
area
Prairie Chicken
Male sage grouse
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Sexual Selection choice of one sex by another

• Sexual Dimorphism males and females look
  differently
• Color- males more brightly colored
• Ornamentation- antlers
• Size (if female larger reverse sexual
  dimorphism)
• Hamilton-Zuk Hypothesis
• More brightly colored males have less parasites
  (healthier)

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Territorial Behavior
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Calling
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Chasing
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Fighting
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Sibling Competition