Internal Fertilization

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Internal Fertilization

• WFSC 422 Ethology
• Presentation 8.1

Dr. Jane M. Packard, WFSC TAMU j-packard_at_tamu.edu
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What is internal fertilization?

• Sperm placed inside female organ (more complex
  behavior learning)
• Diverse mechanisms- divergence
• Penis-mammals
• Pedipalps- spider
• Hemipens- snake
• Cloacal contact- birds
• Spermatophore- salamander/insects

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Hypotheses- Function

• H1 optimal timing for mating is different than
  birthing
• H2 synchronize ovulation fertilization
• H3 extra care for a few large young (better able
  to survive predictable challenges)
• H4 paternity assurance for males

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Optimal timing for mating
Source Courting Trials of Life
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Optimal timing for birth
Source Arriving Trials of Life
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Polygamous Ungulates

• PC Mechanisms
• Female provides all the care
• Males compete for copulations
• UF Functions
• Rainy season migration- good food
• Large young-escape predators
• Mate guarding

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Synchronization ovulation fertilization
Source Courting Trials of Life
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Polygamous rodents

• PC Mechanisms
• Female scent attracts male
• After birth, female ovulates (3 hr)
• Multiple copulations (male leaves, female nurses)
• UF Functions
• Short interbirth interval
• Male mate guarding

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Example- Blue Footed Booby
Source Courting Trials of Life
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Parental care paternity
Source Courting Trials of Life
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Monogamous birds Blue-footed Booby

• PC Mechanisms
• Lift blue feet (in nest colony)
• Head tossing at scrape stick placing
• Mount, brief cloacal contact
• UF Functions
• Bi-parental care more effective
• Male paternity certainty

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Example- Hanging Fly
Source Arriving Trials of Life
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Insects- nuptial gift

• PC Mechanisms
• Male Hanging Fly catches insect gift
• Female takes and eats prey
• Male clasps copulates 20 min
• Struggle for remaining prey
• UF Functions
• Female nutrition better eggs
• Male safety mate guarding

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SUMMARY function (example)

• H1 Optimal time for mating is different than
  birthing (e.g. wildebeest/gazelle
• H2 Synchronize ovulation fertilization (e.g.
  hamster)
• H3 Extra care for a few large young (e.g. booby)
• H4 Paternity assurance for males (e.g. booby,
  hanging fly)

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Action Items

• Do answers for Q8.1, Q8.2
• Search Google Scholar for internal
  fertilization
• Search Animal Behavior for copulation
• Post examples and sources on WebCT Discussion for
  Unit 8