Annual Reproductive Success = Fertilization Success X Offspring Survival - PowerPoint PPT Presentation

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Annual Reproductive Success = Fertilization Success X Offspring Survival

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Title: PowerPoint Presentation Author: Jeff Lane Last modified by: boutin_lab Created Date: 11/6/2003 5:03:30 AM Document presentation format: On-screen Show – PowerPoint PPT presentation

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Title: Annual Reproductive Success = Fertilization Success X Offspring Survival


1
  • Annual Reproductive Success
    Fertilization Success X Offspring Survival

Male
Female
Previous difficulty in assigning paternity
2
Previous work on mammalian male reproductive
success
Large mammals Pronounced sexual dimorphism (size
and weaponry) Harem polygyny
  • Variation in Reproductive Success
  • Lifetime 0-24 calves (n13)
  • Annual 50 of males sire 0 calves lt5 sire gt4

3
  • Exclusive territories
  • Minimal sexual dimorphism (Male/Female mass ratio
    1.05-1.11)
  • Asynchronous estrus
  • Harem defense
  • Pronounced sexual dimorphism (Male/Female mass
    ratio 1.70)

4
  • Hypothesis
  • Reproductive success in male red squirrels will
    be unrelated to size. Rather it will be driven
    by
  • Age
  • Mobility
  • Resource Availability
  • Inbreeding Avoidance

5
The Players
  • 74 Males and 57 Reproductive Females on 2 plots
    (KLOO and SUL)
  • Seasonal OSR 1.3

6
Methodology
  • Radio-collared females
  • Behavioural monitoring of mating chases
  • Time
  • Male/female behaviour
  • Male ID (attending and copulating)
  • Morphological measurements
  • Data set
  • Age
  • Relatedness

7
Squirrel Mating at Kluane 2003
  • February 19 - May 2
  • 49 (usable) mating chases observed
  • 0-3 Estrus bouts/day
  • Number of males/chase
  • 10.4 2.4 (N 19 Range 6-14)

8
Mating Success
  • Male
  • KLOO 3.2 2.3 copulations/male
  • SUL 4.5 2.6 copulations/male
  • Female
  • KLOO 5.9 3.2 copulations/female
  • SUL 8.5 2.3 copulations/female
  • Proportion of males in chase receiving a
    copulation 0.77 0.19 (N 41)

9
Variation in copulatory success
10
Variation in chase attendance
11
R2 0.7 P lt.001
12
  • Hypothesis
  • Reproductive success in male red squirrels will
    be unrelated to size. Rather it will be driven
    by
  • Age
  • Mobility
  • Resource Availability
  • Inbreeding Avoidance

13
n/s
14
  • Hypothesis
  • Reproductive success in male red squirrels will
    be unrelated to size. Rather it will be driven
    by
  • Age
  • Mobility
  • Resource Availability
  • Inbreeding Avoidance

15
Hypothesis Age will affect male reproductive
success
  • Prediction Older males will have a higher
    reproductive success than younger males
  • Have more experience
  • Selected for by females
  • Higher quality genome
  • Confounding issues
  • Independent Variable Age
  • Dependent Variable Mating Success

16
Linear Increase
Senescence
Plateau
17
Age Distribution
  • Mean Age 3.8 2.0 (N44 Range 1-8)

18
n/s
19
Tentative Conclusions
  • Mating success largely unrelated to age or mass
  • Driven by reproductive effort
  • Factors affecting chase attendance
  • Sex ratio of neighbours
  • Inbreeding avoidance
  • Energetics
  • Behavioural attributes (e.g exploration forays)
  • Factors affecting fertilization success
  • Sperm competition
  • Behavioural attributes (e.g. mate guarding)

20
Future Directions
  • Paternity (Coltman/Gunn)
  • Actual Reproductive Success
  • Relatedness (Inbreeding)
  • Sperm Competition
  • Energetics (Humphries)
  • Costs of reproduction for males
  • Effect of resources
  • Endocrinology (Boonstra)
  • Condition
  • Immunocompetence
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