Projects

1. The mating system of red squirrels at Kluane and the correlates of male mating success

2. Energetics of reproduction in male red squirrels

3. Reciprocal effects of physiological condition and reproductive success

4. Sperm competition and the correlates of male siring success

5. Inbreeding avoidance

Project 1: The mating system of red squirrels at Kluane and the correlates of male mating success

Objectives

• Define the mating system of red squirrels at Kluane

• Determine the correlates of male mating success

Mating

• 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)

Chase attendants Successful mates

024681012141618

0 1 2 3 4 5 6 7 8 9 10 11 12

Number of Mates/Chases

Num

ber

of M

ales

CopulationChase

0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13

Chases Attended

Cop

ulat

ions

Atta

ined

R2 = 0.7; P <.001

0

2

4

6

8

10

12

0 500 1000 1500 2000 2500 3000 3500 4000

Total Distance (m)

Co

pu

lati

on

s 2

00

3

Males that traveled further during the mating season had a higher mating success

Conclusions

• Scramble competition polygynandry• Mating success largely driven by mating

effort• To Do:

– Pre-estrous mate searching• General• Specific females

• Behaviour publication incorporating– Mating system– Search effort– Copulatory Success

1992 1:10 000

Project 2: Energetics of reproduction in male red squirrels

Collaborators: Murray Humphries, John Speakman, Dave

Coltman

Objectives

• Measure the costs of reproduction to male red squirrels

• Determine the differential costs of reproduction to males with variable mating effort

• Do males with greater energetic resources invest more in the mating system?

Progress to date

• 20 FMRs (2004)

• 10 males in mating chases/10 males not

• Blood being analyzed in Aberdeen

• Cone count indices of middens (2003 and 2004)

-1

0

1

2

3

4

5

6

7

8

Adult Male Adult Female Juv Male Juv Female

Sex/Age Class

Mid

de

n Q

ua

lity

Sc

ore

Adult males have more cones over winter than all other age/sex classes

Conclusions

• Adult males cache more than adult females• High variability in cache index for individual males• High variability in mating effort of males• To Do:

– Analyze FMR data– Compare cache indices to mating effort and ultimate

reproductive success

• Physiology or Ecology publication incorporating– Mating season energetics– Cache indices– Copulatory Success

Project 3: Reciprocal interactions of physiological condition and reproductive success

Collaborators: Rudy Boonstra, Dave Coltman

Objectives

• Determine how the physiological condition of male red squirrels influences their reproductive success

• Determine how variable reproductive success influences a male’s physiological condition

Hypothalamus

Pituitary

Adrenals

Blood

CRF +

ACTH

Cortisol

Negative Feedback Under Acute Stress

Adapted from Boonstra et al. 1998

Energy Mobilization

Growth Suppression

Immune Suppression

Digestive Suppression

Reproductive Suppression

Stress

BASE sample and ACTH Injection

Sample (P120)

• BASE Sample:

• Basic hematological properties

• Baseline cortisol level

Sample (P60)

Sample (P30)

• ACTH Injection:

• Stimulate Stress Response

• Map changes in plasma cortisol over 120 min

30 min 60 min30 min

Injection Sample

4 d

• Sample (~ 100µL) at day 4

• Differential agglutination indicates humoral immune response

Conclusions

• 24-26 males before and after mating season

• Tissue samples from adults/offspring

• To Do:– Hormone and immune assays (December)– Paternity analyses

• Publication incorporating– Condition data – Cache indices/Body condition– Reproductive success

Project 4: Sperm competition and the correlates of male siring success

Collaborators: Melissa Gunn, Dave Coltman

Objectives

• Determine the direction (if any) of sperm precedence in red squirrels

• How does the testes size of a male influence his siring success?

Paternity Data

• Nine mating chases

• Multiple paternity (1-3 fathers/litter)

• First male/Last male precedence not apparent

Conclusions

• 75 Mating chases

• Offspring from 2003, 2004

• Testes sizes from 2004

• Publication incorporating:– Copulation order, genetic sires, multiple paternity,

testes sizes, age – Good genes/Compatible genes?

Project 5: Inbreeding avoidance in red squirrels

Collaborators: Melissa Gunn, Dave Coltman

Objectives

• Map spatial degree of relatedness

• Assess potential mechanisms of inbreeding avoidance in red squirrels: pre- and post-copulatory

Conclusions

• Pedigree with matrilines

• Copulation and sire identities

• To Do:– Paternal relatedness

• Publication incorporating:– Pre-copulation mechanisms:

• Mating chase distances by males• Avoidance of kin

– Post-copulation mechanisms?

Next steps

1. Agnes2. Heritabilities of “mating effort”

(w/ Andrew, Dave)

3. Larger scale inbreeding avoidance analysis (w/ Mark)

4. Scat analyses:• Genetics• Endocrinology• FECs5. Parasite treatment