Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo...
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![Page 1: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/1.jpg)
Fluctuating asymmetry and fitness in pied flycatchers
Leif Christian Stige – University of Oslo([email protected])
Courtship, nest box 248
(he succeded and she laid 7 eggs)
![Page 2: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/2.jpg)
Fluctuating asymmetry (FA)
- small, random departures from perfect symmetry
e.g. ear lengths:
FA = |L-R|
R L
ASYMMETRY:
(FLUCTUATING asymmetry: L-R values ’fluctuate’ between individuals in the population – the asymmetry is not fixed)
![Page 3: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/3.jpg)
Developmental Stability
- the precision of growth of a given genotype in a given environment
- refers to the ability to buffer growth against ’developmental noise’
e.g. growth trajectories of individuals in a clone under exactlyequal environmental conditions:
random’noise’
Siz
e
Age
A. Unstable B. Stable
random’noise’
Siz
eAge
![Page 4: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/4.jpg)
FA and Developmental Stability
- random developmental noise acts on each side, leading tosmall differences between sides
- the size of this difference, FA, reflects the developmental stability
- the two sides of a bilaterally symmetric trait (e.g. ear lengths)can be assumed to have developed in the same environment and with the same genetic basis
EQUAL GENES
EQUAL ENVIRONMENT
RANDOM NOISE
RANDOM NOISE
![Page 5: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/5.jpg)
FA and fitness
Developmental stability
FA FitnessFUNCTION - SYMMETRYFA AS SIGNAL
FUNCTION –’OPTIMAL’ PHENOTYPE
Genes + Environment
GENETIC + ENVIRONMENTAL
’QUALITY’
![Page 6: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/6.jpg)
Empirical evidence of a FA-fitness relation
Møller (1997, Am.Nat. 149:916-932)
- ’vote-counting’ (# studies): FA-growth: 10 yes: 2 noFA-fecundity: 16 yes: 1 noFA-survival: 19 yes: 2 no
Leung and Forbes (1996, Ecoscience 3:400-413)- meta-analysis 61species: mean r (FA – fitness related traits) = -0.26 (SE 0.06) ( i.e. FA explains 6.7% of variation in fitness)- no differences between functional/non-functional, or sexually selected/not sexually selected traits
Møller (1999, Ecology Letters 2:149-156)
- meta-analysis, weighted r [95 % CI]: FA-growth: -0.16 [-0.11, -0,21] n = 10 spp
FA-fecundity: -0.34 [-0.31, -0.37] n = 14 sppFA-survival: -0.24 [-0.22, -0.26] n = 23 spp
Clarke (1998, Am.Nat 152:762-766)- re-evaluated the data cited by Møller (1997): ”a significant proportion of the data (>50%) reported by Møller as supporting a positive relationship between developmental stability and various fitness components fail to do so, ...”
![Page 7: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/7.jpg)
Pied Flycatchers
• Migratory – breeds May-June Norway• Prefer nest boxes• Mainly monogamous - 1/5 of breeding males bigamous• Females build nests and incubate, both parents feed the young
Our study system
• Sørkedalen, Oslo, 2000 and 2001 • Population of 70-75 pairs each year• Totally 108 males and 125 females• Birds caught, measured and observed throughout breeding season
![Page 8: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/8.jpg)
Fitness measures
• Arrival date• Pairing status
(males: bigamous/monogamous/unpaired, females: primary/secondary)
• Time until pairing(from arrival, corrected for arrival date)
• Time until egg laying(from pairing, corrected for pairing date)
• Number of eggs laid(in primary nest, corrected for pairing date)
• Hatching success• Fledging success• Offspring weight• Total number of fledglings• Return rate
![Page 9: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/9.jpg)
FA measures
Prim 1-2
Prim 2-3
Tail 1-2
Tail 2
Tail 1
![Page 10: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/10.jpg)
Spearman Correlation Coeff. with 95% bootstrap conf. limits
FA - FITNESS CORRELATIONS
-1.0 -0.5 0.0 0.5 1.0
ARRIVAL DATE
PAIRING STATUS
TIME UNTIL PAIRING
TIME UNTIL EGG LAYING
NUMBER OF EGGS LAID
HATCHING SUCCESS
FLEDGING SUCCESS
OFFSPRING WEIGHT
TOTAL FLEDGLING PROD.
RETURN RATE
(bigamous/monog./unpaired male, prim./sec. female)
(from arrival, corrected for arrival date)
(from pairing, corr. for pairing date)
(in primary nest, corr. for pairing date)
positive
negative
positive
positive
negative
negative
negative
negative
negative
negative
(n = 99)
(n = 96)
(n = 89)
(n = 90)
(n = 90)
(n = 90)
(n = 81)
(n = 77)
(n = 88)
(n = 99)
(n = 122)
(n = 122)
(n = 122)
(n = 122)
(n = 122)
(n = 108)
(n = 98)
(n = 108)
(n = 122)
Expectedrelation
femalesmales
RESULTS: FA – fitness correlations
![Page 11: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/11.jpg)
Conclusion
The results do not support the hypothesis that fluctuating asymmetry is negatively correlated with fitness in the investigated population of pied flycatchers
![Page 12: Fluctuating asymmetry and fitness in pied flycatchers Leif Christian Stige – University of Oslo (l.c.stige@bio.uio.no) Courtship, nest box 248 (he succeded.](https://reader036.fdocuments.net/reader036/viewer/2022070413/5697bfdf1a28abf838cb2eec/html5/thumbnails/12.jpg)
Why no correlation?
• The relation between FA and fitness may be indirect, and FA may be a poor indicator of developmental instability - trying to estimate a variance with two data points (high sampling error):
- but averaging across traits (and years) increases precision
Size
Age
FA Developmental instability
• The relation may only be evident in tough conditions
• High measurement error reduces precision (size of error variance 12-71% of inter-individual variation in FA)
• There may be no relation between FA and fitness in pied flycatchers?