Mothers baby, fathers maybe: Occurrence and frequency of multiple paternities in the European wild boar

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1 Mothers baby, fathers maybe: Occurrence and frequency of multiple paternities in the European wild boar Christian Glensk 1 Björn Müller 1, Oliver Keuling 2, Jörg Brün 1 1 Institute of Evolutionary Biology and Ecology, University of Bonn 2 Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover

2 Problem description Increasing stock of wild boars Current knowledge about social behavior and biology are based on the much lower population densities in the second half of the last century Precise knowledge of mating behavior is difficult to obtain, because of complex and expensive long term observations Is there a changing in mating behavior? 2

3 State of knowledge until 2012 Delgado et al (2007): multiple paternities statistically not unlikely, but rare Poteaux et al (2009): first evidence in a european population in 2 of 21 litters 3

4 Objective of this study Is there an evidence of multiple paternities in a german population of wild boars or is it just a local phenomenon of other countries? If so, how often does this phenomenon occure? 4

5 Study area 5

6 mean number of fetuses Genetical analysis 8 microsatellites with a mean information content (PIC, Botstein et al. 1980) of uteri with a total of 213 fetuses (mean 6.1 per uterus) 10 8 n=12 n=16 n= < > 2 age of mother 6

7 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

8 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

9 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

10 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

11 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

12 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

13 Reconstruction of paternal genotypes Based on the data, paternal genotypes where reconstructed 1. MS 2. MS 3. MS 4. MS 5. MS 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele 1. allele 2. allele Mother Fetus Fetus Fetus Father

14 Reconstruction of paternal genotypes 45 putative fathers Only minimum number of neccessary genotypes Multiple paternities in 8 of 35 uteri 14

15 Used software Cervus Colony Pedigree pairwise maximum-likelihood overall maximumlikelihood Cluster of full-sibs/halfsibs two most likely fathers polygamous pairwise likelihood ratio given paternal genotypes unknown paternal genotypes 15

16 Results Cervus In 8 uteri multiple paternities Taking account of the allele frequency Cervus calculated, 14 uteri contain multiple paternities Cluster of half-sibs in this 8 uteri are identical with the observed ones 16

17 Results Colony Multiple paternities in the same 8 uteri 6 uteri with 2, and two uteri with 3 different fathers Cluster of half-sibs identical with previous analyses 17

18 Results Colony Calculation without paternal genotypes leads to an assumption of 39 fathers (reconstruction: 45) Multiple paternities in the same 8 uteri, but: In one case 3 instead of 2 different fathers In one case 4 instead of 3 fathers Additionally found multiple paternities in 3 more uteri 18

19 Results Pedigree 25 groups of full-sibs 10 groups of half-sibs Multiple paternities in 7 of 8 uteri calculated by Cervus & Colony but: One new multiple paternity with 3 different fathers In one case 4 instead of 3 fathers (like Colony) 19

20 Summary Physical evidence of multiple paternities in at least 8 uteri (about 23%) Taking account into different allele frequencies, a higher amount can not be excluded Cervus Colony Pedigree Putative fathers 45 45/39 45 Multiple fatherships /

21 Occurrence of multiple paternities => More fetuses in older (p 2 =0.01; p 2 =0.032) and heavier (p 2 =0,0004) females => No correlation between female s age and multiple paternities (p 2 =0.57) => Tendency, but no significant correlation between litter size and multiple paternities (p 2 =0.08) 21

22 Occurrence and frequency of multiple paternities in Europe Costa et al (2012): Evidence in 5 of 15 uteri (33%) Say et al (2012): Evidence in 50% of the samples Our data set: Evidence in at least 8 of 35 uteri (23%) 22

23 Occurrence and frequency of multiple paternities in Europe A current mating behavior? => multiple paternities in every fourth to second litter! No local phenomenon 23

24 Occurrence and frequency of multiple paternities in Europe 24

25 Benefits Increase of fitness? Two fathers in one litter would increase only the fitness of the second father -> no increase of mother s fitness Another, additional ovulation after the first copulation would increase number of siblings -> increase of mother s fitness 25

26 Other reasons Female protect themself against infertility of mating male Not able to assess fertility of male Cryptic female choice Sperm reservoir allows selection and release of competent spermatozoa 26

27 Other reasons sexual harassment A lack of old dominant males may lead to change in social structure Less dominant males could copulate because sounders are not dominated by a single male 27

28 Conclusion All over Europe Different results -> based on different hunting methods? Reasons for multiple paternities still not clear But seems to be a common behavior 28

29 Thank you for your attention! Irina Muschik