Restrictive mate choice criteria cause age-specific inbreeding in female black grouse, Tetrao tetrix

Soulsbury, Carl D. and Alatalo, Rauno V. and Lebigre, Christophe and Siitari, Heli (2012) Restrictive mate choice criteria cause age-specific inbreeding in female black grouse, Tetrao tetrix. Animal Behaviour, 83 (6). pp. 1497-1503. ISSN 0003-3472

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Official URL: http://dx.doi.org/10.1016/j.anbehav.2012.03.024

Abstract

Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random
with respect to kinship. This suggests that the risks of inbreeding may be small because passive
mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk.
Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an
individual’s life span, but in the lek-breeding black grouse, inbreeding increases with female age.
To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null
models of random mate choice ranging from complete randomness to more biologically realistic mate
choice criteria and compared these to 8 years of data on inbreeding levels at four different female age
classes. We additionally tested whether mate fidelity decreased inbreeding risk. Observed inbreeding in
female age classes 1, 2 or <3 were not significantly different from random, but was approximately 3.5
times higher in female age class <4. Alternative models using mate choice criteria showed no significant
differences between observed and expected levels for any age class. Our results are in line with previous
studies on noncooperatively breeding passerine birds, which indicate that mating is random with respect
to kinship and that increased inbreeding in older females can be explained by reduced male availability
caused by restrictive mate choice criteria. We also found that individuals that switched mates significantly
increased relatedness to partners suggesting that mate fidelity may have evolved as an important
passive inbreeding avoidance mechanism.

Item Type:Article
Additional Information:Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to kinship. This suggests that the risks of inbreeding may be small because passive mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk. Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an individual’s life span, but in the lek-breeding black grouse, inbreeding increases with female age. To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null models of random mate choice ranging from complete randomness to more biologically realistic mate choice criteria and compared these to 8 years of data on inbreeding levels at four different female age classes. We additionally tested whether mate fidelity decreased inbreeding risk. Observed inbreeding in female age classes 1, 2 or <3 were not significantly different from random, but was approximately 3.5 times higher in female age class <4. Alternative models using mate choice criteria showed no significant differences between observed and expected levels for any age class. Our results are in line with previous studies on noncooperatively breeding passerine birds, which indicate that mating is random with respect to kinship and that increased inbreeding in older females can be explained by reduced male availability caused by restrictive mate choice criteria. We also found that individuals that switched mates significantly increased relatedness to partners suggesting that mate fidelity may have evolved as an important passive inbreeding avoidance mechanism.
Keywords:black grouse, inbreeding depression, kinship, lek, monogamy, polygamy
Subjects:C Biological Sciences > C120 Behavioural Biology
C Biological Sciences > C142 Reproductive Biology
C Biological Sciences > C300 Zoology
Divisions:College of Science > School of Life Sciences
ID Code:6405
Deposited By: Carl Soulsbury
Deposited On:03 Oct 2012 16:09
Last Modified:13 Mar 2013 09:15

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