Heritability of life-history traits in a pre-transitional population

MIREIA ESPARZA,; MARTÍNEZ ABADÍAS, NEUS; TORSTEIN SJOVOLD,; GONZÁLEZ-JOSÉ, ROLANDO; MIQUEL HERNÁNDEZ,

Budapest

Congreso; 15th European Congress of the Anthropological Association; 2006

The rate of decrease of variation in a trait due to natural selection depends on how closely such trait is connected to fitness (reproductive success). Since life-history traits are more strongly associated to fitness than morphological or physiological traits, they are under stronger selection and therefore they should show lower additive genetic variance (heritability). But the results of this kind of studies are often contradictory, because the problem of separate the portion of phenotypic variance due to additive genetic variance from that due to environmental and nonadditive genetic factors. A great part of these problems stem from the close relationship between the analyzed individuals, because common shared environments influenced on fecundity and survival and may make us overestimate heritability values. A way of avoiding this problem is to use an analytical method as the "animal model", a restricted maximum-likelihood estimation that takes into account the similarity between individuals of various degrees of relatedness. In this study, variance components heritabilities of two fitness measures (individual ¦Ë and lifetime reproductive success) and five life-history traits (fecundity, age at first child, age at last child, mean interbirth interval and reproductive span) have been analyzed from pedigree data of the population of Hallstatt (Austria) by applying the ¡°animal model¡±. The pedigree has been obtained from church records corresponding to a long period before demographic transition and industrial changes (1602-1852). We also analyzed correlations between traits and fitness, and three multiple regression analysis by stepwise method were performed. Results show that fitness measures present very low heritabilities in Hallstatt¡¯s population, clearly lower than those observed for morphological traits, confirming classical evolutionary theories predictions. This might be due to the expression of cultural and environmental factors, which seemed to have a great influence in the life histories of Hallstatt inhabitants. Grant support: Wenner Gren Foundation for Anthropological Research (Gr. 7149), Spanish Ministerio de Educaci¨®n y Ciencia, MEC-FEDER (CGL2004-00903/BTE).