Inbreeding depression influences lifetime breeding success in a wild population of red deer (Cervus elaphus)

Abstract

Evolutionary and conservation biologists have a long-standing interest in the consequences of inbreeding. It is generally recognized that inbred individuals may experience reduced fitness or inbreeding depression. By the same token, relatively outbred individuals can have greater than average fitness, i.e. heterosis. However, nearly all of the empirical evidence for inbreeding depression comes from laboratory or domestic species. Inbreeding depression and heterosis are difficult to detect in natural populations due to the difficulties in establishing pedigrees. An alternative method is to correlate heterozygosity, which is measured using genetic markers, with a trait related to fitness. The typically studied traits, such as juvenile survival and growth rates, either cover only early life or are weakly correlated with lifetime breeding success (LBS). In this paper we show that heterozygosity is positively associated with male and female adult LBS in a wild population of red deer (Cervus elaphus) on the Isle of Rum, Scotland. To the authors' knowledge, this is the first time that inbreeding depression and/or heterosis have been detected for a trait highly correlated with overall fitness in both sexes in a wild population.

The effects of inbreeding, genetic dissimilarity and phenotype on male reproductive success in a dioecious plant

“…(a) Inbreeding depression in siring success and avoidance of inbreeding While the impact of inbreeding on male reproductive success was shown for some animal species [18,30,32], this study provides the first direct experimental evidence in plants that inbreeding directly and strongly decreased male fitness (siring success) under natural conditions. Previous studies reported inbreeding depression for in vitro pollen germination [26,28] and pollen performance in controlled pollinations [29], including S. latifolia [15].…”

“…A key question that has been understudied, owing to limited access to genetic markers in the past, is whether the high levels of inbreeding and relatedness that often characterize plant populations also impact pollen fate. Higher fitness of outbred individuals is a central prediction of evolutionary biology [32], and inbreeding and relatedness are expected to have major effects on the number, quality and genetic variability of offspring [4]. Here, we examined whether inbreeding, relatedness, plant phenotype and pollen dispersal jointly affected male fitness in an experimental population in which the level of inbreeding was experimentally controlled and spatial structure was randomized and accounted for statistically.…”

Direct and indirect causal effects of heterozygosity on fitness-related traits in Alpine ibex

“…The detrimental effects of inbreeding were first summarized by Darwin [6]. Since then, evidence of the negative impact of inbreeding on fitness and viability at both individual and population levels has accumulated [1,[7][8][9][10]. The expression of recessive deleterious mutations has been indicated as the main cause of inbreeding depression [11 -13].…”

Inbreeding reveals stronger net selection on Drosophila melanogaster males: implications for mutation load and the fitness of sexual females

“…Where compared, however, the majority of results point to males as the more fragile sex. For example, in wild populations a higher sensitivity to inbreeding for males has been suggested for red deer (Slate et al, 2000), although in an isolated population of song sparrows ID for lifetime reproductive success was greater for females (Keller, 1998). In the laboratory, male flour beetles experienced stronger ID than females did (Pray and Goodnight, 1995), and male virility in Drosophila, an important component of male fitness, appears to be more strongly affected by inbreeding than female fertility (Brittnacher, 1981).…”