Effects of inbreeding on male function and self‐fertility in the partially self‐incompatible herb Campanula rapunculoides (Campanulaceae)

Abstract

We examined the effect of inbreeding on fitness (through both male and female functions) and changes in self-fertility in the partially self-incompatible species Campanula rapunculoides. Individuals in natural populations of C. rapunculoides varied extensively in their strength of self-incompatibility (SI). We crossed 11 individuals that differed in their strength of SI to generate families with four levels of inbreeding (f = 0.0, 0.25, 0.5, and 0.75). Progeny were scored for three traits related to male fitness and for outcrossed and selfed seed production. Analyses of variance revealed significant inbreeding depression for the three male traits and seed set. Families with strong or weak SI differed in their response to inbreeding. Families with weak SI had lower levels of inbreeding depression for most traits than families with strong SI, but strong SI families had a greater increase in selfed seed set, but not self-fertility, with inbreeding. Finally, we found evidence of a significant linear response to inbreeding for all three male reproductive traits and outcrossed seed, indicating that inbreeding depression was primarily caused by partially or fully recessive deleterious alleles. Variation in genetic load was associated with variation in self-fertility, a finding that suggests an evolutionary role for partial self-fertility in natural populations of C. rapunculoides.

Parental genetic distance and patterns in nonrandom mating and seed yield in predominately selfing Arabidopsis thaliana

“…For example, Waser et al studied seed yield in populations of Ipomopsis aggregata , a predominately outcrossing plant with late-acting self-incompatibility, and showed that maternal variance in seed yield ranges between 12 and 35 % (Waser et al 1995 ). Similarly, Good-Avila and Stephenson show that in the partially self-incompatible C. rapunculoides , maternal variation accounts for 36 % of the phenotypic variance in seed yield (Good-Avila et al 2003 ). Lipow and Wyatt show that maternal effect accounts for between 20.5 and 37.1 % of the phenotypic variance in seed yield in the largely outcrossing A. incarnate (Lipow and Wyatt 1999 ).…”

“…Maternal roles in differential reproductive success have also been demonstrated using different experimental strategies. For example, diallel analysis verifies significant maternal variation in seed yield in Ipomopsis aggregate, Companula rapunculoides, Asclepias incarnate and Leavenworthia crassa (Waser et al 1995 ; Lyons 1996 ; Lipow and Wyatt 1999 ; Good-Avila et al 2003 ). More direct manipulations that alter the conditions of maternal tissues, such as water, nutrients or age, verify the role of maternal tissues in differential mating [e.g.…”

Inbreeding depression in an autotetraploid herb: a three cohort field study

“…Inbreeding depression for cumulative fitness was very high, with inbred individuals having on average only 6% of the fitness of outcross plants in three separate annual cohorts. This number may even be an overestimate, as male fitness was not measured and often declines with inbreeding (Carr & Dudash, 1997; Good‐Avila et al ., 2003; Hayes et al ., 2005a). Inbreeding depression is the result of the expression of recessive deleterious alleles following inbreeding (reviewed in Charlesworth & Charlesworth, 1999; Carr & Dudash, 2003).…”

Post-pollination hybridization barriers in Nicotiana section Alatae

“…If pollen from outcrossing species has evolved to compete in matings where there is parental conflict, the pollen may have evolved competitive traits that pollen from inbreeding species have not. For example, a study examining the effects of male fertility in Campanula rapunculoides, a species with individuals ranging from SC to strongly SI, Good-Avila et al (2003), found that inbreeding negatively affected pollen performance. In N. plumbaginifolia, we found a significant heterospecific effect on SS in general and in some crosses.…”