Intraspecific Genetic Variation Underlying Postmating Reproductive Barriers between Species in the Wild Tomato Clade (Solanum sect. Lycopersicon)

Abstract

A goal of speciation genetics is to understand how the genetic components underlying interspecific reproductive barriers originate within species. Unilateral incompatibility (UI) is a postmating prezygotic barrier in which pollen rejection in the female reproductive tract (style) occurs in only one direction of an interspecific cross. Natural variation in the strength of UI has been observed among populations within species in the wild tomato clade. In some cases, molecular loci underlying self-incompatibility (SI) are associated with this variation in UI, but the mechanistic connection between these intra- and inter-specific pollen rejection behaviors is poorly understood in most instances. We generated an F2 population between SI and SC genotypes of a single species, Solanum pennellii, to examine the genetic basis of intraspecific variation in UI against other species, and to determine whether loci underlying SI are genetically associated with this variation. We found that F2 individuals vary in the rate at which UI rejection occurs. One large effect QTL detected for this trait co-localized with the SI-determining S-locus. Moreover, individuals that expressed S-RNase—the S-locus protein involved in SI pollen rejection—in their styles had much more rapid UI responses compared with those without S-RNase protein. Our analysis shows that intraspecific variation at mate choice loci—in this case at loci that prevent self-fertilization—can contribute to variation in the expression of interspecific isolation, including postmating prezygotic barriers. Understanding the nature of such intraspecific variation can provide insight into the accumulation of these barriers between diverging lineages.

Intraspecific Genetic Variation for Behavioral Isolation Loci in Drosophila

“…These findings add to previous work (e.g., [17,18]) that demonstrate that loci for behavioral isolation between species may have a high amount of variation within species, where different loci are the primary contributors to behavioral isolation in different populations. Since female D. mauritiana consistently display rejection toward all strains of D. simulans that we tested, our genetic mapping results suggest that the male behavioral traits that isolate these closely related species may occur through different means.…”

“…Similarly, courtship song has been shown to vary within (e.g., [13]) and between (e.g., [14]) species. Within-species variation can influence the potential for incipient speciation between populations [15,16], as well as the strength of isolation between different populations of a species with a sister species [17,18]. While the genetic basis of behavioral variation within a species could reasonably be assumed to also contribute to behavioral isolation between species, there is some evidence that the underlying basis of these two traits is instead genetically distinct [19][20][21], but more studies are needed.…”

Advanced biotechnological strategies towards the development of crops with enhanced micronutrient content

“…Moreover, increasing the concentration of micronutrients via the application of different inorganic fertilizers is quite expensive for the farmers. Besides, excessive application of such chemical fertilizers in the agricultural field is often associated with a reduction in thebiodiversity and enhanced environmental pollution (Jewell et al 2020 ).Within this context,development of crops through genetic improvement is considered as more effective approach. Recent advancements on the identification and characterization of genes associated with micronutrient uptake and accumulation haveopenedup an important avenue to combat the challenge of global micronutrient requirements.…”

Agronomic biofortification of food crops: An emerging opportunity for global food and nutritional security

“…Although the use of inorganic fertilizers is a cost-effective, simple, and quick method of agronomic biofortification, it has several drawbacks. The main downside is related to the misuse of inorganic fertilizers, which has negative environmental consequences such as water pollution, algal bloom, and biodiversity loss in various natural systems (Zhang et al, 2019;Schier et al, 2019;Jewell et al, 2020). Moreover, these are expensive, if considered for bulk application to soil, and labor-intensive to apply, which may further impoverish farmers with small holdings.…”