Growth and fecundity of colonizing hybrid Raphanus populations are environmentally dependent

Abstract

Premise Hybrid gene pools harbor more genetic variation than progenitor populations. Thus, we expect hybrid populations to exhibit more dynamic evolutionary responses to environmental variation. We ask how environmental variation experienced by adapted and transplanted populations influence the success of late‐generation hybrid populations during invasion. Methods For four generations, 20 wild (Raphanus raphanistrum) and 20 hybrid radish (R. sativus × R. raphanistrum) plant populations evolved under experimentally manipulated moisture conditions (dry, wet, control‐sheltered, or control‐unsheltered plots; i.e., evolutionary environment) in old fields near Toronto, Canada. We planted advanced‐generation wild and hybrid radishes in sheltered plots and exposed them to either an evolutionary or a novel watering environment. To determine how soil moisture would influence invasion success, we compared the phenotype and fecundity of plants grown in these various environments. Results Hybridization produced larger plants. In wet environments, hybrid seedlings emerged more frequently and expressed higher photosynthetic activity. Low‐moisture, novel conditions delayed and reduced seedling emergence frequency. Hybrid plants and those that evolved under relatively wet environments exhibited higher aboveground biomass. Hybrid plants from control‐sheltered plots colonizing novel moisture environments were more fecund than comparable wild plants. Conclusions Dry environments are less likely than other evolutionary environments to contribute colonists. However, relatively wet locations support the evolution of relatively fecund plants, especially crop‐wild hybrid populations. Thus, our results provide a strong mechanistic explanation for variation in the relative success of crop‐wild hybrids among study locations and a new standard for studies that assess the risk of crop‐wild hybridization events.

The role of intraspecific crop-weed hybridization in the evolution of weediness and invasiveness: cultivated and weedy radish (Raphanus sativusL.) as a case study

“…These studies allow the acceleration of natural processes in order to explore local ecological scenarios under which the fitness of crop-weed hybrids may equal or exceed the fitness of their parents, favoring the persistence of crop alleles in wild/weedy populations and consequently enhancing weediness and invasiveness (Mercer et al, 2006;Campbell et al, 2009). The Raphanus complex, formed by the cultivated species R. sativus, their feral conspecific forms and their weedy related species R. raphanistrum, is a well-established model system that has been widely used to evaluate the ecological and evolutionary consequences of interspecific crop-weed hybridization (Campbell et al, 2006(Campbell et al, , 2009Hegde et al, 2006;Campbell and Snow, 2007;Ridley et al, 2008;Snow et al, 2010;Hovick et al, 2012;Shukla et al, 2020Shukla et al, , 2021. Evolutionary experiments are often necessary for the observation and characterization of evolutionary changes occurring as a consequence of natural crop-wild/weed hybridization processes (Ellstrand et al, 2010;Hovick and Whitney, 2014).…”

Demographic responses of hybridizing cinquefoils to changing climate in the Colorado Rocky Mountains

“…Additionally, hybrids with transgressive traits have been shown to tolerate extreme environments that could become more prevalent with climate change (e.g., Helianthus hybrids adapted to salt marshes; Lexer, Welch, et al, 2003). However, hybrid performance (relative to parents) under novel conditions may depend on the environments in which they evolve (Shukla et al, 2021), and it is unclear how these insights on aspects of hybrid performance translate into population growth of hybrids across environments.…”

The role of intraspecific crop–weed hybridization in the evolution of weediness and invasiveness: Cultivated and weedy radish (Raphanus sativus) as a case study

“…These studies allow the acceleration of natural processes to evaluate local ecological scenarios in which the fitness of crop-weed hybrids may equal or exceed the fitness of their parents, favoring the persistence of crop alleles in wild/weedy populations and consequently enhancing weediness and invasiveness (Mercer et al, 2006;Campbell et al, 2009). The Raphanus complex, formed by the cultivated species R. sativus, their weedy conspecific forms, and their related weed species, R. raphanistrum, is a well-established model system for evaluating the ecological and evolutionary consequences of interspecific crop-weed hybridization (Campbell et al, 2006(Campbell et al, , 2009Hegde et al, 2006;Campbell and Snow, 2007;Ridley et al, 2008;Snow et al, 2010;Hovick et al, 2012;Shukla et al, 2020Shukla et al, , 2021. We compared the time to flowering, survival to maturity, plant biomass, and reproductive components of bidirectional firstgeneration crop-weed hybrids in relation to both parents under two contrasting ecological environments, agrestal (wheat cultivation, fertilization, weeding) and ruderal (human-disturbed uncultivated area) over 2 years.…”