Water and nutrient availability exert selection on reproductive phenology

Abstract

Premise: Global change has changed resource availability to plants, which could shift the adaptive landscape. We hypothesize that novel water and nutrient availability combinations alter patterns of natural selection on reproductive phenology in Boechera stricta (Brassicaceae) and influence the evolution of local adaptation. Methods: We conducted a multifactorial greenhouse study using 35 accessions of B. stricta sourced from a broad elevational gradient in the Rocky Mountains. We exposed full siblings to three soil water and two nutrient availability treatment levels, reflecting current and projected future conditions. In addition, we quantified fitness (seed count) and four phenological traits: the timing of first flowering, the duration of flowering, and height and leaf number at flowering. Results: Selection favored early flowering and longer duration of flowering, and the genetic correlation between these traits accorded with the direction of selection. In most treatments, we found selection for increased height, but selection on leaf number depended on water availability, with selection favoring more leaves in well-watered conditions and fewer leaves under severe drought. Low-elevation genotypes had the greatest fitness under drought stress, consistent with local adaptation. Conclusions: We found evidence of strong selection on these heritable traits. Furthermore, the direction and strength of selection on size at flowering depended on the variable measured (height vs. leaf number). Finally, selection often favored both early flowering and a longer duration of flowering. Selection on these two components of phenology can be difficult to disentangle due to tight genetic correlations.

Elevated [CO2] and temperature augment gas exchange and shift the fitness landscape in a montane forb

“…(Greenbury et al ., 2022). Water (Lee & Mitchell‐Olds, 2013) and nutrient availability (MacTavish & Anderson, 2022) as well as snowmelt (Anderson & Wadgymar, 2020) are important drivers of fitness and local adaptation in B. stricta . For example, low‐elevation accessions have elevated fitness under drought stress in the glasshouse (MacTavish & Anderson, 2022) and advancing snowmelt projected under climate change in the field (Anderson & Wadgymar, 2020).…”

Native Bee Habitat Restoration- Key Ecological Considerations from Recent Literature

“…If seeds or propagules are relocated for restoration, the flowering window of plant species introduced to a site could differ from the window of pollinator flight times at the restoration site (Buisson et al, 2017). This could lead to restored patches differing in flowering phenology from neighboring landscapes (Buisson et al, 2017;MacTavish and Anderson, 2022). These scenarios increase the risk of mismatches between plant species and their pollinators.…”

What determines the evolutionary trajectories of wild plant species? Approaches to the study of quantitative fitness‐related traits

“…It also permits the detection and measurement of the three distinct modes of selection on individual traits: linear, stabilizing (or optimizing), and disruptive selection. In this issue, many of the investigators used selection analysis to examine or to infer the process of selection on traits such as germination time (Muir et al, 2022), flowering phenology (Johnson et al, 2022, MacTavish and Anderson, 2022, Valdés et al, 2022), flower size and height (Chen and Pannell, 2022), plant size at flowering (MacTavish and Anderson, 2022), specific leaf area and plant height (Waterton et al, 2022), and physiological performance (Mazer et al, 2022; see also Johnson et al, 2022).…”

“…MacTavish and Anderson (2022) performed a greenhouse‐based selection experiment using 35 accessions of the perennial mustard Boechera stricta (Brassicaceae) derived from populations sampled across an elevational gradient in the Rocky Mountains (USA) and cultivated under six combinations of water and nutrient availability. Within each treatment combination, they measured lifetime seed production, the onset of flowering and its duration, and plant size and the number of leaves borne at first flower, and then estimated the selection coefficients for, and the genetic correlations between, these traits.…”