Phenotypic but not genotypic selection for earlier flowering in a perennial herb

Abstract

This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmerc ial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Abstract 1. Timing of reproduction affects the outcome of interactions between plants and their pollinators, grazers and seed predators, as well as with their local abiotic environment. In seasonal environments, phenotypic selection has often been shown to favour early flowering. Yet, we still know little about the agents driving selection in natural populations and whether observed phenotypic selection corresponds to genotypic selection-a prerequisite for evolutionary change. 2. In this study, we experimentally assessed phenotypic and genotypic selection for flowering time in a natural population of the perennial herb Lathyrus vernus. We transplanted sibling individuals, obtained through controlled crosses, to their source population and found net phenotypic selection for earlier flowering in the field. 3. Despite a higher susceptibility to roe deer grazing, early-flowering plants had higher fruit set and more seeds per fruit than late-flowering plants. We found no support for genotypic selection on flowering time, and heritability for first flowering day was very low. 4. Synthesis. Our results suggest that commonly observed patterns of higher fitness in early-flowering plants do not always correspond to selection on genotypic values and are thus not necessarily expected to result in evolutionary change even if the relationship between flowering time and fitness is causal. This finding should be important to understand how species phenology might respond to changing environmental conditions. K E Y W O R D S evolutionary ecology, fitness components, herbivory, heritability, Lathyrus vernus, natural selection, phenology

Plant–animal interactions mediate climatic effects on selection on flowering time

“…Grazing was higher in individuals that flowered early in the season when relatively few other herbs are available, in accordance with previous results with the same species Münzbergová 2009, Fogelström and. The absence of consistent effects of flowering time on seed predation contrasts with the results of studies with several other species (Elzinga et al 2007, Kolb et al 2007), but agrees with previous results for L. vernus (Fogelström and Ehrlén 2019). Still, there was large among-year variation in the relationship among seed predation intensity and individual flowering time (Appendix S2: Fig.…”

“…2007), but agrees with previous results for L . vernus (Fogelström and Ehrlén 2019). Still, there was large among‐year variation in the relationship among seed predation intensity and individual flowering time (Appendix : Fig.…”

Flowering season of vernal herbs is shortened at elevated temperatures with reduced precipitation in early spring

“…Altered climate not only affects the morphological plasticity but also temporal traits such as the timing of phenological events 16 . Appropriate timing of phenological events is important for plant growth and reproduction under specific environments and interspecific interactions 17 , 18 , and higher temperatures can induce faster growth and earlier phenological transition 19 .…”

Simultaneous selection on vegetative and reproductive phenology in a perennial herb

“…Cold April temperatures are associated with weaker selection for early flowering, possibly because frost damage reduces the benefit of flowering early (Ehrlén & Valdés, 2020). Grazing by roe deer ( Capreolus capreolus ) favors later flowering because early‐flowering individuals experience the highest levels of damage (Fogelström & Ehrlén, 2019). Lathyrus vernus individuals rely on pollinators ( Bombus sp.)…”

“…vernus to estimate seed predation (proportion of seeds preyed upon = 1−e −1.218 B . atomarius entry holes per seed; Appendix in Fogelström & Ehrlén, 2019).…”