Environmental patterns of adaptation after range expansion in Leontodon longirostris: The effect of phenological events on fitness‐related traits

• Published in: American journal of botany Vol. 109; no. 4; pp. 602 - 615
• Main Authors: Pedro, Manuel, Mayol, Maria, González‐Martínez, Santiago C., Regalado, Ingrid, Riba, Miquel
• Format: Journal Article
• Language: English
• Published: United States Botanical Society of America, Inc 01-04-2022; Botanical Society of America
• Subjects: Acclimatization; Adaptation; Adaptation, Physiological; Aridity; Asteraceae; biomass allocation; Climate change; Clines; Environmental Sciences; Evolution; expansion load; Fitness; Flowering; flowering time; Genetic diversity; Genetic load; Genotypes; Germination; Leontodon; Leontodon longirostris; Leontodon saxatilis; Life history; life‐history evolution; phenology; Phenotype; Plants; Plants (botany); Populations; range expansion; Range extension; Reproductive fitness; Seedlings; Seeds; Species; Taxa; Variability; germination; range expansion; Leontodon longirostris; expansion load; flowering time; Leontodon saxatilis; Asteraceae; life-history evolution; phenology; biomass allocation
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/ajb2.1815

Premise
Because of expected range shifts associated with climate change, there is a renewed interest in the evolutionary factors constraining adaptation, among which are genetic bottlenecks, drift, and increased mutational load after range expansion.
Here we study adaptation in the short‐lived species Leontodon longirostris showing reduced genetic diversity and increased genetic load along an expansion route.
Methods
We assessed the phenological patterns of variation, and their effect on fitness‐related traits, on 42 L. longirostris populations and six populations of the sister taxa L. saxatilis in a common garden located within the current range of both species. The comparison among L. longirostris populations allowed us to test for genetic clines consistent with local adaptation, whereas the comparison between taxa provided evidence for common adaptive features at the species level.
Results
We found significant within‐species variability for most traits, as well as differences with its close relative L. saxatilis. In general, seeds from drier, warmer, and unpredictable habitats showed overall lower and more restricted conditions for germination, seedlings emerged later and plants flowered earlier. Consequently, genotypes from arid and unpredictable environments attained smaller reproductive sizes and allocated more biomass to reproduction. Flowering time had the strongest direct effect on total plant size, but seedling emergence also showed an important indirect effect.
Conclusions
Our results show the crucial role of phenological patterns in shaping adaptive clines for major life‐history stage transitions. Furthermore, the genetic load observed in L. longirostris does not seem to preclude adaptation to the climatic variability encountered along the expansion route.