Lana F Gaspard, Elissa Harb, Stacy D Holt, Courtney M Patterson, Nicholas J Kooyers
{"title":"Interactions between maternal provisioning and natural selection on seed mass fluctuate across heat waves.","authors":"Lana F Gaspard, Elissa Harb, Stacy D Holt, Courtney M Patterson, Nicholas J Kooyers","doi":"10.1002/ajb2.70196","DOIUrl":"https://doi.org/10.1002/ajb2.70196","url":null,"abstract":"<p><strong>Premise: </strong>Changing climates are leading to more frequent and severe heat waves, potentially threatening plant populations. Both acclimation to stress and selection for heat-escape or heat-resistance phenotypes occur during heat waves. However, plastic responses and selection do not necessarily interact cohesively-even producing trait responses in opposite directions that could cause maladaptation.</p><p><strong>Methods: </strong>We examined patterns of maternal provisioning and natural selection on seed mass and germination characteristics after two natural heat waves across 12 annual populations of Mimulus guttatus. We then recreated heat-wave events occurring early and late within a growing season using a manipulative experiment to determine the reproducibility of our results.</p><p><strong>Results: </strong>There was selection for greater seed mass during the year of the early season heat wave, and seed mass remained high through the late-season heat wave. Maternal provisioning also impacted seed mass and germination during the late-season heat wave. Field observations of seed mass only reflect selection for increased seed mass after the early season heat wave, and plants that experienced a late season heat wave had small seeds that germinated later. This pattern during the late season heat wave reflects decreased maternal provisioning coinciding with selection for larger seeds.</p><p><strong>Conclusions: </strong>Our results demonstrate that the relationship between selection and maternal provisioning fluctuates between years, facilitating adaptive evolution during an early-season heat wave and causing conflict during a late-season heat wave. The consequences for evolutionary responses are uncertain and depend on the seed bank, but could result in high mortality in heat waves occurring during successive years.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70196"},"PeriodicalIF":2.7,"publicationDate":"2026-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147939925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Phenological shifts keep pace with climate change but are slowing down in a semi-arid grassland community.","authors":"Meredith A Zettlemoyer, Peter Lesica","doi":"10.1002/ajb2.70203","DOIUrl":"https://doi.org/10.1002/ajb2.70203","url":null,"abstract":"<p><strong>Premise: </strong>Although many studies document advancing phenology in response to warming, it is challenging to identify which environmental drivers influence phenology and whether phenological shifts suitably track changing environmental conditions. By examining phenological trends on a climate-relevant scale (e.g., heat accumulated at flowering or days between snowmelt and flowering), we can test whether climate change outpaces phenological shifts. If these climate-relevant phenology metrics remain constant over time, that would suggest perfect phenological tracking to match the climate conditions under which plants historically flowered.</p><p><strong>Methods: </strong>We analyzed a long-term data set on timing of first flower and climate from 1995 to 2024 in 25 species in a semiarid intermontane grassland in west-central Montana, United States. We used an information theoretic approach to examine how flowering phenology shifted over time and in response to a suite of environmental variables (temperature, growing degree days [GDD], precipitation, snowmelt, drought), whether responses were nonlinear, and whether responses differed between early- vs. late-spring flowering species. We then asked whether climate-relevant measures of phenology remained constant over time, which would suggest tracking of suitable environmental conditions.</p><p><strong>Results: </strong>Flowering phenology advanced nonlinearly over time and under warmer and drier conditions. In particular, early-spring flowering species advanced flowering under drought conditions. Plants flowered with fewer GDD accumulated and sooner post-snowmelt than historically.</p><p><strong>Conclusions: </strong>Phenological shifts keep pace with climate change in our system. However, nonlinear phenological responses to climate indicate that phenological shifts are slowing. Phenological shifts in spring flowering species may be limited as temperatures continue to increase.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70203"},"PeriodicalIF":2.7,"publicationDate":"2026-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147939886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Phenotypic and genetic bases of variable drought stress response in a widely adapted allotetraploid species.","authors":"Wen-Hsi Kuo, Linda L Small, Kenneth M Olsen","doi":"10.1002/ajb2.70200","DOIUrl":"https://doi.org/10.1002/ajb2.70200","url":null,"abstract":"<p><strong>Premise: </strong>Understanding how plants adapt to spatial and temporal variation in water availability is central to predicting their responses to climate change. However, the genetic and physiological mechanisms underlying local adaptation to drought remain poorly understood, particularly in polyploid species. We investigated these mechanisms in Trifolium repens (white clover), a recently evolved allotetraploid characterized by broad ecological tolerance, global distribution, and extensive variation in life-history traits.</p><p><strong>Methods: </strong>We evaluated drought response in genotypes from three climatically distinct North American locations (Minnesota, Missouri, and Florida), focusing on fitness-related traits and subgenomic gene expression. We used a quantitative trait locus (QTL) mapping population derived from Minnesota and Florida genotypes to characterize the genetic architecture of drought-divergent traits.</p><p><strong>Results: </strong>Genotypes showed divergent drought responses in biomass allocation, flowering time, and photosynthesis. Transcriptomic data revealed genotype-specific expression responses, with parallel regulation across homeologous gene pairs and equal subgenomic contributions. Variability in cyanogenesis, a chemical defense, had no detectable effect on fitness-related traits. QTL analysis identified a major locus on Chromosome 4 with antagonistic pleiotropy across environments, consistent with local adaptation; this QTL partially overlaps genomic regions previously associated with aridity gradients in a landscape genomics analysis.</p><p><strong>Conclusions: </strong>Adaptive divergence in white clover under drought reflects differences in life history, energy allocation, and physiology. Parallel homeolog regulation underscores balanced subgenomic expression in this young polyploid. A key QTL with environment-dependent effects provides evidence for the genetic basis of local adaptation. These findings highlight how polyploid species can evolve context-dependent strategies to cope with climate-induced stresses.</p>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":" ","pages":"e70200"},"PeriodicalIF":2.7,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147832551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
