Biology subjects

Ferris, K. G.

Publications and source records attributed to Ferris, K. G..

9 recordsLinked to original sources

bioRxiv2026

Foliar fungal symbionts in sympatric yellow monkeyflowers along elevation gradients in the Sierra Nevada

1Microbial symbionts have the potential to contribute to host-plants ecological and evolutionary success, especially in plants adaptions to harsh environments, however their role has often been overlooked. Conversely, how host local adaptation (e.g., trait divergence across elevation) shapes the composition of associated microbial symbiont communities remains poorly understood. We explored how foliar endophytic fungi (FEF) abundance, richness, and community composition in three sympatric Monkeyflowers, an ecologically diverse group of flowering plants, change across elevation in the Sierra Nevada, CA, USA. We asked: Q1) Are there differences in leaf functional traits and FEF communities among sympatric Mimulus species populations at similar elevations? Q2) How do traits and FEF communities change across elevation within species? Q3) Are FEF richness, diversity and community composition correlated with leaf functional traits and/or elevation? Q4) How does FEF community composition differ with geographic distance within each species? We collected M. guttatus, M. nasutus, and M.laciniatus individuals from natural populations across the Sierra Nevada, measured leaf functional traits and used ITS sequencing to describe the leaf endophyte community. We found significant associations of FEF community composition with host species, and elevation, suggesting that these factors influence fungal community composition. Furthermore, FEF community dissimilarity was correlated with geographic distance indicating isolation by distance and limited dispersal of fungal endophytes. We detected the prevalence of Vishniacozyma victoriae, an endophyte found most commonly in Antarctica, across all Sierran Mimulus populations. The presence of V. victoriae could play a role in the adaptation of Mimulus to cold, high elevation environments. Our findings offer novel insights into the intricate interactions between fungal endophyte communities, plant traits, and elevation.

ecology↗

bioRxiv2026

The genomic basis of local adaptation to photoperiod across altitude in a self-fertilizing monkeyflower

Local adaptation along altitudinal gradients is well documented in many plant species, however the genetic basis of adaptive variation over these steep environmental clines remains poorly understood. Populations of Mimulus laciniatus, a self-fertilizing annual plant, experience highly differentiated seasonal environments throughout the Sierra Nevada, CA, where the length of the growing season and timing of favorable flowering conditions vary with altitude. These differences have driven divergence in critical photoperiod between low- and high-elevation M. laciniatus, an environmental cue that enables populations to initiate flowering at locally appropriate times. To investigate the genetic basis of local adaptation in this key ecological trait, we used a bulk-segregant quantitative trait locus (QTL) analysis approach. We crossed low- and high-elevation populations of M. laciniatus that differ in critical photoperiod to generate an F2 mapping population, phenotyping plants in a short-day common garden. Genomic differentiation (FST and G-statistic) between flowering and non-flowering pools identified 46 regions genome-wide associated with short-day flowering, including a strong peak on chromosome 8 overlapping GA2ox3, a candidate gene in the gibberellin pathway. Another gibberellin gene (GA20ox2) has been implicated in photoperiodic flowering in the close relative Mimulus guttatus. We found additional loci on chromosomes 2 and 11 that appear unique to M. laciniatus. Our findings suggest that local adaptation in reproductive timing may arise through a combination of shared genetic mechanisms and novel alleles in closely related Monkeyflowers, and that the genetic architecture underlying within-species adaptive divergence can be more complex than comparisons across species.

genomics↗

bioRxiv2025

Phenotypic plasticity is broadly adaptive across an elevation gradient in the Cutleaf Monkeyflower

O_LIPhenotypic plasticity is a key mechanism by which organisms can cope with environmental heterogeneity, but its evolutionary consequences depend on how plastic responses align with the broader adaptive landscape. C_LIO_LIWe tested whether plasticity in leaf shape alongside other traits is associated with differential fitness across an elevational gradient in Mimulus laciniatus, an annual wildflower endemic to montane California. Using a reciprocal transplant experiment and recombinant inbred lines (RILs) previously phenotyped for plasticity in controlled conditions, we measured variation in survival and fecundity in native low- and high-elevation habitats. C_LIO_LIBased on previous work, we expected to find selection against leaf shape plasticity at low-elevation and selection for leaf shape plasticity in the high-elevation direction (increased leaf lobing under long-day conditions) at high-elevation. Interestingly, we found that RIL genotypes exhibiting high-elevation plasticity had the greatest survival to seed production at high-elevations, but that low-elevation plasticity (increased leaf lobing under short-day conditions) was associated with greater fecundity in both elevations. RILs with high-elevation plasticity also outperformed non-plastic genotypes at high-elevation. C_LIO_LIThis pattern suggests that plasticity is broadly beneficial across a species geographic range even if local variation in the direction of plasticity is not always adaptive. C_LI

evolutionary biology↗

bioRxiv2025

Regionally specific and highly pleiotropic loci together mediate skeletal evolution in tropical and temperate house mice

When organisms are exposed to new environments, they often evolve a suite of adaptive phenotypic changes. Understanding the genetic basis of these changes gives us insight into the factors that constrain and facilitate the process of adaptation. Here we use quantitative trait locus (QTL) mapping in wild-derived house mice from temperate and tropical environments to describe the genetic architecture of adaptive skeletal evolution. This study provides a unique view into the evolution of discordant phenotypic changes within the interconnected skeletal system, since tropical and temperate mice have evolved under the opposing forces of Allens and Bergmanns rules (shorter extremities, but larger body size in cold climates). We generated an F3 mapping population of 449 mice and measured a variety of cranial and post-cranial skeletal traits. First, we discovered that temperate and tropical house mice have undergone extensive skeletal divergence in accordance with Allens and Bergmanns rules. Warm-adapted mice have longer limbs, longer pelvic girdles, longer and narrower skulls, but smaller overall body size. Second, we identified 83 QTL across 13 traits and found that the genetic basis of skeletal divergence involved mainly additive, small-effect loci distributed across the genome. While most QTL influenced only one or two traits, we also identified several highly pleiotropic QTL that influenced multiple traits across the skeletal system, often antagonistically to the evolved difference. Such pleiotropic loci may constrain adaptation. Lastly, we found that QTL for overall skeletal variation were enriched for signatures of selection in wild house mouse populations, providing evidence that skeletal variation in this system is indeed driven by adaptive evolution. Article SummaryThe incredible diversity of the vertebrate skeleton offers an opportunity to explore the genetic architecture of phenotypic variation, which is essential to understanding the process of evolution. We characterize the genetic basis of morphological evolution using QTL mapping in house mice adapted to differing climates. Skeletal divergence is widespread in these mice and reflects temperature adaptation. This divergence is mediated by small-effect loci scattered across the genome, as well as several highly-pleiotropic loci. Interestingly, pleiotropic loci often influence phenotypes in the opposite direction from the evolved change, perhaps constraining the process of adaptation. This work demonstrates how complex morphological changes can evolve within an interconnected system, such as the skeleton, under functional, developmental, and selective constraints.

evolutionary biology↗

bioRxiv2024

Short-term fluctuating and long-term divergent selection on sympatric Monkeyflowers: insights from decade-spanning reciprocal transplants

Sympatric species are often locally adapted to distinct microhabitats, yet temporal variation may cause local maladaptation and weaken species boundaries, particularly during extreme climatic events. To examine the interplay between spatially and temporally varying selection, we studied sympatric Monkeyflowers occupying dramatically different niches, Mimulus guttatus and M. laciniatus. We conducted three replicated reciprocal transplants and combined them with previous experiments to leverage a dataset of five single-year transplants spanning a decade. We estimated the strength of phenotypic selection on experimental hybrids in each species habitat across years of drastically differing snowpack. If ecological isolation maintains species differences, we predicted divergent phenotypic selection between habitats consistent with species differences and local adaptation. We found spatial and interannual fluctuations in phenotypic selection, often in unpredicted directions, with temporal variation associated with snowpack. In a combined-year analysis, we detected a significant difference in the strength of long-term selection on flowering time, a key temporally isolating and adaptative trait, between species habitats, suggesting that selection may reinforce species boundaries despite short-term fluctuations. Finally, we found parental local adaptation varied among years where M. laciniatus was locally adapted during low snowpack years, while an extreme snowfall event contributed to overall local maladaptation of M. guttatus.

evolutionary biology↗

bioRxiv2024

Fluctuating selection in a Monkeyflower hybrid zone

While hybridization was viewed as a hindrance to adaptation and speciation by early evolutionary biologists, recent studies have demonstrated the importance of hybridization in facilitating evolutionary processes. However, it is still not well-known what role spatial and temporal variation in natural selection play in the maintenance of naturally occurring hybrid zones. To identify whether hybridization is adaptive between two closely related monkeyflower species, Mimulus guttatus and Mimulus laciniatus, we performed repeated reciprocal transplants between natural hybrid and pure species populations. We planted parental genotypes along with multiple experimental hybrid generations in a dry (2021) and extremely wet (2023) year in the Sierra Nevada, CA. By taking fine scale environmental measurements, we found that the environment of the hybrid zone is more similar to M. laciniatuss seasonally dry rocky outcrop habitat than M. guttatuss moist meadows. In our transplants hybridization does not appear to be maintained by a consistent fitness advantage of hybrids over parental species in hybrid zones, but rather a lack of strong selection against hybrids. We also found higher fitness of the drought adapted species, M. laciniatus, than M. guttatus in both species habitats, as well as phenotypic selection for M. laciniatus-like traits in the hybrid habitat in the dry year of our experiment. These findings suggest that in this system hybridization might function to introduce drought-adapted traits and genes from M. laciniatus into M. guttatus, specifically in years with limited soil moisture. However, we also find evidence of genetic incompatibilities in second generation hybrids in the wetter year, which may balance a selective advantage of M. laciniatus introgression. Therefore, we find that hybridization in this system is both potentially adaptive and costly, and that the interaction of positive and negative selection likely determines patterns of gene flow between these Mimulus species. Lay SummaryEarly evolutionary biologists understood hybridization, or interbreeding between species, as limiting to adaptation. While recent studies have shown that hybridization is important for adaptation, much remains to be learned about the role of natural selection in maintaining hybridization. We use a repeated transplant experiment in dry and wet years with two closely related monkeyflower species, Mimulus guttatus and Mimulus laciniatus, and experimental hybrids, to identify how hybridization is maintained. By measuring environmental variables, we found that the hybrid zone is more similar to M. laciniatuss habitat than M. guttatuss in some years. We found that hybrids do equally well as parental species in hybrid zones. Additionally, the drought adapted species, M. laciniatus, performed better than M. guttatus in both parental habitats, and there was selection for more M. laciniatus-like traits in the hybrid habitat. These results suggest that hybridization might introduce drought-adapted traits and genes from M. laciniatus in a dry year. In a wet year, first generation hybrids performed better than advanced generation hybrids, possibly due to negative genetic interactions. In summary, we find that hybridization is beneficial and costly, and variation in environmental factors likely determines patterns of hybridization.

evolutionary biology↗

bioRxiv2023

Local adaptation to an altitudinal gradient: the interplay between constitutive trait variation and phenotypic plasticity in Mimulus laciniatus

Organisms can adapt to environmental heterogeneity through two mechanisms: (1) expression of population genetic variation or (2) phenotypic plasticity. In this study we investigated whether patterns of variation in both trait means and phenotypic plasticity along elevational and latitudinal clines in a North American endemic plant, Mimulus laciniatus, were consistent with local adaptation. We grew inbred lines of M. laciniatus from across the species range in two common gardens varying in day length to measure mean and plastic trait expression in several traits previously shown to be involved in adaptation to M. laciniatuss rocky outcrop microhabitat: flowering time, size-related traits, and leaf shape. We examined correlations between the mean phenotype and phenotypic plasticity, and tested for a relationship between trait variation and population elevation and latitude. We did not find a strong correlation between mean and plastic trait expression at the individual genotype level suggesting that they operate under independent genetic controls. We identified multiple traits that show patterns consistent with local adaptation to elevation: critical photoperiod, flowering time, flower size, mean leaf lobing, and leaf lobing plasticity. These trends occur along multiple geographically independent altitudinal clines indicating that selection is a more likely cause of this pattern than gene flow among nearby populations with similar trait values. We also found that population variation in mean leaf lobing is associated with latitude. Our results indicate that both having more highly lobed leaves and greater leaf shape plasticity may be adaptive at high elevation within M. laciniatus. Our data strongly suggest that traits known to be under divergent selection between M. laciniatus and close relative Mimulus guttatus are also under locally varying selection within M. laciniatus.

evolutionary biology↗

bioRxiv2022

Spatially and temporally varying selection influence species boundaries in two sympatric Mimulus

Spatially and temporally varying selection can maintain genetic variation within and between populations, but it is less known how these forces influence divergence between closely related species. We identify the interaction of temporal and spatial variation in selection and their role in either reinforcing or eroding divergence between two closely related Mimulus species. Using repeated reciprocal transplant experiments with advanced generation hybrids we compare the strength of selection on quantitative traits involved in adaptation and reproductive isolation in Mimulus guttatus and Mimulus laciniatus between two years with dramatically different water availability. We found strong divergent habitat mediated selection on traits in the direction of species differences during a drought in 2013, suggesting that spatially varying selection maintains species divergence. However, a relaxation in divergent selection on most traits in an unusually wet year (2019), including flowering time which is involved in pre-zygotic isolation, suggests that temporal variation in selection may weaken species differences. Therefore, we find evidence that temporally and spatially varying selection may have opposing roles in mediating species boundaries. Given our changing climate, future growing seasons are expected to be more similar to the dry year, suggesting that in this system climate change may actually increase species divergence.

evolutionary biology↗

bioRxiv2016

The Phenotypic, Genotypic, & Environmental Drivers of Local Adaptation to a Harsh Granite Outcrop Environment in Mimulus

A primary goal in evolutionary biology is to understand which environmental variables and traits drive adaptation to harsh environments. This is difficult since many traits evolve simultaneously as populations or species diverge. Here we investigate the ecological variables and traits that underlie Mimulus laciniatus adaptation to granite outcrops compared to its sympatric, mesic-adapted progenitor M. guttatus. We use fine scale measurements of soil moisture and herbivory to examine differences in selective forces between the species habitats, and measure selection on flowering time, flower size, plant height, and leaf shape in a reciprocal transplant using M. laciniatus x M. guttatus F4 hybrids. We find that differences in drought & herbivory drive survival differences between habitats, that M. laciniatus and M. guttatus are each better adapted to their native habitat, and differential habitat selection on flowering time, plant stature, and leaf shape. We conclude that while early flowering time, small stature, and lobed leaf shape underlie plant fitness in M. laciniatus seasonally dry environment, increased plant size is advantageous in a competitive mesic environment replete with herbivores like M. guttatus.

evolutionary biology↗