Biology subjects

Weber, M. G.

Publications and source records attributed to Weber, M. G..

6 recordsLinked to original sources

bioRxiv2025

Opposing seasonal dynamics in phylogenetic and flower color diversity of co-flowering wildflower assemblages

Flower color is a key trait mediating plant-pollinator interactions, yet the ecological rules governing its distribution across co-flowering assemblages remain poorly understood. We examined spatiotemporal patterns of flower color and phylogenetic diversity in Eastern North American wildflowers to test for non-random community structure, seasonal shifts, and associations between flower color similarity and phylogenetic relatedness. Using occurrence, phenology, and color data from community science datasets, we reconstructed communities of co-flowering assemblages and calculated standardized effect sizes of mean pairwise distances for both flower color and phylogenetic relatedness. We analyzed seasonal trends using mixed models and assessed whether closely related species co-flowered non-randomly with respect to color similarity using bootstrap correlations. We found that, on average, co-flowering assemblages were overdispersed for both flower color and phylogeny. However, flower color dispersion significantly decreased over the growing season, while phylogenetic dispersion significantly increased, reflecting a pattern in which co-flowering assemblages shifted to more distantly related but similarly colored assemblages. Finally, color and phylogenetic dispersion were negatively correlated across communities, indicating that communities composed of more closely related species tended to exhibit more dissimilar flowers. Together, our results suggest that wildflower assemblages in Eastern North America show detectable, non-random structure across space and time with respect to color and relatedness at the broad scale, and that mechanisms underlying the structure of co-flowering groups may shift throughout the growing season.

ecology↗

bioRxiv2024

Stochastic Character Mapping of Continuous Traits on Phlyogenies

AO_SCPLOWBSTRACTC_SCPLOWFossilized organisms only represent a small fraction of Earths evolutionary history, motivating "ancestral state reconstruction" techniques for inferring unobserved phenotypes of evolving lineages based on measurements of their relatives. Stochastic character mapping has emerged as a particularly powerful approach in this regard, allowing researchers to sample histories of discrete variables on phylogenies and better account for the inherent uncertainty of reconstructed ancestral states. Here, we generalize this procedure to work with continuous variables by developing an efficient algorithm for sampling evolutionary histories under Brownian Motion, implemented in a new R package contsimmap. To demonstrate potential applications of these "continuous stochastic character maps", we develop a pipeline for inferring relationships between rates of continuous trait evolution and continuously-varying factors (e.g., body size, generation time)--a difficult statistical problem for which relatively few methods are available. After verifying this novel pipelines performance on simulated data, we use it to show that smaller eucalypt trees tend to exhibit higher rates of flower and leaf trait evolution overall, aligning with well-established predictions based on life history theory as well as empirical patterns in other systems. Ultimately, continuous stochastic character mapping is a valuable new tool for analyzing macroevolutionary data, enabling rigorous yet flexible investigation of complex evolutionary dynamics involving continuous traits and/or continuous variables hypothesized to affect evolutionary processes.

evolutionary biology↗

bioRxiv2024

Small, but mitey: Investigating the molecular genetic basis for mite domatia development and intraspecific variation in Vitis riparia using transcriptomics

* Here, we investigated the molecular genetic basis of mite domatia, structures on the underside of leaves that house mutualistic mites, and intraspecific variation in domatia size in Vitis riparia (riverbank grape). * Domatia and leaf traits were measured, and the transcriptomes of mite domatia from two genotypes of V. riparia with distinct domatia sizes were sequenced to investigate the molecular genetic pathways that regulate domatia development and intraspecific variation in domatia traits. * Key trichome regulators as well as auxin and jasmonic acid are involved in domatia development. Genes involved in cell wall biosynthesis, biotic interactions, and molecule transport/metabolism are upregulated in domatia, consistent with their role in domatia development and function. * This work is one of the first to date that provides insight into the molecular genetic bases of mite domatia. We identified key genetic pathways involved in domatia development and function, and uncovered unexpected pathways that provide an avenue for future investigation. We also found that intraspecific variation in domatia size in V. riparia seems to be driven by differences in overall leaf development between genotypes.

plant biology↗

bioRxiv2024

More than a token photo: humanizing scientists enhances student engagement

Highlighting scientists from historically excluded groups in educational materials increases student engagement in STEM. However, which specific elements of these educational materials maximize their impact remains untested, leaving educators guessing how to best highlight counter-stereotypical scientists in their classrooms. We tested the effects of including visual and humanizing descriptions of scientists featured in quantitative biology activities on over 3,700 students across 36 undergraduate institutions. We found that including humanizing information about counter-stereotypical scientists increased the extent to which students related to those scientists, which in turn translated to higher student engagement. Students who shared one or more excluded identity(s) with the featured scientists related most strongly. Our findings demonstrate the importance of humanizing counter-stereotypical scientists in classrooms, beyond simply adding a photo to increase representation.

scientific communication and education↗

bioRxiv2022

Modeling the Evolution of Rates of Continuous Trait Evolution

AO_SCPLOWBSTRACTC_SCPLOWRates of phenotypic evolution vary markedly across the tree of life, from the accelerated evolution apparent in adaptive radiations to the remarkable evolutionary stasis exhibited by so-called "living fossils". Such rate variation has important consequences for large-scale evolutionary dynamics, generating vast disparities in phenotypic diversity across space, time, and taxa. Despite this, most methods for estimating trait evolution rates assume rates vary deterministically with respect to some variable of interest or change infrequently during a clades history. These assumptions may cause underfitting of trait evolution models and mislead hypothesis testing. Here, we develop a new trait evolution model that allows rates to vary gradually and stochastically across a clade. Further, we extend this model to accommodate generally decreasing or increasing rates over time, allowing for flexible modeling of "early/late bursts" of trait evolution. We implement a Bayesian method, termed "evolving rates" (evorates for short), to efficiently fit this model to comparative data. Through simulation, we demonstrate that evorates can reliably infer both how and in which lineages trait evolution rates varied during a clades history. We apply this method to body size evolution in cetaceans, recovering substantial support for an overall slowdown in body size evolution over time with recent bursts among some oceanic dolphins and relative stasis among beaked whales of the genus Mesoplodon. These results unify and expand on previous research, demonstrating the empirical utility of evorates.

evolutionary biology↗

bioRxiv2021

An increase in atypical petal numbers during a shift to autogamy in a coastal sand verbena and potential evolutionary mechanisms

PremiseIn plants, meristic traits, such as petal and sepal numbers, are usually considered invariant within taxa, yet certain species consistently exhibit great variability in these traits. The factors contributing to "atypical" counts are not well-known, published hypotheses include relaxation of pollinator selection, inbreeding, and hybridization, among others. The sand verbenas, Abronia (Nyctaginaceae), usually have five perianth lobes ( petals), yet certain taxa exhibit marked departures from this norm. MethodsHere we integrate an analysis of images from community science data (iNaturalist) and common garden experiments to evaluate a comprehensive set of adaptive and nonadaptive explanations for the production of these atypical flowers across an evolutionary transition from xenogamy (outcrossing) to autogamy (selfing) in the coastal sand verbena Abronia umbellata. Key resultsThe shift to autogamy in this lineage correlated with a higher frequency of atypical flowers from ~7% to ~20% and a significant reduction in mean petal number per inflorescence. Autogamous success did not change with petal number, and neither hybridization or up to three generations of inbreeding consistently increased production of atypical flowers or decreased mean petal number, all in contrast to previously-published hypotheses. In contrast, intra-inflorescence, inter-plant (intra-population), inter-population, and inter-variety comparisons demonstrated a correlation of reduced floral size with reduced petal number, suggesting correlated evolution due to a well-established relation between organ number and meristem size. ConclusionsThe reduction in petal number was probably a consequence of selection for smaller flowers associated with increased selfing. While we could not completely eliminate several alternative hypotheses, including a long-term history of inbreeding or relaxed selection on petal number constancy, those are less likely to explain the observed changes, though they may have contributed to the trend. In general, we develop a framework of hypotheses for evolutionary investigations of meristic variation in floral organs.

evolutionary biology↗