Biology subjects

Yoder, J. B.

Publications and source records attributed to Yoder, J. B..

7 recordsLinked to original sources

bioRxiv2026

Climate-driven decoupling of a coevolved mutualism between Joshua trees (Yucca brevifolia and Y. jaegeriana, Asparagaceae) and pollinating yucca moths (Tegeticula synthetica and T. antithetica, Prodoxidae)

Environmental change can disrupt ecologically important mutualisms, if coadapted partners respond to changes differently---but modeling differential responses by specialized mutualists can be challenging. Here, we use TARDIS (Temporal Analysis of Reproduction Distributed in Space) to examine how annual weather variation drives flowering in Joshua trees (Yucca brevifolia and Y. jaegeriana; Asparagaceae), and subsequent fruit production that relies on obligate yucca moth pollinators (Tegeticula antithetica and T. synthetica; Prodoxidae). We used more than 16,000 observations of Joshua trees and corresponding weather records, covering an 18-year period, to train Bayesian additive regression tree models of flowering and fruiting activity. The models find flowering and fruiting respond differently to temperature and inter-annual precipitation variation, and a hindcast for the years 1900-2025 reveals that years with conditions favoring flowering have become slightly more frequent, while conditions favoring fruiting--and moth activity--have been stable or declining. Trends in this predicted mismatch between Joshua tree flowering and yucca moth activity vary with latitude and elevation, but do not differ in regions identified as climate refugia. Overall, our results suggest climate change to date has had pervasive, if so far small, impacts on both these specialized mutualists.

ecology↗

bioRxiv2026

Limited role of climate change in out-of-season Joshua tree flowering

Climate change is expected to touch every ecological community on the planet, but connecting climate change to specific ecological events remains challenging. The emerging practice of climate change attribution can identify how anthropogenic climate change contributes to extreme weather events--but has not yet been applied to unusual ecological events. Here, we demonstrate attribution of a recent, striking ecological anomaly: Joshua trees (Yucca brevifolia and Y. jaegeriana) flowering in October 2025, fully four months earlier than normal. We used crowdsourced records of Joshua tree flowering to train a machine learning model that recovers weather triggers of flowering, and successfully predicts regular-seasonal and out-of-season flowering events. We then simulated weather without human-caused climate change using the output of 10 global climate models, and projected Joshua tree flowering under those counterfactual conditions with our trained model. Surprisingly, we found out-of-season blooms were driven by high winter rainfall, not rising temperatures--and therefore, are probably the result of natural weather variability. Our results place out-of-season flowering in context with climate change threats facing Joshua trees, while providing a prototype attribution analysis of an extreme ecological event and identifying priorities for future climate modeling.

ecology↗

bioRxiv2026

Specialists drive biodiversity scaling in symbiotic relationships

The stunning diversity of symbiotic life forms, and their unique vulnerability to extinction, emerge from the close relationship between host and symbiont species richness. The general form of this relationship should be linear, but simulation studies have shown that it becomes sub-linear (and even power law-like) when sampling within a host-symbiont network. Here, we resolve this paradox with a new mathematical model of scaling in bipartite graphs, based on the independent behavior of specialist (single-host) and generalist (multi-host) symbionts. Using this model, we show that specialists constrain the architecture of ecological networks, and at global scales, drive the accumulation of symbiont biodiversity. By definition, specialists also face the highest risk of coextinction with their hosts and -- despite substantial uncertainty about their true richness -- we show that they could easily account for the majority of threatened species on Earth. Our study reveals that symbiosis remains one of the most poorly-understood building blocks of ecosystem function and evolutionary diversification, and serves as a reminder that foundational macroecological principles are still waiting to be discovered from first principles.

ecology↗

bioRxiv2025

Temporal analysis of reproduction distributed in space illuminates the climate-change resiliency of toyon (Heteromeles arbutifolia)

PremiseToyon, Heteromeles arbutifolia (Lindl.) M. Roem. (Rosaceae), is an iconic and ecologically important member of California chaparral and oak woodland communities. Toyons habitat faces changing wildfire regimes, widening variation in annual rainfall, and competition by introduced species. We used a new modeling method, temporal analysis of reproduction distributed in space (TARDIS) to examine how recent climate change alters habitat suitability for toyon. MethodsAs data for TARDIS, we annotated flowering and fruiting in images from 4,105 observations of toyon contributed to the iNaturalist crowdsourcing platform. From these records we trained Bayesian additive regression tree models relating weather to toyon flowering. We used a trained model to hindcast flowering each year back to 1900, and examined trends in hindcast flowering. For comparison, we also modeled changing habitat suitability using a conventional species distribution model (SDM) relating toyon presence to 30-year climate averages. Key resultsToyon flowering is associated with greater winter precipitation and warmer fall and winter temperatures. Our hindcast finds mean flowering intensity has been stable to slightly increasing since 1900, with greater increases at higher elevations, but also at lower latitudes. Variation in flowering intensity has also increased, especially at lower latitudes. Trends in flowering are positively correlated with changes in SDM-predicted suit-ability. ConclusionsTARDIS recovers biologically realistic predictors of toyon flowering, and hindcast changes in flowering intensity indicate the species range remains suitable after 125 years of changing climate. Overall our results indicate toyon populations remain healthy, but may have limited opportunity to migrate northwards as climate change continues.

ecology↗

bioRxiv2021

Plant-associate interactions and diversification across trophic levels

Interactions between species are widely understood to have promoted the diversification of life on Earth, but how interactions spur the formation of new species remains unclear. Interacting species often become locally adapted to each other, but they may also be subject to shared dispersal limitations and environmental conditions. Moreover, theory predicts that different kinds of interactions have different effects on diversification. To better understand how species interactions promote diversification, we compiled population genetic studies of host plants and intimately associated herbivores, parasites, and mutualists. We used Bayesian multiple regressions and the BEDASSLE modeling framework to test whether host and associate population structures were correlated over and above the potentially confounding effects of geography and shared environmental variation. We found that associates population structure often paralleled their hosts population structure, and that this effect is robust to accounting for geographic distance and climate. Associate genetic structure was significantly explained by plant genetic structure somewhat more often in antagonistic interactions than in mutualistic ones. This aligns with a key prediction of coevolutionary theory, that antagonistic interactions promote diversity through local adaptation of antagonists to hosts, while mutualistic interactions more often promote diversity via the effect of hosts geographic distribution on mutualists dispersal.

evolutionary biology↗

bioRxiv2019

Zygomorphic flowers have fewer visitors

Botanists have long identified bilaterally symmetrical (zygomorphic) flowers with more specialized pollination interactions than radially symmetrical (actinomorphic) flowers. Zygomorphic flowers facilitate more precise contact with pollinators, guide pollinator behaviour, and exclude less effective pollinators. However, whether zygomorphic flowers are actually visited by a smaller subset of available pollinator species has not been broadly evaluated. We compiled 53,609 floral visitation records in 159 communities and classified the plants floral symmetry. Globally and within individual communities, plants with zygomorphic flowers are indeed visited by fewer species. At the same time, zygomorphic flowers share a somewhat larger proportion of their visitor species with other co-occurring plants, and have particularly high sharing with co-occurring plants that also have zygomorphic flowers. Visitation sub-networks for zygomorphic species also show differences that may arise from reduced visitor diversity, including greater connectance, greater web asymmetry, and lower coextinction robustness of both plants and visitor species -- but these changes do not necessarily translate to whole plant-visitor communities. These results provide context for widely documented associations between zygomorphy and diversification and imply that species with zygomorphic flowers may face greater risk of extinction due to pollinator loss.

ecology↗

bioRxiv2019

Evaluating genomic data for management of local adaptation in a changing climate: A lodgepole pine case study

The need for tools to cost-effectively identify adaptive variation within ecologically and economically important plant species is mounting as the detrimental effects of climate change become increasingly apparent. For crop and wild populations alike, mismatches between adaptive variation and climatic optima will reduce health, growth, survival, reproduction, and continued establishment. The ease with which land managers can quantify the relative importance of different climate factors or the spatial scale of local adaptation to climate will have direct implications for the potential of mitigating or resolving such risks. Using seed collected from 281 provenances of lodgepole pine (Pinus contorta) from across western Canada, we compare genomic data to phenotypic and climatic data to assess their effectiveness in characterizing the climatic drivers and spatial scale of local adaptation in this species. We find that genomic and climate data are nearly equivalent for describing local adaptation in seedling traits. We also find strong agreement between the climate variables associated with genomic variation and with 20-year heights from a long-term provenance trial, suggesting that genomic data may be a viable option for identifying climatic drivers of local adaptation where phenotypic data are unavailable. Genetic clines associated with cold injury occur at broad spatial scales, suggesting that standing variation of adaptive alleles for this and similar species does not require management at scales finer than are indicated by phenotypic data. This study demonstrates that genomic data are most useful when paired with phenotypic data, but can also fill some of the traditional roles of phenotypic data in management of species for which phenotypic trials are not feasible.

evolutionary biology↗