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Whole‐genome duplication (polyploidy) is an important force shaping flowering‐plant evolution. Ploidy‐specific plant–pollinator interactions represent important community‐level biotic interactions that can lead to nonrandom mating and the persistence of mixed‐ploidy populations.

At a naturally occurring diploid–tetraploid contact zone of the autopolyploid desert shrubLarrea tridentata, we combined flower phenology analyses, collections of bees on plants of known cytotype, and flow cytometry analyses of bee‐collected pollen loads to investigate whether (1) diploid and tetraploid plants have unique bee pollinator assemblages, (2) bee taxa exhibit ploidy‐specific visitation and pollen collection biases, and (3) specialist and generalist bee taxa have ploidy‐specific visitation and pollen collection biases.

Although bee assemblages overlapped, we found significant differences in bee visitation to co‐occurring diploids and tetraploids, with the introduced honeybee (Apis mellifera) and one native species (Andrenaspecies 12) more frequently visiting tetraploids. Consistent with bee assemblage differences, we found that diploid pollen was overrepresented among pollen loads on native bees, while pollen loads onA. melliferadid not deviate from the random expectation. However, mismatches between the ploidy of pollen loads and plants were common, consistent with ongoing intercytotype gene flow.

Our data are consistent with cytotype‐specific bee visitation and suggest that pollinator behavior contributes to reduced diploid–tetraploid mating. Differences in bee visitation and pollen movement potentially contribute to an easing of minority cytotype exclusion and the facilitation of cytotype co‐occurrence.

Obtaining phenotypic data from herbarium specimens can provide important insights into plant evolution and ecology but requires significant manual effort and time. Here, we present LeafMachine, an application designed to autonomously measure leaves from digitized herbarium specimens or leaf images using an ensemble of machine learning algorithms.

We trained LeafMachine on 2685 randomly sampled specimens from 138 herbaria and evaluated its performance on specimens spanning 20 diverse families and varying widely in resolution, quality, and layout. LeafMachine successfully extracted at least one leaf measurement from 82.0% and 60.8% of high‐ and low‐resolution images, respectively. Of the unmeasured specimens, only 0.9% and 2.1% of high‐ and low‐resolution images, respectively, were visually judged to have measurable leaves.

This flexible autonomous tool has the potential to vastly increase available trait information from herbarium specimens, and inform a multitude of evolutionary and ecological studies.

Whole‐genome duplication (polyploidy) can influence the biogeography and ecology of plants that differ in ploidy level (cytotype). Here, we address how two consequences of plant polyploidy (parapatry of cytotypes and altered species interactions) shape the biogeography of herbivorous insects.

Warm deserts of North America.

Gall midges (Asphondylia auripilagroup, Diptera: Cecidomyiidae) that attack three parapatric cytotypes of creosote bush (Larrea tridentata, Zygophyllaceae).

We surveyedAsphondyliaspecies diversity at 177 sites across a 2300‐km extent. After noting a correspondence between the distributions of eightAsphondyliaspecies andL. tridentatacytotypes, we fine‐mappedAsphondyliaspecies range limits with transects spanning cytotype contact zones. We then tested whether plant–insect interactions and/or abiotic factors explain this coincidence by (a) comparing attack rates and gall midge communities on alternative cytotypes in a narrow zone of sympatry and (b) using species distribution models (SDMs) to determine if climatically suitable habitat for each midge species extended beyond cytotype contact zones.

The range limits of 6/17Asphondyliaspecies (including two novel putative species confirmed withCOIsequencing) perfectly coincided with the contact zone of diploid and tetraploidL. tridentata. One midge species was restricted to diploid host plants while five were restricted to tetraploid and hexaploid host plants. Where diploid and tetraploidL. tridentataare sympatric, cytotype‐restricted midge species more frequently attacked their typical host andAsphondyliacommunity structure differed markedly between cytotypes.SDMs predicted that distributions of cytotype‐restricted midge species were not constrained by climatic conditions near cytotype contact zones.

Contact zones between plant cytotypes are dispersal barriers for manyAsphondyliaspecies due to plant–insect interactions. The distribution ofL. tridentatacytotypes therefore shapes herbivore species ranges and herbivore community structure across North American deserts. Our results demonstrate that polyploidy in plants can affect the biogeography of ecological communities.

Alternative hypotheses of Darwin's Naturalization Conundrum (DNC) predict that the non‐native species that successfully establish within a community are those either more closely or more distantly related to the resident native species. Despite the increasing number of studies using phylogenetic data to testDNCand evaluate community assembly, it remains unknown whether phylogenetic relationships alone can be used to predict invasion susceptibility across communities differing environmentally and in disturbance history. In this study, we evaluate whether phylogenetic structure of diverse native communities predicts the occurrence of non‐native species and offers insight into community assembly.

Eastern United States of America.

We examine multiple communities across a north–south transect of the eastern United States to test whether non‐native species richness and abundance are associated with phylogenetic diversity measures of the native community. We also test whether non‐native species are consistently closely or distantly related to native species using two approaches differing in phylogenetic scale and whether this differs with ecologically successful species.

Our analyses did not unambiguously resolveDNC. Non‐native species richness and abundance decreased with increasing native species phylogenetic diversity. Within some communities, non‐native species were significantly more closely related to native species than expected by chance, and tended to be more often closely related to a native species than that native species was to other native relatives. When considering species abundance, only one community showed that ecologically successful non‐native species were closely related to resident species.

Phylogenetic relationships can reveal important details about community assembly in diverse ecological settings. However, given the multifaceted nature of community assembly, phylogenetic metrics alone have limited utility as a general predictive tool for community invasion. Our study highlights a need to incorporate additional types of data to better understand why some communities are more susceptible to non‐native species establishment.