Framing the future for taxonomic monography: Improving recognition, support, and access

No abstract available

Framing the future for taxonomic monography: Improving recognition, support, and access

Taxonomic monographs synthesize biodiversity knowledge and document biodiversity change through recent and geological time for a particular organismal group, sometimes also incorporating cultural and place-based knowledge. They are a vehicle through which broader questions about ecological and evolutionary patterns and processes can be generated and answered (e.g., Muñoz Rodríguez et al., 2019). Chiefly, monography represents the foundational research upon which all biological work is based (Hamilton et al., 2021). Moreover, monography can be a pathway to developing inclusive scientific practices, engaging diverse audiences in expanding and disseminating indigenous and local knowledge and significance of place. Apart from the scientific importance of monography, these comprehensive biodiversity treatments are also crucial for policy, conservation, human wellbeing, and the sustainable use of natural resources. Taxonomic, cultural and biodiversity data within monographs aid in the implementation of law and policy, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Nagoya Protocol of the Convention on Biological Diversity (Buck & Hamilton, 2011), and the International Union for Conservation of Nature (IUCN) Red List (e.g., Neo et al., 2017). While vital as a knowledge resource and tool for conservation and research, monographs are not available for many groups of organisms. This is of particular concern for organisms that are threatened with extinction, of medical or economic importance, and those organisms that have the potential to provide insight into biodiversity change over time because they are most susceptible to global change. In discussing the future of collections-based systematics, researchers have highlighted the importance of updated monographic workflows, collaborative teams, and effective ways to educate and disseminate the results of monographs to the public and scientific community (e.g., Wen et al., 2015; Grace et al., 2021). Here, we discuss how improving recognition, support, and access can lead to greater inclusivity while promoting a more active, sustainable, and collaborative outlook for monographic research. </p

Radiation of the rock daisies in the desert mountains of the southwest U.S. and northern Mexico: a phylogenomic, systematic, and historical biogeographic analysis of tribe Perityleae (Compositae)

Rock daisies (Perityleae; Compositae) are a diverse clade of seven genera and ca. 84 minimum-rank taxa that mostly occur as narrow endemics on sheer rock-cliffs throughout the southwest U.S. and northern Mexico. Taxonomy of Perityleae has traditionally been based on morphology and cytogenetics. To test taxonomic hypotheses and utility of characters emphasized in past treatments, we present the first densely sampled molecular phylogenies of Perityleae and reconstruct trait and chromosome evolution. We inferred phylogenetic trees from whole chloroplast genomes, nuclear ribosomal cistrons, and hundreds of low-copy nuclear genes using genome skimming and target-capture. Discordance between sources of molecular data suggests an underappreciated history of hybridization in Perityleae. Phylogenies support the monophyly of subtribe Peritylinae, a distinctive group possessing a four-lobed disc corolla; however, all the phylogenetic trees generated in this study reject the monophyly of the most species-rich genus, Perityle, as well as its sections: Perityle sect. Perityle, Perityle sect. Laphamia, and Perityle sect. Pappothrix. Results of reversible jump MCMC suggest that morphological characters traditionally used to classify members of Perityleae have evolved multiple times within the group. A base chromosome number of x=9 gave rise to higher base numbers in subtribe Peritylinae (x=12, 13, 16, 17, 18 and 19) through polyploidization followed by ascending or descending dysploidy. Most taxa constitute a monophyletic lineage with a base chromosome number of x=17, with multiple neo-polyploidization events. These results demonstrate the advantages and obstacles to next-generation sequencing approaches in synantherology while laying the foundation for taxonomic revision and comparative study of the evolutionary ecology of Perityleae. Phylogenomic analyses of sequence data from chloroplast and nuclear genomes as well as morphological and cytological analyses resolves long standing phylogenetic uncertainty in the rock daisy tribe (Perityleae; Asteraceae) and supports reclassification at the generic level to reflect evolutionary relationships. The previously recognized genera Eutetras, Amauria, and Pericome were all upheld as clades and continue to be recognized in the new classification. The large genus Perityle as treated in previous taxonomies was found not to be monophyletic and is thus reclassified in four genera, using the available names Laphamia (in an expanded sense), Galinsogeopsis (in an expanded sense), Nesothamnus, and Perityle (in a restricted sense). The type species of Perityle belongs to an early diverging lineage of the rock daisy tribe, in a clade including four other minimum-rank taxa of northwest Mexican annuals, with base chromosome numbers of x=11, 12, 13, 16, or 19. Nesothamnus is reinstated as a monotypic genus for the Guadalupe island endemic shrub Nesothamnus incanus. Laphamia and Galinsogeopsis together constitute a clade of woody and herbaceous perennials or annuals with a stabilized base chromosome number of x=17 (n=34, 51, 68) that have diversified throughout the Basin and Range Province and the Sierra Madre Occidental of the southwest U.S. and northern Mexico. Laphamia and Galinsogeopsis have overlapping geographic distributions but can be distinguished by a combination of fruit and flower traits. This new generic classification of Perityleae resolves long standing conflict about the circumscription of Perityle without expanding the genus to encompass the entire subtribe Peritylinae and recognizes two independent evolutionary radiations onto island-like rock habitats in the North American deserts as taxonomically distinct components of this fascinating tribe of composites. Evolutionary diversifications in extreme environments like islands, mountain tops, and deserts stand out as some of the most unexpected achievements of life on earth. These evolutionary radiations have taken place in recently emerged, novel ecosystems and therefore challenge prevailing ideas about niche conservatism, but in general, we know little about the conditions that precipitate successful shifts into novel biomes and lead to diversification there. Here, we investigate the roles of adaptive evolution and pre-adaptation during shifts into the North American Deserts in the rock daisies (Perityleae). We sequenced 74 additional samples of Perityleae from across two geographically separated regions of biome contact between tropical deciduous forests and deserts in the Baja California peninsula and northwest mainland Mexico. We infer the first densely sampled time-calibrated phylogenetic hypothesis for this tribe based on a target capture sequence dataset and reconstruct their historical biogeography and ecology using Bayesian statistical inference with paleobiome-informed models, finding evidence for seven independent shifts into desert habitats occurring since the onset of aridification in the mid-Miocene. The earliest of these shifts occurred in the late Miocene out of tropical deciduous forests in northwest Mexico and led to an extensive radiation throughout all the North American deserts of species in the genus Laphamia, which account for the majority of extant desert Perityleae. Through detailed reconstructions of life-history and micro-habitat, we find evidence for a tight evolutionary correlation between a suffrutescent life history strategy and strict edaphic affinities for bare rocky outcrops in Perityleae, making it possible to infer historical occupancy of bare habitats as a precursor to successful shifts into the desert biome. Our analysis shows that the extensive diversification of desert Perityleae in the genus Laphamia descended from ancestors pre-adapted for dry conditions through past ecological specialization onto edaphically arid rock outcrops in the otherwise densely vegetated tropical deciduous forests of northwest Mexico. This provides some of the first empirical support for the long-standing hypothesis that desert plants evolved unique life forms prior to the onset of widespread arid conditions through pre-adaptation to edaphically dry microsites within older biomes, enabling them to readily shift and diversify in the novel environments as they recently emerged

Edaphic specialization onto bare, rocky outcrops as a factor in the evolution of desert angiosperms

Understanding the processes that enable organisms to shift into more arid environments as they emerge is critical for gauging resilience to climate change, yet these forces remain poorly known. In a comprehensive clade-based study, we investigate recent shifts into North American deserts in the rock daisies (tribe Perityleae), a diverse tribe of desert sunflowers (Compositae). We sample rock daisies across two separate contact zones between tropical deciduous forest and desert biomes in western North America and infer a time-calibrated phylogeny based on target capture sequence data. We infer biome shifts using Bayesian inference with paleobiome-informed models and find evidence for seven independent shifts into desert habitats since the onset of aridification in the late Miocene. The earliest shift occurred out of tropical deciduous forests and led to an extensive radiation throughout North American deserts that accounts for the majority of extant desert rock daisies. Estimates of life history and micro-habitat in the rock daisies reveal a correlation between a suffrutescent perennial life history and edaphic endemism onto rocky outcrops, an ecological specialization that evolved prior to establishment and diversification in deserts. That the insular radiation of desert rock daisies stemmed from ancestors preadapted for dry conditions as edaphic endemics in otherwise densely vegetated tropical deciduous forests in northwest Mexico underscores the crucial role of exaptation and dispersal for shifts into arid environments

Phylogenomics of Perityleae (Compositae) provides new insights into morphological and chromosomal evolution of the rock daisies

Rock daisies (Perityleae; Compositae) are a diverse clade of seven genera and ca. 84 minimum-rank taxa that mostly occur as narrow endemics on sheer rock cliffs throughout the southwest United States and northern Mexico. Taxonomy of Perityleae has traditionally been based on morphology and cytogenetics. To test taxonomic hypotheses and utility of characters emphasized in past treatments, we present the first densely sampled molecular phylogenies of Perityleae and reconstruct trait and chromosome evolution. We inferred phylogenetic trees from whole chloroplast genomes, nuclear ribosomal cistrons, and hundreds of low-copy nuclear genes using genome skimming and target capture. Discordance between sources of molecular data suggests an underappreciated history of hybridization in Perityleae. Phylogenies support the monophyly of subtribe Peritylinae, a distinctive group possessing a four-lobed disc corolla; however, all of the phylogenetic trees generated in this study reject the monophyly of the most species-rich genus, Perityle, as well as its sections: Perityle sect. Perityle, Perityle sect. Laphamia, and Perityle sect. Pappothrix. Using reversible jump MCMC, our results suggest that morphological characters traditionally used to classify members of Perityleae have evolved multiple times within the group. A base chromosome number x = 9 gave rise to higher base numbers in subtribe Peritylinae (x = 12, 13, 16, 17, 18, and 19) through polyploidization, followed by ascending or descending dysploidy. Most taxa constitute a monophyletic lineage with a base chromosome number of x = 17, with multiple neo-polyploidization events. These results demonstrate the advantages and obstacles of next-generation sequencing approaches in synantherology while laying the foundation for taxonomic revision and comparative study of the evolutionary ecology of Perityleae

Data for analyses reported in article

This Excel file contains one page for each of the four SAS analyses performed. The Codebook page describes the meaning of the headings. Please consult the Methods section of the article for further information about analyses and data

Herbivore diet breadth mediates the cascading effects of carnivores in food webs.

Predicting the impact of carnivores on plants has challenged community and food web ecologists for decades. At the same time, the role of predators in the evolution of herbivore dietary specialization has been an unresolved issue in evolutionary ecology. Here, we integrate these perspectives by testing the role of herbivore diet breadth as a predictor of top-down effects of avian predators on herbivores and plants in a forest food web. Using experimental bird exclosures to study a complex community of trees, caterpillars, and birds, we found a robust positive association between caterpillar diet breadth (phylodiversity of host plants used) and the strength of bird predation across 41 caterpillar and eight tree species. Dietary specialization was associated with increased enemy-free space for both camouflaged (n = 33) and warningly signaled (n = 8) caterpillar species. Furthermore, dietary specialization was associated with increased crypsis (camouflaged species only) and more stereotyped resting poses (camouflaged and warningly signaled species), but was unrelated to caterpillar body size. These dynamics in turn cascaded down to plants: a metaanalysis (n = 15 tree species) showed the beneficial effect of birds on trees (i.e., reduced leaf damage) decreased with the proportion of dietary specialist taxa composing a tree species' herbivore fauna. We conclude that herbivore diet breadth is a key functional trait underlying the trophic effects of carnivores on both herbivores and plants

Herbivore diet breadth mediates the cascading effects of carnivores in food webs

Predicting the impact of carnivores on plants has challenged community and food web ecologists for decades. At the same time, the role of predators in the evolution of herbivore dietary specialization has been an unresolved issue in evolutionary ecology. Here, we integrate these perspectives by testing the role of herbivore diet breadth as a predictor of top-down effects of avian predators on herbivores and plants in a forest food web. Using experimental bird exclosures to study a complex community of trees, caterpillars, and birds, we found a robust positive association between caterpillar diet breadth (phylodiversity of host plants used) and the strength of bird predation across 41 caterpillar and eight tree species. Dietary specialization was associated with increased enemy-free space for both camouflaged (n = 33) and warningly signaled (n = 8) caterpillar species. Furthermore, dietary specialization was associated with increased crypsis (camouflaged species only) and more stereotyped resting poses (camouflaged and warningly signaled species), but was unrelated to caterpillar body size. These dynamics in turn cascaded down to plants: a metaanalysis (n = 15 tree species) showed the beneficial effect of birds on trees (i.e., reduced leaf damage) decreased with the proportion of dietary specialist taxa composing a tree species’ herbivore fauna. We conclude that herbivore diet breadth is a key functional trait underlying the trophic effects of carnivores on both herbivores and plants