Evaluating plant lineage losses and gains in temperate forest understories: a phylogenetic perspective on climate change and nitrogen deposition.

Global change has accelerated local species extinctions and colonizations, often resulting in losses and gains of evolutionary lineages with unique features. Do these losses and gains occur randomly across the phylogeny? We quantified: temporal changes in plant phylogenetic diversity (PD); and the phylogenetic relatedness (PR) of lost and gained species in 2672 semi-permanent vegetation plots in European temperate forest understories resurveyed over an average period of 40 yr. Controlling for differences in species richness, PD increased slightly over time and across plots. Moreover, lost species within plots exhibited a higher degree of PR than gained species. This implies that gained species originated from a more diverse set of evolutionary lineages than lost species. Certain lineages also lost and gained more species than expected by chance, with Ericaceae, Fabaceae, and Orchidaceae experiencing losses and Amaranthaceae, Cyperaceae, and Rosaceae showing gains. Species losses and gains displayed no significant phylogenetic signal in response to changes in macroclimatic conditions and nitrogen deposition. As anthropogenic global change intensifies, temperate forest understories experience losses and gains in specific phylogenetic branches and ecological strategies, while the overall mean PD remains relatively stable.

Les changements globaux accélèrent les processus de colonisation et d'extinction locales d'espèces, aboutissant à des gains ou à des pertes de lignées évolutives uniques. Ces gains et pertes se produisent-ils de manière aléatoire dans l'arbre phylogénétique ? Nous avons mesuré: les changements de diversité phylogénétique; et la parenté phylogénétique des espèces végétales gagnées ou perdues dans 2672 placettes semi-permanentes disposées dans le sous-bois de forêts tempérées d'Europe sur une période moyenne de 40 ans. Une fois corrigée par la richesse spécifique, la diversité phylogénétique a légèrement augmenté au cours du temps dans les différentes placettes. Les espèces perdues ont une plus grande parenté phylogénétique que les espèces gagnées. Les espèces gagnées sont donc issues d'un plus grand nombre de lignées évolutives que les espèces perdues. Certaines lignées ont gagné ou perdu davantage d'espèces que ce qui est prédit par le hasard : les Ericaceae, les Fabaceae et les Orchidaceae ayant davantage perdu, tandis que les Amaranthaceae, les Cyperaceae, et les Rosaceae ont plus gagné. Il n'y a pas de signal phylogénétique des gains ou pertes d'espèces en réponse aux changements de conditions macroclimatiques ou des dépôts atmosphériques d'azote. Alors que les changements globaux d'origine anthropique s'intensifient, les sous-bois des forêts tempérées connaissent des gains et des pertes de certaines lignées évolutives et de certaines stratégies écologiques, sans que la diversité phylogénétique moyenne ne s'en trouve véritablement affectée.

El cambio global ha acelerado las extinciones y colonizaciones a escala local, lo que a menudo ha supuesto pérdidas y ganancias de linajes evolutivos con características únicas. Ahora bien, ¿estas pérdidas y ganancias ocurren aleatoriamente a lo largo de la filogenia? Cuantificamos: los cambios temporales en la diversidad filogenética de las plantas; y la relación filogenética de las especies perdidas y ganadas en 2.672 parcelas de vegetación semipermanente en sotobosques templados europeos y re-muestreadas durante un período promedio de 40 años. Al controlar por las diferencias en la riqueza de especies, la diversidad filogenética aumentó ligeramente con el tiempo y entre parcelas. Además, las especies perdidas dentro de las parcelas exhibieron un mayor grado de relación filogenética que las especies ganadas. Esto implica que las especies ganadas se originaron en un conjunto de linajes evolutivos más diversos que las especies perdidas. Ciertos linajes también perdieron y ganaron más especies de las esperadas aleatoriamente: Ericaceae, Fabaceae y Orchidaceae experimentaron pérdidas y Amaranthaceae, Cyperaceae y Rosaceae mostraron ganancias. Las pérdidas y ganancias de especies no mostraron ninguna señal filogenética significativa en respuesta a los cambios en las condiciones macro-climáticas y la deposición de nitrógeno. A medida que se intensifica el cambio global antropogénico, los sotobosques temperados experimentan pérdidas y ganancias en ramas filogenéticas y estrategias ecológicas específicas, mientras que la diversidad filogenética media general permanece relativamente estable.

Climate and plant community diversity in space and time.

Climate strongly shapes plant diversity over large spatial scales, with relatively warm and wet (benign, productive) regions supporting greater numbers of species. Unresolved aspects of this relationship include what causes it, whether it permeates to community diversity at smaller spatial scales, whether it is accompanied by patterns in functional and phylogenetic diversity as some hypotheses predict, and whether it is paralleled by climate-driven changes in diversity over time. Here, studies of Californian plants are reviewed and new analyses are conducted to synthesize climate-diversity relationships in space and time. Across spatial scales and organizational levels, plant diversity is maximized in more productive (wetter) climates, and these consistent spatial relationships are mirrored in losses of taxonomic, functional, and phylogenetic diversity over time during a recent climatic drying trend. These results support the tolerance and climatic niche conservatism hypotheses for climate-diversity relationships, and suggest there is some predictability to future changes in diversity in water-limited climates.

Functional traits mediate individualistic species-environment distributions at broad spatial scales while fine-scale species associations remain unpredictable.

PREMISE: Numerous processes influence plant distributions and co-occurrence patterns, including ecological sorting, limiting similarity, and stochastic effects. To discriminate among these processes and determine the spatial scales at which they operate, we investigated how functional traits and phylogenetic relatedness influence the distribution of temperate forest herbs. METHODS: We surveyed understory plant communities across 257 forest stands in Wisconsin and Michigan (USA) and applied Bayesian phylogenetic linear mixed-effects models (PGLMMs) to quantify how functional traits and phylogenetic relatedness influence the environmental distribution of 139 herbaceous plant species along broad edaphic, climatic, and light gradients. These models also allowed us to test how functional and phylogenetic similarity affect species co-occurrence within microsites. RESULTS: Leaf height, specific leaf area, and seed mass all influenced individualistic plant distributions along landscape-scale gradients in soil texture, soil fertility, light availability, and climate. In contrast, phylogenetic relationships did not consistently predict species-environment relationships. Neither functionally similar nor phylogenetically related herbs segregated among microsites within forest stands. CONCLUSIONS: Trait-mediated ecological sorting appears to drive temperate-forest community assembly, generating individualistic plant distributions along regional environmental gradients. This finding links classic studies in plant ecology and prior research in plant physiological ecology to current trait-based approaches in community ecology. However, our results fail to support the common assumption that limiting similarity governs local plant co-occurrences. Strong ecological sorting among forest stands coupled with stochastic fine-scale interactions among species appear to weaken deterministic, niche-based assembly processes at local scales.

Climate drives loss of phylogenetic diversity in a grassland community.

While climate change has already profoundly influenced biodiversity through local extinctions, range shifts, and altered interactions, its effects on the evolutionary history contained within sets of coexisting species-or phylogenetic community diversity-have yet to be documented. Phylogenetic community diversity may be a proxy for the diversity of functional strategies that can help sustain ecological systems in the face of disturbances. Under climatic warming, phylogenetic diversity may be especially vulnerable to decline in plant communities in warm, water-limited regions, as intensified water stress eliminates drought-intolerant species that may be relicts of past wetter climates and may be distantly related to coexisting species. Here, we document a 19-y decline of phylogenetic diversity in a grassland community as moisture became less abundant and predictable at a critical time of the year. This decline was strongest in native forbs, particularly those with high specific leaf area, a trait indicating drought sensitivity. This decline occurred at the small spatial scale where species interact, but the larger regional community has so far been buffered against loss of phylogenetic diversity by its high levels of physical and biotic heterogeneity.

Climate drivers of adult insect activity are conditioned by life history traits.

Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanisation on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Species extended their period of adult activity similarly in warmer conditions regardless of voltinism classification. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments are likely underreported. This effort provides a framework to address the drivers of adult insect phenology at continental scales and a basis for predicting species response to environmental change.

Climate, urbanization, and species traits interactively drive flowering duration.

A wave of green leaves and multi-colored flowers advances from low to high latitudes each spring. However, little is known about how flowering offset (i.e., ending of flowering) and duration of populations of the same species vary along environmental gradients. Understanding these patterns is critical for predicting the effects of future climate and land-use change on plants, pollinators, and herbivores. Here, we investigated potential climatic and landscape drivers of flowering onset, offset, and duration of 52 plant species with varying key traits. We generated phenology estimates using >270,000 community-science photographs and a novel presence-only phenometric estimation method. We found longer flowering durations in warmer areas, which is more obvious for summer-blooming species compared to spring-bloomers driven by their strongly differing offset dynamics. We also found that higher human population density and higher annual precipitation are associated with delayed flowering offset and extended flowering duration. Finally, offset of woody perennials was more sensitive than herbaceous species to both climate and urbanization drivers. Empirical forecast models suggested that flowering durations will be longer in 2030 and 2050 under representative concentration pathway (RCP) 8.5, especially for summer-blooming species. Our study provides critical insight into drivers of key flowering phenophases and confirms that Hopkins' Bioclimatic Law also applies to flowering durations for summer-blooming species and herbaceous spring-blooming species.

Changes in taxonomic and phylogenetic diversity in the Anthropocene.

To better understand how ecosystems are changing, a multifaceted approach to measuring biodiversity that considers species richness (SR) and evolutionary history across spatial scales is needed. Here, we compiled 162 datasets for fish, bird and plant assemblages across the globe and measured how taxonomic and phylogenetic diversity changed at different spatial scales (within site α diversity and between sites spatial ß diversity). Biodiversity change is measured from these datasets in three ways: across land use gradients, from species lists, and through sampling of the same locations across two time periods. We found that local SR and phylogenetic α diversity (Faith's PD (phylogenetic diversity)) increased for all taxonomic groups. However, when measured with a metric that is independent of SR (phylogenetic species variation, PSV), phylogenetic α diversity declined for all taxonomic groups. Land use datasets showed declines in SR, Faith's PD and PSV. For all taxonomic groups and data types, spatial taxonomic and phylogenetic ß diversity decreased when measured with Sorensen dissimilarity and phylogenetic Sorensen dissimilarity, respectively, providing strong evidence of global biotic homogenization. The decoupling of α and ß diversity, as well as taxonomic and phylogenetic diversity, highlights the need for a broader perspective on contemporary biodiversity changes. Conservation and environmental policy decisions thus need to consider biodiversity beyond local SR to protect biodiversity and ecosystem services.

Global environmental change effects on plant community composition trajectories depend upon management legacies.

The contemporary state of functional traits and species richness in plant communities depends on legacy effects of past disturbances. Whether temporal responses of community properties to current environmental changes are altered by such legacies is, however, unknown. We expect global environmental changes to interact with land-use legacies given different community trajectories initiated by prior management, and subsequent responses to altered resources and conditions. We tested this expectation for species richness and functional traits using 1814 survey-resurvey plot pairs of understorey communities from 40 European temperate forest datasets, syntheses of management transitions since the year 1800, and a trait database. We also examined how plant community indicators of resources and conditions changed in response to management legacies and environmental change. Community trajectories were clearly influenced by interactions between management legacies from over 200 years ago and environmental change. Importantly, higher rates of nitrogen deposition led to increased species richness and plant height in forests managed less intensively in 1800 (i.e., high forests), and to decreases in forests with a more intensive historical management in 1800 (i.e., coppiced forests). There was evidence that these declines in community variables in formerly coppiced forests were ameliorated by increased rates of temperature change between surveys. Responses were generally apparent regardless of sites' contemporary management classifications, although sometimes the management transition itself, rather than historic or contemporary management types, better explained understorey responses. Main effects of environmental change were rare, although higher rates of precipitation change increased plant height, accompanied by increases in fertility indicator values. Analysis of indicator values suggested the importance of directly characterising resources and conditions to better understand legacy and environmental change effects. Accounting for legacies of past disturbance can reconcile contradictory literature results and appears crucial to anticipating future responses to global environmental change.

Community phylogeny of the globally critically imperiled pine rockland ecosystem.

PREMISE OF THE STUDY: Community phylogenetic methods incorporate information on evolutionary relationships into studies of organismal assemblages. We used a community phylogenetic framework to investigate relationships and biogeographic affinities and to calculate phylogenetic signal of endemism and invasiveness for the flora of the pine rocklands-a globally critically imperiled ecosystem with a significant portion of its distribution in South Florida, United States. METHODS: We reconstructed phylogenetic relationships of 538 vascular plant taxa, which represent 92.28% of the vascular flora of the pine rocklands. We estimated phylogenetic signal for endemism and invasiveness using phylogenetic generalized linear mixed models. We determined the native range for each species in the data set and calculated the total number of species sourced from each region and all possible combinations of these regions. KEY RESULTS: The pine rockland flora includes representatives of all major vascular plant lineages, and most species have native ranges in the New World. There was strong phylogenetic signal for endemism, but not for invasiveness. CONCLUSIONS: Community phylogenetics has high potential value for conservation planning, particularly for fragmented and endangered ecosystems like the pine rockland. Strong phylogenetic signal for endemic species in our data set, which also tend to be threatened or endangered, can help to identify species at risk, as well as fragments where those species occur, highlighting conservation priorities. Our results indicate, at least in the pine rockland ecosystem, no phylogenetic signal for invasive species, and thus other information must be used to predict the potential for invasiveness.

Community assembly of the ferns of Florida.

PREMISE OF THE STUDY: Many ecological and evolutionary processes shape the assembly of organisms into local communities from a regional pool of species. We analyzed phylogenetic and functional diversity to understand community assembly of the ferns of Florida at two spatial scales. METHODS: We built a phylogeny for 125 of the 141 species of ferns in Florida using five chloroplast markers. We calculated mean pairwise dissimilarity (MPD) and mean nearest taxon distance (MNTD) from phylogenetic distances and functional trait data for both spatial scales and compared the results to null models to assess significance. KEY RESULTS: Our results for over vs. underdispersion in functional and phylogenetic diversity differed depending on spatial scale and metric considered. At the county scale, MPD revealed evidence for phylogenetic overdispersion, while MNTD revealed phylogenetic and functional underdispersion, and at the conservation area scale, MPD revealed phylogenetic and functional underdispersion while MNTD revealed evidence only of functional underdispersion. CONCLUSIONS: Our results are consistent with environmental filtering playing a larger role at the smaller, conservation area scale. The smaller spatial units are likely composed of fewer local habitat types that are selecting for closely related species, with the larger-scale units more likely to be composed of multiple habitat types that bring together a larger pool of species from across the phylogeny. Several aspects of fern biology, including their unique physiology and water relations and the importance of the independent gametophyte stage of the life cycle, make ferns highly sensitive to local, microhabitat conditions.

Can functional traits account for phylogenetic signal in community composition?

Phylogenetic and functional trait-based analyses inform our understanding of community composition, yet methods for quantifying the overlap in information derived from functional traits and phylogenies remain underdeveloped. Does adding traits to analyses of community composition reduce the phylogenetic signal in the residual variation? If not, then measured functional traits alone may be insufficient to explain community assembly. We propose a general statistical framework to quantify the proportion of phylogenetic pattern in community composition that remains after including measured functional traits. We then illustrate the framework with applications to two empirical data sets. Both data sets showed strong phylogenetic attraction, with related species likely to co-occur in the same communities. In one data set, including traits eliminated all phylogenetic signals in the residual variation of both abundance and presence/absence patterns. In the second data set, including traits reduced phylogenetic signal in residuals by 25% and 98% for abundance and presence/absence data, respectively. Our framework provides an explicit way to estimate how much phylogenetic community pattern remains in the residual variation after including measured functional traits. Knowing that functional traits account for most of the phylogenetic pattern should provide confidence that important traits for phylogenetic community structure have been identified. Conversely, knowing that there is unexplained residual phylogenetic information should spur the search for additional functional traits or other processes underlying community assembly.

Combining community resurvey data to advance global change research.

More and more ecologists have started to resurvey communities sampled in earlier decades to determine long-term shifts in community composition and infer the likely drivers of the ecological changes observed. However, to assess the relative importance of, and interactions among, multiple drivers joint analyses of resurvey data from many regions spanning large environmental gradients are needed. In this paper we illustrate how combining resurvey data from multiple regions can increase the likelihood of driver-orthogonality within the design and show that repeatedly surveying across multiple regions provides higher representativeness and comprehensiveness, allowing us to answer more completely a broader range of questions. We provide general guidelines to aid implementation of multi-region resurvey databases. In so doing, we aim to encourage resurvey database development across other community types and biomes to advance global environmental change research.

Drivers of observed biotic homogenization in pine barrens of central Wisconsin.

Fire suppression throughout the 20th century greatly altered plant communities in fire-dominated systems across North America. Our ability to assess these effects over the long-term, however, is handicapped by the paucity of baseline data. Here, we used detailed baseline data from the 1950s to track changes in the over- and understory composition of pine-barrens vegetation growing on sandy, glacial lake-bed sediments in central Wisconsin. We expected fire suppression to favor succession to closed-canopy conditions, leading to decreases in shade-intolerant and fire-adapted species and consequent reductions in alpha and gamma diversity. We also expected beta diversity to decline due to increases in shade-tolerant, fire-sensitive, and exotic species. In fact, fire suppression has greatly altered the structure and composition of these pine-barrens communities over the past 54 years. Woody, wind-pollinated, and shade-tolerant species all increased in richness and abundance, as expected, with succession following fire suppression. Contrary to expectations, local and regional species richness increased by 12% and 26%, respectively, while Shannon beta diversity declined 24.1%. Increases in canopy coverage and number of native species appear to have driven this biotic homogenization. In contrast, increases in exotic species in our study did not promote biotic homogenization, reflecting their relative rarity across sites. Our findings highlight the key role fire plays in shaping the assembly of these pine-barrens communities.

Climate change filtered out resource-acquisitive plants in a temperate grassland in Inner Mongolia, China.

Global climate change has led to the decline of species and functional diversity in ecosystems, changing community composition and ecosystem functions. However, we still know little about how species with different resource-use strategies (different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits, including acquisitive resource-use strategy and conservative resource-use strategy) would change in response to climate change, and how the changes in the diversity of species with different resource-use strategies may influence community-level productivity. Here, using long-term (1982-2017) observatory data in a temperate grassland in Inner Mongolia, we investigated how climate change had affected the species richness (SR) and functional richness (FRic) for the whole community and for species with different resource-use strategies. Specifically, based on data for four traits representing leaf economics spectrum (leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, and specific leaf area), we divided 81 plant species appearing in the grassland community into three plant functional types representing resource-acquisitive, medium, and resource-conservative species. We then analyzed the changes in community-level productivity in response to the decline of SR and FRic at the community level and for different resource-use strategies. We found that community-level SR and FRic decreased with drying climate, which was largely driven by the decline of diversity for resource-acquisitive species. However, community-level productivity remained stable because resource-conservative species dominating this grassland were barely affected by climate change. Our study revealed distinctive responses of species with different resource-use strategies to climate change and provided a new approach based on species functional traits for predicting the magnitude and direction of climate change effects on ecosystem functions.

Online toolkits for collaborative and inclusive global research in urban evolutionary ecology.

Urban evolutionary ecology is inherently interdisciplinary. Moreover, it is a field with global significance. However, bringing researchers and resources together across fields and countries is challenging. Therefore, an online collaborative research hub, where common methods and best practices are shared among scientists from diverse geographic, ethnic, and career backgrounds would make research focused on urban evolutionary ecology more inclusive. Here, we describe a freely available online research hub for toolkits that facilitate global research in urban evolutionary ecology. We provide rationales and descriptions of toolkits for: (1) decolonizing urban evolutionary ecology; (2) identifying and fostering international collaborative partnerships; (3) common methods and freely-available datasets for trait mapping across cities; (4) common methods and freely-available datasets for cross-city evolutionary ecology experiments; and (5) best practices and freely available resources for public outreach and communication of research findings in urban evolutionary ecology. We outline how the toolkits can be accessed, archived, and modified over time in order to sustain long-term global research that will advance our understanding of urban evolutionary ecology.

Phylogenetic diversity of eastern Asia-eastern North America disjunct plants is mainly associated with divergence time.

The underlying causes of biodiversity disparities among geographic regions have long been a fundamental theme in ecology and evolution. However, the patterns of phylogenetic diversity (PD) and phylogenetic beta diversity (PBD) of congeners that are disjunctly distributed between eastern Asia-eastern North America (EA-ENA disjuncts) and their associated factors remain unknown. Here we investigated the standardized effect size of PD (SES-PD), PBD, and potentially associated factors in 11 natural mixed forest sites (five in EA and six in ENA) where abundant EA-ENA disjuncts occur. We found that the disjuncts in ENA possessed higher SES-PD than those in EA at the continental scale (1.96 vs -1.12), even though the number of disjunct species in ENA is much lower than in EA (128 vs 263). SES-PD of the EA-ENA disjuncts tended to decrease with increasing latitude in 11 sites. The latitudinal diversity gradient of SES-PD was stronger in EA sites than in ENA sites. Based on the unweighted unique fraction metric (UniFrac) distance and the phylogenetic community dissimilarity, PBD showed that the two northern sites in EA were more similar to the six-site ENA group than to the remaining southern EA sites. Based on the standardized effect size of mean pairwise distances (SES-MPD), nine of eleven studied sites showed a neutral community structure (-1.96 ≤ SES-MPD ≤ 1.96). Both Pearson's r and structural equation modeling suggested that SES-PD of the EA-ENA disjuncts was mostly associated with mean divergence time. Moreover, SES-PD of the EA-ENA disjuncts was positively correlated with temperature-related climatic factors, although negatively correlated with mean diversification rate and community structure. By applying approaches from phylogenetics and community ecology, our work sheds light on historical patterns of the EA-ENA disjunction and paves the way for further research.

Functional trait data for vascular plant species from northeastern North America.

Wisconsin's plant communities are responding to shifting disturbance regimes, habitat fragmentation, aerial nitrogen deposition, exotic species invasions, ungulate herbivory, and successional processes. To better understand how plant functional traits mediate species' responses to changing environmental conditions, we collected a large set of functional trait data for vascular plant species occupying Wisconsin forests and grasslands. We used standard protocols to make 76,213 measurements of 34 quantitative traits. These data provide rich information on genome size, physical leaf traits (length, width, circularity, thickness, dry matter content, specific leaf area, etc.), chemical leaf traits (carbon, nitrogen, phosphorus, potassium, calcium, magnesium, ash), life history traits (vegetative and flower heights, seed mass), and traits affecting plant palatability (leaf fiber, fat, and lignin). These trait values derive from replicate measurements on 12+ individuals of each species from multiple sites and 45+ individuals for a selected subset of species. Measurements typically reflect values for individuals although some chemical traits involved composite samples from several individuals at the same site. We also qualitatively characterized each species by plant family, woodiness, functional group, and Raunkiaer lifeform. These data allow us to characterize trait dimensionality, differentiation, and covariation among temperate plant species (e.g., leaf and stem economic syndromes). We can also characterize species' responses to environmental gradients and drivers of ecological change. With survey and resurvey data available from >400 sites in Wisconsin, we can analyze variation in community trait distributions and diversity over time and space. These data therefore allow us to assess how trait divergence vs. convergence affects community assembly and how traits may be related to half-century shifts in the distribution and abundance of these species. The data set can be used for non-commercial purposes. The data set is licensed as follows: CC-By Attribution 4.0 International. We request users cite both the OSF data set and this Ecology data paper publication.

Mammalian body size is determined by interactions between climate, urbanization, and ecological traits.

Anthropogenically-driven climate warming is a hypothesized driver of animal body size reductions. Less understood are effects of other human-caused disturbances on body size, such as urbanization. We compiled 140,499 body size records of over 100 North American mammals to test how climate and human population density, a proxy for urbanization, and their interactions with species traits, impact body size. We tested three hypotheses of body size variation across urbanization gradients: urban heat island effects, habitat fragmentation, and resource availability. Our results demonstrate that both urbanization and temperature influence mammalian body size variation, most often leading to larger individuals, thus supporting the resource availability hypothesis. In addition, life history and other ecological factors play a critical role in mediating the effects of climate and urbanization on body size. Larger mammals and species that utilize thermal buffering are more sensitive to warmer temperatures, while flexibility in activity time appears to be advantageous in urbanized areas. This work highlights the value of using digitized, natural history data to track how human disturbance drives morphological variation.

Analyzing a phenological anomaly in Yucca of the southwestern United States.

Yucca in the American desert Southwest typically flowers in early spring, but a well-documented anomalous bloom event occurred during an unusually cold and wet late fall and early winter 2018-2019. We used community science photographs to generate flowering presence and absence data. We fit phenoclimatic models to determine which climate variables are explanatory for normal flowering, and then we tested if the same conditions that drive normal blooming also drove the anomalous blooming event. Flowering for Yucca brevifolia (Joshua tree) and Yucca schidigera (Mojave yucca) is driven by complex, nonlinear interactions between daylength, temperature, and precipitation. To our surprise, early-season flowering odds are highest in colder and drier conditions, especially for Joshua trees, but increase with precipitation late-season. However, the models used to fit normal blooming overpredicted the number of anomalous blooms compared to what was actually observed. Thus, predicting anomalous flowering events remains a challenge for quantitative phenological models. Because our model overpredicted the number of anomalous blooms, there are likely other factors, such as biotic interactions or other seasonal factors, which may be especially important in controlling what is presumed to be rare, out-of-season flowering in desert-adapted Yucca.

Body size trends in response to climate and urbanization in the widespread North American deer mouse, Peromyscus maniculatus.

Body size decline is hypothesized to be a key response to climate warming, including warming driven by urban heat islands. However, urbanization may also generate selective gradients for body size increases in smaller endotherms via habitat fragmentation. Here we utilize a densely sampled, multi-source dataset to examine how climate and urbanization affect body size of Peromyscus maniculatus (PEMA), an abundant rodent found across North America. We predicted PEMA would conform to Bergmann's Rule, e.g. larger individuals in colder climates, spatially and temporally. Hypotheses regarding body size in relation to urbanization are less clear; however, with increased food resources due to greater anthropogenic activity, we expected an increase in PEMA size. Spatial mixed-models showed that PEMA conform to Bergmann's Rule and that PEMA were shorter in more urbanized areas. With the inclusion of decade in mixed-models, we found PEMA mass, but not length, is decreasing over time irrespective of climate or population density. We also unexpectedly found that, over time, smaller-bodied populations of PEMA are getting larger, while larger-bodied populations are getting smaller. Our work highlights the importance of using dense spatiotemporal datasets, and modeling frameworks that account for bias, to better disentangle broad-scale climatic and urbanization effects on body size.