Christina M. Caruso

Ecological data are increasingly collected by networks of collaborators using replicated designs and methods, which can significantly improve the quality and quantity of data throughout the ecological niche and geographic range of species or communities. The coordinated generation and management of data is critical for producing datasets (Standard Data Products) across multiple sites that can be used by different researchers, over extended time periods and for multiple purposes. We describe and use a Quality Assurance framework for the design, collection and production of reproducible Standard Data Products for distributed ecology projects. We identified six critical project elements of a Quality Assurance framework (QA1‐6) to produce ecological Standard Data Products with high immediate and future value. We applied the Quality Assurance framework to the Plantpopnet project as a case‐study. Plantpopnet is a coordinated distributed system for population macroecology using the model species Plantago lanceolata . We mapped Plantpopnet activities to the Quality Assurance Framework as follows: (QA1) Measurable objectives : research project objectives with data requirements, (QA2) Process control : governance policies, (QA3) Project specific procedures : model organism selection and data collection protocol, (QA4) Supporting production of high quality data : recruitment, retention and engagement of participants, (QA5) Data management : data management plan and reproducible data cleaning workflow, (QA6) Production and management of outputs : Standard Data Products and papers. Explicit use of Quality Assurance, project and data management tools together with standardised ecological methods facilitated the design, collection, maintenance and sustainability of high‐quality data products. We provide a Quality Assurance framework together with governance documents, code and data for a reproducible Standard Data Product. This framework supports a distributed funding model which can be sustainably applied to facilitate future research and applications of coordinated distributed ecology projects.

Premise of research: In plant species that depend on pollinators to produce seeds, declines in pollinator populations should strengthen natural selection for floral traits that increase outcross pollen receipt by increasing the probability of pollinator visitation. One such trait is floral longevity, the amount of time that a flower is open and functional. If flowers that are open longer have a higher probability of pollinator visitation and this pollination benefit outweighs the resource cost of maintaining floral tissue, then pollinator decline should strengthen selection for extended floral longevity. Methodology: To test whether pollinator decline could strengthen selection for extended longevity, we studied the pollinator-dependent species Lobelia siphilitica . We exposed L. siphilitica plants to either an ambient open-pollination treatment or a reduced open-pollination treatment that simulates pollinator decline. Within each pollination treatment, we measured floral longevity and seeds per fruit and used these data to estimate directional selection on longevity. This experiment was repeated twice. Pivotal results: In one experiment, there was significant selection within both ambient and reduced pollination treatments for shortened (rather than extended) floral longevity. In the other experiment, selection on floral longevity within both ambient and reduced pollination treatments was not significantly different from zero. Conclusions: We found no evidence of selection for extended floral longevity, regardless of the pollination environment. These results suggest that pollinator decline will not strengthen selection for extended longevity and thus that pollinator-dependent species such as L. siphilitica may not respond to pollinator decline by evolving extended floral longevity.

Premise: Declines in pollinator populations can reduce pollination services to plants, resulting in lower seed production. In response to these reductions, plants could increase the probability of pollinator visitation by plastically extending floral longevity. However, whether extended floral longevity increases seed production as pollinators decline depends on the limits to and costs of plasticity in longevity, both of which could be affected by drought stress. Methods: To test whether drought stress affects the limits to and costs of plasticity in floral longevity in response to pollinator decline, we exposed Lobelia siphilitica to droughted and well‐watered treatments and measured floral longevity and the number of seeds produced by flowers pollinated on day 1 vs. day 5 of the female phase. If floral longevity is shorter in the droughted treatment, then drought stress could limit the expression of extended longevity. If delaying pollination until day 5 reduces seed production more in the droughted treatment, then drought stress could increase the cost of extended longevity. Results: The droughted treatment reduced floral longevity by ~18% but did not affect the number of seeds produced by flowers pollinated on day 1 vs. day 5. Instead, delaying pollination until day 5 reduced the number of seeds by ~24% in both the droughted and well‐watered treatments. Conclusions: Drought stress does not affect the cost of plasticity in floral longevity but could limit the expression of extended longevity. Consequently, whether extended floral longevity could increase seed production as pollinators decline may depend on human‐induced changes in precipitation.

Background and Aims: Trees are increasingly at risk of maladaptation to their environment as climates change rapidly worldwide. Although adaptive evolution through natural selection is a key mechanism by which populations and species can persist in changing environments, we have limited information regarding the phenotypic traits under selection in warm and dry environments. We answer the following research questions: (1) What ecophysiological traits are under selection in warm, dry environments? (2) Does intrapopulation trait integration affect the response to selection in the warmer, drier site? (3) Is the plastic response of traits under selection adaptive? Methods: Using Picea mariana (black spruce) as a case study, we studied 425 trees representing seven provenances across three 50-year-old common garden trials established along a spatial climate gradient across eastern Canada. We measured height growth rate as a performance metric, and ten traits that reflect water use, thermoregulation, structural support and photosynthetic rate. Results: All traits were under selection in at least one site, mostly in combination with other traits. For two trait combinations, the strength of selection gradients significantly increased from the colder, wetter site to the warmer, drier site: water use efficiency (WUE) with Huber value (HV), and carbon-to-nitrogen ratio (CN) with HV. In the warmer and drier site, trait–trait correlations among these three traits were largely absent, except for CN:HV in two provenances. Overall, reaction norms suggest that the plastic response was not aligned with selection for trait pairs in warm, dry climates. Conclusions: Results suggest that adaptive evolution in response to climate change in P. mariana may favour phenotypes with fewer needles that are conservative for water and resource use. In the seven study provenances, intrapopulation trait integration should minimally impede adaptive evolution, but plastic responses to warmer and drier conditions may constrain the expression of optimally adapted phenotypes.

Individual plant size often determines the vital rates of growth, survival and reproduction. However, size can be measured in several ways (e.g. height, biomass, leaf length). There is no consensus on the best size metric for modelling vital rates in plants. Demographic datasets are expanding in geographic extent, leading to choices about how to represent size for the same species in multiple ecological contexts. If the choice of size variable varies among locations, inter‐population comparative demography increases in complexity. Here, we present a framework to perform size metric selection in large‐scale demographic studies. We highlight potential pitfalls and suggest methods applicable to diverse study organisms. We assessed the performance of five different size metrics for the perennial herb Plantago lanceolata , across 55 populations on three continents within its native and non‐native ranges, using the spatially replicated demographic dataset PlantPopNet. We compared the performance of each candidate size metric for four vital rates (growth, survival, flowering probability and reproductive output) using generalized linear mixed models. We ranked the candidate size metrics based on their overall performance (highest generalized R ² ) and homogeneity of performance across populations (lowest total magnitude of, and variance in, population‐level error). While all size variables performed well for modelling vital rates, the number of leaves (modelled as a discrete variable, without transformation) was selected as the best size metric, followed by leaf length. We show how to interrogate potential trade‐offs between overall explanatory power and homogeneity of predictions across populations in any organism. Synthesis . Size is an important determinant of vital rates. Using a dataset of unprecedented spatial extent, we find (a) consistent size‐based models of growth, survival and reproduction across native and non‐native populations of this cosmopolitan plant species and (b) that several tested size metrics perform similarly well. This is encouraging for large‐scale demographic studies and for comparative projects using different size metrics, as they may be robust to this methodological difference.

In response to novel anthropogenic stresses, defense strategies, including resistance, tolerance, and escape, can evolve. However, if the evolution of one or more of these strategies is limited by weak natural selection or a lack of genetic variation, then a mixed strategy (e.g., resistance and tolerance) is unlikely to evolve. To determine the mechanisms that limit the evolution of defense strategies, we studied escape from and tolerance to glyphosate herbicide in Amaranthus palmeri, an agricultural weed that has evolved glyphosate resistance. We grew A. palmeri in fields planted with corn, soybean, or no crop; manipulated their exposure to glyphosate; and measured escape and tolerance. We did not detect selection or genetic variation for glyphosate escape in any agricultural environment, suggesting that a mixed strategy of resistance and escape is unlikely to evolve in A. palmeri. We also did not detect selection for glyphosate tolerance, but there was genetic variation for tolerance in a corn crop environment, suggesting the potential for a mixed strategy of resistance and tolerance to evolve in A. palmeri in only a subset of environments. These results suggest that exposure to herbicides is unlikely to cause the widespread evolution of a mixed defense strategy in agricultural weeds.

Human‐mediated environmental change, by reducing mean fitness, is hypothesized to strengthen selection on traits that mediate interactions among species. For example, human‐mediated declines in pollinator populations are hypothesized to reduce mean seed production by increasing the magnitude of pollen limitation and thus strengthen pollinator‐mediated selection on floral traits that increase pollinator attraction or pollen transfer efficiency. To test this hypothesis, we measured two female fitness components and six floral traits of Lobelia siphilitica plants exposed to supplemental hand‐pollination, ambient open‐pollination, or reduced open‐pollination treatments. The reduced treatment simulated pollinator decline, while the supplemental treatment was used to estimate pollen limitation and pollinator‐mediated selection. We found that plants in the reduced pollination treatment were significantly pollen limited, resulting in pollinator‐mediated selection for taller inflorescences and more vibrant petals, both traits that could increase pollinator attraction. This contrasts with plants in the ambient pollination treatment, where reproduction was not pollen limited and there was not significant pollinator‐mediated selection on any floral trait. Our results support the hypothesis that human‐mediated environmental change can strengthen selection on traits of interacting species and suggest that these traits have the potential to evolve in response to changing environments.

Premise: Pollinator decline, by reducing seed production, is predicted to strengthen natural selection on floral traits. However, the effect of pollinator decline on gender dimorphic species (such as gynodioecious species, where plants produce female or hermaphrodite flowers) may differ between the sex morphs: if pollinator decline reduces the seed production of females more than hermaphrodites, then it should also have a larger effect on selection on floral traits in females than in hermaphrodites.Methods: To simulate pollinator decline, we experimentally reduced pollinator access to female and hermaphrodite Lobelia siphilitica plants. We compared the seed production of plants in the reduced pollination treatment to plants that were exposed to ambient pollination conditions. Within each treatment, we also measured directional selection on four floral traits of females and hermaphrodites.Results: Experimentally reducing pollination decreased seed production of both females and hermaphrodites by ~21%. Reducing pollination also strengthened selection on floral traits, but this effect was not larger in females than in hermaphrodites. Instead, reducing pollination intensified selection for taller inflorescences in hermaphrodites, but did not intensify selection on any floral trait in females.Conclusions: Our results suggest that pollinator decline will not have a larger effect on either seed production or selection on floral traits of female plants. As such, any effect of pollinator decline on seed production may be similar for gender dimorphic and monomorphic species. However, the potential for floral traits of females (and thus of gender dimorphic species) to evolve in response to pollinator decline may be limited.

Understanding the causes and limits of population divergence in phenotypic traits is a fundamental aim of evolutionary biology, with the potential to yield predictions of adaptation to environmental change. Reciprocal transplant experiments and the evaluation of optimality models suggest that local adaptation is common but not universal, and some studies suggest that trait divergence is highly constrained by genetic variances and covariances of complex phenotypes. We analyze a large database of population divergence in plants and evaluate whether evolutionary divergence scales positively with standing genetic variation within populations (evolvability), as expected if genetic constraints are evolutionarily important. We further evaluate differences in divergence and evolvability–divergence relationships between reproductive and vegetative traits and between selfing, mixed-mating, and outcrossing species, as these factors are expected to influence both patterns of selection and evolutionary potentials. Evolutionary divergence scaled positively with evolvability. Furthermore, trait divergence was greater for vegetative traits than for floral (reproductive) traits, but largely independent of the mating system. Jointly, these factors explained ~40% of the variance in evolutionary divergence. The consistency of the evolvability–divergence relationships across diverse species suggests substantial predictability of trait divergence. The results are also consistent with genetic constraints playing a role in evolutionary divergence.

Premise: Pollinator declines can reduce the quantity and quality of pollination services, resulting in less pollen deposited on flowers and lower seed production by plants. In response to these reductions, plant species that cannot autonomously self‐pollinate and thus are dependent on pollinators to set seed could plastically adjust their floral traits. Such plasticity could increase the opportunity for outcross pollination directly, as well as indirectly by affecting inflorescence traits.Methods: To test whether plants can respond to pollinator declines by plastically adjusting their floral traits, we simulated declines by experimentally reducing pollinator access to Lobelia siphilitica plants and measuring two traits of early‐ and late‐season flowers: (1) floral longevity; and (2) sex‐phase duration. To test whether plasticity in these floral traits affected inflorescence traits, we measured daily display size and phenotypic gender.Results: We found that experimentally reducing pollination did not affect female‐phase duration, but did extend the male‐phase duration of early‐season flowers by 13% and the longevity of late‐season flowers by 12.8%. However, plants with an extended male phase did not have a more male‐biased phenotypic gender, and plants with an extended floral longevity did not have a larger daily display.Conclusions: Our results suggest that plants can respond to pollinator declines by plastically adjusting both the longevity and sex‐phase duration of their flowers. If this plasticity increases the opportunity for outcross pollination, then it could be one mechanism by which pollinator‐dependent plant species maintain seed production as pollinators decline.