Susan J. Mazer, Ph.D. - US grants

The process and consequences of natural selection in wild plant species will be pursued in three specific and complementary research projects. In the first, the causes and evolutionary significance of variation in life history and reproductive traits within and among different populations of several sympatric wild plant species in the eastern Sierra Mountains will be investigated. Another project will continue ongoing experimental studies of the constancy of genetic parameter estimates (heritability and genetic correlation) in wild radish in which growing conditions will be manipulated to evaluate the rate and direction of evolution under diverse environmental conditions. The third project will involve work to establish the relative importance of seed dispersal and post-dispersal events as determinants of the species distributions of economically important trees in a Peruvian rainforest.

9520611 Mazer The focus of the proposed research is to better understand competition for reproduction among plants. Plants that produce flowers will compete because ultimately there are many more pollen grains produced than there are flowers to be fertilized. The experiments proposed will focus on the competition that occurs after pollination. One consequence of competition during this phase is that some individuals may father more seeds in the next generation than other individuals. Are there differences among plants in this ability? What influences how well a plant's pollen performs during this phase? The investigators will examine elements of the environment and of the plant itself to determine: 1) how these factors influence a plant's success during the post-pollination phase; 2) the number of seeds fathered following competition; 3) pollen performance on burned and unburned habitats; and 4) success by plants competing for flowers with varying morphologies. Flowering plants may have invaded so many niches in the world because of their ability to remove inferior genes through the type of competition described above. Thus this research may have important implications for all flowering plants. Moreover, the research may yield information useful in applied fields, as understanding of pollen competition could be applied to improvements in crop species.

Mazer
9815300

Flowering plants have evolved a variety of mechanisms that ensure pollination. Many species are "outcrossing", relying on insects to transfer pollen, while others are self-fertilized (each flower pollinates itself). The evolution of self-fertilization from outcrossing ancestors has often had similar outcomes. For example, animal-pollinated outcrossers often produce larger flowers and higher ratios of pollen to ovule production per flower than closely related self-fertilizing species.

This study asks: Does natural selection operate as predicted to generate more subtle genetic differences between selfing and outcrossing species? Several predictions will be tested, including that outcrossers are more likely than selfers to exhibit an inverse relationship between the allocation of resources to male vs. female function. Three pairs of closely related outcrossing and self-fertilizing species in the wildflower genus Clarkia will be compared with respect to genetic variation in, and genetically based correlations among, male and female reproductive traits. Greenhouse and field experiments will be conducted to examine constraints on the independent evolution of floral traits in outcrossers vs. selfers.

Ten to twelve undergraduate students and one post-doctoral researcher will receive training in evolutionary theory, plant breeding and reproduction, statistical analysis, and the presentation of results. This study will contribute to our understanding of both the potential and limits of natural selection to effect evolutionary changes associated with mating system.

0081024
Mazer and Reichman

A fundamental problem in population biology is determining the extent of the spread of novel genes in natural populations and its effect on evolutionary and ecological processes. In plants, the introduction of novel genetic material into indigenous populations is becoming more common due to the accidental spread of seeds and due to attempts to restore native vegetation. While the introduction of new genetic material may benefit populations with little genetic diversity, there are also serious potential risks. For example, when individuals representing genetically distinct populations mate and hybridize, the mixing of the genetic material from the two populations through sexual reproduction can result in hybrid offspring (or grandoffspring, two generations later) that are poorly adapted to local ecological conditions. This phenomenon is known as "hybrid breakdown" and can result in an increased risk of extinction. To date, the possibility that major restoration efforts may hold such a "poison pill" for future generations (i.e., hybrid breakdown) has just begun to be discussed by ecologists. The collaboration to be initiated here will be the first study of this possibility in grassland species, which have been a major focus of restoration efforts. The investigators will use molecular fingerprinting techniques to seek evidence for hybridization and hybrid breakdown between introduced and resident populations of three species of native California perennial grasses at an extensive grassland/oak woodland reserve managed by the University of California.

The majority of flowering plant species rely on animals to pollinate their flowers, and in most cases such pollination results in cross-fertilization (i.e., mating between different individuals). However, nearly 25% of species regularly self-fertilize, with pollen being transferred within or between flowers on the same plant. Within natural populations, self-fertilization causes a reduction in genetic variation within individuals and their descendents, in a similar way to the effects of inbreeding in cultivated crops. Given that there are many potential ecological and evolutionary disadvantages to this loss of genetic variation, the evolution of self-fertilization in many plant species remains enigmatic. To date, most explanations for the phenomenon have proposed reproductive advantages that could outweigh the known genetic disadvantages. For example, natural selection might favor self-fertilization when pollinators are scarce or unreliable, or when short growing seasons favor rapid reproduction. However, selfing often evolves along with a suite of physiological, morphological, and life history traits, which raises the alternative possibility that its evolution is influenced by selection on other traits with which it is developmentally, physiologically, or genetically correlated. The goal of this research is to seek evidence for that alternative explanation. Specifically, using a combination of quantitative genetic and physiological approaches, the investigators will test the hypothesis that selfing can evolve as a consequence of genetic correlations between (a) floral traits that affect the rate of self-fertilization and (b) life history or physiological traits that enable plants to escape drought. If selection on life history or physiological traits does influence selfing rates, this will have cascading effects on the genetic structure of populations, potentially limiting their ability to adapt to future environmental change. The annual wildflower genus Clarkia (Onagraceae) provides a rich opportunity to investigate such effects because it includes several species in which self-fertilization has evolved independently.

Broader impacts: This project will initiate a collaboration and reciprocal training among four PIs and include the participation of at least 15 undergraduates, including those of under-represented groups. PIs will work with the University of California, Santa Barbara's "Kids in Nature" program to integrate research and education. In addition, physiological comparisons between species and subspecies may generate predictions about changes in species' distributions and the genetic risks associated with inbreeding in the face of an increasing frequency of droughts that the southern Sierra Nevada is expected to experience in coming years.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This project is to replace a cluster of greenhouse bays on the UCSB campus. The current greenhouse has four bays, is old and decrepit, and is scheduled for demolition. The University intends to replace the existing facility with a new greenhouse complex located adjacent to the old. This will have three components: (1) a three-bay greenhouse on the site of a lath house that is to be demolished, (2) a small greenhouse what will maintain alpine conditions, (the ?Alpine House?), to be newly built on a currently open site, and (3) a second three-bay greenhouse to be built on a site that currently holds two small buildings that will be demolished. The alpine house is designed to simulate the temperature, light and humidity of high alpine environments. The first component is already under construction as a separate project. The current project is to construct the second and third components, and to finish the interior of two of the three bays in the first component to make them operational. The existing greenhouse will ultimately be demolished.

The new greenhouse facility will enable year-round controlled environments and provide many options for experimental research that are unavailable with the current greenhouse. It will be possible to control light, watering regimes, and temperature, and to determine their impacts on plant growth and reproduction. The replacement facility will make it possible to exclude (or include) pollinators, pests and herbivores, and thus enable ecological, genetic and evolutionary experimental research that requires a controlled setting. The facility will be used for research on the specific morphological, physiological, and demographic traits responsible for the maintenance of plant diversity; the identification of the genetic basis for adaptations to extreme environments and specific pollinators; tests of how attributes of the physical environment influence plant distributions, productivity, and phenology; and research on the genetic mechanisms underlying plant recognition and responses to a variety of stresses such as drought. Work will include studies of the genetic and environmental controls of the critical events of flowering time, pollination, seed production, and germination. These studies include the discovery and analysis of the morphological and biochemical changes in floral structure that drive pollinator specialization.

In addition to providing infrastructure for research, the facility will be used for research training of undergraduates, graduate students and postdoctoral associates. Research that is likely to have societal impacts includes research on invasive species and their biological control, and research into the genetic mechanisms affecting seed quality and germination (which is relevant to the mitigation of crop losses.) The facility will be used to advance the development of a new model genomic system that will be made available to the wider research community.

The campus has a number of activities designed to facilitate the recruitment and financial support of members of underrepresented groups, economically disadvantaged students, and highly talented undergraduates. Students in these programs participate in plant biology research and will be able to take advantage of research training opportunities in the new greenhouses. The University?s Center for Biodiversity and Ecological Restoration provides internship opportunities for undergraduates to provide hands-on botanical activities to students in local public schools.

Climate change has widespread regional impacts on diverse biotic systems but most field stations are not yet instrumented with automated data collection systems that would allow integrated measurements of ecophysiology of plants and vertebrates at micro-climate scales needed for detailed studies of physiology, ecology, behavior, evolution and ecosystems, both locally and across large regions. The central hypothesis motivating this instrument investment is that the risk of extinction of organisms due to climate change arises from: a) the direct effects of climate, acting via evolved physiological adaptations that exacerbate extinction risk, and b) the cascading effects of climate change impacts on plant diversity and habitats. These data, together with research that uses them, will allow us to forecast future climate impacts on biotic systems, and to eventually assess historical impacts of climate in and around each of the field stations. The Institute for the Study of the Ecological and Evolutionary Climate Impacts (ISEECI) organizes diverse scientists across the UC System and are integrating these studies with the scientists using Northern Arizona University's Southwest Experimental Garden Array (SEGA). This array of ecophysiological plant and animal sensors will ensure cross-site consistency and comparability at a sufficiently large spatial scale to address regional impacts of climate on coastal, central valley, montane and desert ecosystems of the Southwest.

This new sensor network will instrument 12 sites in the California and 8 sites in Northern Arizona with data loggers and sensors designed to measure environmental parameters relevant to a wide range of animal and plant species. Selected conifers and coastal redwoods will be monitored for sap flow and soil temperature and moisture, and more open grassland/forb and shrub communities with soil temperature and moisture sensors as well as surface temperature at biologically salient heights to complement the existing system of upgraded weather stations already present at NRS and SEGA sites. Temperature sensors will collect similar data on environmental temperatures of endothermic and ectothermic animal taxa, and install phenocams to record phenological changes in trees driven by climate change. The system can be upgraded with new sensors, is expandable with respect to the kinds of data we gather and biotic systems we can instrument, and will be very adaptable for future research. The instruments will capture salient measurements of temperature and drought impacts on terrestrial systems that will allow a unified analysis of ecosystem functioning in the face of changing climate, adding scientific value to each individual field station with a more in-depth biotic record of historical change, and also across the system of field stations enhancing collaboration across the west coast and southwest region of the US. Sensor data will be available immediately online to all ISEECI and SEGA scientists groups, and once fully operational to other researchers. Integration with education and public outreach will give hundreds of students critical messages about climate change and using science to help mitigate its impacts. NAU and the UC system provide graduate and undergraduate students with many experiential learning opportunities in environmental sciences, and detailed, long-term data will supplement and contextualize classwork and research projects. UC and NAU actively work to enhance student diversity: NAU has particular expertise in reaching Native American students, while the Hispanic representation at universities in both states is increasing and being actively incorporated into campus programs and labs.

It is well known that plants alter their flowering times in response to local climatic conditions, but the factors influencing the magnitude and direction of their responses are not well understood. Moreover, not all species change their seasonal flowering time in response to the same climate factors. Consequently, as climate changes, some species may flower too early, resulting in exposure to winter frosts, while others may flower too late or fail to shift their flowering enough to reproduce successfully. This project will improve our understanding of how the timing of flowering by individual species and groups of plant species shift in response to future climatic conditions. This research is essential for forecasting the future availability of floral resources for pollinators and other animals that feed on nectar and pollen, as well as for assessing plant risk of exposure to frost damage, herbivore activity, and other seasonal stresses (e.g., summer drought). To date, however, no comprehensive, continental study of the direction and magnitude of changes in flowering time in response to changes in climate has been conducted. This project will create a single, large database and make all data available online to the public. In addition, this project will provide research training to undergraduate and graduate students.

Preliminary evidence suggests that the magnitude of phenological responsiveness (or sensitivity) to climate changes may be conserved among closely related and functionally similar taxa. Consequently, it may be possible to predict the phenology of species that have not been studied through examination of closely related taxa that are well-documented. Hundreds of thousands of electronic records archived in educational and research institutions throughout the United States provide standardized information about plant specimens collected by botanists across the U.S. over the past 200 years, including the date and location where each specimen was collected and whether it was flowering on the date of collection. This research integrates these disparate records into a single database, and leverages them to evaluate the factors influencing historical and contemporary flowering times across >1000 well-sampled species. In turn, this information will be used to forecast shifts in seasonal flowering under projected climate scenarios. Digital herbarium records and recorded in situ observations will be used to evaluate the factors influencing historical and contemporary flowering times across an unprecedented diversity of angiosperms (>1000 species, each represented by >100 specimens; >400 genera; 80 families). Predictive models will be generated to enable researchers to forecast phenological changes of individual species given specific climatic conditions.

This project will test long-standing evolutionary theory about how rapidly populations can adapt to changing environments by investigating rates of adaptation to intensifying drought in a wild, flowering plant native to California, commonly known as baby blue eyes. The ability of populations to adapt to stressful environmental conditions depends on the presence of genetic variation in survival and reproduction, as well as a genetic variation in the traits that affect survival and reproduction, such as plant physiology and timing of reproduction. Very few studies have measured the process of adaptation to identify the factors that determine how rapidly plant populations adapt to water-limited conditions, in nature. This research will integrate measures of: (1) genetic variation in plant survival and reproduction, both within and among natural populations, as well as in the traits that contribute to plant performance; (2) natural selection in wild populations; and (3) changes between generations in the genetically based aspects of survival and reproduction. Statistical models based on evolutionary theory will be used to predict the magnitude of adaptive change that should occur in each study population. These predictions will be compared to the actual change in survivoral and reproduction observed between generations. Undergraduate students in under-represented groups will be recruited to participate in this research through the Ecological Society of America, the American Indian Science and Engineering Society, and the Society for the Advancement of Chicano and Native Americans in Science. These students will be trained in the design, implementation, and analysis of genetic data collected from field and breeding experiments. Cooperative relationships will be built with the Environmental and Lands departments of Tribal communities, and workshops will be offered to local communities to inform them of the goals, methods, and outcomes of this research.

Many studies of plant species have detected plastic responses of phenological or morphological traits to experimentally induced or natural environmental variation, or changes in the strength or direction of phenotypic selection in populations occupying different environments. To date, however, no studies have assessed evolutionary change between generations, in real time, across natural environmental gradients with respect to phenological, morphological, and physiological traits. This study will combine detailed studies of geographic variation in fitness-related traits among populations of a widespread herb (Nemophila menziesii, Hydrophyllaceae) with measures of: phenotypic selection on traits that contribute to drought-tolerance; inter-generational change in additive genetic variance in fitness; and the response to selection in order to test predictions regarding adaptation to environmental conditions across an aridity gradient. Aster models will be used to estimate additive genetic variance in individual fitness in pedigreed populations under field conditions and to estimate the strength and direction of selection on phenological, morphological, and physiological traits. These models will facilitate the empirical evaluation of the accuracy of Fisher's Fundamental Theorem of Natural Selection (FFT), which predicts that the rate of change in population mean fitness should equal the ratio of additive genetic variance in fitness to mean absolute fitness. This ratio represents a population's capacity to adapt to current conditions, or its "adaptive capacity". This project will be the first rigorous evaluation of FFT in wild populations across an environmental gradient. This study will contribute to the understanding of how natural selection operates across a species' range, potentially identifying mechanisms, such as the existence of multiple combinations of traits associated with fitness optima, that promote the maintenance of genetic variation in wild populations.

Environmental change of all kinds – including climate change, urbanization, and wildfire – affects the seasonal timing of life cycle events in plants worldwide. Most notable are the effects of environmental conditions on the seasonal onset and duration of flowering. The timing of flowering within and among species is important for the persistence of natural populations because it affects interactions between plants, and the availability of flowers and fruits for the animals that depend on them. But the effects of environmental change on flowering differ among species and regions. This project aims to understand and forecast changes in flowering and fruiting among thousands of different plant species across the continental U.S.A. This project takes full advantage of millions of observations of flowering times collected by scientists working with the National Ecological Observation Network (NEON) and citizen-scientists contributing observations from their homes, neighborhoods, and public lands to the National Phenology Network (NPN). The researchers will augment these records of flowering times with the data from millions more herbarium specimens that are available on-line to detect the responses of flowering times to the past century of climate change. These observations will be combined with soil quality, plant cover, land use history, climate, and disturbance data to better understand how different environmental conditions influence species-specific and regional flowering times. Finally, the researchers will use statistical models to forecast short and long-term changes in future flowering times. The combined dataset will be a valuable resource available to other researchers examining the effects of environmental change on plant species and community traits. In addition, the research will provide educational opportunities for K-12, undergraduate and graduate students, and postdoctoral researchers. The project will also engage citizen-scientists who will contribute to a database of flowering times observed from herbarium collections through the CrowdCurio crowdsourcing platform.

Plant phenology–the seasonal timing of key developmental events–is essential for species’ reproductive success. However, critical gaps remain in our understanding of phenology across space, time, and taxa. Increasingly, online herbaria and associated data are being mobilized to address these knowledge gaps because they provide extensive data that can be used to detect phenological responses to climatic change within and among biomes, functional groups, and taxonomic groups. In this project, the standardized, replicated, and focused phenological observations provided by NEON and the USA National Phenology Network will be harmonized for the first time with the taxonomic, spatial, and geographic breadth of herbarium data. First, flowering times derived from herbarium specimens will be assembled and augmented to include > 4400 plant species that collectively span much of the continental US, with specific attention to key regions that have been digitized but overlooked: prairie, alpine, and urban biomes. Second, sources of variation in phenology within and among species, geographic regions, and higher taxa, and the effects of numerous understudied extrinsic factors (e.g., fire history, soil quality, disturbance) will be modeled. Third, forecasts of near- and long-term changes in the phenological behavior of populations, species, and communities will be modeled to better understand phenological responses at multiple ecological, phylogenetic, and temporal scales. Collectively, these efforts will help to elucidate plausible mechanistic responses to climatic and geographic factors that will determine species’ future phenology.

This project is jointly funded by the Division of Environmental Biology/Macrosystems Biology and NEON-enabled Science Program and the Division of Biological Infrastructure/Capacity: Cyberinfrastructure Program.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.