Ingrid M Parker

Ingrid M Parker
University of California, Santa Cruz | UCSC · Department of Ecology & Evolutionary Biology

PhD

About

167
Publications
58,866
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15,885
Citations
Citations since 2017
28 Research Items
5672 Citations
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Introduction
Ingrid M Parker is a Professor in the Department of Ecology & Evolutionary Biology at the University of California, Santa Cruz and is a Research Associate at the Smithsonian Tropical Research Institute. Her research focuses on plant ecology, evolution, and conservation, specializing in biological invasions and plant-pathogen interactions. She has ongoing projects on the evolutionary dynamics of invasion, on microbe-mediated interactions between invasive and native plants, on the evolution of domestication in tropical fruit trees, and on the structure of plant-fungal networks, among other topics.
Additional affiliations
January 2007 - present
Smithsonian Tropical Research Institute
Position
  • Research Associate
September 1998 - present
University of California, Santa Cruz
Position
  • Professor (Full)

Publications

Publications (167)
Article
Full-text available
Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traits across multiple ecolog...
Article
Plants interact with numerous enemies and mutualists simultaneously and sequentially. Such multispecies interactions can give rise to trait-mediated indirect effects that are likely to be common in nature but which are also inherently difficult to predict. Understanding multispecies interactions is also important in the use of biological control ag...
Article
An important question in the study of biological invasions is the degree to which successful invasion can be explained by release from control by natural enemies. Natural enemies dominate explanations of two alternate phenomena: that most introduced plants fail to establish viable populations (biotic resistance hypothesis) and that some introduced...
Article
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A major aim in invasion ecology is to understand the role of exotic species in plant communities. Whereas most studies have explored the traits of exotic species in the context of the introduced community, functional comparisons of entire assemblages of species in their native and introduced communities have rarely been analysed. Taking advantage o...
Article
Plant pathogens are often hypothesized to promote species coexistence by generating conspecific negative density dependence (CNDD). However, the relative importance of fungal vs. oomycete pathogens in maintaining plant species coexistence and community composition remains unresolved, despite their recognized effects on plant performance. Here, we u...
Article
The Stress Gradient Hypothesis (SGH) predicts facilitation will become more important than competition where abiotic stress is high, and the framework successfully predicts positive interactions between species in many systems. Fewer studies have focused on intraspecific facilitation, and to our knowledge none examine intraspecific interactions in...
Article
Although ecological niche models have been instrumental in understanding the widespread species distribution shifts under global change, rapid niche shifts limit model transferability to novel locations or time periods. Niche shifts during range expansion have been studied extensively in invasive species, but may also occur in native populations tr...
Article
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Racial and ethnic discrimination persist in science, technology, engineering and mathematics fields, including ecology, evolution and conservation biology (EECB) and related disciplines. Marginalization and oppression as a result of institutional and structural racism continue to create barriers to inclusion for Black people, Indigenous people and...
Preprint
Full-text available
Aim Although ecological niche models have been instrumental in understanding the widespread species distribution shifts under global change, rapid niche shifts limit model transferability to novel locations or time periods. Niche shifts during range expansion have been studied extensively in invasive species, but may also occur in native population...
Article
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Background and aims Plant-soil feedbacks may determine the long-term success of introduced species. Here we examined plant-soil feedbacks of a globally invasive shrub, Cytisus scoparius (hereafter Cytisus), which associates with multiple guilds of microbial mutualists and dominates harvested Douglas-fir forests in the Pacific Northwest. Methods We...
Article
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Political and economic initiatives intended to increase energy production while reducing carbon emissions are driving demand for solar energy. Consequently, desert regions are now targeted for development of large‐scale photovoltaic solar energy facilities. Where vegetation communities are left intact or restored within facilities, ground‐mounted i...
Article
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Seed bank survival underpins plant population persistence but studies on seed bank trait-environment interactions are few. Changes in environmental conditions relevant to seed banks occur in desert ecosystems owing to solar energy development. We developed a conceptual model of seed bank survival to complement methodologies using in-situ seed bank...
Article
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Invasion ecology has grown to include scientists with diverse skill sets who focus on a range of taxa and biomes. These researchers have the capacity to contribute to practical management solutions while also answering fundamental biological questions; however, scientific endeavors often fail to meet the perceived needs of practitioners involved in...
Preprint
Seed bank survival underpins plant population persistence but studies on seed bank trait-environment interactions are few. Changes in environmental conditions relevant to seed banks occur in desert ecosystems owing to solar energy development. We developed a conceptual model of seed bank survival to complement methodologies using in-situ seed bank...
Article
Full-text available
Predicting how communities re-arrange in response to changes in species composition remains a key challenge in ecology. Migratory species, which enter and leave communities across latitudinal gradients, offer us a unique opportunity to evaluate community- and species-level responses to a shift in community composition. We focused on a migratory hum...
Article
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The introduction of exotic species to new regions offers opportunities to test fundamental questions in ecology, such as the context-dependency of community structure and assembly. Annual grasslands provide a model system of a major unidirectional introduction of plant species from Europe to North America. We compared the community structure of gra...
Article
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Solar energy development is a significant driver of land-use change worldwide, and desert ecosystems are particularly well suited to energy production because of their high insolation rates. Deserts are also characterized by uncertain rainfall, high species endemism, and distinct landforms that vary in geo-physical properties. Weather and physical...
Article
We conducted a large-scale, multiple-year study in harvested areas of Douglas-fir forests in western Washington, examining the effectiveness of control methods on the widespread invasive shrub Scotch broom [ Cytisus scoparius (L.) Link]. We tested both chemical and physical control methods, using three different approaches that are management-relev...
Article
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The relationship between plant diversity and productivity and the mechanisms underpinning that relationship remain poorly resolved in species-rich forests. We combined extensive field observations and experimental manipulations in a subtropical forest to test how species richness (SR) and phylogenetic diversity (PD) interact with putative root-asso...
Article
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Non-native tree (NNT) species have been transported worldwide to create or enhance services that are fundamental for human well-being, such as timber provision, erosion control or ornamental value; yet NNTs can also produce undesired effects, such as fire proneness or pollen allergenicity. Despite the variety of effects that NNTs have on multiple e...
Article
Reforestation is challenging when timber harvested areas have been degraded, invaded by non‐native species, or are of marginal suitability to begin with. Conifers form mutualistic partnerships with ectomycorrhizal fungi (EMF) to obtain greater access to soil resources, and these partnerships may be especially important in degraded areas. However, t...
Article
Plant pathogens reduce the performance of their hosts and therefore may contribute to ecological mechanisms of coexistence. In Chesson’s framework, pathogens contribute to stabilizing mechanisms when they intensify negative intraspecific interactions, such as density‐dependent disease. Additionally, pathogens contribute to equalizing mechanisms whe...
Article
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Erect veldtgrass ( Ehrharta erecta Lam.) is an invasive grass actively spreading in California that is capable of invading multiple habitats. Our objective is to contribute to a better understanding of the ecology, impacts, and potential for control of E. erecta in order to guide management practices. In a mixed-evergreen forest in Santa Cruz Count...
Article
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Social factors play a critical role in almost every conservation problem. There is a pressing need for conservation researchers and practitioners to understand both the ecological and human dimensions of their systems in order for projects to be successful. At the same time, many conservation professionals come from a natural science background wit...
Article
An increasingly recognized impact of plant invaders is the disruption of positive interactions between native plants and their belowground mutualistic mycorrhizal fungi. We reviewed 112 studies from 61 publications that report invader impacts on mycorrhizal fungi. We describe emerging patterns on the frequency of negative, neutral and positive inva...
Article
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Invasive plants often occupy large ranges in the introduced region and consequently, local population dynamics vary in ways that affect the potential for biological control. We used matrix models to describe how density and population growth rate of Centaurea solstitialis varies in time and space. Matrix models were parameterized with data collecte...
Article
Impacts of invasive species may change in magnitude and even direction with invasion age. Impacts could increase as the population increases, individuals grow in size, and ecological changes accumulate. 2.We used a chronosequence approach to characterize the development of soil impacts over time following the invasion of Cytisus scoparius, a widesp...
Article
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Premise of the study: Self incompatibility (SI) in rare plants presents a unique challenge-SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreedi...
Article
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Through competition for pollinators, invasive plants may suppress native flora. Community-level studies provide an integrative assessment of invasion impacts and insights into factors that influence the vulnerability of different native species. We investigated effects of the non-native herb Lythrum salicaria on pollination of native species in 14...
Article
Species introductions are a dominant component of biodiversity change but are not explicitly included in most discussions of biodiversity-disease relationships. This is a major oversight given the multitude of effects that introduced species have on both parasitism and native hosts. Drawing on both animal and plant systems, we review the competing...
Article
An explicit phylogenetic perspective provides useful tools for phytopathology and plant disease ecology because the traits of both plants and microbes are shaped by their evolutionary histories. We present brief primers on phylogenetic signal and the analytical tools of phylogenetic ecology. We review the literature and find abundant evidence of ph...
Article
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Models are simplified representations of more complex systems that help scientists structure the knowledge they acquire. As such, they are ubiquitous and invaluable in scientific research and communication. Because science education strives to make classroom activities more closely reflect science in practice, models have become integral teaching a...
Article
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Aims To assess the impacts of Ailanthus altissima and Robinia pseudoacacia on the whole litterfall process and on soil properties of riparian ecosystems of Central Spain by comparing invaded and non-invaded forests. Methods We selected 3–4 plots of four different types of forests: invaded by A. altissima or R. pseudoacacia, or dominated by the nati...
Article
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Vast effort and resources are spent to control invasive plants. Often with the assumption that once these resources are spent and the invader is successfully removed, the impact of that species on the community is also eliminated. However, invasive species may change the environment in ways that persist, as legacy effects, after the species itself...
Article
Pathogens play an important part in shaping the structure and dynamics of natural communities, because species are not affected by them equally. A shared goal of ecology and epidemiology is to predict when a species is most vulnerable to disease. A leading hypothesis asserts that the impact of disease should increase with host abundance, producing...
Article
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Summary Schedules of survival, growth and reproduction are key life-history traits. Data on how these traits vary among species and populations are fundamental to our understanding of the ecological conditions that have shaped plant evolution. Because these demographic schedules determine population growth or decline, such data help us understand h...
Article
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An age-old conflict around a seemingly simple question has resurfaced: why do we conserve nature? Contention around this issue has come and gone many times, but in the past several years we believe that it has reappeared as an increasingly acrimonious debate between, in essence, those who argue that nature should be protected for its own sake (intr...
Conference Paper
Background/Question/Methods Islands and island-like habitats are biodiversity hotspots. The insular nature of these environments limits gene flow and facilitates local adaptation. The Zayante sandhills of Santa Cruz County, California, contain many plants and animals restricted to these exceptionally xeric soils surrounded by mesic forests. Erysi...
Conference Paper
Background/Question/Methods Rare host species are expected to suffer less damage from pathogens and pests than common hosts. This rare-species advantage is a key feature of hypotheses that explain how pathogens can help maintain diversity (e.g., Janzen-Connell hypothesis) or regulate invasions (e.g., Escape from Natural Enemies hypothesis). Howev...
Conference Paper
Full-text available
Background/Question/Methods Ehrharta erecta is a highly invasive perennial grass actively spreading in forest understory habitats across coastal California. Despite the attention placed on this species as a wildland weed, there is little published information on its impacts or control. We quantified the impacts of E. erecta on native plant physio...
Conference Paper
Full-text available
Background/Question/Methods Invasive plants compete with native plants for pollination when pollinators preferentially visit the flowers of the invader. Over a broader scale, invaders may facilitate native plant pollination by attracting visitors to the invaded site or by increasing population sizes of pollinators at the site. Reviews of studies...
Conference Paper
Background/Question/Methods It is typically assumed that once an invasive species is successfully removed, the impact of that species on the community is also eliminated. However, invasive species may change the environment in ways that persist, as legacy effects, long after the species itself is gone. To evaluate the persistence of soil legacy ef...
Article
Full-text available
Establishing new populations is essential for preventing the extinction of critically endangered plant species. However, defining the range of environmental conditions suitable for the most severely endangered species is challenging, since few wild populations remain for study. Experimental reintroductions of these species can achieve multiple cons...
Article
To identify the geographic origin of nodule bacteria associated with invasion of the European legume Cytisus scoparius in the United States, isolates from 15 sites in six states were compared to >200 Bradyrhizobium strains from indigenous legumes in the U.S., Mexico, Europe (six countries), Morocco and Australia. Portions of five housekeeping loci...
Article
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Species in the early stages of domestication, in which wild and cultivated forms co-occur, provide important opportunities to develop and test hypotheses about the origins of crop species. Chrysophyllum cainito (Sapotaceae), the star apple or caimito, is a semidomesticated tree widely cultivated for its edible fruits; it is known to be native to th...
Article
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• Premise of the study: We developed microsatellite primers for the tropical tree Chrysophyllum cainito (Sapotaceae) to determine the native range of the species, investigate the origin of cultivated populations, and examine the partitioning of genetic diversity in wild and cultivated populations. • Methods and Results: We developed 10 polymorphic...
Conference Paper
Background/Question/Methods Even after the removal of the invasive shrub Cytisus scoparius, standard reforestation efforts in previously invaded areas often fail. In our previous work, we found that soils invaded by Cytisus harbored fewer ectomycorrhizal fungi than uninvaded forest soils, and that growth of Douglas-fir seedlings was linked to the...
Article
Background and aim: Exotic plant species can alter the nitrogen cycle in invaded ecosystems. We assess the differences in nitrogen use strategies and litter production and dynamics among three native riparian trees (Fraxinus angustifolia, Populus alba and Ulmus minor) and three co-occurring exotics (Ailanthus altissima, Robinia pseudoacacia and Ulm...
Article
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Herbivores, seed predators, and pollinators can exert strong impacts on their host plants. They can also affect the strength of each other's impact by modifying traits in their shared host, producing super- or sub-additive outcomes. This phenomenon is especially relevant to biological control of invasive plants because most invaders are attacked by...
Article
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Forest restoration uses active management to re-establish natural forest habitat after disturbance. However, competition from early successional species, often aggressively invasive exotic plant species, can inhibit tree establishment and forest regeneration. Ideally, restoration ecologists can plant native tree species that not only establish and...
Article
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Invasive species may leave behind legacies that persist even after removal, inhibiting subsequent restoration efforts. We examined the soil legacy of Cytisus scoparius, a nitrogen-fixing, putatively allelopathic shrub invading the western US. We tested the hypothesis that allelopathy plays a critical role in the depressive effect of Cytisus on the...
Conference Paper
Background/Question/Methods Invasive species offer excellent opportunities to test evolutionary hypothesis and to study basic processes in population biology. In particular, invasive species represent attractive study models to test the predictions of life history theory, since the selective pressures in the native and introduced habitats can be...
Conference Paper
Background/Question/Methods Even after the removal of the invasive shrub Cytisus scoparius, standard reforestation efforts in previously invaded areas often fail. In our previous work, we have found that soils invaded by Cytisus harbor less ectomycorrhizal fungi, and that growth of Douglas-fir seedlings is linked to the abundance of these fungi....
Conference Paper
Background/Question/Methods Studying the differences in the nitrogen use strategy between native and exotic plant species can help to explain invasion success and to predict potential impacts on the nitrogen cycle of invaded communities. Plants adapted to nitrogen-rich ecosystems usually show leaf traits related to non-conservative nitrogen use s...
Conference Paper
Full-text available
Background/Question/Methods Forest restoration is the re-introduction of native species to naturally or anthropogenically disturbed areas to re-establish the natural habitat. Early successional species, especially invasive exotic species, can inhibit or delay succession to the desired restoration endpoint. Restoration of areas occupied by undesir...
Article
Premise of the study: Understanding patterns and processes associated with domestication has implications for crop development and agricultural biodiversity conservation. Semi-domesticated crops provide excellent opportunities to examine the interplay of natural and anthropogenic influences on plant evolution. The domestication process has not bee...
Conference Paper
Background/Question/Methods Plants affect the microbial communities in the soil in which they grow. Exotic invasive plants that have not coevolved with the mycorrhizal species in the introduced environment may decrease the abundance and richness of the native mycorrhizal fungi. After two consecutive years of wholesale failure of Douglas-fir (DF) r...
Conference Paper
Background/Question/Methods In abandoned agricultural areas in the tropics, the high light conditions and low nutrient availability that follow intense agricultural practices can hinder natural succession and favor colonization by exotic species. In Panama, the exotic C4 grass Saccharum spontaneum now dominates many abandoned pastures. Efforts to...
Conference Paper
Background/Question/Methods The exotic shrub Cytisus scoparius (Scotch broom) has been implicated in failed reforestation efforts in the Pacific Northwest. While competition from C. scoparius may directly affect the establishment success of Douglas fir (Pseudotsuga menziesii), there is also the potential for indirect interactions through effects on...
Article
Full-text available
Domestication Syndrome in Caimito ( Chrysophyllum cainito L.): Fruit and Seed Characteristics: The process of domestication is understudied and poorly known for many tropical fruit tree crops. The star apple or caimito tree (Chrysophyllum cainito L., Sapotaceae) is cultivated throughout the New World tropics for its edible fruits. We studied this s...
Article
In some plant populations, the availability of seeds strongly regulates recruitment. However, a scarcity of germination microsites, granivory or density-dependent mortality can reduce the number of plants that germinate or survive to flower. The relative strengths of these controls are unknown for most plant populations and for exotic invaders in p...
Article
Question: How do the diversity, size structure, and spatial pattern of woody species in a temperate (Mediterranean climate) forest compare to temperate and tropical forests? Location: Mixed evergreen coastal forest in the Santa Cruz Mountains, California, USA. Methods: We mapped, tagged, identified, and measured all woody stems (≥1 cm diameter) in...
Article
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Plant species introduced into new regions can both leave behind co-evolved pathogens and acquire new ones. Traits important to infection and virulence are subject to rapid evolutionary change in both plant and pathogen. Using Stemphylium solani, a native foliar necrotroph on clovers (Trifolium and Medicago) in California, USA, we explore how plant-...
Article
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Habitat differentiation is thought to play a role in polyploidy establishment and coexistence. Differences in morphology and microhabitat association could play a role in cytotype distribution, but random factors could also be important. Little work has been performed to examine mechanisms affecting local-scale cytotype spatial distribution. Multip...
Article
An enduring puzzle in gynodioecious species is the great variation in female frequency seen among populations. We quantified sex ratio in 44 populations of gynodioecious Kallstroemia grandiflora. Then, we measured pollinator visitation, pollen deposition, autonomous selfing rate and pollen limitation of females. Finally, using experimental populati...
Article
Human-mediated species introductions offer opportunities to investigate when and how non-native species to adapt to novel environments, and whether evolution has the potential to contribute to colonization success. Many long-established introductions harbour high genetic diversity, raising the possibility that multiple introductions of genetic mate...