Jamie Kneitel

California State University, Sacramento | CSUS · Department of Biological Sciences

The loss of freshwater wetlands worldwide has underscored the importance of restoration to enhance biodiversity and functional objectives. While aquatic invertebrate communities within restored perennial freshwaters are well studied, few studies have occurred in the greatly reduced habitat of seasonal wetlands, such as vernal pools. California vern...

Plant community assembly can be influenced by many environmental factors. In seasonal wetlands, most studies focus on the considerable variation that occurs from the hydro-regime (patterns of inundation and desiccation). Other factors and their interactions also influence plants but are seldom studied, including nutrient and thatch levels. Furtherm...

Climate change has been associated with alterations in temperature and precipitation regimes. Increased temperatures can change the structure and function of aquatic communities through both biotic and abiotic interactions. Many warming experiments have been conducted in permanent freshwater systems, but few in temporary freshwater systems that are...

Ecologists have been interested in understanding communities through the lens of specialists and generalists to predict species diversity and distribution patterns and to ameliorate worldwide declines in specialist species. Dispersal traits are assumed to be associated with specialization (specialists are weaker dispersers than generalists), but di...

Many endemic large branchiopods inhabit ephemeral freshwater ecosystems, including California vernal pools. Hydroperiod, inundation length, has been well studied in these systems that cycle between aquatic and terrestrial phases, but species’ responses to other ecological processes are still poorly known. For example, temporal (plant thatch from th...

Wildfires have become larger and more severe in recent decades. Fire retardant is one of the most common wildfire response tools to protect against loss of life and property. Previous studies have documented various effects of fire retardant, which commonly contains chemicals used in fertilizers, on plant and invertebrate community composition. Thi...

Estimating organisms' responses to environmental variables and taxon associations across broad spatial scales is vital for predicting their responses to climate change. Macroinvertebrates play a major role in wetland processes, but studies simultaneously exploring both community structure and community trait responses to environmental gradients are...

Past efforts to explain variation of invertebrate assemblages in freshwater wetlands have been less productive than anticipated. To explore why efforts are disappointing, we assembled large invertebrate data sets from North Dakota prairie potholes, California rock pools, and Georgia Carolina bay wetlands that addressed spatial (among wetlands) and...

etlands are among the most threatened ecosystems worldwide due to climate change and land-use conversion. Regional biodiversity of temporary wetlands is dependent on the existence of habitat complexes with variable hydroperiods. Because temperature and rainfall regimes are predicted to shift globally, together with land-use patterns, different scen...

Climate change is rapidly driving global biodiversity declines. How wetland macroinvertebrate assemblages are responding is unclear, a concern given their vital function in these ecosystems. Using a data set from 769 minimally impacted depressional wetlands across the globe (467 temporary and 302 permanent), we evaluated how temperature and precipi...

Fire retardants are commonly used for fighting wildfires. Retardant chemicals washed via runoff into aquatic systems may be concentrated, thus exposing aquatic species to high levels of ammonium, phosphate, and iron. These chemicals directly affect individual species, which can also cascade to the rest of the aquatic community. We investigated the...

The efficiency of biodiversity assessments and biomonitoring studies is commonly challenged by limitations in taxonomic identification and quantification approaches. In this study, we assessed the effects of different taxonomic and numerical resolutions on a range of community structure metrics in invertebrate compositional data sets from six regio...

Environmental productivity and biodiversity are two intricately linked ecological concepts. One commonly observed pattern is a unimodal curve with biodiversity peaking at intermediate levels of productivity. While unimodal relationships are by no means universal, biodiversity declines at high productivity levels (eutrophication) raise serious conce...

The dynamics of trophic niche width in animals at both population level and individual level is potentially influenced by temporal variation of food resources, by between‐individual differences in food‐resource rank preferences, and also by competition. Using stable isotope of carbon and nitrogen ( δ ¹³ C and δ 15 N) of fecal samples, we investigat...

Urban development alters landscape structure and available resources, potentially threatening avian diversity worldwide. However, it is unclear how bird communities respond in areas currently undergoing urban development, particularly in the non-breeding season. We examined avian communities at 8 parks in urban (within established urban matrix; >50...

The mosquito Aedes phoeniciae is a potential disease vector that inhabits the coastal rock-pools of the Southeastern Mediterranean Sea. Our year-long study examined the abundance and distribution of Ae. phoeniciae in 49 rock-pools along HaBonim Beach Nature Reserve (Israeli coast) on a monthly basis (September 2016 to August 2017). Additionally, th...

1. Fire retardants are composed of fertilising salts that are commonly used for fighting wildfires. These chemicals have various effects on individual arthropod species and aquatic communities. 2. This study investigated the effects of four treatments of a prevalent fire retardant [FR CROS 134 (FR), applied at concentrations of 0, 3.8 × 10 ² , 7.6...

The mosquito Aedes phoeniciae is a potential disease vector that inhabits the coastal rock-pools of the Southeastern Mediterranean Sea. Our year-long study examined the abundance and distribution of Ae. phoeniciae in 49 rock-pools along HaBonim Beach Nature Reserve (Israeli coast) on a monthly basis (September 2016 to August 2017). Additionally, th...

• The number and quality of temporary wetlands are declining worldwide and many of the remaining habitats are used as pastures and drinking sites for livestock. Livestock can impact wetlands through a combination of herbivory (defoliation), trampling (physical disturbance), and defecation (nutrient input), but how these influence community structur...

creased temperatures can change the structure and function of aquatic communities through both biotic (productivity, competition, predation) and abiotic (nutrient cycling, disturbance) interactions. California vernal pools are temporary wetlands which provide habitat for many endemic and endangered species during the aquatic phase. Hydro-regime cha...

Rosas-Saenz & Kneitel poster addressing how endangered and endemic species respond to hydro-regime, nutrient, and thatch treatments

Mediterranean temporary ponds are present in five biogeographical regions, which are characterized by hot dry summers and cool mild winters. These ponds host high levels of biodiversity and endemism. More than 200 families and 630 genera of invertebrates have been reported, including iconic large branchiopods. Mediterranean climates show strong tem...

The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology, typically showing decreasing species diversity with increasing latitude. Studies of these patterns also used different spatial scales and dispersal traits to better understand the underpinning ecological factors. Seasonal freshwater ecosystems are less...

The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology, typically showing decreasing species diversity with increasing latitude. Studies of these patterns also used different spatial scales and dispersal traits to better understand the underpinning ecological factors. Seasonal freshwater ecosystems are less...

Species interactions are well known to affect species diversity in communities, but the effects of parasites have been less studied. Previous studies on parasitic plants have found both positive and negative effects on plant community diversity. Cuscuta howelliana is an abundant endemic parasitic plant that inhabits California vernal pools. We test...

Biotic interactions between herbivores and primary producers are believed to play a major role in determining community composition of many ecological communities. How differences in herbivore abundance alter the relative importance of these interactions is not well understood, especially in seasonal wetland systems. This study investigated the eff...

Background/Question/Methods Decreasing species richness with increasing latitude has been a well-established pattern found in a wide range of taxonomic groups and ecosystems. Temporary aquatic ecosystems, however, have been understudied in this regard. In California, precipitation increases and temperature decreases with increasing latitude. Cons...

The hydroregime (duration, timing, and frequency of inundation) of temporary aquatic ecosystems are well known to affect relative abundance, species richness, and community composition. The effects of hydroperiod (inundation duration) have been well studied, but this is not the case with inundation timing. I conducted an experiment in mesocosms tha...

The ‘competitive exclusion principle’ (CEP) states that two species with identical niches cannot coexist indefinitely. Natural historians (i.e., Grinnell) and ecological theorists (i.e., Lotka and Volterra) had concluded this during the early part of the twentieth century; however, this concept has been primarily attributed to Georgii Frantsevich G...

Background/Question/Methods Climate change has been found to be important in structuring many freshwater ecosystems. In addition to temperature, variation in precipitation can determine the hydroperiod gradient, which is among the most important factors determining the composition, structure, and function of these ecosystems. Less understood is h...

Trade-offs among species' ecological interactions is a pervasive explanation for species coexistence. The traits associated with trade-offs are typically measured to mechanistically explain species coexistence at a single spatial scale. However, species potentially interact at multiple scales and this may be reflected in the traits among coexisting...

Aquatic containers, including tree holes and vehicle tires, harbor a diverse assemblage of mosquitoes capable of vectoring important diseases. Many studies have examined containers as a mosquito breeding site, although no data exist that have simultaneously compared mosquito communities between tree holes and tires, and few have quantified differen...

Aquatic containers, including tree holes and vehicle tires, harbor a diverse assemblage of mosquitoes capable of vectoring important diseases. Many studies have examined containers as a mosquito breeding site, although no data exist that have simultaneously compared mosquito communities between tree holes and tires, and few have quantified differen...

Wetland ecosystems are vulnerable to plant species invasions, which can greatly alter species composition and ecosystem functioning. The response of these communities to restoration can vary following invader removal, but few studies have evaluated how recent and long-term invasions can affect the plant community's restoration potential. Perennial...

Explaining patterns of species richness is a central theme in community ecology and conservation. Ecologists have focused on local (within a site), regional (among sites in a given region), or geographical (among regions) explanations of diversity patterns. In the case of freshwater fish, studies illustrate that biological factors (competition and...

Background/Question/Methods Alternative stable states in shallow lakes and ponds are commonly observed in response to eutrophication, one of the greatest threats to aquatic ecosystems worldwide. Models of alternative stable states use turbidity as a key variable in the ecosystem shift, and turbidity is controlled by a combination of nutrient level...

In California, much of the remaining vernal pool habitat is used for cattle grazing. Some studies suggest that grazing helps promote native plant diversity on grasslands, but the impact of grazing on plants that reside in pool basins is largely unknown. We investigated how one aspect of cattle grazing, the deposition of waste, affects these plant s...

An example of ecosystem engineering gaining attention in aquatic systems is bioturbation, the disruption of sediment at the water–sediment interface due to burrowing and foraging. One consequence of bioturbation can be increased turbidity from suspended sediment, which generally inhibits macrophyte growth and reduces ecosystem functioning. Converse...

Background/Question/Methods Sierra Nevada subalpine meadow plant communities are highly diverse and harbor many rare taxa. This diversity is often attributed to the unique patchy hydrology of the geologically young meadow soils. However, species interactions such as competition and facilitation may play roles in community assembly as well. A numbe...

Discarded vehicle tires are a common habitat for container mosquito larvae, although the environmental factors that may control their presence or abundance within a tire are largely unknown. We sampled discarded vehicle tires in six sites located within four counties of central Illinois during the spring and summer of 2006 to determine associations...

Although studies of container mosquitoes have focused on tree holes and automobile tires, few studies have compared mosquito communities between container types simultaneously; the factors important for differences between mosquito communities between container types are unknown. We sampled mosquitoes, microorganisms, and microorganism productivity...

Eutrophication has long been known to negatively affect aquatic and terrestrial ecosystems worldwide. In freshwater ecosystems, excessive nutrient input results in a shift from vascular plant dominance to algal dominance, while the nutrient-species richness relationship is found to be unimodal. Eutrophication studies are usually conducted in contin...

Background/Question/Methods Conservation efforts inclusive of local communities have been widely implemented however, the effectiveness of this paradigm remains contentious. We investigate whether an Integrated Conservation and Development Project (ICDP), located in Guyana, has effectively translated into successful conservation at the village leve...

Background/Question/Methods The spatial movement of resources or predators among different ecosystems (e.g., from rivers to adjacent terrestrial habitat) has been well studied. However, the potential for different phases to interact within an ecosystem has been seldom considered. Phases can be generated by temporal heterogeneity (e.g., climatic va...

The relationship between average body masses (M) of individuals within species and densities (N) of populations of different species and the mechanisms and consequences of this relationship have been extensively studied. Most published work has focused on collections of data for populations of species from a single broad taxon or trophic level (suc...

Most theoretical and empirical studies of productivity-species richness relationships fail to consider linkages among trophic levels. We quantified productivity-richness relationships in detritus-based, water-filled tree-hole communities for two trophic levels: invertebrate consumers and the protozoans on which they feed. By analogy to theory for b...

1. Omnivory is an important interaction that has been the centre of numerous theoretical and empirical studies in recent years. Most of these studies examine the conditions necessary for coexistence between an omnivore and an intermediate consumer. Trait variation in ecological interactions (competition and predator tolerance) among intermediate co...

The process of biological invasions is necessary to understand to prevent future invasions and their negative impacts. Ecological theory and empirical work can provide a framework for approaching the process. Extrinsic factors, such as disturbances, can increase the probability of a successful invasion through several mechanisms. Disturbances may d...

Isolated habitats generally have fewer species at local spatial scales than more connected habitats. However, over larger spatial scales, the response of species richness to variation in the degree of isolation is variable. Here, we hypothesized that the effects of habitat isolation on patterns of regional level species richness may depend at least...

Although the influence of dispersal on coexistence mechanisms in metacommunities has received great emphasis, few studies have addressed how such influence is affected varying regional heterogeneity. We present a mechanistic model of resource competition in a metacommunity based on classical models of plant competition for limiting resources. We de...

A model of species interactions based on their use of shared resources was proposed in 1972 by Robert MacArthur and later expanded in an article (1980) and a book (1982) by David Tilman. This "resource-ratio theory" has been used to make a number of testable predictions about competition and community patterns. We reviewed 1,333 papers that cite Ti...

A model of species interactions based on their use of shared resources was proposed in 1972 by Robert MacArthur and later expanded in an article (1980) and a book (1982) by David Tilman. This “resource‐ratio theory” has been used to make a number of testable predictions about competition and community patterns. We reviewed 1,333 papers that cite Ti...

We examined the environmental factors associated with community structure in the inquiline communities of the purple pitcher plant (Sarracenia purpurea L.). We sampled all 141 communities in a 10- × 20-m grid and recorded their spatial relationships to determine the relative influence of environmental and spatial factors on community structure. Env...

Species diversity at the local-community scale can be altered by numerous factors, including disturbances, predators, and resource levels. Intermediate levels of these three factors are predicted to enhance coexistence and diversity. However, no study has examined how these factors may interact to alter community composition. The protozoan and roti...

Trade-offs in species performances of different ecological functions is one of the most common explanations for coexistence in communities. Despite the potential for species coexistence occurring at local or regional spatial scales, trade-offs are typically approached at a single scale. In recent years, ecologists have increasingly provided evidenc...

Many previous studies have assumed that a linear relationship between local and regional species richness indicates that communities are limited by regional processes, while a saturating relationship suggests that species interactions restrict local richness. We show theoretically that the relationship between local and regional richness changes in...

Dispersal among local communities can have a variety of effects on species composition and diversity at local and regional scales. Local conditions (e.g., resource and predator densities) can have independent effects, as well as interact with dispersal, to alter these patterns. Based on metacommunity models, we predicted that local diversity would...

The effects of top-down and bottom-up forces on species abundance and diversity were quantified in the inquiline communities found in the water-filled leaves of the pitcher plant, Sarracenia purpurea. A press field experiment was conducted in which the abundances of resources (dead ants) and the top predators (larva of the mosquito Wyeomiia smithii...

Typescript. Thesis (Ph. D.)--Florida State University, 2002. Includes bibliographical references (leaves 96-105).

Although invasion has long been recognised as an important eoclogical process, there are very few experimental studies of invasion in natural communities and virtually no studies that determine how trophic structure affects the probability of invasion. We introduced novel protozoans and rotifers into the natural communities found in the water-fille...

This review synthesizes published data and new results concerning the evolutionary ecology of carnivorous plants. These diverse taxa occur in many angiosperm clades, but are united by a common ecological “niche” — botanical carnivory. Aspects of their life-history, including developmental preformation and rapid responses to nutrient additions, make...