Jamie Kneitel

California State University, Sacramento, Biological Sciences, Faculty Member

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I study how environmental variation (in space and time) affects the diversity and functioning of ecological communities. I use laboratory, mesocosm, field, and data mining studies with temporary wetlands (including vernal pools and rock pools) to address questions at all ecological levels (individuals to ecosystem). My students and I research wet and dry phase taxa, including bacteria, algae, plants, invertebrates, and vertebrates. This research addresses many topics, including food webs, metacommunity ecology, latitudinal gradients, spatiotemporal linkages, eutrophication, species invasions, endangered species, restoration ecology, and disturbance ecology.
Address: Department of Biological Sciences
California State University
Sacramento, CA 95819-6077

Web: http://kneitel.weebly.com

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Norwegian Institute for Nature Research, NINA

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University of Kalyani

David Seamon

Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

Merrill L Gassman

University of Illinois at Chicago

Herve Bocherens

Eberhard Karls Universität Tübingen

Camilo A. Calderón-Acevedo

Rutgers at Newark

Peter Deines

Christian-Albrechts-Universität zu Kiel

Noé U de la Sancha

DePaul University

Jordan Grigor

Vanderbilt University

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Papers by Jamie Kneitel

Gause’s Competitive Exclusion Principle

The ‘competitive exclusion principle’ (CEP) states that two species with identical niches cannot ... more 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 attributed to Georgii Frantsevitch Gause. In Gause’s landmark 1934 book, The Struggle of Existence, his experimental tests using protozoa supported the predictions of Lotka–Volterra equations, finding protozoa that use similar resources could not coexist, leading ecologists to identify him with CEP. Gause helped propel ecology by his approach of experimentally testing mathematical models, and his unifying the concept of the niche with resource competition. Gause’s CEP has been one of the central themes of research in ecology: trying to understand the mechanisms of species coexistence and patterns of biodiversity. Most of the explanations are niche-based in origin, including resource partitioning, character displacement, and niche tradeoffs. Criticisms (e.g., neutral theory) of these explanations state that these deterministic processes cannot, by itself, explain very high levels of species diversity; however, the current consensus is that species coexistence and diversity patterns are likely a combination of stochastic and niche-based explanations.

Warming and inundation timing effects on California vernal pool mesocosm communities

F1000Research, Aug 2, 2017

Avian community composition, but not richness, differs between urban and exurban parks

Journal of Urban Ecology, 2020

Urban development alters landscape structure and available resources, potentially threatening avi... more 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% built cover) and 9 parks in exurban (within adjacent grassland; 5-20% built cover) areas in Sacramento County, CA. We measured bird species and abundance, conducting five line-transect surveys per park (85 total). We investigated factors influencing avian assemblage, including local habitat features (land cover, number of trees, fruiting trees and tree species, tree height and diameter at breast height, park size, park age), and landscape features (land cover within 500 m and distance to riparian habitat). Fifty bird species, including 15 migrants, were observed. Total species richness and abundance at urban and exurban parks was not significantly different, but community assemblages differed significantly. Park area positively predicted species richness. Abundance was negatively associated with inpark percent built cover, average number of fruiting trees and landscape-scale percent water cover. Species composition changes were associated with distance to riparian habitat and landscape percent grass cover for all but one exurban park; and with tree height, DBH and park and landscape percent tree cover for urban parks. The expansion of exurban areas in many parts of the world poses a significant risk for natural habitat loss. Parks in such areas should be planned to harbor some of the displaced biodiversity.

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Climate-driven habitat size determines the latitudinal diversity gradient in temporary ponds

Ecology, Nov 3, 2015

The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology,... more 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 studied and may exhibit different patterns because they are more sensitive to climatic variation, which result in an inundation-desiccation cycle. In California, precipitation increases and temperature decreases with increasing latitude and thus the LDG pattern may be associated with this climatic gradient. Using collected data and United States Fish & Wildlife Service reports across 7 degrees of latitude, analysis of California vernal pool invertebrate community (total richness and richness of passive and active dispersers) was conducted using correlations (Spearman rank and partial). Alpha diversity (total and passive dispersers) increased and beta diversity (passive dispersers) decreased with increasing latitude. Vernal pool surface area was correlated with active disperser alpha and passive disperser beta diversity. This suggests that climate-driven habitat size influences alpha and beta diversity patterns depending on dispersal ability. Active dispersers and predators exhibited higher beta diversity than passive dispersers and prey respectively. Species composition differed among counties and some of these differences were correlated with pool depth and temperature. These results suggest that seasonal habitats will have diversity patterns strongly associated with local scale characteristics (habitat size and hydroperiod) determined by climate variation along the latitudinal gradient. Understanding these diversity patterns along the gradient will also contribute to management and restoration of these ecosystems with high endemism and diversity.

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Invertebrates of Freshwater Temporary Ponds in Mediterranean Climates

Springer eBooks, 2016

Mediterranean temporary ponds are present in five biogeographical regions, which are characterize... more 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 temporal variability, reflected in large intra- and inter-annual changes in pond hydroperiod that drive patterns in invertebrate communities. Consequently, community dynamics are more temporally variable than in cold-temperate temporary ponds. Globally, temporary pond conservation has been neglected and many ponds have already been lost despite the presence of legal protections and high ecological importance. Future biodiversity protection requires mosaics of ponds with diverse hydroperiods, preserving natural hydroregimes.KeywordsInvertebrates, temporary ponds, Mediterranean regions, seasonal succession, life‑histories, predation, conservation

Metacommunities

University of California Press eBooks, Dec 31, 2019

Winter Freeze Decreases the Emergence of Fauna and Flora in California Vernal Pools

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Impacts of kelp forest restoration on species richness and carbon sequestration

Kelp forests are highly valuable Kelp forests are very productive marine ecosystem with high spec... more Kelp forests are highly valuable Kelp forests are very productive marine ecosystem with high species diversity. They are located in many parts of the world, including off the coast of California. Kelp forests are a major contributor to atmospheric carbon sequestration (storage) on the North American Pacific Coast. While sequestration by kelp receive most of the attention, little work has been conducted to assess sequestration in the fauna associated with kelp forests. Kelp forests have been destroyed Overpopulation of Strongylocentrotus purpuratus (purple sea urchin) reduces kelp growth, productivity, and species diversity (urchin barrens). The rocky reefs along the southern end of the Santa Monica Bay contain 61.5 hectares of urchin barrens. Kelp forests are being restored Organizations are working to remove the urchins, restore kelp forests, and monitor the outcome as part of the Palos Verdes Kelp Forest Restoration Project (KFRP). Three types of areas are monitored and compared to measure restoration efforts; see Figure 2.

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Gause׳s Competitive Exclusion Principle

Elsevier eBooks, 2019

Searching for the Achilles heel(s) for maintaining invertebrate biodiversity across complexes of depressional wetlands

Journal for Nature Conservation, Apr 1, 2023

Eutrophication effects differ among functional groups in vernal pool invertebrate communities

Hydrobiologia, Mar 2, 2021

Environmental productivity and biodiversity are two intricately linked ecological concepts. One c... more 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 concerns given anthropogenic nutrient inputs into waterbodies. One habitat that may be particularly vulnerable to eutrophication are California vernal pools. These ephemeral wetlands provide habitat to numerous threatened or endangered invertebrate taxa. To investigate the impact of eutrophication on invertebrates, experimental mesocosms were setup in the California State University, Sacramento Arboretum. Thirty mesocosms were inoculated with vernal pool soil and divided into five nutrient treatments in each of six blocks. Data was collected over a 21-week hydroperiod to quantify changes over a vernal pool hydroperiod. Nutrient addition increased mesocosm turbidity, chlorophyll-a, and phosphorus levels, in addition to causing larger shifts in dissolved oxygen and pH. While nutrient enrichment increased abundances of small crustaceans, there were no effects on taxa richness, or abundances of large branchiopods or insects. While these findings improve our understanding of bottom-up effects in vernal pools, questions remain over long-term nutrient inputs and interactions with other human activities.

Hydro-regime, Thatch, and Nutrient Effects on California Vernal Pool Crustaceans

Perils of life on the edge: Climatic threats to global diversity patterns of wetland macroinvertebrates

Science of The Total Environment, 2022

Perils of life on the edge: Climatic threats to global diversity patterns of wetland macroinverte... more

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Seasonal isotopic niche of a rodent: High between‐individual variation but no changes in individual niche width during the rich‐resource period

Biotropica, 2021

The dynamics of trophic niche width in animals at both population level and individual level is p... more 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 (δ13C and δ15 N) of fecal samples, we investigated the trophic niche dynamics and individual variation in food‐resource use by the arboreal rat Rhipidomys macrurus, in the highly seasonal Brazilian savanna (Cerrado). We tested the hypothesis that dietary niche expansion during the rich‐resource period (wet season) occurs via individual specialization and consequently lower individual niche overlap in contrast with niche retraction during the low‐resource period (dry season) via increase in niche overlap and expansion of individual niches. The results indicated that R. macrurus is primarily frugivorous and presents a wider isotopic niche in the rich‐resource period in comparison with the low...

NUTRIENT ADDITION EFFECTS AND THE ROLE OF VEGETATION IN CALIFORNIA VERNAL POOLS A Thesis