5th Annual Bay Area Conservation Biology Symposium
University of California at BerkeleySaturday February 1st, 2003
Valley Life Sciences Building8.00 am - 7.30 pm

Papers A-G

Papers A-G | Papers H-N | Papers O-Z | Posters

Title:Effect of disturbance by mammals on abundance of native and non-native plants in a coastal grassland in northern California
Author: Peter Alpert, University of Massachusetts at Amherst
Madeline Scheintaub, University of Massachusetts at Amherst
Format:paper
Presentation:Concurrent Sessions IV, Communities, 3:10 - 4:10 pm, 2063 VLSB
Abstract:Disturbance, or the removal of biomass, strongly influences invasion by non-native plants into natural communities. Burrowing and grazing by mammals are major sources of disturbance in the coastal prairie at the University of California Bodega Marine Reserve. To test the hypothesis that burrowing and grazing promote invasion by non-native plants in this grassland, we compared plant species cover and biomass on and off gopher mounds in lightly invaded grassland and inside and outside exclosures in both lightly and heavily invaded grassland. Mounds did not have significantly higher relative abundances of non-natives than adjacent grassland, although the few individual species that were more abundant on mounds were non-native. Grazing significantly decreased standing biomass in both lightly and heavily invaded grassland, but did not remove more biomass in lightly than in heavily invaded grassland nor decrease biomass of natives more than that of non-natives. These results do not suggest that burrowing or grazing facilitates invasion in this system.

Title:Population structure and history of Rana blairi, the plains leopard frog
Author: Yvette Alva, San Francisco State University
Susan Masta, San Francisco State University
Eric Routman, San Francisco State University
Format:paper
Presentation:Concurrent Sessions III, Phylogeography and Conservation, 1:30 - 2:50 pm, 2060 VLSB
Abstract:To understand how historical and current factors have influenced the population structure of the Plains Leopard Frog, Rana blairi, I have examined the geographic distribution of alleles by use of phylogeographic analysis and the nested clade method. A partial sequence of the ND2 mtDNA region was isolated among 22 widely distributed populations of Rana blairi. Closely related haplotypes seen in both parsimony trees and the minimum spanning network of haplotypes reflect range expansion following Pleistocene glaciation. Using the nested cladistic analysis I found isolation-by-distance among two high level nested clades, a gradual northeastward expansion within a high level nested clade, and a long distance colonization event from north to south within a lower nested clade. Due to the limited vagility of amphibians, evidence of a long distance colonization event is suspicious, I suggest that this event is an artifact of a southward gradual range expansion. To gain further insight about the genetic structuring of Rana blairi, I performed a Mantel test and found a significant relationship between geographic distance and Fst (r=0.265 p=0.007), which supports an isolation-by-distance model, but this relationship is small, suggesting that genetic drift and gene flow are not at equilibrium. Furthermore, I concluded from the pattern of the scatter plot of geographic distance versus genetic distance that genetic drift is overriding gene flow among populations of Rana blairi. Evidence of low gene flow and strong drift suggests that loss of allelic variation in small fragmented populations is likely in R. blairi.

Title:The evolution of beta diversity among Lesser Antillean Anolis lizards
Author: Lauren B. Buckley, Stanford University
Joan E. Roughgarden, Stanford University
Format:paper
Presentation:Concurrent Sessions II, Community Ecology and Biodiversity, 11:20 - 12:20 pm, 2060 VLSB
Abstract:We compare habitat use by Anolis lizard species pairs on two Lesser Antilles islands with differential topography using new GIS methodology. St. Kitts anoles segregate habitat with respect to perch height. Grenada anoles exhibit some local microclimate habitat partitioning, but observations over an expanded elevation breadth suggest that this partitioning is less pervasive than previously thought. Grenada exhibits a greater degree of broad scale horizontal habitat segregation than St. Kitts, with the larger species predominantly occupying mesic, higher elevation sites and the smaller species predominantly occupying xeric, lower elevation sites. Grenada’s more equal distribution of habitat types may induce the evolution of habitat specialization, whereas St. Kitts’ predominance of a single habitat type may result in local habitat partitioning rather than broad scale habitat specialization. An individual based model of anole population dynamics that includes thermal physiology offers a starting point to determine to what extent the evolution of beta diversity can be traced to physiological adaptation.

Title:Ecology of bovine tuberculosis in African buffalo
Author: Paul Cross, University of California at Berkeley
Johan du Toit, University of Pretoria
Wayne Getz, University of California at Berkeley
Format:paper
Presentation:Concurrent Sessions III, African Conservation, 1:30 - 2:50 pm, 2050 VLSB
Abstract:Bovine tuberculosis (BTB) occurs in cattle and wildlife worldwide and can be controlled in cattle with test-and-slaughter programs, but this has not been successful in areas where wildlife species are reservoir hosts. BTB is increasing in prevalence and moving northwards through the buffalo population of the Kruger National Park (KNP), South Africa. BTB appears to have minor effects upon the buffalo population, but the disease is spreading to other species such as lions, leopards, cheetahs, greater kudus, and chacma baboons. It remains unclear how BTB will affect the ecological dynamics of the herbivore and predator guilds of the KNP. We discuss several ongoing research projects on BTB in buffalo and the conservation implications. They include the security of the South African livestock industry outside the park, the political acceptance of transfrontier conservation management along Kruger’s boundaries with Mozambique and Zimbabwe, and the maintenance of genetic connectivity between wildlife subpopulations across southern Africa.

Title:Top-down from the bottom-up: Indirect effect of species introductions to islands
Author: Eric Danner, University of California at Santa Cruz
Jim Estes, University of California at Santa Cruz
Don Croll, University of California at Santa Cruz
Jon Maron, University of Montana
Format:paper
Presentation:Concurrent Sessions IV, Communities, 3:10 - 4:10 pm, 2063 VLSB
Abstract:We are examining the indirect effects of introduced predators on terrestrial plant communities on islands in the Aleutian archipelago, Alaska. Foxes have substantially reduced seabird populations on many Alaskan islands since being introduced in the late 19th and early 20th centuries. We hypothesize that prior to fox introductions, large populations of seabirds were an important vector of nutrients from the marine environment to nutrient impoverished terrestrial plant communities. By reducing these nutrient subsidies through seabird predation, foxes may have caused a shift in the plant species composition from a nutrient replete grass community to a nutrient deplete moss, sedge and lichen community. We are examining these shifts in community structure by comparing fox-infested and fox-free islands throughout the Aleutian chain using a combination of small-scale island sampling, nutrient addition experiments, and landscape-level analysis using remote sensing. Our objective is to determine the spatial and temporal scales at which the allochthonous input of nutrients via seabirds affects the biomass and species composition of insular plant communities.

Title:The influence of abiotic factors and temporal variation on invasion patterns of the Argentine ant (Linepithema humile)
Author: Lisa DiGirolamo, University of California at Santa Cruz
Laurel Fox, University of California at Santa Cruz
Format:paper
Presentation:Concurrent Sessions III, Invertebrates, 1:30 - 2:50 pm, 2063 VLSB
Abstract:This study investigates the patterns of spread and possible causes of those patterns of the invasive exotic Argentine ant, Linepithema humile. I explore three areas: 1) spatial and temporal patterns of invasion at a local scale; 2) the effects of this invader on native ant communities; and 3) causal mechanisms for these spatial, temporal and numerical patterns, particularly in relation to local climate. Both relative densities and movement of L. humile varied across seasons and years, and correlate with air temperature and precipitation. In contrast, native ants (except the primarily winter-foraging Prenolepis imparis) showed no relation to precipitation or air temperature. Most important, L. humile abundance correlates most strongly with precipitation 6 months in the past. In some seasons and years at Fort Ord, the relative densities of L. humile workers were more than 8 times that of all ground foraging ants combined. Since most or all ground-foraging species of ants succumb to L. humile, their invasion reduces ecological complexity in the ant community, replacing the various roles of the natives with just one type of feeding and nesting behavior. In California, rainfall (and therefore water availability) varies greatly among years and seasons, with potential impacts on the ability of the Argentine ant to invade new areas. I examine how small scale invasion patterns may be caused by large scale weather phenomena, describing the invasion at a scale critical to and useful for land managers.

Title:The Ecuadorian Andes as a barrier to gene flow in neotropical passerines
Author: Caroline Dingle, San Francisco State University
Thomas B. Smith, University of California at Los Angeles
Format:paper
Presentation:Concurrent Sessions III, Phylogeography and Conservation, 1:30 - 2:50 pm, 2060 VLSB
Abstract:Understanding the evolutionary processes that lead to speciation is essential to conservation programs aiming to preserve future as well as extant diversity. Several hypotheses have been proposed to explain the speciation processes that have led to the high levels of biodiversity found in the tropics. Many of these hypotheses are based on allopatric speciation, where populations become isolated on either side of a geographic barrier and are thus prevented from interbreeding. This study examines the hypothesis that the Andes mountains form a major barrier to gene flow, thereby acting as an important agent of speciation in the South America. To address this hypothesis, genetic sequences were obtained from two species of passerines (Mionectes striaticollis, Streak-necked Flycatcher, and Henicorhina leucophrys, Gray-breasted Wood-wren). Both species inhabit the understory of cloud forest along the eastern and western slopes of the Andes. Genetic analysis of the mitochondrial ATPase gene revealed no genetic structure in M. striaticollis, suggesting that there has been some level of genetic mixing across the Andes in this species. In contrast, analysis of the same gene in H. leucophrys revealed a high level of genetic structuring, with an average of 6% sequence divergence between eastern and western populations. These results suggest that the effectiveness of the Andes as a barrier to gene flow varies depending on the species in question. In the future, morphological analyses will be conducted on these two species to see if the results are concordant with the results of the genetic data.

Title:Population genetic detection of reduction in population size
Author: Carlos Garza, Southwest Fisheries Science Center
Format:paper
Presentation:Concurrent Sessions III, Phylogeography and Conservation, 1:30 - 2:50 pm, 2060 VLSB
Abstract:Several methods have been described for detecting recent reductions in effective population size using population genetic data. A more sensitive version of one of these methods is presented and three methods are compared. Error rates, recovery times and effects of migration are examined. A method for estimating the loss of genetic variation due to reduction in population size is also presented. These techniques are employed to analyze data from over 40 populations of ESA listed steelhead trout. The results emphasis the importance of using multiple methods and suggest a way to detect migration into the focal population.

Title:Susceptibility of California's remaining roadless grasslands to yellow starthistle invasion
Author: Jonathan Gelbard, University of California at Davis
Susan Harrison, University of California at Davis
Format:paper
Presentation:Concurrent Sessions I, Plants, 10:00 - 11:00 am, 2063 VLSB
Abstract:Roadless habitats have been shown to be refuges for native plant diversity against exotic invasions, but few studies have tested whether this results from propagule limitation or resistance. We examined mechanisms responsible for lower abundance of Centaurea solstitialis in California grasslands >1000 m vs. 10 m from roads. During winter 2001 and 2002, we planted 100 Centaurea seeds in 64 pairs of 0.1m2 plots (uncleared and cleared of plant material) at sites stratified by distance from roads (10 m and >1000 m), soil (non-serpentine and serpentine), and aspect (cool, warm, and neutral slopes). In non-serpentine grasslands, Centaurea's seedling survivorship, flowerhead numbers, and biomass were greater in 10 m (near) than >1000 m (distant) uncleared plots and its biomass was greater in near than distant uncleared and cleared plots. These effects were not significant after we compensated for higher native grass richness and lower cover by bare ground in distant sites. When we included in our models distance, native grass richness, bare ground, and interactions, the effect of distance was significant only in interaction with bare ground; there was significantly less Centaurea in distant plots only where they contained little bare ground. Native grass richness remained significantly negatively correlated with Centaurea's seedling survivorship, but not with flowerhead numbers or biomass. On serpentine, there was no effect of road proximity on planted Centaurea. Our results suggest that Centaurea seeds can establish in grasslands regardless of distance from roads. Beyond the seedling stage, however, biotic resistance conferred by high native grass richness and isolation from human disturbances may protect roadless non-serpentine grasslands. Roadless serpentine grasslands may be vulnerable to invasion if propagules are introduced, especially into more productive sites. To protect California's roadless grasslands from Centaurea invasion, land managers should prevent introductions of its propagules and limit disturbances that reduce native grass richness.

Title:Defining a wildland network in the Sierra Nevada/Modoc Plateau using GIS: Methods, comparisons, and feasibility for acquisition
Author: Evan Girvetz, University of California at Davis
Fraser Shilling, University of California at Davis
Format:paper
Presentation:Concurrent Sessions I, Conservation Planning, 10:00 - 11:00 am, 2050 VLSB
Abstract:A geographic information systems (GIS) based analysis was used to define a wildland reserve network for the Sierra Nevada, eastern Sierra Nevada, Modoc Plateau, and southern Cascade ecoregions within California. This analysis was conducted as part of the Wildlands Project, which is dedicated to protecting biodiversity and natural processes. We used the GIS-linked fuzzy logic knowledge-base program Ecosystem Management Decision Support (EMDS) to score each 500-meter grid cell in the landscape for its potential contribution a wildland network based on aquatic integrity, terrestrial integrity, and presence of focal species habitat. Contiguous core areas with high wildland potential were then delineated using a simulated annealing function algorithm (SITES, Adelman et al. 1999) that created a portfolio of areas that maximized core area potential, and plant community representation, while minimizing core area boundary length. EMDS was then used to identify areas with high corridor potential for four vegetation/elevation zones: foothill oak woodland, mid-elevation conifer, high-elevation alpine, and eastern forest/scrub. Corridor potential took into account wildland area potential, topography, and human population density. Connecting core areas using a least cost path analysis run over the corridor potential grids completed the "wildland network". The final reserve network requires the protection of an additional 22-37% of the landscape (beyond that already protected) to protect 78-86% of plant community types for a given ecoregion. This reserve network was found to have better plant community and elevation representation when compared with a hypothetical reserve network that protected all unroaded areas greater than 2023 hectares (5000 acres). A parcel acquisition analysis of Nevada County found that acquiring all parcels within the reserve network for this rapidly developing county would be prohibitively expensive. Moreover, only acquiring the larger, cheaper parcels severely fragments the reserve network and reduces plant community representation, especially in the low and middle elevations.

Title:How can we most effectively restore riparian areas: Biological, social and economic considerations (CANCELLED)
Author: Elizabeth Gray, The Nature Conservancy
Format:paper
Presentation:Concurrent Sessions I, Conservation Planning, 10:00 - 11:00 am, 2050 VLSB
Abstract:Restoration of degraded riparian areas has become a priority for many Nature Conservancy projects, as scientists strive to restore natural processes to disturbed sites. In California, incompatible ranching has caused substantial erosion, decreased water quality, fragmented habitat, and a lack of tree recruitment in many riparian areas. One of the most common solutions to overgrazing is to fence cattle out of riparian areas. This tends, however, to be exceptionally expensive and may lead to rampant invasion of weedy species. An alternative is to seasonally graze a broader zone which includes adjacent grasslands. No comparison has been made documenting the relative costs and benefits of these two restoration methods on the same system. This study experimentally compares the effectiveness of each strategy on the increasingly rare sycamore and cottonwood-willow riparian forests of California’s central coast. Twelve miles along two creeks were fenced, with the lower portions designated as total cattle exclusion and the upper portions accommodating seasonal usage. Negotiations are underway to include two additional creeks in this design. We documented baseline conditions by surveying the herb, shrub and tree layers using point-intercept and belt transect methods; breeding bird occurrences were sampled using variable circular plot methods; fish, amphibian and reptile inventories were conducted using visual encounter surveys; and benthic macroinvertebrates were sampled using California rapid bioassessment protocols. Over 105 plant, 50 vertebrate and 100 invertebrate species were found in the study area, with ~22% non-natives. Preliminary data indicate a substantial increase in breeding bird abundance, specifically passerines and raptors, after one year of cattle removal. The Nature Conservancy plans to use these data in an adaptive learning framework so that social and economic factors, as well as biological factors, are considered when designing landscape scale restoration projects.

Papers A-G | Papers H-N | Papers O-Z | Posters

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