Biological Sciences, Department of

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Does the Earth's Magnetic Field Serve as a Reference for Alignment of the Honeybee Waggle Dance?

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-26
Abstract: 

The honeybee (Apis mellifera) waggle dance, which is performed inside the hive by forager bees, informs hive mates about a potent food source, and recruits them to its location. It consists of a repeated figure-8 pattern: two oppositely directed turns interspersed by a short straight segment, the “waggle run”. The waggle run consists of a single stride emphasized by lateral waggling motions of the abdomen. Directional information pointing to a food source relative to the sun's azimuth is encoded in the angle between the waggle run line and a reference line, which is generally thought to be established by gravity. Yet, there is tantalizing evidence that the local (ambient) geomagnetic field (LGMF) could play a role. We tested the effect of the LGMF on the recruitment success of forager bees by placing observation hives inside large Helmholtz coils, and then either reducing the LGMF to 2% or shifting its apparent declination. Neither of these treatments reduced the number of nest mates that waggle dancing forager bees recruited to a feeding station located 200 m north of the hive. These results indicate that the LGMF does not act as the reference for the alignment of waggle-dancing bees.

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(R)-Desmolactone Is a Sex Pheromone or Sex Attractant for the Endangered Valley Elderberry Longhorn Beetle Desmocerus californicus dimorphus and Several Congeners (Cerambycidae: Lepturinae)

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-18
Abstract: 

We report here that (4R,9Z)-hexadec-9-en-4-olide [(R)-desmolactone] is a sex attractant or sex pheromone for multiple species and subspecies in the cerambycid genus Desmocerus. This compound was previously identified as a female-produced sex attractant pheromone of Desmocerus californicus californicus. Headspace volatiles from female Desmocerus aureipennis aureipennis contained (R)-desmolactone, and the antennae of adult males of two species responded strongly to synthetic (R)-desmolactone in coupled gas chromatography-electroantennogram analyses. In field bioassays in California, Oregon, and British Columbia, traps baited with synthetic (R)-desmolactone captured males of several Desmocerus species and subspecies. Only male beetles were captured, indicating that this compound acts as a sex-specific attractant, rather than as a signal for aggregation. In targeted field bioassays, males of the US federally threatened subspecies Desmocerus californicus dimorphus responded to the synthetic attractant in a dose dependent manner. Our results represent the first example of a “generic” sex pheromone used by multiple species in the subfamily Lepturinae, and demonstrate that pheromone-baited traps may be a sensitive and efficient method of monitoring the threatened species Desmocerus californicus dimorphus, commonly known as the valley elderberry longhorn beetle.

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Measuring Evolutionary Isolation for Conservation

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-10
Abstract: 

Conservation planning needs to account for limited resources when choosing those species on which to focus attention and resources. Currently, funding is biased to small sections of the tree of life, such as raptors and carnivores. One new approach for increasing the diversity of species under consideration considers how many close relatives a species has in its evolutionary tree. At least eleven different ways to measure this characteristic on phylogenies for the purposes of setting species-specific priorities for conservation have been proposed. We find that there is much redundancy within the current set, with three pairs of metrics being essentially identical. Non-redundant metrics represent different trade-offs between the unique evolutionary history represented by a species verses its average distance to all other species. Depending on which metric is used, species priority lists can differ as much as 85% for the top 100 species. We call for some consensus on the theory behind these metrics and suggest that all future developments are compared to the current published set, and offer scripts to aid such comparisons.

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Article
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Assessing the Effect of Marine Reserves on Household Food Security in Kenyan Coral Reef Fishing Communities

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-11-25
Abstract: 

Measuring the success or failure of natural resource management is a key challenge to evaluate the impact of conservation for ecological, economic and social outcomes. Marine reserves are a popular tool for managing coastal ecosystems and resources yet surprisingly few studies have quantified the social-economic impacts of marine reserves on food security despite the critical importance of this outcome for fisheries management in developing countries. Here, I conducted semi-structured household surveys with 113 women heads-of-households to investigate the influence of two old, well-enforced, no-take marine reserves on food security in four coastal fishing communities in Kenya, East Africa. Multi-model information-theoretic inference and matching methods found that marine reserves did not influence household food security, as measured by protein consumption, diet diversity and food coping strategies. Instead, food security was strongly influenced by fishing livelihoods and household wealth: fishing families and wealthier households were more food secure than non-fishing and poorer households. These findings highlight the importance of complex social and economic landscapes of livelihoods, urbanization, power and gender dynamics that can drive the outcomes of marine conservation and management.

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Article
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Species, Habitats, Society: An Evaluation of Research Supporting EU's Natura 2000 Network

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-11-21
Abstract: 

The Natura 2000 network is regarded as one of the conservation success stories in the global effort to protect biodiversity. However, significant challenges remain in Natura 2000 implementation, owing to its rapid expansion, and lack of a coherent vision for its future. Scientific research is critical for identifying conservation priorities, setting management goals, and reconciling biodiversity protection and society in the complex political European landscape. Thus, there is an urgent need for a comprehensive evaluation of published Natura 2000 research to highlight prevalent research themes, disciplinary approaches, and spatial entities. We conducted a systematic review of 572 scientific articles and conference proceedings focused on Natura 2000 research, published between 1996 and 2014. We grouped these articles into ‘ecological’ and ‘social and policy’ categories. Using a novel application of network analysis of article keywords, we found that Natura 2000 research forms a cohesive small-world network, owing to the emphasis on ecological research (79% of studies, with a strong focus on spatial conservation planning), and the underrepresentation of studies addressing ‘social and policy’ issues (typically focused on environmental impact assessment, multi-level governance, agri-environment policy, and ecosystem services valuation). ‘Ecological’ and ‘social and policy’ research shared only general concepts (e.g., Natura 2000, Habitats Directive) suggesting a disconnection between these disciplines. The UK and the Mediterranean basin countries dominated Natura 2000 research, and there was a weak correlation between number of studies and proportion of national territory protected. Approximately 40% of ‘social and policy’ research and 26% of ‘ecological’ studies highlighted negative implications of Natura 2000, while 21% of studies found positive social and biodiversity effects. We emphasize the need for designing inter- and transdisciplinary research in order to promote a social-ecological understanding of Natura 2000, and advance EU conservation policies.

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Article
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Dietary Mechanism behind the Costs Associated with Resistance to Bacillus thuringiensis in the Cabbage Looper, Trichoplusia ni

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-08-29
Abstract: 

Beneficial alleles that spread rapidly as an adaptation to a new environment are often associated with costs that reduce the fitness of the population in the original environment. Several species of insect pests have evolved resistance to Bacillus thuringiensis (Bt) toxins in the field, jeopardizing its future use. This has most commonly occurred through the alteration of insect midgut binding sites specific for Bt toxins. While fitness costs related to Bt resistance alleles have often been recorded, the mechanisms behind them have remained obscure. We asked whether evolved resistance to Bt alters dietary nutrient intake, and if reduced efficiency of converting ingested nutrients to body growth are associated with fitness costs and variation in susceptibility to Bt. We fed the cabbage looper Trichoplusia ni artificial diets differing in levels of dietary imbalance in two major macronutrients, protein and digestible carbohydrate. By comparing a Bt-resistant T. ni strain with a susceptible strain we found that the mechanism behind reduced pupal weights and growth rates associated with Bt-resistance in T. ni was reduced consumption rather than impaired conversion of ingested nutrients to growth. In fact, Bt-resistant T. ni showed more efficient conversion of nutrients than the susceptible strain under certain dietary conditions. Although increasing levels of dietary protein prior to Bt challenge had a positive effect on larval survival, the LC50 of the resistant strain decreased when fed high levels of excess protein, whereas the LC50 of the susceptible strain continued to rise. Our study demonstrates that examining the nutritional basis of fitness costs may help elucidate the mechanisms underpinning them.

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IglC and PdpA Are Important for Promoting Francisella Invasion and Intracellular Growth in Epithelial Cells

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-08-12
Abstract: 

The highly infectious bacteria, Francisella tularensis, colonize a variety of organs and replicate within both phagocytic as well as non-phagocytic cells, to cause the disease tularemia. These microbes contain a conserved cluster of important virulence genes referred to as the Francisella Pathogenicity Island (FPI). Two of the most characterized FPI genes, iglC and pdpA, play a central role in bacterial survival and proliferation within phagocytes, but do not influence bacterial internalization. Yet, their involvement in non-phagocytic epithelial cell infections remains unexplored. To examine the functions of IglC and PdpA on bacterial invasion and replication during epithelial cell infections, we infected liver and lung epithelial cells with F. novicida and F. tularensis ‘Type B’ Live Vaccine Strain (LVS) deletion mutants (ΔiglC and ΔpdpA) as well as their respective gene complements. We found that deletion of either gene significantly reduced their ability to invade and replicate in epithelial cells. Gene complementation of iglC and pdpA partially rescued bacterial invasion and intracellular growth. Additionally, substantial LAMP1-association with both deletion mutants was observed up to 12 h suggesting that the absence of IglC and PdpA caused deficiencies in their ability to dissociate from LAMP1-positive Francisella Containing Vacuoles (FCVs). This work provides the first evidence that IglC and PdpA are important pathogenic factors for invasion and intracellular growth of Francisella in epithelial cells, and further highlights the discrete mechanisms involved in Francisella infections between phagocytic and non-phagocytic cells.

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Article
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Indigenous Knowledge and Science Unite to Reveal Spatial and Temporal Dimensions of Distributional Shift in Wildlife of Conservation Concern

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-07-23
Abstract: 

Range shifts among wildlife can occur rapidly and impose cascading ecological, economic, and cultural consequences. However, occurrence data used to define distributional limits derived from scientific approaches are often outdated for wide ranging and elusive species, especially in remote environments. Accordingly, our aim was to amalgamate indigenous and western scientific evidence of grizzly bear (Ursus arctos horribilis) records and detail a potential range shift on the central coast of British Columbia, Canada. In addition, we test the hypothesis that data from each method yield similar results, as well as illustrate the complementary nature of this coupled approach. Combining information from traditional and local ecological knowledge (TEK/LEK) interviews with remote camera, genetic, and hunting data revealed that grizzly bears are now present on 10 islands outside their current management boundary. LEK interview data suggested this expansion has accelerated over the last 10 years. Both approaches provided complementary details and primarily affirmed one another: all islands with scientific evidence for occupation had consistent TEK/LEK evidence. Moreover, our complementary methods approach enabled a more spatially and temporally detailed account than either method would have afforded alone. In many cases, knowledge already held by local indigenous people could provide timely and inexpensive data about changing ecological processes. However, verifying the accuracy of scientific and experiential knowledge by pairing sources at the same spatial scale allows for increased confidence and detail. A similarly coupled approach may be useful across taxa in many regions.

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Time-Delayed Subsidies: Interspecies Population Effects in Salmon

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-06-09
Abstract: 

Cross-boundary nutrient inputs can enhance and sustain populations of organisms in nutrient-poor recipient ecosystems. For example, Pacific salmon (Oncorhynchus spp.) can deliver large amounts of marine-derived nutrients to freshwater ecosystems through their eggs, excretion, or carcasses. This has led to the question of whether nutrients from one generation of salmon can benefit juvenile salmon from subsequent generations. In a study of 12 streams on the central coast of British Columbia, we found that the abundance of juvenile coho salmon was most closely correlated with the abundance of adult pink salmon from previous years. There was a secondary role for adult chum salmon and watershed size, followed by other physical characteristics of streams. Most of the coho sampled emerged in the spring, and had little to no direct contact with spawning salmon nutrients at the time of sampling in the summer and fall. A combination of techniques suggest that subsidies from spawning salmon can have a strong, positive, time-delayed influence on the productivity of salmon-bearing streams through indirect effects from previous spawning events. This is the first study on the impacts of nutrients from naturally-occurring spawning salmon on juvenile population abundance of other salmon species.

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Article
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Genetic Similarity of Island Populations of Tent Caterpillars during Successive Outbreaks

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-05-23
Abstract: 

Cyclic or fluctuating populations experience regular periods of low population density. Genetic bottlenecks during these periods could give rise to temporal or spatial genetic differentiation of populations. High levels of movement among increasing populations, however, could ameliorate any differences and could also synchronize the dynamics of geographically separated populations. We use microsatellite markers to investigate the genetic differentiation of four island and one mainland population of western tent caterpillars, Malacosoma californicum pluviale, in two periods of peak or pre-peak density separated by 8 years. Populations showed high levels of genetic variation and little genetic differentiation either temporally between peaks or spatially among sites. Mitochondrial haplotypes were also shared between one island population and one mainland population in the two years studied. An isolation-by-distance analysis showed the FST values of the two geographically closest populations to have the highest level of differentiation in both years. We conclude that high levels of dispersal among populations maintain both synchrony of population dynamics and override potential genetic differentiation that might occur during population troughs. As far we are aware, this is the first time that genetic similarity between temporally separated population outbreaks in insects has been investigated. A review of genetic data for both vertebrate and invertebrate species of cyclic animals shows that a lack of spatial genetic differentiation is typical, and may result from high levels of dispersal associated with fluctuating dynamics.

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