Physiological Responses to Selection for Desiccation Resistance in Drosophila melanogaster

Comparative physiologists and physiological ecologists havestriven to elucidate the physiological adaptations which eliminateor mitigate environmental stress. Stress tolerance is thoughtto influence the distribution of species as well as the fitnessof individuals within various habitats. Differential stresstolerance depends in large part on physiological mechanismswhich mitigate the deleterious effects of stress. Very littleinformation is available, however, regarding the mechanismsand pathways by which such physiological adaptations arose andwere modified. We point out two methods by which one can investigatethe evolution of stress tolerance: phylogenetic studies andselection studies. Phylogenetic studies have the advantage thatthey can be used to study wild populations, with the drawbackthat species numbers and distribution may be limiting. In addition,for many physiologically interesting clades, the phylogeneticrelationships have yet to be determined. Selection studies havethe advantage that the evolution of physiological systems canbe studied in response to very specific forms of stress. Inaddition, the phytogeny of the organisms can be experimentallymanipulated and replication permits rigorous statistical analysis.The results of studies of the evolution of increased desiccationresistance in Drosophila are presented as an example of themethods by which insights can be obtained regarding the variableswhich respond to selection, the rate of evolutionary changeand the process by which physiological performance changes overevolutionary time. Selection studies can be designed to providemodels regarding the mechanisms, tuning and directions of physiologicalevolution.     

Evidence for the Heterolobosea from Phylogenetic Analysis of Genes Encoding Glyceraldehyde-3-Phosphate Dehydrogenase

ABSTRACT The phylogenetic relationships between major slime mould groups and the identification of their unicellular relatives has been a subject of controversy for many years. Traditionally, it has been assumed that two slime mould groups, the acrasids and the dictyostelids were related by virtue of their cellular slime mould habit; a view still endorsed by at least one current classification scheme, However, a decade ago, on the basis of detailed ultrastructural resemblances, it was proposed that acrasids of the family Acrasidae were not relatives of other slime moulds but instead related to a group of mostly free-living unicellular amoebae, the Schizopyrenida. The class Heterolobosea was created to contain these organisms and has since figured in many discussions of protist evolution. We sought to test the validity of Heterolobosea by characterizing homologs of the highly conserved glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from an acrasid, Acrasis rosea ; a dictyostelid, Dictyostelium discoideum ; and the schizopyrenid Naegleria andersoni. Phylogenetic analysis of these and other GAPDH sequences, using maximum parsimony, neighbour-joining distance and maximum likelihood methods strongly supports the Heterolobosea hypothesis and discredits the concept of a cellular slime mould grouping. Moreover, all of our analyses place Dictyostelium discoideum as a relatively recently originating lineage, most closely related to the Metazoa, similar to other recently published phylogenies of protein-coding genes. However, GAPDH phylogenies do not show robust branching orders for most of the relationships between major groups. We propose that several of the incongruencies observed between GAPDH and other molecular phylogenies are artifacts resulting from substitutional saturation of this enzyme.     

Influence of Behavior on Bird Mortality in Wind Energy Developments

ABSTRACT As wind power generation is rapidly expanding worldwide, there is a need to understand whether and how preconstruction surveys can be used to predict impacts and to place turbines to minimize impacts to birds. Wind turbines in the 165-km² Altamont Pass Wind Resource Area (APWRA), California, USA, cause thousands of bird fatalities annually, including hundreds of raptors. To test whether avian fatality rates related to rates of utilization and specific behaviors within the APWRA, from March 1998 to April 2000 we performed 1,959 30-minute behavior observation sessions (360° visual scans using binoculars) among 28 nonoverlapping plots varying from 23 ha to 165 ha in area and including 10–67 turbines per plot, totaling 1,165 turbines. Activity levels were highly seasonal and species specific. Only 1% of perch time was on towers of operating turbines, but 22% was on towers of turbines broken, missing, or not operating. Of those species that most often flew through the rotor zone, fatality rates were high for some (e.g., 0.357 deaths/megawatt of rated capacity [MW]/yr for red-tailed hawk [Buteo jamaicensis] and 0.522 deaths/MW/yr for American kestrel [Falco sparverius]) and low for others (e.g., 0.060 deaths/MW/yr for common raven [Corvus corax] and 0.012 deaths/MW/yr for turkey vulture [Cathartes aura]), indicating specific behaviors or visual acuity differentiated these species by susceptibility to collision. Fatality rates did not correlate with utilization rates measured among wind turbine rows or plots for any species except burrowing owl (Athene cunicularia) and mallard (Anas platyrhynchos). However, mean monthly fatality rates of red-tailed hawks increased with mean monthly utilization rates (r² = 0.67) and especially with mean monthly flights through turbine rows (r² = 0.92). Fatality rates increased linearly with rates of utilization (r² = 0.99) and flights near rotor zones (r² = 1.00) for large raptor species and with rates of perching (r² = 0.13) and close flights (r² = 0.77) for small non-raptor species. Fatalities could be minimized or reduced by shutting down turbines during ≥1 season or in very strong winds or by leaving sufficiently large areas within a wind farm free of wind turbines to enable safer foraging and travel by birds.     

DNA microsatellites in Acanthochromis polyacanthus

To determine genetic substructuring in populations of the spiny damselfish Acanthochromis polyacanthus among different reefs of the Great Barrier Reef, Australia, we characterized six polymorphic microsatellite loci.     

Energy Budgets for Eared Grebes on the Great Salt Lake and Implications for Harvest of Brine Shrimp

ABSTRACT About 1.5-million eared grebes (Podiceps nigricollis), representing half of the North American population, stage on Utah's Great Salt Lake, USA (GSL) during autumn migration to forage on brine shrimp (Artemia franciscana). Indirectly competing with birds for brine shrimp are commercial harvesters who annually collect >1 million kg (dry wt) of shrimp cysts (i.e., hardened eggs), an amount that during some years equals up to half of all brine shrimp cysts produced annually on the GSL. No information was available regarding what impact this commercial harvest was having on eared grebes. We determined daily energy requirements of eared grebes so that regulations governing brine shrimp cyst harvest would better reflect foraging needs of grebes. We measured basal metabolic rate (BMR) of eared grebes from June 2000 to October 2000. Mean BMR of 106 adult and subadult eared grebes was 0.023 kJ/g/hour (SD = 0.004), and mean BMR of 37 juveniles was 0.024 kJ/g/hour (SD = 0.003). Resting and preening metabolic rates were 1.2 times higher than BMR, whereas diving-bout metabolic rate was 1.7 times higher than BMR. Daily energy needs of an average-sized grebe (550 g) during November were 391 kJ. Meeting this energy need requires daily consumption of 24,400 adult brine shrimp. In addition, grebes must consume 2,100–5,200 adult shrimp daily to obtain enough energy reserves to continue their migration to California, USA, and Mexico. Hence, grebes need to consume 26,500–29,600 adult brine shrimp daily while staging on GSL. To achieve this high harvest rate, grebes need adult brine shrimp densities at >380 shrimp/m³during autumn. Commercial harvest of brine shrimp cysts from GSL should be curtailed when cyst densities fall below 20,000 cysts/m³to ensure enough adult brine shrimp for grebes during the subsequent year.     

Cross‐species amplification at microsatellite loci in Australian quolls including the description of five new markers from the Chuditch (Dasyurus geoffroii)

The quolls are the largest native predators remaining on mainland Australia. We describe the cross‐species testing of all available microsatellite loci for representative across the entire distribution of quolls, with the additional characterization of five new microsatellite loci from the Chuditch. All primers produced clear and polymorphic amplification patterns containing between nine and 17 alleles and with high levels of diagnostic variability. These highly polymorphic primers make them useful additional tools in planning conservation strategies across related conspecifics, many of which are under threat.     

Habitat selection and web plasticity by the orb spider Argiope keyserlingi (Argiopidae): Do they compromise foraging success for predator avoidance?

Abstract Orb web spiders face a dilemma: forage in open habitats and risk predation or forage in closed habitats to minimize risk but at reduced foraging profitability. We tested whether Argiope keyserlingi opts for safer habitats at the expense of foraging success by (i) determining habitat selection indices in open and closed habitats; (ii) marking and releasing individual juvenile, subadult and adults over two 4‐week periods to determine if life‐history stage influences habitat selection; and (iii) determining the biotic and abiotic environmental parameters that relate to A. keyserlingi abundance. We found that A. keyserlingi selected closed habitats. Sedge and anthropogenic structures were selected and trees were avoided. Juveniles were never found in open habitats, most likely because of high postdispersal mortality. Subadults and adults may shift from closed to open habitats while juveniles never shifted habitat. Foliage density, plant height, potential prey abundance, and mantid and bird abundance were correlated with A. keyserlingi abundance, with only bird abundance explaining habitat selection. We measured web capture area, spiral distance (distance between spiral threads) and the number of decoration arms (0, 1, 2, 3 or 4) in the field and did laboratory experiments to test the influence of (i) space and vegetation; (ii) prey abundance; and (iii) web damage, on web architecture. Argiope keyserlingi webs exhibited geometric plasticity by having larger prey capture areas and spiral distances in open habitats. Decoration design did not differ between habitats however. Variation in space availability, air temperature, prey abundance and web damage explained the variations in web architecture. Potential prey size and diversity differed between habitats but prey abundance did not. As large prey may be important for spider survivorship, foraging success appears to be compromised by occupying closed habitats.     

Resource Selection by Translocated Three-Toed Box Turtles in Missouri

Abstract Resource selection is a multi-staged process of behavioral responses to various resource cues or stimuli. Previous research suggests some aspects of resource selection may be inherent (i.e., genetic predisposition) or based on early experience and that individuals respond to certain resource cues but not to others. In other words, resource selection may be based on a template that specifies which cues to use in the resource-selection process and the appropriate response to those cues. We used resource utilization functions (RUFs) to examine the resource-selection template of translocated three-toed box turtles (Terrapene carolina triunguis; hereafter turtles) and made comparisons to resident turtles. Translocated turtles, previously residents of a predominantly forested landscape with low edge-density, used forest openings, forest edges, and southwest-facing slopes before and after translocation to a fragmented site containing resident turtles. In contrast, resident turtles used forested areas and northeast-facing slopes within a predominantly open landscape with high edge-density. Our comparison of resource selection by translocated and resident turtles revealed population-specific resource selection and consistency in selection following translocation, which reinforces the idea of a resource-selection template and suggests that in the short-term box turtles may not adapt their predisposed behavior to local conditions. Thus, translocated animals may evaluate and respond to resource cues as if they were at the original site. Lack of site fidelity may result from individuals seeking additional resources to match their resource-selection template. Successful translocation of turtles may require an assessment of resource selection prior to translocation and development of management strategies that mitigate turtle response to translocation.     

Conspecific Attraction is a Missing Component in Wildlife Habitat Modeling

Abstract Wildlife biologists use knowledge about wildlife-habitat relationships to create habitat models to predict species occurrence across a landscape. Researchers attribute limitations in predictive ability of a habitat model to data deficiencies, missing parameters, error introduced by specifications of the statistical model, and natural variation. Few wildlife biologists, however, have incorporated intra- and interspecific interactions (e.g., conspecific attraction, competition, predator-prey relationships) to increase predictive accuracy of habitat models. Based on our literature review and preliminary data analysis, conspecific attraction can be a primary factor influencing habitat selection in wildlife. Conspecific attraction can lead to clustered distributions of wildlife within available habitat, reducing the predictive ability of habitat models based on vegetative and geographic parameters alone. We suggest wildlife biologists consider incorporating a parameter in habitat models for the clustered distribution of individuals within available habitat and investigate the mechanisms leading to clustered distributions of species, especially conspecific attraction.