Fire resilience of ant assemblages in long‐unburnt savanna of northern Australia

Abstract Tropical savannas and rainforests contrast in their flammability and the fire resilience of their associated species. While savanna species generally exhibit high resilience to burning, there is much debate about the fire resilience of forest‐associated species, and the persistence of forest patches in a flammable savanna matrix. Where fire has been excluded, savanna tends on a trajectory towards forest, with an increase in forest‐associated plants and animal species. This study tested the idea that given the high proportion of forest‐associated taxa in long‐unburnt savanna, the fauna of these areas would be expected to exhibit less resilience to fire than the fauna in frequently burnt savannas. The study investigated the immediate and short‐term effects on ant assemblages of re‐introducing fire into long‐unburnt savanna in northern Australia. The ant fauna exhibited high resistance to fires, with no significant short‐term change in mean abundance or species richness; instead, seasonality had a far stronger influence on overall ant activity. Fire caused dramatic declines in dominance of the patchily distributed forest‐associated species Oecophylla smaragdina and Papyrius sp., but had no effect on overall dominance by open savanna species of Iridomyrmex. Dominance by Iridomyrmex pallidus declined, but this was compensated for by increases in I. reburrus, while two other species of Iridomyrmex showed no change. This indicates a high level of functional redundancy among dominant species of Iridomyrmex, which universally dominate open savanna communities, but not of dominant forest‐associated species. Overall, our findings demonstrate a high degree of fire‐resilience of the long‐unburnt savanna ant fauna. Despite the occurrence of forest‐associated species, the high proportion of savanna species persisting in this habitat means that long‐unburnt savanna retains the general response characteristics of frequently burnt savanna.     

Dominant (AFLP) and co‐dominant (microsatellite) markers for the kelp Postelsia palmaeformis (Laminariales)

To aid in understanding the structure, dispersal and genetic dynamics of their populations, we developed microsatellite and amplified fragment length polymorphism (AFLP) markers for the sea palm, Postelsia palmaeformis (Laminariales) for samples taken from nine sites in the area of Cape Flattery, Washington State, USA. We identified two AFLP primers that yielded 798 variable fragments and five microsatellite markers with three to seven alleles each. We also report patterns of allelic variation for four previously identified microsatellite markers in this species and several new alleles.     

Effects of US 1 Project on Florida Key Deer Mortality

ABSTRACT Approximately 26% of annual mortality for the endangered Florida Key deer (Odocoileus virginianus clavium) occurs as deer-vehicle collisions (DVCs) on the 5.6-km section of United States Highway 1 (US 1) on Big Pine Key (BPK), but extensive urban development adjacent to sections of US 1 complicates efforts to reduce DVCs. Our objective was to evaluate the effectiveness of the US 1 Project (continuous 2.6-km system of 2.4-m fencing, 2 underpasses, and 4 experimental deer guards constructed on US 1 on BPK) in reducing DVCs along US 1. Deer used the underpasses all 3 postproject years (2003–2005); however, we observed higher underpass use in 2004 and 2005 compared to 2003. Exclusion fencing reduced deer intrusions onto the fenced section of US 1 during the 3-year period (2003, n = 7 deer; 2004, n = 4; 2005, n = 12). With a reduction of deer intrusions onto this section of US 1, DVCs decreased in the fenced area by 73–100%; however, US 1 DVCs within the unfenced sections of US 1 also increased (40%) as expected. In controlling for effects of increasing deer density and traffic volume, study results suggest that highway improvements have decreased the net risk of DVCs along US 1, which indicates that use of deer fencing, deer guards, and underpasses is applicable in other urban communities experiencing unacceptable levels of DVCs.     

Cougar Prey Selection in a White-Tailed Deer and Mule Deer Community

Abstract Widespread mule deer (Odocoilus hemionous) declines coupled with white-tailed deer (O. virginianus) increases prompted us to investigate the role of cougar (Puma concolor) predation in a white-tailed deer, mule deer, and cougar community in northeast Washington, USA. We hypothesized that cougars select for and disproportionately prey on mule deer in such multiple-prey communities. We estimated relative annual and seasonal prey abundance (prey availability) and documented 60 cougar kills (prey usage) from 2002 to 2004. White-tailed deer and mule deer comprised 72% and 28% of the total large prey population and 60% and 40% of the total large prey killed, respectively. Cougars selected for mule deer on an annual basis (α_md = 0.63 vs. α_wt = 0.37; P = 0.066). We also detected strong seasonal selection for mule deer with cougars killing more mule deer in summer (α_md = 0.64) but not in winter (α_md = 0.53). Cougars showed no seasonal selection for white-tailed deer despite their higher relative abundance. The mean annual kill interval of 6.68 days between kills varied little by season (winter = 7.0 days/kill, summer = 6.6 days/kill; P = 0.78) or prey species (white-tailed deer = 7.0 days/kill, mule deer = 6.1 days/kill; P = 0.58). Kill locations for both prey species occurred at higher elevations during summer months (summer = 1,090 m, winter = 908 m; P = 0.066). We suspect that cougars are primarily subsisting on abundant white-tailed deer during winter but following these deer to higher elevations as they migrate to their summer ranges, resulting in a greater spatial overlap between cougars and mule deer and disproportionate predation on mule deer.     

Growth and Photosynthetic Characteristics of Two Biotypes of the Weed Black-grass (Alopecurus myosuroides Huds.) Resistant and Susceptible to the Herbicide Chlorotoluron

Response of two biotypes of black-grass (Alopecurus myosuroidesHuds.) to the herbicide, chlorotoluron, was characterized inglasshouse and laboratory studies. ED₅₀values, defined as theamount (kg active ingredient ha^-1) of chlorotoluron requiredto reduce fresh mass by 50% under standard conditions, weredetermined for a resistant biotype (39.3 kg a.i. ha^-1) collectedfrom Peldon, Essex, UK and a susceptible biotype (0.93 kg a.i.ha^-1) obtained commercially, giving a resistance factor of 42.The resistance factor was calculated as the ratio of ED₅₀valuesand describes the increase in amount of herbicide needed toreduce fresh mass by 50% in the resistant, compared to the susceptible,biotype. Resistance was further characterized by measurementsof whole plant growth and photosynthesis. Relative growth rate,number of tillers, leaf area and mean fresh mass were the samein untreated plants of both biotypes, and rates of photosynthesisat both high and low photon flux were similar, with no differencein apparent quantum yield. Photosynthesis by whole plants wasstudied over a 24 h period following chlorotoluron treatment.Resistant plants showed no reduction in photosynthesis overthis period, whereas photosynthesis by susceptible plants ceased10 h after treatment and did not recover. Alopecurus myosuroides ; black-grass; herbicide resistance; chlorotoluron     

Isolation and characterization of 17 new microsatellite markers for the ember parrotfish Scarus rubroviolaceus,and cross‐amplification in four other parrotfish species

We describe the isolation and characterization of 17 polymorphic microsatellite loci for the ember parrotfish Scarus rubrioviolaceus. In a Hawaiian sample of 69 fish, we found between three and 20 alleles per locus, and observed heterozygosity ranging from 0.283 to 0.896. Four of these loci consistently cross‐amplified in the stareye parrotfish Calotomus carolinus, the spectacled parrotfish Chlorurus perspicillatus, the palenose parrotfish Scarus psittacus, and the bullethead parrotfish Chlorurus sordidus, but others gave mixed results. These loci will be useful for describing mating systems and population structure in marine species with broad dispersal potential that play key ecological roles in tropical environments.     

Atyid shrimps (Decapoda: Atyidae) influence the spatial heterogeneity of algal communities over different scales in tropical montane streams, Puerto Rico

1. Atyid (Decapoda: Atyidae) shrimps influence the distribution of algal communities over different scales in tropical montane streams of Puerto Rico. Within pools of an atyid-dominated stream, atyid shrimps enhanced patchiness in algal communities along the depth gradient. Algal bands occurred in shallow pool margins where atyids did not forage (< 3 cm below water surface), with significantly greater standing crop, taxon richness, and structural complexity than deeper areas. In deeper water, atyids reduced small-scale patchiness in algal community composition and maintained a low-growing understorey turf dominated by sessile diatoms (Bacillariophyta) and, sometimes, closely cropped, filamentous blue-greens (Cyanophyta).
2. Among pools of the atyid-dominated stream, atyids interacted with light to determine algal patchiness between stream margins and deeper areas. In sunny pools, algal standing crop was 140-fold greater in pool margins than in deeper areas where atyids foraged. In shaded pools, however, standing crop in pool margins was only 5-fold greater than in deeper areas. Effects of light on algal standing crop were greater outside atyid foraging areas than within, indicating that shrimp grazing overrides the positive effects of light.
3. In contrast to the atyid-dominated stream, algal communities in an atyid-poor stream were characterized by a high biomass of loosely attached epipelic diatoms and no depth zonation. Interstream rock and shrimp transplant experiments indicated that atyids significantly reduced algal standing crop and altered community composition on rocks from atyid-poor streams within 24 h. Results support the hypothesis that atyid shrimps play a major role in determining observed interstream differences in algal communities.     

Emerging Applications of Bacteriocins as Antimicrobials,Anticancer Drugs,and Modulators of The Gastrointestinal Microbiota

The use of bacteriocins holds great promise in different areas such as health, food, nutrition, veterinary, nanotechnology, among others. Many research groups worldwide continue to advance the knowledge to unravel a novel range of therapeutic agents and food preservatives. This review addresses the advances of bacteriocins and their producer organisms as biocontrol agents for applications in the medical industry and agriculture. Furthermore, the bacteriocin mechanism of action and structural characteristics will be reviewed. Finally, the potential role of bacteriocins to modulate the signaling in host-associated microbial communities will be discussed.