Evidence for hybridization and introgression within a species-rich oak (<Emphasis Type="Italic">Quercus</Emphasis> spp.) community

Background  

Analysis of interspecific gene flow is crucial for the understanding of speciation processes and maintenance of species integrity. Oaks (genus Quercus, Fagaceae) are among the model species for the study of hybridization. Natural co-occurrence of four closely related oak species is a very rare case in the temperate forests of Europe. We used both morphological characters and genetic markers to characterize hybridization in a natural community situated in west-central Romania and which consists of Quercus robur, Q. petraea, Q. pubescen s, and Q. frainetto, respectively.     

DNA-microarrays identification of <Emphasis Type="Italic">Streptococcus mutans</Emphasis> genes associated with biofilm thickness

Background  

A biofilm is a complex community of microorganisms that develop on surfaces in diverse environments. The thickness of the biofilm plays a crucial role in the physiology of the immobilized bacteria. The most cariogenic bacteria, mutans streptococci, are common inhabitants of a dental biofilm community. In this study, DNA-microarray analysis was used to identify differentially expressed genes associated with the thickness of S. mutans biofilms.     

Hormonal induction of gamete release,and in-vitro fertilisation,in the critically endangered Southern Corroboree Frog, <Emphasis Type="Italic">Pseudophryne corroboree</Emphasis>

Background  

Conservation Breeding Programs (CBP's) are playing an important role in the protection of critically endangered anuran amphibians, but for many species recruitment is not successful enough to maintain captive populations, or provide individuals for release. In response, there has been an increasing focus on the use of Assisted Reproductive Technologies (ART), including the administration of reproductive hormones to induce gamete release followed by in vitro fertilisation. The objective of this study was to test the efficacy of two exogenous hormones to induce gamete release, for the purpose of conducting in vitro fertilisation (IVF), in one of Australia's most critically endangered frog species, Pseudophryne corroboree.     

Inhibitory effects of Eucalyptus globulus on understorey plant growth and species richness are greater in non‐native regions

Aim

We studied the novel weapons hypothesis in the context of the broadly distributed tree species Eucalyptus globulus. We evaluated the hypothesis that this Australian species would produce stronger inhibitory effects on species from its non‐native range than on species from its native range.

Location

We worked in four countries where this species is exotic (U.S.A., Chile, India, Portugal) and one country where it is native (Australia).

Time period

2009–2012.

Major taxa studied

Plants.

Methods

We compared species composition, richness and height of plant communities in 20 paired plots underneath E. globulus individuals and open areas in two sites within its native range and each non‐native region. We also compared effects of litter leachates of E. globulus on root growth of seedlings in species from Australia, Chile, the U.S.A. and India.

Results

In all sites and countries, the plant community under E. globulus canopies had lower species richness than did the plant community in open areas. However, the reduction was much greater in the non‐native ranges: species richness declined by an average of 51% in the eight non‐native sites versus 8% in the two native Australian sites. The root growth of 15 out of 21 species from the non‐native range were highly suppressed by E. globulus litter leachates, whereas the effect of litter leachate varied from facilitation to suppression for six species native to Australia. The mean reduction in root growth for Australian plants was significantly lower than for plants from the U.S.A., Chile and India.

Main conclusions

Our results show biogeographical differences in the impact of an exotic species on understorey plant communities. Consistent with the novel weapons hypothesis, our findings suggest that different adaptations of species from the native and non‐native ranges to biochemical compounds produced by an exotic species may play a role in these biogeographical differences.     

Determination of vertebral heart score in three species of Spider monkey (Ateles fusciceps,A. hybridus and A. paniscus)

Background

The vertebral heart score (VHS) is a method of evaluation of cardiac size well documented in domestic mammals and in other primate species, and the aim of this study was to determine the VHS in three species of Spider monkey.

Methods

In this retrospective study, right lateral radiographs of thirty clinically well animals were reviewed and VHS determined. The species included were Ateles fusciceps (n=17), Ateles hybridus (n=8) and Ateles paniscus (n=5).

Results

The VHS was found to vary between species and was 9.73±0.81 for A. fusciceps, 10.53±0.37 for A. hybridus and 10.45±0.27 for A. paniscus.

Conclusions

The observed values appear consistent with values determined for other primate species. There was statistically significant variation noted between species, and so VHS should be considered species‐specific in this genus. The values determined may be of benefit in objectively evaluating cardiac size in the species investigated.     

Responses of community structure of amoA‐encoding archaea and ammonia‐oxidizing bacteria in ammonia biofilter with rockwool mixtures to the gradual increases in ammonium and nitrate

Aims

To investigate community shifts of amoA‐encoding archaea (AEA) and ammonia‐oxidizing bacteria (AOB) in biofilter under nitrogen accumulation process.

Methods and Results

A laboratory‐scale rockwool biofilter with an irrigated water circulation system was operated for 436 days with ammonia loading rates of 49–63 NH₃ g m^?3 day^?1. The AEA and AOB communities were investigated by denaturing gradient gel electrophoresis, sequencing and real‐time PCR analysis based on amoA genes. The results indicated that changes in abundance and community compositions occurred in a different manner between archaeal and bacterial amoA during the operation. However, both microbial community structures mainly varied when free ammonia (FA) concentrations in circulation water were increasing, which caused a temporal decline in reactor performance. Dominant amoA sequences after this transition were related to Thaumarchaeotal Group I.1b, Nitrosomonas europaea lineages and one subcluster within Nitrosospira sp. cluster 3, for archaea and bacteria, respectively.

Conclusions

The specific FA in circulation water seems to be the important factor, which relates to the AOB and AEA community shifts in the biofilter besides ammonium and pH.

Significance and Impact of the Study

One of the key factors for regulating AEA and AOB communities was proposed that is useful for optimizing biofiltration technology.     

Species specificity,surface exposure,protein expression,immunogenicity, and participation in biofilm formation of <Emphasis Type="Italic">Porphyromonas gingivalis</Emphasis> HmuY

Background  

Porphyromonas gingivalis is a major etiological agent of chronic periodontitis. The aim of this study was to examine the species specificity, surface exposure, protein expression, immunogenicity, and participation in biofilm formation of the P. gingivalis heme-binding protein HmuY.     

Observations of mixed-species bird flocks at Kichwa Tembo Camp,Kenya

Mixed-species foraging flocks were studied at Kichwa Tembo Camp on the edge of the Masai Mara National Reserve in Kenya between July and September 2004. Observations were made on 29 mixed-species flocks, in which 24 species participated. African Paradise-Flycatcher Terpsiphone viridis, Black-backed Puffback Dryoscopus cubla, Grey-backed Camaroptera Camaroptera brachyura, Collared Sunbird Hedydipna collars and Cabanis's Greenbul Phyllastrephus cabanisi were the most common participants in mixed-species flocks, as well as among the most frequently encountered bird species overall. The Black-backed Puffback was identified as the nuclear species in flocks due to their abundance and frequency with which they were followed by other species. Mixed-species flocks represent another niche dimension in this diverse bird community, but few of these species could be described as flock specialists; most of the birds observed in mixed-species flocks in this study were opportunistic attendant species, including the African Pygmy-Kingfisher Ispidina picta, not previously described as joining mixed-species flocks.