Population structure

Although stony corals are most frequently studied on high-relief reef structures, many coral species occur in a wide variety of nearshore tropical habitats, including mangrove creeks, seagrass beds and rocky platforms. This study estimated overall population size, potential reproductive output, and population structure for several species across sandy-bottom, hard-bottom, and patch reef habitats. The density of coral colonies, area of available habitat, and size distribution of resident Siderastrea radians, Favia fragum, and Diploria clivosa colonies were recorded for several island bank systems across habitat types in the central Bahamas. Nearshore patch reefs generally exhibited larger population sizes and higher density of colonies, and contained more larger or older colonies. Nearshore hardbar communities had smaller population sizes and a lower density of colonies, and supported more small colonies, which may either be recruits or asexual clones. High numbers of larger colony s...

The present study involves the inventory of the four growth stages, seedling, sapling, juvenile trees and trees of Red sanders in tropical dry deciduous forests in hill ranges of Kadapa region. A total of 20 (1 ha) study sites were laid and in each of the study site, a total of ten (10×100 m) belt transacts were randomly laid to enumerate the growth stages. The objective is to derive quantitative information about the population of Red sanders in its natural occurrence area. Results indicated that seedlings are the dominant growth-form across the hill ranges and juvenile trees showed high variation in their distribution. The suffrutex stage, justified by the presence of multiple stems; among seedlings and saplings seems to play a major role in Red sanders regeneration success to overcome the prevailing drought, hot weather conditions and fire. The general population structure in reference to four growth stages of Red sanders was: seedlings > saplings > juvenile trees < Adult trees. Although inverse J shape population structure was recorded for the whole study area, variations in population structure profiles were noticed at one ha level. The occurrence of Red sanders abundance along the elevation revealed that lower elevation sites featured lower tree density and it reached maximum at 400-600 m and decreased later till 600-900 m. Overall Red sanders can be ranked as the dominant trees in these forests, but the progression of sapling stage to established stage like juvenile tree and trees is the bottleneck in the progression of population of Red sanders rather than the seedling germination and survival rates.

The Cape Dwarf Chameleon (Bradypodion pumilum) is an endemic South African species that is currently threatened by habitat loss and fragmentation of its natural habitat through urbanization and agriculture. To conduct studies that will assist in understanding these anthropogenic effects on gene flow, population structure, and genetic diversity, we developed eight microsatellite loci using an enrichment protocol. Number of alleles ranged from 5 to 26 with observed heterozygosities of 0.279–0.930. Several loci did not meet HW expectations, but this may be a result of extreme demographic fluctuations that have been noted for this species. These loci will prove useful to examine the population genetics of these threatened reptiles and for providing information that will be used for generating and updating conservation assessments.

Background: The invasion by Pinus elliottii is one of the most serious threats to the remaining native cerrado vegetation in São Paulo State, Brazil, causing biodiversity losses yet to be evaluated. We conducted a study in an area where P. elliottii began establishing in 1988. Aims: To estimate diversity losses in the plant community and to understand the floristic and structural changes resulting from pine tree invasion of grassland savannah. Methods: All plants taller than 50 cm were sampled in 35 plots (64 m2 each) within an area densely invaded by P. elliottii and in 10 plots in non-invaded grassland savannah. Density, species richness, diversity, ground cover and spatial distribution were compared by Wilcoxon tests, non-metric multidimensional scaling and Payandeh indices. Results: Twenty-two years after the arrival of the first invasive trees (founders), the grassland savannah has become a dense pine forest with 12,455 individuals ha−1, a basal area of 26.44 m2 ha−1, a sparse native woody understory comprised of 16 species (H' = 0.44), density of 1210 individuals ha−1 and the herbaceous layer totally absent. Conclusions: Invasion by Pinus elliottii has completely changed the structure of the grassland savannah and caused severe plant diversity losses. Native species surviving the invasion in the understory do not typically represent the previous composition and functional traits of the native vegetation.

SUMMARY Grapevine fanleaf virus (GFLV) is responsible for fan- leaf degeneration, which is one of the most severe virus diseases of grapevines worldwide. GFLV causes substan- tial crop losses, reduces fruit quality and shortens the longevity of grapevines in the vineyard. GFLV is trans- mitted specifically from grapevine to grapevine by the ectoparasitic nematode Xiphinema index, and belongs to the

Lee E, Klöcker U, Croft DB and Ramp D, 2004. Kangaroo-vehicle collisions in Australia&#39;s sheep rangelands, during and following drought periods. Australian Mammalogy 26: 215-226. The effects of roads on wildlife behaviour and ecological function are poorly known in arid Australia. The most obvious impact is roadkill from wildlife-vehicle collisions. Therefore we collected statistics on kangaroo-vehicle collisions, investigated the causal

Biomass and population structure of Constrictotermes cyphergaster (Silvestri) were studied in an area of dry forest of caatinga in the State of Paraiba, northeastern Brazil. Twelve nests of different sizes were randomly collected, being six during the dry season (November 2004 and 2005) and six during the wet season (March 2004). Soldier and worker populations varied between 4880 and 118800 individuals per nest. The ratio between soldiers and workers did not significantly vary between seasons. Biomass (measured as fresh weight) of individuals varied between 13.9 and 408.8 g per nest, and soldiers and workers had significantly greater biomass during the wet season. The estimated density of nests of C. cyphergaster was 59.0 ± 22.53 active nests/ha. Quantitative data of the study colonies and data on the nest abundance showed that C. cyphergaster encompassed some 278.2 individuals/m2, with approximately 0.9 g (fresh weight)/m2. These data suggest that C. cyphergaster is an important consumer of vegetal matter and, therefore, an important species affecting the nutrient cycling and energy flow in the caatinga vegetation.

Xanthomonas axonopodis pv manihotis is the causal agent of cassava bacterial blight (CBB) worldwide. CBB disease is a major constraint to cassava cultivation, and losses can be extremely severe in regions where highly susceptible cultivars are grown. To develop an efficient disease management policy, the genetic diversity of the pathogens population must be known. There is dearth of information on the genetic diversity of X. axonopodis pv manihotis population in Nigeria. We used RAPD (random amplified polymorphic DNA) and AFLP (amplified fragment length polymorphism), a PCR-based technique, to characterize the X. axonopodis pv manihotis isolates from the western States of Nigeria. Thirteen strains Xam and 2 reference strains were tested with eight primers combination of AFLP and 4 RAPD primers. RAPD amplified DNA fragment data showed four major clusters at 80 % similarity coefficient level and two strains were not clustered by this analysis. Strains Kwa76A and Ond48A were also separated in the principal component analysis of the same data. Numerical analysis differentiated the AFLP patterns into four distinct clusters and grouped two strains separately at 66 % similarity. PCA assembly grouped the bacterial strains into 4 and one of the strains was singled out from the others. The two DNA analyses techniques seem to be complimentary to one another and informative on the genomic structure of Xam population in Western Nigeria. The genetic analysis presented here contributes to understanding of the Xam population structure in Western Nigeria.