Genetic variation in growth traits in whitewood (Endospurmum medullosum LS Smith) in Vanuatu

Whitewood (Endospermum medullosum LS Smith) is a very important timber tree in Vanuatu. It is relatively easy to grow and early maturing. This tree species is contributing to Vanuatu's economy in a big way in terms of employment and revenue but its stands are getting thinner due to continuous logging and lack of replanting. Therefore to establish a breeding programme, genetic variation studies were conducted on a four year-old whitewood family trial established by the Vanuatu Department of Forests under the South Pacific Regional Initiative on Forest Genetic Resources (SPRIG). A total of 97 whitewood families with seed lots collected throughout the Vanuatu were assessed using a row-column design. Characters of economic importance like tree height, diameter at breast height (dbh), wood volume and survival rate were included in this study. Mean height of four year-old trees in families in this trial ranged from 7.8 - 9.2 meters, dbh from 14.8 - 16.8 cm, volume ranged from 0.09m3 - 0.12m3 and survival rate from 70 - 88%. Ranking of the trees within and between families was based on differential weighting system for different characters. Therefore economic weight of 1 was assigned to height and 2 to dbh. All the trees in the trial were ranked but only 20 best trees in the ranking were discussed in detail with the focus on the five best trees for their utility in hybridization programme to improve whitewood provenances. Estimated volume per hectare from the best families and provenances was 166m3 and 100m3 respectively. Mean annual increment (MAI) for the fastest growing family and provenances were 29.2 and 25.0m3 ha-1 yr-1 respectively. Analysis of variance showed highly significant differences (P<0.001) in height, dbh, volume, survival rate and growth of families at 4 years of age. The nested analysis of variance for families and provenances also indicated highly significant differences (P<0.001)) for height, dbh, volume and survival rate

Genetic Evidence for Modifying Oceanic Boundaries Relative to Fiji

We present the most comprehensive genetic characterization to date of five Fijian island populations: Viti Levu, Vanua Levu, Kadavu, the Lau Islands, and Rotuma, including non-recombinant Y (NRY) chromosome and mitochondrial DNA (mtDNA) haplotypes and haplogroups. As a whole, Fijians are genetically intermediate between Melanesians and Polynesians, but the individual Fijian island populations exhibit significant genetic structure reflecting different settlement experiences in which the Rotumans and the Lau Islanders were more influenced by Polynesians, and the other Fijian island populations were more influenced by Melanesians. In particular, Rotuman and Lau Islander NRY chromosomal and mtDNA haplogroup frequencies and Rotuman mtDNA hypervariable segment 1 (HVS1) region haplotypes more closely resemble those of Polynesians, while genetic markers of the other populations more closely resemble those of the Near Oceanic Melanesians. Our findings provide genetic evidence supportive of modifying regional boundaries relative to Fiji, as has been suggested by others based on a variety of non-genetic evidence. Specifically, for the traditional Melanesia/Polynesia/Micronesia scheme, our findings support moving the Melanesia-Polynesia boundary so as to include Rotuma and the Lau Islands in Polynesia. For the newer Near/Remote Oceania scheme, our findings support keeping Rotuma and the Lau Islands in Remote Oceania and locating the other Fijian island populations in an intermediate or “Central Oceania” region to better reflect the great diversity of Oceania

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Cytogenetics and reproductive biology of some Bele (Abelmoschus manihot Linn. Medic., subspecies manihot) cultivars

Four locally grown (from Fiji Islands) and three imported (from Papua New Guinea), a total of seven BELE (Abelmoschus manihot Linn., Medic sub-species manihot) cultivars were investigated for their cytogenetics and reproductive biology. Chromosome counting from flower buds and root tips showed that chromosome number in all the seven cultivars does not exceed 2n=66. Pollen viability in all the seven cultivars was high, exceeding 85% from pollen staining technique and 78% from pollen germination technique. All the seven Bele cultivars were fully self-compatible. Cross-compatibility among four local cultivars and three cultivars from Papua New Guinea was very high. However cross compatibility between local (Fijian) cultivars and cultivars from Papua New Guinea was partial indicating some degree of genetic difference between cultivars from two countries. This could be due to differences in compatibility alleles between cultivars from Fiji and Papua New Guinea. Procedures such as cutting the style shorter and placing pollen grains to enhance and affect fertilisation to get cross seed were suggested

Precipitation effects on flowering and propagule setting in mangroves of the family Rhizophoraceae

Fijian seashores are dominated by Rhizophora samoensis (Hochr.), Rhizophora stylosa Griff. and Bruguiera gymnorhiza (L.) Lam. These three species were studied at two locations—western (dry zone) and eastern (wet zone) parts of VitiLevu (the Main Island of Fiji)—over 2 years consisting of a normal-precipitation and a low-precipitation (drought) year. The research was conducted to understand the flowering pattern, propagule development and propagule size at maturity before dispersal from the mother plant. The flowering pattern and number of propagules at maturity were observed to be significantly different among the three species and within species between a normal-precipitation and very low-precipitation (drought) year. In the drought year (1998), the number of flowers produced per plant and propagule setting were significantly lower than in the normal-precipitation year (1997) at both locations. Only 1–2% of total flowers in each species became mature propagules in the normal-precipitation year. This percentage was significantly lower in the drought year for all three species. Propagule size (weight, length and girth) was found to be significantly different in the three species. R. stylosa produced the biggest propagules, followed by R. samoensis and B. gymnorhiza. Longer and heavier propagules were recorded in the normal-precipitation year than in the low-precipitation year. Flowering patterns, propagule setting and propagule size at maturity are species specific, while differences within species between two zones could be due to different climatic conditions (the amount of rainfall, relative humidity and temperature regimes) prevailing over the 2 years

Cytogenetics and reproductive biology of mangroves in Rhizophoraceae

Three mangrove species, Bruguiera gymnorrhiza (L.) Lam., Rhizophora samoensis (Hochr.) Salvoza, Rhizophora stylosa Griff. and a putative hybrid Rhizophora ×selala (Salvoza) between the latter two species were studied for their cytogenetics and reproductive biology. Although chromosome numbers in all four taxa were confirmed as 2n = 36, the size of the chromosomes was slightly larger in genus Bruguiera. Regular chromosome pairing was observed in the three species; however, in the hybrid meiosis was very irregular. Pollen viability in all three species was very high (>80%); however, in the hybrid pollen viability was <10%. This could be due to non-homology in the chromosomes of the two parental species and irregular meiosis in the hybrid. Due to highly irregular meiosis in the hybrid and uneven distribution of chromosomes to the two poles, most of the pollen was non-viable. All three species were fully self-compatible. Between B. gymnorrhiza and the two Rhizophora species, pollen in crosses and reciprocal crosses failed to germinate, indicating cross-incompatibility between these two genera. Partial cross-compatibility was recorded between R. samoensis and R. stylosa. In many crosses, pollen tubes were observed growing freely up to the base of the style. This also accords with occasional crossing of these species in nature. However, due to only partial homology in the chromosomes of these two species, the hybrids produced are always sterile. Similarly, cross-compatibility between the hybrid and its two parental species was also partial. This could be attributed to allelic differences between the two species and their hybrid and also to physiological and/or chemical hindrance of the pollen-tube growth through the stylar tissue

Chromosomal pairing and pollen viability in Rhizophora mangl and Rhizophora stylosa hybrids

Two prominent mangrove species of Fiji, Rhizophora mangle, Linn. Rhizophora stylosa Griff and their puative hyubrid (R x selala) were analysed for chromosome number and pairing. Both parental species and their hybrid possess a diploid number of (2n) = 36 chromosomes. Regular 18 bivalents were observed in two species but the hybrid lacked proper chromosome pairing during meiosis. Analysis of tetrads showed normal tetrad and microspores development in parental species but very high abnormality in the hybrid. Pollen fertility determined by staining technique and pollen germination technique showed very high pollen viability in both parental species but very low pollen viability in the putative hybrid. Lack of chromosomal homology appears to be contributing to high percentage of non-viable pollen resulting in complete sterility in the putative hybrid