Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km2 were recorded. Sharks ranged between four and eight metres’ estimated total length (mean 6.92±1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs.

New primer pairs of genomic DNA microsatellite markers were tested to assess the genetic diversity of eleven date palm genotypes. The results indicated that out of thirty, only seven primers (23.3%) failed to amplify the expected PCR fragments, while thirteen primers (43.3%) amplified monomorphic banding patterns and the remaining ten primers (33.4%) generated polymorphic banding patterns. A total of 77 alleles have been observed with a mean of 7.7 alleles per locus. The average of gene diversity was 0.80 ranging from 0.6 (in marker DP168) to 0.9 (in two markers DP157 and DP175). These new co-dominant markers will be a starting point for researchers making use of the markers for genetic mapping and diversity analysis of date palm.

Microsatellite markers containing simple sequence repeats (SSRs) are a valuable tool for genetic analysis. Our objective was to identify microsatellite markers that could be used to differentiate between male and female date palm (Phoenix dactylifera). The date palm is a dioecious plant whose sex cannot be determined until it reaches a reproductive age between 5 and 10 years. An early selection and/or differentiation of young seedlings into males and females could enhance breeding and assist research programs for genetic improvements of the date palm. Here, we report on the use of microsatellites for determining the sex of immature date palm. Using 14 microsatellite primer pairs with 129 date palm leaves and tissue culture samples from 34 cultivars which represent the major date palm diversity of Qatar, 254 microsatellite loci were detected, of these, 22 microsatellite loci could be used to identify 9 out of 12 male date palm samples (75%). The data also indicated that the heterozygous allele with the size 160/190 produced by the primer mPdCIR048 reoccurred 4 times exclusively in the 12 individual male samples but not in any of the 117 female date palm samples tested, and hence it is a promising candidate marker to detect male sex in date palm. Principal coordinate analysis (PCoA) of 12 male samples with 7 female Khasab cultivars produced 2 autonomous groups of males and females and similar results were observed with 13 female Shishi cultivars. Our results suggest that the SSR markers described here have potential in sex identification of date palm.

ABSTRACT. The genetic diversity in the date palm germplasm of 59 female accessions representing 12 cultivars from different locations in Qatar was investigated using 14 loci of simple-sequence repeat (SSR) primers. A total of 94 alleles, with a mean of 6.7 alleles per locus, were scored. The number of alleles per locus varied from 3 (primer mPdCIR090) to 11 (primers mPdCIR010 and mPdCIR015). The amplified SSR band sizes ranged from 104 to 330 bp. The mean gene diversity was 0.66 and ranged from 0.39 (locus mPdCIRO93) to 0.86 (locus mPdCIR015), indicating that the Qatari date palm collection has a high degree of genetic diversity. The heterozygosity ranged from 0 (marker mPdCIR090) to 98% (marker mPdCIR010). Forty-four percent of the variability is explained at the inter-population level, while 56% of the variability is maintained within individuals. However, the loci mPdCIR044, mPdCIR057, mPdCIR090, and mPdCIR093 revealed that the total gene diversity is explained at the inter-population level. The Qatari populations Khalas, Shishi, Barhi, Hillali, Khnaizi, Gar, and Jabri showed significant differentiation compared to all other populations. The average fixation index was 0.24814, showing that about 24.81% of 1625 Genetic diversity of Qatari date palm ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (1): 1624-1635 (2015) the genetic variation was present among populations, which correlated with analysis of molecular variance.

Diversity within and among the populations of Prosopis cineraria and