Thailand is the only place known where large populations of Mainland and Sundaland Apis cerana come into contact and where native strains of both Varroa destructor and V. jacobsoni occur. This provides a unique opportunity to investigate occurrence of Varroa species and mitochondrial lineages on different genetic lineages of A. cerana in a natural setting. We sampled Thai Varroa and A. cerana on a north to south transect, and identified mite and bee mtDNA haplotypes by RFLPs and COI sequence. Ranges of Mainland and Sundaland A. cerana meet at the Kra ecotone, between 10°34'N and 11°24'N. Varroa jacobsoni was found on both Sundaland and Mainland A. cerana; south of Kra ecotone (on Sundaland A. cerana) mites had the Malaysia haplotype, while north of Kra ecotone (on Mainland A. cerana) mites had the NorthThai1 or NorthThai2 haplotype. Varroa destructor was only found in Chiang Mai and Chiang Rai Provinces (18°36'N, 98°48'E) at altitudes above 1000 m. We found no evidence of V. destructor with so-called Japan-Thailand haplotype on Thai A. cerana.
Apis cerana / Varroa / coevolution / mitochondrial DNA / Thailand
Concordance between the mitochondrial haplotypes of the Eastern honey bee, Apis cerana, and its ectoparasitic Varroa mites across the Isthmus of Kra in Thailand has suggested that local host-pathogen co-evolution may be responsible for the geographic distribution of particular genotypes. To investigate nuclear microsatellites population structure in A. cerana, single workers of A. cerana colonies from Thailand were genotyped at 18 microsatellite loci. The loci showed intermediate to high levels of heterozygosity and a range of allele numbers. The analyses confirmed a fundamental subdivision of the Thai A. cerana population into the "Asia Mainland" and "Sundaland" regions at the Isthmus of Kra. However, the nuclear microsatellite differentiation was less distinct than mtDNA haplotype differences, suggesting male-biased dispersal and population admixture. Overall, samples showed a weak isolation-by-distance effect. The isolated population on Samui island was most differentiated from the other samples. The results do not support our initial hypothesis of local host-pathogen co-evolution, which predicts a strict correspondence between the nuclear genome and the lineage of parasitic Varroa mite of the A. cerana samples, because the gene flow indicated by our nuclear microsatellite markers should also mix potential Varroa resistance alleles among subpopulations. Instead, our study suggests that the coincidental distribution of Varroa lineages and A. cerana population structure in Thailand are the result of biogeographic history and current migration patterns Keywords: biogeography | co-evolution | local adaptation | microsatellites | population structure | apis cerana | honey bees | Thailand | Varroa mite association | social insects | biology Article:
-DNA sequence diversity in a non-coding portion of the mitochondrial genome was investigated in samples of Apis cerana from 47 locations in China. Nine haplotypes (mitochondrial genotypes) were found: Japan1, Japan2, Korea4, and Cambodia2, which were previously reported from other populations, and China1−5, which are new. All nine sequences belong to the Mainland mitochondrial lineage, and none differs from the Japan1 haplotype by more than a single base substitution and/or a single insertion/deletion. Japan1 is the most common haplotype, making up 39 of 49 sequences. Haplotype diversity was 0.4 (s.d. 0.089) and nucleotide diversity was 0.00569 (s.d. 0.00154). By both measures the Chinese samples were more diverse than those from Japan and Thailand, similar to populations from Pakistan, Burma and Korea, and less diverse than samples from Indochina (Laos-Cambodia-Vietnam).mitochondrial DNA / Apis cerana / China / phylogeography
1 Global population declines of insect pollinators highlight the need for a greater ecological understanding of the responses of wild pollinators to local management actions and to human alterations of landscapes, especially in the tropics where crops are highly dependent on wild pollinators. 2 We examined the effects of local and landscape factors on the richness and abundance of bees in farms around Bangkok, Thailand. Bee communities in 24 mango (Mangifera indica L.) orchards in heavily modified landscapes (61-99% anthropogenic land cover) were compared. We predicted that bees would be more species rich in orchards with higher flower diversity, whereas small-sized bees with non-eusocial and/or below-ground nesting habits would be more sensitive to human disturbance, and hence rare. 3 Twenty-eight species were caught and individuals of genus Apis comprised >92% of 3842 bees sampled and dominated all 24 sites. 4 Habitat effects on bee richness and abundance were stronger at the farm scale than at the landscape scale. At the farm scale, total bee richness and abundance, as well as small, non-eusocial and below-ground nesting bee richness and abundance, were negatively associated with field size and positively associated with flowering plant diversity. The percentage of urban land cover within a 1-km radius was weakly but positively related to total bee richness and small-sized bee richness; total bee abundance was positively associated with wetland cover. 5 A greater diversity of flowering plants retained in smaller fields maintained higher bee richness and abundances, particularly small-sized bees. Farmers can enhance bee populations by maintaining small patches of flowers in their fields.
The segmented trapdoor spiders (Liphistiidae) are the sole surviving family of the suborder Mesothelae, which forms the sister lineage to all other living spiders. Liphistiids have retained a number of plesiomorphic traits and their present-day distribution is limited to East and Southeast Asia. Studying this group has the potential to shed light on the deep evolutionary history of spiders, but the phylogeny and divergence times of the family have not been resolved with confidence. We performed phylogenomic and molecular dating analyses of 2765 ultraconserved element loci from 185 liphistiid taxa. Our analyses show that the crown group of Liphistiidae appeared in the mid-Cretaceous at 102 Ma (95% credibility interval 92–113 Ma), but it was not until the Neogene that much of the diversification within the family occurred in mainland Southeast and East Asia. This diversification was coincident with tectonic events such as the extension of the East Asian continental margin, as well as geological upheavals in Indochina induced by the collision between India and Asia. Our study highlights the important role of major tectonic events in shaping the evolutionary history, present-day diversity, and geographical distribution of mesothele and liphistiid spiders. [biogeography; concatenation; Liphistiidae; molecular dating; summary coalescent; UCEs.]
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