Rapid evolution, rearrangements and whole mitogenome duplication in the Australian stingless bees Tetragonula (Hymenoptera: Apidae): A steppingstone towards understanding mitochondrial function and evolution.

The extreme conservation of mitochondrial genomes in metazoans poses a significant challenge to understanding mitogenome evolution. However, the presence of variation in gene order or genome structure, found in a small number of taxa, can provide unique insights into this evolution. Previous work on two stingless bees in the genus Tetragonula (T. carbonaria and T. hockingsi) revealed highly divergent CO1 regions between them and when compared to the bees from the same tribe (Meliponini), indicating rapid evolution. Using mtDNA isolation and Illumina sequencing, we elucidated the mitogenomes of both species. In both species, there has been a duplication of the whole mitogenome to give a total genome size of 30,666 bp in T. carbonaria; and 30,662 bp in T. hockingsi. These duplicated genomes present a circular structure with two identical and mirrored copies of all 13 protein coding genes and 22 tRNAs, with the exception of a few tRNAs that are present as single copies. In addition, the mitogenomes are characterized by rearrangements of two block of genes. We believe that rapid evolution is present in the whole Indo-Malay/Australasian group of Meliponini but is extraordinarily elevated in T. carbonaria and T. hockingsi, probably due to founder effect, low effective population size and the mitogenome duplication. All these features - rapid evolution, rearrangements, and duplication - deviate significantly from the vast majority of the mitogenomes described so far, making the mitogenomes of Tetragonula unique opportunities to address fundamental questions of mitogenome function and evolution.

Conserved numts mask a highly divergent mitochondrial-COI gene in a species complex of Australian stingless bees Tetragonula (Hymenoptera: Apidae).

Tetragonula carbonaria, Tetragonula davenporti, Tetragonula hockingsi and Tetragonula mellipes comprise a species complex of Australian stingless bee species known as the 'Carbonaria' group. The species are difficult to distinguish morphologically and the major species-defining characters relate to comb architecture and nest entrance ornamentation. The taxonomy of the group is further complicated by likely nuclear mitochondrial pseudogenes (numts) and inter-specific hybrids. Here we demonstrate the existence of COI numts and isolate and characterize the 'true' mt-COI gene in T. carbonaria and T. hockingsi. Numts were isolated from enriched-nuclear DNA extraction followed by PCR amplification and Sanger sequencing, and were recognized by the presence of deletions and/or premature stop codons in the translated sequences. The mt-COI sequences were obtained from NGS sequencing using purified mtDNA. In T. carbonaria, two numts (numt1 and numt2) were identified and a third (numt3) was identified in T. hockingsi. Numt2 and numt3 are similar (1.2% sequence divergence), indicating a recent common origin. The genetic distance between the mt-COI of the two Tetragonula species was higher than might be expected for closely related species, 16.5%, corroborating previous studies in which T. carbonaria and T. hockingsi were regarded as separate species. The three numts are more similar to the COI of other stingless bee species, including Australian Austroplebia australis and South American Melipona bicolor (81.7-83.9%) than to the mt-COI of their own species (70-71.4%). This is because the mt-COI of T. carbonaria and T. hockingsi differ greatly from other Meliponinae. Our findings explain some formerly puzzling aspects of Carbonaria biogeography, and misinterpreted amplifications.

Sex-specific adaptation and genomic responses to Y chromosome presence in female reproductive and neural tissues.

Y chromosomes typically harbour a small number of genes and an abundance of repetitive sequences. In Drosophila, the Y chromosome comprises multimegabase long segments of repetitive DNA and a handful of protein-coding genes. In mammals, the Y chromosome also harbours a disproportionally high abundance of repeats. Here, we built on a Drosophila melanogaster model in which the Y chromosome is decoupled from sexual determination. Genotypes were genetically identical for the autosomes, X chromosome, and mitochondria, but differ by the presence or dose of the Y chromosome. Addition of an extra Y chromosome had limited impact in males. However, the presence of a Y chromosome in females induced a disproportionate response in genes expressed in the ovaries as well as genes encoded by the mitochondrial genome. Furthermore, the data revealed significant consequences of Y chromosome presence in larvae neuronal tissue. This included the repression of genes implicated in reproductive behaviour, courtship, mating and synaptic function. Our findings exhibit the Y chromosome as a hotspot for sex-specific adaptation. They suggest roles for natural selection on Y-linked genetic elements exerting impact on sex-specific tissues as well as somatic tissues shared by males and females.

Very low mitochondrial variability in a stingless bee endemic to cerrado.

Partamona mulata is a stingless bee species endemic to cerrado, a severely threatened phytogeographical domain. Clearing for pasture without proper soil treatment in the cerrado facilitates the proliferation of termite ground nests, which are the nesting sites for P. mulata. The genetic consequences of these changes in the cerrado environment for bee populations are still understudied. In this work, we analyzed the genetic diversity of 48 colonies of P. mulata collected throughout the species' distribution range by sequencing two mitochondrial genes, cytochrome oxidase I and cytochrome B. A very low polymorphism rate was observed when compared to another Partamona species from the Atlantic forest. Exclusive haplotypes were observed in two of the five areas sampled. The sharing of two haplotypes between collection sites separated by a distance greater than the flight range of queens indicates an ancient distribution for these haplotypes. The low haplotype and nucleotide diversity observed here suggests that P. mulata is either a young species or one that has been through population bottlenecks. Locally predominant and exclusive haplotypes (H2 and H4) may have been derived from local remnants through cerrado deforestation and the expansion of a few colonies with abundant nesting sites.

A fauna apícola do Parque Municipal da Cachoeirinha (Iporá, GO) / The bee fauna from Parque Municipal da Cachoeirinha (Iporá, Goiás state, Brazil)

As abelhas possuem grande importância econômica e ecológica, em vista de sua dependência dos recursos florais como o pólen e o néctar (principais fontes de proteínas e energia, respectivamente), representando cerca de 40 a 90 por cento dos agentes polinizadores de fanerógamas em diversos ecossistemas. No presente trabalho, foi realizado o inventário apícola do Parque Municipal da Cachoeirinha (Iporá, GO). Foram realizadas 58 horas de coleta no total, realizadas nos meses de novembro/dezembro de 2004 e março e maio de 2005. Foi coletado um total de 933 indivíduos, distribuídos em uma família, 16 tribos, 33 gêneros e 62 espécies. A tribo Meliponini foi a mais abundante em número de indivíduos e espécies. As espécies mais abundantes foram Trigona chanchamayoensis (16,51 por cento), Tetragona clavipes (14,79 por cento) e Apis mellifera e Trigona recursa (12,33 por cento). Este trabalho apresenta a primeira ocorrência no estado de Goiás para seis gêneros e 12 espécies.

Bees are dependent on flower nectar and pollen (main sources of protein and energy, respectively) and have an important economic and ecological role as pollinators, representing about 40 to 90 percent of phanerogams pollinators in several ecosystems. This work presents a description of bee species from Parque Municipal da Cachoeirinha in Iporá, Goiás state, Brazil. A total of 58 hours of capturing were performed on November and December 2004 and on March and May 2005. A total of 933 individuals were collected, distributed in one family, 16 tribes, 33 genera, and 62 species. Meliponini tribe presented the highest number of individuals and species. Most abundant species were Trigona chanchamayoensis (16.51 percent), Tetragona clavipes (14.79 percent) and Apis mellifera and Trigona recursa (12.33 percent). This work presents the first occurrence in Goiás state for six genera and 12 species.

Alelle number and heterozigosity for microsatellite loci in different stingless bee species (Hymenoptera: Apidae, Meliponini).

In the present study we compare genetic characteristics (allele diversity and observed heterozygosity) of microsatellite loci, from three stingless bee species (Plebeia remota Holmberg, Partamona mulata Moure In Camargo and Partamona helleri Friese), amplified by using heterospecific primers originally designed for Melipona bicolor Lepeletier and Scaptotrigona postica Latreille. We analyzed 360 individuals of P. remota from 72 nests, 58 individuals of R. mulata from 58 nests, and 47 individuals of P. helleri from 47 nests. The three species studied showed low level of polymorphism for the loci amplified with primers derived from M. bicolor. However, for the loci amplified with primers derived from S. postica, only P. remota presented low level of polymorphism.

Alelle number and heterozigosity for microsatellite loci in different stingless bee species (Hymenoptera: Apidae, Meliponini)

In the present study we compare genetic characteristics (allele diversity and observed heterozygosity) of microsatellite loci, from three stingless bee species (Plebeia remota Holmberg, Partamona mulata Moure In Camargo and Partamona helleri Friese), amplified by using heterospecific primers originally designed for Melipona bicolor Lepeletier and Scaptotrigona postica Latreille. We analyzed 360 individuals of P. remota from 72 nests, 58 individuals of P. mulata from 58 nests, and 47 individuals of P. helleri from 47 nests. The three species studied showed low level of polymorphism for the loci amplified with primers derived from M. bicolor. However, for the loci amplified with primers derived from S. postica, only P. remota presented low level of polymorphism.

No presente trabalho compararam-se as características de locos de microssatélite, como diversidade alélica e taxa de heterozigose observada, de três espécies de abelhas sem ferrão (Plebeia remota Holmberg, Partamona mulata Moure In Camargo e Partamona helleri Friese), amplificados com oligonucleotídeos heteroespecíficos originalmente desenhados para Melipona bicolor Lepeletier e Scaptotrigona postica Latreille. Foram analisados 360 indivíduos de P. remota de 72 ninhos, 58 indivíduos de P. mulata de 58 ninhos e 47 indivíduos de P. helleri de 47 ninhos. As três espécies apresentaram baixo nível de polimorfismo para locos amplificados com oligonucleotídeos derivados de Melipona bicolor. Entretanto, para os locos amplificados com oligonucleotídeos derivados de S. postica, somente P. remota apresentou baixo nível de polimorfismo.

Cytogenetic data of Partamona peckolti (Hymenoptera, Apidae, Meliponini) by C banding and fluorochrome staining with DA/CMA(3) and DA/DAPI

The stingless bees of the Partamona genus have been studied taxonomically, ecologically and behaviourally, but cytogenetic studies are still rare. The objective of this study was to obtain cytogenetic data to contribute to Partamona peckolti species characterization. Heterochromatin was localized in all chromosome pericentromeric regions but some blocks could be visualized on some large chromosomes arms. A large heterozygous DA-CMA(3)-positive band was observed on one large chromosome arm, but was completely absent when C banding was applied before fluorochrome staining, with only one small positive band being visualized. Sequential DA-CMA(3)-NOR staining of interphase nuclei provided coincident positive responses. This suggests that DA-CMA(3)-positive bands of P. peckolti correspond to nucleolar organizer regions, as previously confirmed for another Partamona species by FISH