Colonização e dispersão nos sítios de ocorrência, a genética das populações e história natural de Partamona ailyae Camargo, 1980 (Hymenoptera: Apidae: Meliponini)
Resumen
Particular biological features of different bee groups can affect how a certain area will be
occupied by them and this can affect directly the genetics of their populations over the long
term. In Brazil, there are few studies about gene variation and genetic structure of bee natural
populations, as well as on the genetic differentiation levels between eusocial bee populations.
The Partamona genus comprises 33 species, distributed from Southern Mexico to Southern
Brazil. Partamona ailyae, the model species of this study, occurs in rainforests of
Southwestern Amazonia, Central Brazil and xeric regions of Piauí. Its wide distribution, as
well as the ability to occupy such heterogeneous environments, piqued our interest to take P.
ailyae as a study model. This work aimed to analyze the occupation process at the P. ailyae
occurrence sites, population genetics and interpopulational gene flow, and the natural history
of this species. Eight expeditions were carried out, and 41 localities of 10 states of Brazil were
visited. Among them, active colonies of P. ailyae were found only in 17 localities, being
collected specimens of 75 nests. To identify the mitochondrial lineages present in the sampled
colonies, five gene regions were used (COI, CytB, 12S, 16S and COI-COII). Estimates of
polymorphism levels showed COI and CytB as the most variable regions (11 and seven
haplotypes, respectively). For the ribosomal genes, only a few samples were analyzed,
because few differences were identified among the sequences. All the 31 samples analyzed
for the 12S showed a five bases insertion starting from the position 25 of the sequence, a
result not observed in other Partamona species. The most informative genes (COI and CytB)
had their sequences concatenated (1114pb). For these regions, 13 haplotypes were observed,
two of them were shared and 11 characterized as exclusive of localities. The AMOVA
showed that 94.3% of the gene variation is due to interpopulacional differences, revealing a
high differentiation among the populations (ΦST = 0.9426; P = 0.000). In addition, one
individual from each colony was analyzed for eight heterologous microsatellite loci designed
from Melipona bicolor and Partamona helleri. A moderate and statistically significant
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interpopulational genetic differentiation (ΦST = 0.1491; P = 0.000) was found. The cluster
analysis identified four groups by ΔK as the ideal model, and STRUCTURE software showed
that all individuals could belong to more than one group, corroborating the “Assignment test”,
which indicated that only 50% of the samples were correctly assigned to their original
population. Phenotypic segregation analysis was realized in some offsprings, revealing a
monoginic/monandric familial structure. From the mitochondrial data, the Mantel test showed
a significant correlation between genetic distance and geographic distance (r = 0.2589; P =
0.0231), whereas on basis of the nuclear data, the Mantel test did not indicate significant
correlation between genetic distance and geographic distance (r = 0.2090; P = 0.0610). Fu’s
Fs and R2 tests did not show significant values. The Bayesian Skyline Plot analysis (BSP) did
not show significant fluctuations in the effective size populations of P. ailyae, indicating
population stability over time. The values of ΦST estimated for mitochondrial genes and
microsatellites were compared, being detected evidence of sex-asymmetric dispersal, in which
females are responsible for the areas occupation, and males constitute the disperser sex. In
addition, some relevant aspects of the natural history of P. ailyae are shown.