José Galián

Genetic structure and distinctness of Apis mellifera L. populations from the Canary Islands

The genetic structure of Apis mellifera populations from the Canary Islands has been assessed by mitochondrial (restriction fragment length polymorphisms of the intergenic transfer RNAleu‐COII region) and nuclear (microsatellites) studies. These populations show a low level of genetic variation in terms of average number of alleles and degree of heterozygosity. Significant differences in the distribution of alleles were found in both data sets, confirming the genetic differentiation among some of the islands but not within them. Two mitochondrial haplotypes characteristic of the Canary Islands are found at high frequencies, although populations are introgressed by imported honeybees of eastern European C lineage. This introgression is rather high on Tenerife and El Hierro and low on Gran Canaria and La Gomera, whereas on La Palma it has not been recorded. The finding of microsatellite alleles characteristic of the eastern European lineage corroborates the genetic introgression. Phylogenetic analyses indicate that the Canarian honeybees are differentiated from other lineages and provide genetic evidence of their African origin.

Mitochondrial DNA variability in the Canary Islands honeybees (Apis mellifera L.).

The mitochondrial DNA (mtDNA) of individuals from 79 colonies of Apis mellifera from five Canary Islands was studied using the DraI test based on the restriction of PCR products of the tRNAleu–COII intergenic region. Five haplotypes of the African (A) lineage and one of the west European (C) lineage were found. The haplotypes A14 and A15 are described for the first time. These haplotypes have a new P sequence named P1. The wide distribution and high frequency of haplotype A15 suggest that it is characteristic of the Canarian Archipelago. Sources of haplotype variability of honeybee mtDNA in the Canary Islands (waves of colonization from Africa, queen importations, habitat diversification) are discussed.

Genetic structure of Balearic honeybee populations based on microsatellite polymorphism

The genetic variation of honeybee colonies collected in 22 localities on the Balearic Islands (Spain) was analysed using eight polymorphic microsatellite loci. Previous studies have demonstrated that these colonies belong either to the African or west European evolutionary lineages. These populations display low variability estimated from both the number of alleles and heterozygosity values, as expected for the honeybee island populations. Although genetic differentiation within the islands is low, significant heterozygote deficiency is present, indicating a subpopulation genetic structure. According to the genetic differentiation test, the honeybee populations of the Balearic Islands cluster into two groups: Gimnesias (Mallorca and Menorca) and Pitiusas (Ibiza and Formentera), which agrees with the biogeography postulated for this archipelago. The phylogenetic analysis suggests an Iberian origin of the Balearic honeybees, thus confirming the postulated evolutionary scenario for Apis mellifera in the Mediterranean basin. The microsatellite data from Formentera, Ibiza and Menorca show that ancestral populations are threatened by queen importations, indicating that adequate conservation measures should be developed for protecting Balearic bees.

Biodiversity of Apis mellifera populations from Tenerife (Canary Islands) and hybridisation with East European races

The biodiversity of honeybee (Apis mellifera) populations from Tenerife (Canary Islands, Spain) has been assessed by restriction analysis of a mitochondrial non-coding intergenic region. Seventy-nine colonies were analysed from thirteen apiaries in six populations that have been kept from recent queen introduction. The length and restriction pattern of the PCR amplified products of the intergenic region identified four mitochondrial haplotypes. One of these haplotypes shows the same restriction pattern and composition of the intergenic region carried by honeybees belonging to the African lineage. Two haplotypes are characterised by a particular intergenic region found with high frequency in the Canarian populations. The haplotype representative of the East European honeybee lineage shows a frequency of 35%, thus indicating introduction of queen honeybees. The finding of this haplotype in Canarian honeybees suggests that hybridisation between the endemic Apis mellifera populations and imported bees is occurring in Tenerife.

Conservation Genetics of Cicindela Deserticoloides, an Endangered Tiger Beetle Endemic to Southeastern Spain

Population surveys of the tiger beetle, Cicindela (Cephalota) deserticoloides, endemic to the few remaining salt steppes of southeastern Spain revealed only four extant colonies. DNA sequencing of some 1896 base pairs of mitochondrial DNA for one specimen each from three populations revealed only a single base pair change confined to a single of the three specimens, thus indicating an extremely low level of differentiation when compared to similar populations of Cicindela (s.l.) elsewhere. Divergence of C. deserticoloides from the closest relatives in the Iberian Peninsula was between 6.9 and 9.9%, attesting to the uniqueness of the species and its high conservation status. Habitat requirements appear to be phylogenetically conserved within Cephalota, but C. deserticoloides seems to be more narrowly confined to relatively drier conditions than its less endangered relatives. The geographic range of the relatives is wider and their local abundance higher, indicating that habitat specialization, low abundance and small geographic range in C. deserticoloides are correlated and in sum are responsible for its vulnerability to extinction.

Microsatellite variability reveals beekeeping influences on Iberian honeybee populations

The genetic structure of the Iberian honey bee (Apis mellifera iberiensis) was studied by analysing 10 microsatellite loci in 362 workers representative of nine Spanish provinces. Heterozygosity values of Iberian honeybee populations are intermediate between African and west European ones whereas allelic diversity is remarkably high at several loci. There is no definite geographic structure of Iberian honeybee populations. At a peninsular scale, the expected clinal pattern observed with mitochondrial data has been probably lost due to the extensive practice of mobile beekeeping and increased colony trade-off. Due to these practices, it is expected that the genetic homogenisation will increase during the next years. Though this might have positive effects on honey production, putative ecotypes existing in Iberia would be prone to disappear.

Biodiversity of Apis mellifera iberica (Hymenoptera: Apidae) from northeastern Spain assessed by mitochondrial Analysis

The molecular variability has been analysed at the mitochondrial level in 288 honeybee colonies from 28 localities distributed along the four Catalonian provinces. In total sixteen different haplotypes belonging to three evolutionary lineages were found. The west European M lineage has been found at a high frequency in the four provinces and is fixed in Lerida, whereas the African A lineage shows a cline of distribution being more frequent in the northern Catalonia. The east European C lineage has been found in three colonies (one in Gerona and two from Barcelona). These results are most likely attributable to natural evolution events but the human influence should also be considered as an agent causing recent changes in the distribution of the honeybee populations. New insights about the evolution of the honeybee populations from the Iberian Peninsula are discussed in the light of the new information provided.

Evolutionary dynamics of autosomal-heterosomal rearrangements in a multiple-X chromosome system of tiger beetles (Cicindelidae)

BackgroundGenetic systems involving multiple X chromosomes have arisen repeatedly in sexually reproducing animals. Tiger beetles (Cicindelidae) exhibit a phylogenetically ancient multiple-X system typically consisting of 2–4 X chromosomes and a single Y. Because recombination rates are suppressed in sex chromosomes, changes in their numbers and movement of genes between sex chromosomes and autosomes, could have important consequences for gene evolution and rates of speciation induced by these rearrangements. However, it remains unclear how frequent these rearrangements are and which genes are affected.ResultsKaryotype analyses were performed for a total of 26 North American species in the highly diverse genus Cicindela, tallying the number of X chromosomes and autosomes during mitosis and meiosis. The chromosomal location of the ribosomal rRNA gene cluster (rDNA) was used as an easily scored marker for genic turnover between sex chromosomes or autosomes. The findings were assessed in the light of a recent phylogenetic analysis of the group. While autosome numbers remained constant throughout the lineage, sex chromosome numbers varied. The predominant karyotype was n = 9+X1X2X3Y which was also inferred to be the ancestral state, with several changes to X1X2Y and X1X2X3X4Y confined to phylogenetically isolated species. The total (haploid) numbers of rDNA clusters varied between two, three, and six (in one exceptional case), and clusters were localized either on the autosomes, the sex chromosomes, or both. Transitions in rDNA localization and in numbers of rDNA clusters varied independently of each other, and also independently of changes in sex chromosome numbers.ConclusionChanges of X chromosome numbers and transposition of the rDNA locus (and presumably other genes) between autosomes and sex chromosomes in Cicindela occur frequently, and are likely to be the result of fusions or fissions between X chromosomes, rather than between sex chromosomes and autosomes. Yet, translocations between sex chromosomes and autosomes appear to be common, as indicated by the patterns of rDNA localization. Rearranged karyotypes involving multiple sex chromosomes would reduce recombination, and hybrid dysgenesis selects against polymorphic populations. Hence, the high frequency of these rearrangements could be a cause of the great species diversity in Cicindela.

Karyotypes of nine species of Cicindelini and cytotaxonomic notes on Cicindelinae (Coleoptera, Carabidae).

The male meioformula of seven species of Cicindelini from the Iberian Peninsula and one species from Canada is 9+XXXY. In addition, female data of Cylindera paludosa corroborate previous reports of males. The Palearctic species show a generalized karyotype which presents specific modifications, but it is not possible to establish if it is also present in species of other faunas.Present data indicate that multiple sex chromosomes is an ancestral condition for the subfamily Cicindelinae. It is postulated that the meioformula of the tribe Cicindelini is 9 or 10 plus XXY and that trends in karyotypic evolution are partially related to the geographic distribution of lineages. Numerical deviations observed in the tribe can be explained by changes occurring independently in autosomes and heterosomes, so that autosome-heterosome fusions do not seem to be a generalized event. A number of criteria may be developed for determining the polarity of change of karyotypic characters, thus making cytotaxonomic studies a valuable tool for understanding the systematics of Cicindelini.

Evaluation of the biodiversity of honey bee (Apis mellifera) populations from eastern Spain

SUMMARY The mitochondrial DNA of 260 honey bee (Apis mellifera) colonies located in eastern Spain was characterized through the RFLP analysis of the intergenic tRNAleu-COII region. In total, 16 different mitochondrial haplotypes were found, eight of which belong to the African evolutionary lineage and eight to the west European. The results indicate a high level of genetic diversity in this region. The haplotype frequency is congruent with a north-east-south-west gradient extending across the whole Iberian peninsula. Several beekeeping techniques (transhumance movements, purchase of queens and colonies) and recent laws about colony location are discussed in relation to the biodiversity of this honey bee population.