Out of Anatolia: longitudinal gradients in genetic diversity support an eastern origin for a circum-Mediterranean oak gallwasp Andricus quercustozae

Cryptic diversity and phylogeographic patterns of Mediodactylus species in the Eastern Mediterranean region

Cryptic diversity poses a great obstacle in our attempts to assess the current biodiversity crisis and may hamper conservation efforts. The gekkonid genus Mediodactylus, a well-known case of hidden species and genetic diversity, has been taxonomically reclassified several times during the last decade. Focusing on the Mediterranean populations, a recent study within the M. kotschyi species complex using classic mtDNA/nuDNA markers suggested the existence of five distinct species, some being endemic and some possibly threatened, yet their relationships have not been fully resolved. Here, we generated genome-wide SNPs (using ddRADseq) and applied molecular species delimitation approaches and population genomic analyses to further disentangle these relationships. Τhe most extensive nuclear dataset, so far, encompassing 2,360 loci and ∼ 699,000 bp from across the genome of Mediodactylus gecko, enabled us to resolve previously obscure phylogenetic relationships among the five, recently elevated, Mediodactylus species and to support the hypothesis that the taxon includes several new, undescribed species. Population genomic analyses within each of the proposed species showed strong genetic structure and high levels of genetic differentiation among populations.

Cynipidae (Hymenoptera, Cynipoidea) fauna of Burdur province (Türkiye)

Field studies were conducted between September 2020 and June 2022 to assess the gall wasp (Hymenoptera: Cynipidae) fauna of Burdur province (Southwestern Türkiye). A total of 69 species in 18 genera were recorded. Gall samples were collected from 150 samples collected in 100 different localities in the surveyed area. The identified species include three new records (Andricus melikai Pujade-Villar & Kwast, 2002; A. pseudocecconii Melika, Tavakoli & Stone, 2022; Saphonecrus undulatus (Мауr, 1872)) for the Turkish cynipid fauna. As a result of this study, 44 species of the current Turkish cynipid fauna were recorded from Burdur province for the first time. A checklist of the species and their host plants and/or host galls recorded in the study area is provided. The gall wasp richness and geomorphic-topographic structure of Burdur province is discussed.

The story of a rock-star: multilocus phylogeny and species delimitation in the starred or roughtail rock agama, Laudakia stellio (Reptilia: Agamidae)

Situated at the junction of three continents, Europe, Asia and Africa, the Eastern Mediterranean is an ideal region to study the effects of palaeogeography, ecology and long human presence on animal evolution. Laudakia stellio (Squamata: Agamidae) is found across this region and offers an excellent opportunity for such studies. The high morphological variation across their range suggests that these lizards might represent a species complex. This is the first study exploring their evolutionary history, using molecular markers and individuals from all described subspecies. We employed the latest phylogenetic and species-delimitation methods to identify all distinct evolutionary lineages, their genetic variation and divergence times. The phenotypical diversity of L. stellio matches its genetic differentiation: almost all subspecies correspond to well-supported retrieved subclades and additional distinct lineages representing intermediate morphs have been retrieved. ‘Laudakia stellio’ represents three distinct evolutionary entities that diverged during the Plio-Pleistocene transition, which we propose as distinct species. One includes Greek and Turkish populations, as well as cryptic Anatolian lineages. The second comprises all other Near East populations and the third is endemic to Cyprus. Our results indicate a role of humans in shaping present distribution patterns, and highlight the importance of the Aegean, Anatolia and the Levant as glacial refugia and diversity hotspots.

Discordant Pleistocene population size histories in a guild of hymenopteran parasitoids

Signatures of past changes in population size have been detected in genome-wide variation in many species. However, the causes of such demographic changes and the extent to which they are shared across co-distributed species remain poorly understood. During Pleistocene glacial maxima, many temperate European species were confined to southern refugia. While vicariance and range expansion processes associated with glacial cycles have been widely documented, it is unclear whether refugial populations of co-distributed species have experienced shared histories of population size change. We analyse whole-genome sequence data to reconstruct and compare demographic histories during the Quaternary for Iberian refuge populations in a single ecological guild (seven species of chalcid parasitoid wasps associated with oak cynipid galls). For four of these species, we find support for large changes in effective population size (N_e ) through the Pleistocene that coincide with major climate events. However, there is little evidence that the timing, direction and magnitude of demographic change are shared across species, suggesting that demographic histories in this guild are largely idiosyncratic, even at the scale of a single glacial refugium.

Gall-Colonizing Ants and Their Role as Plant Defenders: From 'Bad Job' to 'Useful Service'

Galls are neoformed structures on host plant tissues caused by the attack of insects or other organisms. They support different communities of specialized parasitic insects (the gall inducers), and can also provide refuge to other insects, such as moths, beetles and ants, referred to as secondary occupants. This study focuses on galls induced by the oak gall wasp Andricus quercustozae and secondarily colonized by ants in a mixed oak forest. A field survey and two experiments were carried out to a) study ant (species-specific) preferences for different features of the galls, b) describe differences in gall architecture due to ant activity, c) analyse the effects of the presence of gall-dwelling ants on plant health. The results show that there are differences between ant species in gall colonization and in the alteration of gall opening and inner structure. We verified that gall-dwelling ants protect their host plants efficiently, offering them an indirect defence mechanism against enemies (predators and pathogens). The data suggest a new paradigm in ant–plant relationships mediated by the presence of galls on the plants whose ecological and evolutionary implications are discussed.

A continent-scale study of the social structure and phylogeography of the bent-wing bat, Miniopterus schreibersii (Mammalia: Chiroptera), using new microsatellite data

Miniopterus schreibersii is a cave-dwelling bat species with a wide distribution in the western Palearctic spanning southern and central Europe, North Africa, Anatolia, the Middle East, and the Caucasus. We investigated the social structure and its effects on the genetic makeup of this species, using 10 nuclear microsatellite markers and a partial fragment of the mitochondrial cytochrome b gene. Samples were examined from the species' entire circum-Mediterranean range. Local structuring that was previously detected among populations of M. schreibersii using mitochondrial markers was not observed for microsatellite markers, indicating male-biased dispersal for the species. Some support was found for postglacial expansions in Europe, with Anatolia potentially acting as the primary refugium during the Last Glacial Maximum (LGM). However, support for this hypothesis is not as strong as that previously detected using mitochondrial DNA markers. This is likely due to the diminishing effect of male-mediated dispersal, replenishing the nuclear diversity faster than the mitochondrial diversity in regions that are relatively far from the glacial refugia.

Molecular identification of Andricus species (Hymenoptera: Cynipidae) inducing various oak galls in Central Zagros of Iran

This study uses an integrated approach to address the taxonomic status of six different and problematic oak galls and their inducing wasps sampled from two sites in the Central Zagros Mountains (Lorestan province) in western Iran. Our aim was to establish whether morphologically similar but different galls are induced by the same or distinct gall-inducers. The gall wasp specimens were identified morphologically to species level, and their genomic DNA was extracted. We used PCR and Sanger sequencing to amplify three fragments comprising cytochrome oxidase subunit I (COI), cytochrome b (cytB), and a multi-gene fragment of ribosomal DNA (rDNA) including partial 5.8S, complete internal transcribed spacer 2 (ITS2), and partial 28S rRNA. We found that a pair of structurally similar but differently coloured galls are induced by the sexual generation of Andricus grossulariae, while another similar pair are induced by the asexual generation of A. sternlichti. In contrast, we found that two similar galls that differ in some structural details and in developmental phenology are induced by two closely related but different gall wasps; one is the sexual generation of A. cecconii, while the second is a new but closely related sexual generation Andricus sp.

Genetic characterization of the Turkish gray hamster (Cricetulus migratorius) based on mitochondrial cytochrome b and 12S rRNA sequences

Although genetic diversity and phylogenetic status of the gray hamster (Cricetulus migratorius) have been investigated from different regions in previous studies, genetic data on this species from Turkey are still lacking, since previous data have been based on a limited number of gray hamsters sampled across the Anatolian part of Turkey. The aim of this study was to determine the genetic diversity of the Anatolian population and to reveal the phylogenetic relationships among the Anatolian population and conspecific populations of the gray hamster. The complete and partial fragments of mitochondrial Cyt b and 12S rRNA from the 20 Turkish samples were amplified and sequenced. Ten 12S rRNA (901 bp) and 15 Cyt b (1140 bp) haplotypes found in this work were not previously reported. Based on Bayesian, Maximum Likelihood, Neighbour-Joining and Median-Joining network analyses by using mitochondrial data under the name Cricetulus, the results of phylogenetic and network analyses indicated that there was a deep separation among the distinct lineages within the genus Cricetulus. When considering the position of the Turkish haplotypes in median joining network, the Anatolian part of Turkey may have hosted a source population of the gray hamster for expansion to adjacent regions in the past period. Additionally, the Anatolian population of gray hamster had relatively high haplotype diversity and the present study propounded the importance of data obtained from the Anatolian population of gray hamster to reveal the phylogenetic relationships among conspecific populations of the gray hamster.

Pleistocene range shifts, refugia and the origin of widespread species in western Palaearctic water beetles

Quaternary glacial cycles drove major shifts in both the extent and location of the geographical ranges of many organisms. During glacial maxima, large areas of central and northern Europe were inhospitable to temperate species, and these areas are generally assumed to have been recolonized during interglacials by range expansions from Mediterranean refugia. An alternative is that this recolonization was from non-Mediterranean refugia, in central Europe or western Asia, but data on the origin of widespread central and north European species remain fragmentary, especially for insects. We studied three widely distributed lineages of freshwater beetles (the Platambus maculatus complex, the Hydraena gracilis complex, and the genus Oreodytes), all restricted to running waters and including both narrowly distributed southern endemics and widespread European species, some with distributions spanning the Palearctic. Our main goal was to determine the role of the Pleistocene glaciations in shaping the diversification and current distribution of these lineages. We sequenced four mitochondrial and two nuclear genes in populations drawn from across the ranges of these taxa, and used Bayesian probabilities and Maximum Likelihood to reconstruct their phylogenetic relationships, age and geographical origin. Our results suggest that all extant species in these groups are of Pleistocene origin. In the H. gracilis complex, the widespread European H. gracilis has experienced a rapid, recent range expansion from northern Anatolia, to occupy almost the whole of Europe. However, in the other two groups widespread central and northern European taxa appear to originate from central Asia, rather than the Mediterranean. These widespread species of eastern origin typically have peripherally isolated forms in the southern Mediterranean peninsulas, which may be remnants of earlier expansion-diversification cycles or result from incipient isolation of populations during the most recent Holocene expansion. The accumulation of narrow endemics of such lineages in the Mediterranean may result from successive cycles of range expansion, with subsequent speciation (and local extinction in glaciated areas) through multiple Pleistocene climatic cycles.

Pre-Quaternary divergence and subsequent radiation explain longitudinal patterns of genetic and morphological variation in the striped skink, Heremites vittatus

Background

Many animal and plant species in the Middle East and northern Africa have a predominantly longitudinal distribution, extending from Iran and Turkey along the eastern Mediterranean coast into northern Africa. These species are potentially characterized by longitudinal patterns of biological diversity, but little is known about the underlying biogeographic mechanisms and evolutionary timescales. We examined these questions in the striped skink, Heremites vittatus, one such species with a roughly longitudinal distribution across the Middle East and northern Africa, by analyzing range-wide patterns of mitochondrial DNA (mtDNA) sequence and multi-trait morphological variation.

Results

The striped skink exhibits a basic longitudinal organization of mtDNA diversity, with three major mitochondrial lineages inhabiting northern Africa, the eastern Mediterranean coast, and Turkey/Iran. Remarkably, these lineages are of pre-Quaternary origin, and are characterized by p-distances of 9–10%. In addition, within each of these lineages a more recent Quaternary genetic diversification was observed, as evidenced by deep subclades and high haplotype diversity especially in the Turkish/Iranian and eastern Mediterranean lineages. Consistent with the genetic variation, our morphological analysis revealed that the majority of morphological traits show significant mean differences between specimens from northern Africa, the eastern Mediterranean coast, and Turkey/Iran, suggesting lineage-specific trait evolution. In addition, a subset of traits exhibits clinal variation along the eastern Mediterranean coast, potentially indicating selection gradients at the geographic transition from northern Africa to Anatolia. The existence of allopatric, morphologically and genetically divergent lineages suggests that Heremites vittatus might represent a complex with several taxa.

Conclusions

Our work demonstrates that early divergence events in the Pliocene, likely driven by both climatic and geological factors, established the longitudinal patterns and distribution of Heremites vittatus. Subsequent radiation during the Pleistocene generated the genetic and morphological diversity observed today. Our study provides further evidence that longitudinal diversity patterns and species distributions in the Middle East and northern Africa were shaped by complex evolutionary processes, involving the region’s intricate geological history, climatic oscillations, and the presence of the Sahara.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0969-0) contains supplementary material, which is available to authorized users.

A reinvestigation of phylogeny and divergence times of the Ablepharus kitaibelii species complex (Sauria, Scincidae) based on mtDNA and nuDNA genes

Morphological and DNA data support that the East Mediterranean snake-eyed skink Ablepharus kitaibelii represents a species complex that includes four species A. kitaibelii, A. budaki, A. chernovi, and A. rueppellii, highlighting the need of its taxonomic reevaluation. Here, we used Bayesian and Maximum Likelihood methods to estimate the phylogenetic relationships of all members of the complex based on two mitochondrial (cyt b, 16S rRNA) and two nuclear markers (MC1R, and NKTR) and using Chalcides, Eumeces, and Eutropis as outgroups. The biogeographic history of the complex was also investigated through the application of several phylogeographic (BEAST) and biogeographic (BBM) analyses. Paleogeographic and paleoclimatic data were used to support the inferred phylogeographic patterns. The A. kitaibelli species complex exhibits high genetic diversity, revealing cases of hidden diversity and cases of non-monophyletic species such as A. kitaibelii and A. budaki. Our results indicate that A. pannonicus branches off first and a group that comprises specimens of A. kitaibelli and A. budaki from Kastelorizo Island group (southeast Greece) and southwest Turkey, respectively is differentiated from the rest A. kitaibelli and A. budaki populations and may represent a new species. The estimated divergence times place the origin of the complex in the Middle Miocene (∼16Mya) and the divergence of most currently recognized species in the Late Miocene. The inferred ancestral distribution suggests that the complex originated in Anatolia, supposing that several vicariance and dispersal events that are related with the formation of the Mid-Aegean Trench, the Anatolian Diagonal and the orogenesis of the mountain chains in southern and eastern Anatolia have led to current distribution pattern of A. kitaibelii species complex in the Balkans and Middle East.

Ecological niche and phylogeography elucidate complex biogeographic patterns in Loxosceles rufescens (Araneae, Sicariidae) in the Mediterranean Basin

BACKGROUND

Understanding the evolutionary history of morphologically cryptic species complexes is difficult, and made even more challenging when geographic distributions have been modified by human-mediated dispersal. This situation is common in the Mediterranean Basin where, aside from the environmental heterogeneity of the region, protracted human presence has obscured the biogeographic processes that shaped current diversity. Loxosceles rufescens (Araneae, Sicariidae) is an ideal example: native to the Mediterranean, the species has dispersed worldwide via cohabitation with humans. A previous study revealed considerable molecular diversity, suggesting cryptic species, but relationships among lineages did not correspond to geographic location.

RESULTS

Delimitation analyses on cytochrome c oxidase subunit I identified 11 different evolutionary lineages, presenting two contrasting phylogeographic patterns: (1) lineages with well-structured populations in Morocco and Iberia, and (2) lineages lacking geographic structure across the Mediterranean Basin. Dating analyses placed main diversification events in the Pleistocene, and multiple Pleistocene refugia, identified using ecological niche modeling (ENM), are compatible with allopatric differentiation of lineages. Human-mediated transportation appears to have complicated the current biogeography of this medically important and synanthropic spider.

CONCLUSIONS

We integrated ecological niche models with phylogeographic analyses to elucidate the evolutionary history of L. rufescens in the Mediterranean Basin, with emphasis on the origins of mtDNA diversity. We found support for the hypothesis that northern Africa was the center of origin for L. rufescens, and that current genetic diversity originated in allopatry, likely promoted by successive glaciations during the Pleistocene. We corroborated the scenario of multiple refugia within the Mediterranean, principally in northern Africa, combining results from eight atmosphere-ocean general circulation models (AOGCMs) with two different refugium-delimitation methodologies. ENM results were useful for providing general views of putative refugia, with fine-scale details depending on the level of stringency applied for agreement among models.

ABC inference of multi-population divergence with admixture from unphased population genomic data

Rapidly developing sequencing technologies and declining costs have made it possible to collect genome-scale data from population-level samples in nonmodel systems. Inferential tools for historical demography given these data sets are, at present, underdeveloped. In particular, approximate Bayesian computation (ABC) has yet to be widely embraced by researchers generating these data. Here, we demonstrate the promise of ABC for analysis of the large data sets that are now attainable from nonmodel taxa through current genomic sequencing technologies. We develop and test an ABC framework for model selection and parameter estimation, given histories of three-population divergence with admixture. We then explore different sampling regimes to illustrate how sampling more loci, longer loci or more individuals affects the quality of model selection and parameter estimation in this ABC framework. Our results show that inferences improved substantially with increases in the number and/or length of sequenced loci, while less benefit was gained by sampling large numbers of individuals. Optimal sampling strategies given our inferential models included at least 2000 loci, each approximately 2 kb in length, sampled from five diploid individuals per population, although specific strategies are model and question dependent. We tested our ABC approach through simulation-based cross-validations and illustrate its application using previously analysed data from the oak gall wasp, Biorhiza pallida.

Population genetic studies revealed local adaptation in a high gene-flow marine fish, the small yellow croaker (Larimichthys polyactis)

The genetic differentiation of many marine fish species is low. Yet local adaptation may be common in marine fish species as the vast and changing marine environment provides more chances for natural selection. Here, we used anonymous as well as known protein gene linked microsatellites and mitochondrial DNA to detect the population structure of the small yellow croaker (Larimichthys polyactis) in the Northwest Pacific marginal seas. Among these loci, we detected at least two microsatellites, anonymous H16 and HSP27 to be clearly under diversifying selection in outlier tests. Sequence cloning and analysis revealed that H16 was located in the intron of BAHCC1 gene. Landscape genetic analysis showed that H16 mutations were significantly associated with temperature, which further supported the diversifying selection at this locus. These marker types presented different patterns of population structure: (i) mitochondrial DNA phylogeny showed no evidence of genetic divergence and demonstrated only one glacial linage; (ii) population differentiation using putatively neutral microsatellites presented a pattern of high gene flow in the L. polyactis. In addition, several genetic barriers were identified; (iii) the population differentiation pattern revealed by loci under diversifying selection was rather different from that revealed by putatively neutral loci. The results above suggest local adaptation in the small yellow croaker. In summary, population genetic studies based on different marker types disentangle the effects of demographic history, migration, genetic drift and local adaptation on population structure and also provide valuable new insights for the design of management strategies in L. polyactis.

No concordant phylogeographies of the rose gall wasp Diplolepis rosae (Hymenoptera, Cynipidae) and two associated parasitoids across Europe

According to the Host-tracking Hypothesis, species of higher trophic levels with a close relationship to their hosts, such as parasites or parasitoids, are expected to show spatio-temporal phylogeographic patterns similar to those of their host. Alternatively, with ecological sorting, a subset of the local species pools might shift to a related host species, thereby disengaging common phylogeographic patterns. Here, we compare the phylogeographic structures of the cynipid rose gall wasp Diplolepis rosae across Europe and of two of its most common parasitoids, the wasps Orthopelma mediator and Glyphomerus stigma, by analysing the sequences of two gene fragments (COI and ITS 2). The phylogeographic structures of the three species associated with roses were incongruent. D. rosae had the lowest genetic diversity with one major clade, O. mediator showed the classical phylogeographic structure for Europe with one eastern and one western clade, and G. stigma had the highest diversity but no geographical structuring. This discordance of geographical patterns may be explained by 1) the dispersal propensity of adult parasitoids or 2) the parasitoids having the ability to switch to another host, while the primary host becomes rare or is even not available. Furthermore there was no indication that phylogenetic patterns were affected by Wolbachia infections. Our results document that communities of closely interacting species may be the result of idiosyncratic biogeographic histories.

Large-scale longitudinal gradients of genetic diversity: a meta-analysis across six phyla in the Mediterranean basin

Biodiversity is the diversity of life at all scales, from genes to ecosystems. Predicting its patterns of variation across the globe is a fundamental issue in ecology and evolution. Diversity within species, that is, genetic diversity, is of prime importance for understanding past and present evolutionary patterns, and highlighting areas where conservation might be a priority. Using published data on the genetic diversity of species whose populations occur in the Mediterranean basin, we calculated a coefficient of correlation between within-population genetic diversity indices and longitude. Using a meta-analysis framework, we estimated the role of biological, ecological, biogeographic, and marker type factors on the strength and magnitude of this correlation in six phylla. Overall, genetic diversity increases from west to east in the Mediterranean basin. This correlation is significant for both animals and plants, but is not uniformly expressed for all groups. It is stronger in the southern than in the northern Mediterranean, in true Mediterranean plants than in plants found at higher elevations, in trees than in other plants, and in bi-parentally and paternally than in maternally inherited DNA makers. Overall, this correlation between genetic diversity and longitude, and its patterns across biological and ecological traits, suggests the role of two non-mutually exclusive major processes that shaped the genetic diversity in the Mediterranean during and after the cold periods of the Pleistocene: east-west recolonization during the Holocene and population size contraction under local Last Glacial Maximum climate in resident western and low elevation Mediterranean populations.

Mitochondrial barcodes are diagnostic of shared refugia but not species in hybridizing oak gallwasps

Mitochondrial DNA barcodes provide a simple taxonomic tool for systematic and ecological research, with particular benefit for poorly studied or species-rich taxa. Barcoding assumes genetic diversity follows species boundaries; however, many processes disrupt species-level monophyly of barcodes leading to incorrect classifications. Spatial population structure, particularly when shared across closely related and potentially hybridizing taxa, can invalidate barcoding approaches yet few data exist to examine its impacts. We test how shared population structure across hybridizing species impacts upon mitochondrial barcodes by sequencing the cytochrome b gene for 518 individuals of four well-delimited Western Palaearctic gallwasp species within the Andricus quercuscalicis species group. Mitochondrial barcodes clustered individuals into mixed-species clades corresponding to refugia, with no difference in within- and between-species divergence. Four nuclear genes were also sequenced from 4 to 11 individuals per refugial population of each species. Multi-locus analyses of these data supported established species, with no support for the refugial clustering across species seen in mitochondrial barcodes. This pattern is consistent with mitochondrial introgression among populations of species sharing the same glacial refugium, such that mitochondrial barcodes identify a shared history of population structure rather than species. Many taxa show phylogeographic structure across glacial refugia, suggesting that mitochondrial barcoding may fail when applied to other sets of co-distributed, closely related species. Robust barcoding approaches must sample extensively across population structure to disentangle spatial from species-level variation. Methods incorporating multiple unlinked loci are also essential to accommodate coalescent variation among genes and provide power to resolve recently diverged species.

Patterns of distribution of tree frogs in Turkey based on molecular data

Despite previous work on the phylogeny of PalearcticHyla, several problems still exist regarding systematics ofHylain Turkey. The systematics of tree frogs (Hyla orientalisandHyla savignyi) in Turkey was studied using combined mitochondrial genes (12S ribosomal RNA and cytochromeb) and a nuclear gene (H3), and sampling a total of 102 individuals from 51 localities. We find thatHyla orientalisis represented by a single lineage, whereasHyla savignyiwas divided into two lineages by the mitochondrial genes, but not the nuclear gene. We also confirm thatHyla arborea schelkownikowiis a junior synonym ofHyla orientalis.

Host tracking or cryptic adaptation? Phylogeography of Pediobius saulius (Hymenoptera, Eulophidae), a parasitoid of the highly invasive horse-chestnut leafminer

Classical biological control is often advocated as a tool for managing invasive species. However, accurate evaluations of parasitoid species complexes and assessment of host specificity are impeded by the lack of morphological variation. Here, we study the possibility of host races/species within the eulophid wasp Pediobius saulius, a pupal generalist parasitoid that parasitize the highly invasive horse-chestnut leaf-mining moth Cameraria ohridella. We analysed the population genetic structure, host associations and phylogeographic patterns of P. saulius in Europe using the COI mitochondrial gene. This marker strongly supports a division into at least five highly differentiated parasitoid complexes, within two of which clades with differing degrees of host specialization were found: a Balkan clade that mainly (but not only) attacks C. ohridella and a more generalist European group that attacks many hosts, including C. ohridella. The divergence in COI (up to 7.6%) suggests the existence of cryptic species, although this is neither confirmed by nuclear divergence nor morphology. We do not find evidence of host tracking. The higher parasitism rates observed in the Balkans and the scarcity of the Balkan–Cameraria haplotypes out of the Balkans open the possibility of using these Balkan haplotypes as biological control agents of C. ohridella elsewhere in Europe.

Evolution of reproductive mode variation and host associations in a sexual-asexual complex of aphid parasitoids

Background

The Lysiphlebus fabarum group is a taxonomically poorly resolved complex of aphid parasitoids, presently split into three described species that comprise sexual (arrhenotokous) and asexual (thelytokous) lineages of unknown relationship. Specifically, it is unclear how asexuals evolved from sexuals in this system, to what extent reproductive modes are still connected by genetic exchange, how much the complex is structured by geography or by host-associated differentiation, and whether species designations are valid. Using a combination of population genetic and phylogenetic approaches, we addressed these issues in a comprehensive sample of parasitoid wasps from across Europe.

Results

Asexual reproduction predominated in parasitoids of the L. fabarum group, with asexual populations exhibiting high genotypic diversity. Sexual populations were only common in southern France; elsewhere sexual reproduction was restricted to specific aphid hosts. Although reproductive modes were aggregated on the mitochondrial genealogy and significantly differentiated at nuclear microsatellite loci, there was clear evidence for genetic exchange, especially on hosts attacked by sexual and asexual parasitoids. The microsatellite data further revealed that parasitoids collected from certain host aphids were significantly differentiated, yet the mitochondrial sequence variation across the entire L. fabarum group did not exceed 1.32% and exhibited a very shallow topology. Morphological characters used for delineation of described species were found to be phylogenetically non-conservative.

Conclusions

Our results suggest that the sexual-asexual L. fabarum group represents a young complex of lineages with incomplete isolation between reproductive modes. We propose three mechanisms of genetic exchange that may jointly explain the high genotypic diversity observed in asexual parasitoids: (i) the formation of new asexual lineages via 'contagious parthenogenesis', (ii) introgression from sexual lineages through matings between sexual males and thelytokous females, and (iii) 'cryptic sex' within asexuals, mediated by rare males that thelytokous lines are known to produce spontaneously. The partially strong differentiation among wasps collected from different aphids suggests that host specialization can evolve readily in these parasitoids. Finally, we conclude that in the light of our data, the current taxonomic division of the L. fabarum group into three species cannot be upheld.

The importance of Anatolian mountains as the cradle of global diversity in Arabis alpina, a key arctic-alpine species

BACKGROUND AND AIMS

Anatolia is a biologically diverse, but phylogeographically under-explored region. It is described as either a centre of origin and long-term Pleistocene refugium, or as a centre for genetic amalgamation, fed from distinct neighbouring refugia. These contrasting hypotheses are tested through a global phylogeographic analysis of the arctic-alpine herb, Arabis alpina.

METHODS

Herbarium and field collections were used to sample comprehensively the entire global range, with special focus on Anatolia and Levant. Sequence variation in the chloroplast DNA trnL-trnF region was examined in 483 accessions. A haplotype genealogy was constructed and phylogeographic methods, demographic analysis and divergence time estimations were used to identify the centres of diversity and to infer colonization history.

KEY RESULTS

Fifty-seven haplotypes were recovered, belonging to three haplogroups with non-overlapping distributions in (1) North America/Europe/northern Africa, (2) the Caucuses/Iranian Plateau/Arabian Peninsula and (3) Ethiopia-eastern Africa. All haplogroups occur within Anatolia, and all intermediate haplotypes linking the three haplogroups are endemic to central Anatolia and Levant, where haplotypic and nucleotide diversities exceeded all other regions. The local pattern of haplotype distribution strongly resembles the global pattern, and the haplotypes began to diverge approx. 2·7 Mya, coinciding with the climate cooling of the early Middle Pleistocene.

CONCLUSIONS

The phylogeographic structure of Arabis alpina is consistent with Anatolia being the cradle of origin for global genetic diversification. The highly structured landscape in combination with the Pleistocene climate fluctuations has created a network of mountain refugia and the accumulation of spatially arranged genotypes. This local Pleistocene population history has subsequently left a genetic imprint at the global scale, through four range expansions from the Anatolian diversity centre into Europe, the Near East, Arabia and Africa. Hence this study also illustrates the importance of sampling and scaling effects when translating global from local diversity patterns during phylogeographic analyses.

Back to the suture: the distribution of intraspecific genetic diversity in and around anatolia

The effect of ice ages in speciation and diversification is well established in the literature. In Europe, the Iberian, the Italian and the Balkan peninsulas comprise the main glacial refugia, where the subsequent re-population of Europe started. Though not studied as extensively, Anatolia has also been hinted to be a potential glacial refugium for Europe, and with its proximity to the Caucasus and the Middle East at the same time, has potential to exhibit high levels of intraspecific diversity. The more ubiquitous use and cheaper availability of molecular methods globally now makes it possible to better understand molecular ecology and evolution of the fauna and flora in the genetically understudied regions of the world, such as Anatolia. In this review, the molecular genetic studies undertaken in Anatolia in the last decade, for 29 species of plants and animals, are examined to determine general phylogeographic patterns. In this regard, two major patterns are observed and defined, showing genetic breaks within Anatolia and between Anatolia and the Balkans. A third pattern is also outlined, which suggests Anatolia may be a center of diversity for the surrounding regions. The patterns observed are discussed in terms of their relevance to the location of suture zones, postglacial expansion scenarios, the effect of geographic barriers to gene flow and divergence time estimates, in order to better understand the effect of the geological history of Anatolia on the evolutionary history of the inhabitant species. In view of the current state of knowledge delineated in the review, future research directions are suggested.

Controlling for non-independence in comparative analysis of patterns across populations within species

How do we quantify patterns (such as responses to local selection) sampled across multiple populations within a single species? Key to this question is the extent to which populations within species represent statistically independent data points in our analysis. Comparative analyses across species and higher taxa have long recognized the need to control for the non-independence of species data that arises through patterns of shared common ancestry among them (phylogenetic non-independence), as have quantitative genetic studies of individuals linked by a pedigree. Analyses across populations lacking pedigree information fall in the middle, and not only have to deal with shared common ancestry, but also the impact of exchange of migrants between populations (gene flow). As a result, phenotypes measured in one population are influenced by processes acting on others, and may not be a good guide to either the strength or direction of local selection. Although many studies examine patterns across populations within species, few consider such non-independence. Here, we discuss the sources of non-independence in comparative analysis, and show why the phylogeny-based approaches widely used in cross-species analyses are unlikely to be useful in analyses across populations within species. We outline the approaches (intraspecific contrasts, generalized least squares, generalized linear mixed models and autoregression) that have been used in this context, and explain their specific assumptions. We highlight the power of 'mixed models' in many contexts where problems of non-independence arise, and show that these allow incorporation of both shared common ancestry and gene flow. We suggest what can be done when ideal solutions are inaccessible, highlight the need for incorporation of a wider range of population models in intraspecific comparative methods and call for simulation studies of the error rates associated with alternative approaches.