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Figure 5 in Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species

Figure 5. Cline analyses of mitochondrial DNA and microsatellite data. Transects (top) through the two different contact zones of grass snake lineages (helvetica/eastern lineages – left; yellow/red lineages – right) and associated Maximum Likelihood clines for microsatellites (centre) and mtDNA (bottom). Grey: fuzzy 95% credible cline region. Red points (top) indicate cline centres. Maps were created using ARCGIS 10.2 (http://www. esri.com/arcgis) and ADOBE ILLUSTRATOR CS6 (http://www.adobe.com/products/illustrator.html).

Figure 4. PCA axes 1–2 in Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species

Figure 4. PCA axes 1–2 for microsatellite data. Samples are coloured according to mitochondrial lineages (top) or STRUCTURE clusters (bottom). Admixed individuals were identified according to HYBRIDLAB results. PCAs for the yellow and red lineages correspond to the samples from Fig. 3c. Non-native samples were excluded. The oval outlines represent 95% confidential intervals. For helvetica and the eastern lineages (left) the x axis explains 16.6% and the y axis 4.5% of variation. For the eastern lineages (right) the x axis explains 3.8% and the y axis 2.9% of variation. Analyses along axes 1–3 produced nearly identical results (see Supplementary Fig. S4).

Figure 3 in Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species

Figure 3. Genotypic structuring of grass snakes. On the left, the mitochondrial lineage of each sample is shown above the STRUCTURE diagrams, with haplotypes of Natrix natrix helvetica indicated in blue and haplotypes of the eastern lineages in colours corresponding to Fig. 1 (yellow, red, lilac, grey, green; white = missing data). In (a), orange and dark blue corresponds to non-native snakes (Italian lineages). Samples in STRUCTURE diagrams are arranged within each country from west to east (a) or from north to south (b,c). In STRUCTURE diagrams, an individual sample is represented by a vertical bar reflecting its inferred ancestry. In (a), the blue cluster corresponds to N. n. helvetica and the light green cluster to all other lineages. The isolated red/light green block (first row) represents the allochthonous population from the Neander valley, Germany. In (b), samples with genetic impact of helvetica are excluded. The pink cluster corresponds to samples from the yellow and red lineages. Brown percentages indicate genetic impact of adjacent lineages (lilac, grey, green). In (c) only samples from the yellow and red lineages and their hybrids, without genetic signatures of other lineages, were processed. Country abbreviations: Ba – Balkans (Albania, Bosnia and Herzegovina, Montenegro, Serbia, Kosovo, Former Yugoslav Republic of Macedonia, Romania, Bulgaria, and Greece), CH – Switzerland, CRO – Croatia, CZ – Czech Republic, FI – Finland, H – Hungary, N – Norway, NL – Netherlands, PL – Poland, S – Sweden. Maps were created using ARCGIS 10.2 (http://www.esri.com/arcgis) and ADOBE ILLUSTRATOR CS6 (http://www.adobe. com/products/ illustrator.html).

Figure 1 in Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species

Figure 1. Distribution of mitochondrial lineages of 1,580 grass snakes used in this study. Total sample size of each clade shown in the legend. Eight allochthonous grass snakes with haplotypes of Italian lineages caught in southern Great Britain and Hesse, Germany, not shown. Map was created using ARCGIS 10.2 (http://www.esri. com/arcgis) and ADOBE ILLUSTRATOR CS6 (http://www.adobe.com/products/illustrator.html). Inset: Natrix natrix helvetica (Linz am Rhein, Germany); photo: Wolfgang Böhme.

Figure 2 in Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species

Figure 2. Parsimony networks of mtDNA sequences. Symbol sizes reflect haplotype frequencies. Small black circles are missing node haplotypes; each line connecting two haplotypes corresponds to one mutation step, if not otherwise indicated by numbers. Haplotype colours correspond to lineages, i.e. Natrix natrix helvetica (h) in blue; eastern lineages in yellow (y) and in red (r).

opencc-zeroDec 2012View details →

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Data from: Evidence for past and present hybridization in three Antarctic icefish species provides new perspectives on an evolutionary radiation

Determining the timing, extent, and underlying causes of inter-specific gene exchange during or following speciation is central to understanding species' evolution. Antarctic notothenioid fish, thanks to the acquisition of antifreeze glycoproteins during Oligocene transition to polar conditions, experienced a spectacular radiation to >100 species during Late Miocene cooling events. The impact of recent glacial cycles on this group is poorly known, but alternating warming and cooling periods may have affected species' distributions, promoted ecological divergence into recurrently opening niches, and/or possibly brought allopatric species into contact. Using microsatellite markers and statistical methods including Approximate Bayesian Computation, we investigated genetic differentiation, hybridization and the possible influence of the last glaciation/deglaciation events in three icefish species of the genus Chionodraco. Our results provide strong evidence of contemporary and past introgression by showing that: i) a substantial fraction of contemporary individuals in each species has mixed ancestry; ii) evolutionary scenarios excluding hybridization or including it only in ancient times have small or zero posterior probabilities; iii) the data support a scenario of interspecific gene flow associated with the two most recent interglacial periods. Glacial cycles might therefore have had a profound impact on the genetic composition of Antarctic fauna, as newly available shelf areas during the warmer intervals might have favoured secondary contacts and hybridization between diversified groups. If our findings are confirmed in other notothenioids, they offer new perspectives for understanding evolutionary dynamics of Antarctic fish, and suggest a need for new predictions on the effects of global warming in this group.

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Data from: New evidence for hybrid zones of forest and savanna elephants in Central and West Africa

The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo (DRC). Here we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples - many more than have been previously identified - only two of which are from the Garamba region. The remaining 44 are from three other geographically-distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic, and a smaller fraction of hybrids in the Pendjari-Arli complex of West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that hybrids are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat modification. The localized geography and rarity of hybrid zones, their possible facilitation from human pressures, and the high divergence and genetic distinctness of forest and savanna elephants throughout their ranges, are consistent with calls for separate species classification.

opencc-zeroDec 2014View details →

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Data from: Genetic analysis of river, swamp and hybrid buffaloes of north-east India throw new light on phylogeography of water buffalo (Bubalus bubalis)

This study analysed buffaloes from north-east India and compared their nuclear and mitochondrial DNA variations with buffaloes of mainland India, China, Mediterranean and South-East Asia. Microsatellite genotypes of 338 buffaloes including 210 from six north-east Indian buffalo populations and three mainland Indian breeds were analysed to evaluate their genetic structure and evolutionary relationships. Phylogenetic analysis and multidimensional scaling plot of pairwise FST revealed the clustering of all swamp-type buffaloes of north-east India with Lower Assamese (significantly hybrid type) buffaloes in one plane and all the mainland river buffaloes in another plane while the upper Assamese buffaloes being distinct from both these clusters. Analysis of mtDNA D-loop region of 530-bp length was performed on 345 sequences belonging to 23 buffalo populations from various geographical regions to establish the phylogeography of Indian water buffalo. The swamp buffaloes of north-east India clustered with both the lineages of Chinese swamp buffalo. Multidimensional scaling display of pairwise FST derived from mitochondrial DNA data showed clustering of upper Assamese, Chilika and Mediterranean buffaloes distinctly from all the other Indian buffalo populations. Median-joining network analysis further confirmed the distinctness and ancestral nature of these buffaloes. The study revealed north-east region of India forming part of the wider hybrid zone of water buffalo that may probably extend from north-east India to South-East Asia.

opencc-zeroDec 2014View details →

FIGURE 10 in Cryptic species and hybridization in the Anolis polylepis complex, with the description of a new species from the Osa Peninsula, Costa Rica (Squamata: Polychrotidae)

FIGURE 10. Adult male of Anolis osa (not collected) at Puerto Escondido in life with extended dewlap.

FIGURE 7 in Cryptic species and hybridization in the Anolis polylepis complex, with the description of a new species from the Osa Peninsula, Costa Rica (Squamata: Polychrotidae)

FIGURE 7. Principal component scatterplots (axes one and two) for males and females of the two hemipenial types of Central American anoles formerly referred to as Anolis polylepis. Open circles = Type A; open triangles = Type B. See text for details.

FIGURE 5 in Cryptic species and hybridization in the Anolis polylepis complex, with the description of a new species from the Osa Peninsula, Costa Rica (Squamata: Polychrotidae)

FIGURE 5. Hemipenis of a suspected hybrid (SMF 89181) between Anolis polylepis and A. osa. Scale bar = 1.0 mm.

FIGURE 6 in Cryptic species and hybridization in the Anolis polylepis complex, with the description of a new species from the Osa Peninsula, Costa Rica (Squamata: Polychrotidae)

FIGURE 6. Map indicating known collecting sites mentioned in text of Central American anoles formerly referred to as Anolis polylepis. Each symbol can represent one or more nearby localities. Areas above 500 and 1000 m are shaded gray. Circles: Hemipenis Type A; squares: Hemipenis Type B. Insert: Map indicating the suspected hybrid zone. See text for details. Circles: Hemipenis Type A; squares: Hemipenis Type B; triangles: specimens with intermediate hemipenial morphology. Areas above 200 m are shaded gray.

FIGURE 1 in Cryptic species and hybridization in the Anolis polylepis complex, with the description of a new species from the Osa Peninsula, Costa Rica (Squamata: Polychrotidae)

FIGURE 1. Designation of nasal scalation types. (a) Type A (UCR 20713); (b) Type B (SMF 89430); (c) Type C (SMF 89210); (d) Type D (UCR 14257); (e) Type E (UCR 20732). Scale bar = 1.0 mm. See Text for details.

FIGURE 6 in A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song

FIGURE 6. Field recordings of putative hybrids between subspecies of Neotibicen similaris; A–D; spectrograms showing a range of phenotypes exhibiting different combinations of the parental song characters from four different locations (see track ID at bottom right); E, zoomed waveform and spectrogram of the song in D, showing the long high-pitched echeme of N. similaris apalachicola n. subsp. followed by a set of short echemes matching those of N. similaris similaris. Sound energy below 1.8 kHz has been removed.

FIGURE 5 in A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song

FIGURE 5. Distribution records of Neotibicen similaris similaris (blue), N. similaris apalachicola n. subsp. (orange), and hybrid cicadas (X and + symbols). Symbols with central dots or a + symbol indicate that a specimen was collected or a voucher recording was made; other records were aurally noted; A, regional scale map of southeastern USA with labeled states outlined in black and with state counties outlined in grey; zoomed section in B is indicated by the dashed line; B, moderate scale map, zoomed section in C is indicated by the dashed line; C, core N. similaris apalachicola distribution surrounding Tallahassee, FL (grey star).

FIGURE 4 in A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song

FIGURE 4. Neotibicen similaris similaris, field recording of male calling song from Wakulla Co., Florida (recording 08.US.FL.FOR.T01.WAV). Each panel shows a waveform above a spectrogram; A, complete song phrase, with annotation identifying two parts in the main phrase that differ in rate of alternation between high- and low-pitched echemes; B, zoom centered about 0.48 s into the clip in A, at the transition from part I to part II; C, further zoom of part I; D, further zoom of part II; E, segment of song that precedes and follows the main phrase. Sound energy below 1.8 kHz has been removed.

FIGURE 2 in A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song

FIGURE 2. Pygofer preparations showing aedeagus (ae) beneath uncus (u): A, Neotibicen similaris apalachicola, n. subsp., specimen 08.US.FL.LMC.02; B, N. similaris similaris, specimen 08.US.FL.HSC.20. White scale bar = 1 mm.

FIGURE 3. Neotibicen similaris apalachicola, n in A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song

FIGURE 3. Neotibicen similaris apalachicola, n. subsp., field recording of male calling song from Wakulla Co., Florida (recording 08.US.FL.BXU.T08.WAV). Each panel shows a waveform above a spectrogram; A, complete song phrase; B, partial zoom of the central portion of the phrase; C, further zoom of one of the four oscillations in B; D, segment of song that precedes the main phrase. Sound energy below 1.8 kHz has been removed.