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Fig. 14 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 14. Aquattuor nguruensis sp. nov., holotype, ♂ (VMNH110617). A–E. Left gonopod coxa. A. Anterior view. B. Mesal view. C. Meso-posterior view. D. Posterior view. E. Apical view. F. Midbody dorsal limbus. Abbreviations: pa = palette; pp = proplica. Scale bars: A–D = 0.1 mm; E = 0.05 mm; F = 0.01 mm.

Fig. 12 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 12. Aquattuor mollilobus sp. nov., paratype, ♂ (NHMD 621648). A–D. Left gonopod coxa. A. Anterior view. B. Anterior-mesal view. C. Mesal view. D. Posterior-lateral view. E. Midbody dorsal limbus. Abbreviations: li = lateral incision; mi = mesal incision; pa = palette; pp = proplica. Scale bars: A–D = 0.1 mm; E = 0.02 mm.

Fig. 18. Aquattuor submajor Enghoff, 2015 and A. udzungwensis Enghoff, 2015 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 18. Aquattuor submajor Enghoff, 2015 and A. udzungwensis Enghoff, 2015; numbers of podous rings as a function of altitude.

Fig. 11. Aquattuor longipala Enghoff, 2015 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 11. Aquattuor longipala Enghoff, 2015, male, specimen from Udzungwa Mts National Park, Mito Mitatu (NHMD 621642), left gonopod. A–C. Coxa. A. Anterior view. B. Mesal view. C. Posterior view. D–H. Telopodite. D. Tip of telomere. E. Posterior view. F. Anterior view. G. Posterior-ventral view. H. Distal (ventral) view. Abbreviations: li = lateral incision; mi = mesal incision; mpl = mesal-posterior telomeral lamella; pa = palette; slm = solenomere; tm = telomere. Scale bars: A–C, E–H = 0.1 mm; D = 0.05 mm.

Fig. 10 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 10. Aquattuor claudiahempae Enghoff & Frederiksen, 2015, male, specimen from the Udzungwa Mts (NHMD 621639), left gonopod. A–C. Coxa. A. Anterior view. B. Mesal view. C. Posterior view. D–G. Telopodite. D. Tip of telomere. E. Anterior view. F. Posterior view. G. Mesal view. Abbreviations: btl = basal telomeral lamella; li = lateral incision; mbl = meso-basal lobe of palette; mi = mesal incision; mpl = mesal-posterior telomeral lamella; pa = palette. Scale bars: A–C, E–G = 0.1 mm; D = 0.02 mm.

Fig. 9 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 9. Aquattuor spp. Body size (number of podous rings and midbody vertical diameter) in males of Aquattuor species from the Udzungwa Mts, and of A. claudiahempae Enghoff & Frederiksen, 2015 from Mt Kilimanjaro. In case of (almost) coinciding values, symbols have been slightly displaced horizontally.

Fig. 17. Aquattuor udzungwensis Enghoff, 2015 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 17. Aquattuor udzungwensis Enghoff, 2015, male from Udzungwa Mts National Park, Kidatu (NHMD 621659), left gonopod telopodite. A. (Meso-)posterior view. B. Basal telomeral lamella, distal (ventral) view. C. Telomere, sublateral view. Abbreviations: btl = basal telomeral lamella; mpl = mesoposterior telomeral lamella, the arrow points to the diagnostic angle; slm = solenomere; spl = spinose lid-like flap; tm = telomere. Scale bars = 0.05 mm.

Fig. 5 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 5. Aquattuor spp., first pair of male legs. A–C. A. major Enghoff, 2015, paratype, ♂ (NHMD 621644), first pair of legs in situ. D–F. A. longipala Enghoff, 2015, male from Udzungwa Mts National Park, Mito Mitatu (NHMD 621642). A, D. Anterior view. B, E. Sublateral view. C, F. Sub-ventral view. Abbreviations: dpl = distal prefemoral lobe; pfp = prefemoral process. Scale bars = 0.1 mm.

Fig. 7 in A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae)

Fig. 7. Aquattuor spp., first pair of male legs. A–C. A. submajor Enghoff, 2015, paratype, ♂ (NHMD 621651). A. Anterior view. B. Sublateral view. C. Ventral view. D–E. A. udzungwensis Enghoff, 2015, male from Udzungwa Mts National Park, Kidatu (NHMD 621662). D. Anterior view. E. Ventral view. Scale bars = 0.1 mm.

opencc-zeroDec 2020View details →

The origin of the parrotfish species Scarus compressus in the Tropical Eastern Pacific: region-wide hybridization between ancient species pairs

Background: An increasing number of hybrid zones with varying evolutionary outcomes have been documented from different reef fish families. In the Tropical Eastern Pacific (TEP), four species of parrotfishes occur in sympatry on rocky reefs from Baja California to Ecuador: Scarus. compressus,S. ghobban, S. perrico, and S. rubroviolaceus; and have complex phylogeographic histories. The most divergent,S. perrico, belongs to a Tropical American clade that diverged from a Central Indo-Pacific ancestor in the late Miocene (6.6 Ma). We tested the hypothesis that S. compressuswas the result of ongoing hybridization among the other three species by sequencing four nuclear markers and a mitochondrial locus in samples spanning 2/3 of the latitudinal extent of the TEP. Results: A structure model of all samples indicated that K=3 was the best fit to the nuclear data and that individuals identified as S. compressushad admixed assignment values (Q). Power analyses indicated our data could correctly detect and assign pure adults and F1 hybrids with > 0.90 probability, and correct assignment of F2 was also high in some cases. NewHybrids models revealed that 89.8% (n= 59) of the Scarus compressus samples were F1 hybrids of crosses between divergent species pairs: S. perrico × S. ghobbanand S. perrico × S. rubroviolaceus. Similarly, S.ghobban and S. rubroviolaceuswere also hybridizing, with ½ of the admixed individuals assigned to F1 hybrids and the remainder likely deep generation hybrids. We observed strong mito-nuclear discordance in all three hybrid pairs, but found little evidence for accelerated mt vs. nuclear evolution in the paternal species. Bayesian analysis of Migrate models favours gene flow between S. perricoand S. ghobban, but not other species pairs. Conclusions: Mating between species whose ancestors diverged in the late Miocene is giving rise to region wide, hybrid complex, characterized by a high frequency of parental and F1 genotypes but a low frequency of deep generation hybrids. Trimodal structure, combined with reproductive evidence for fertility of both male and female F1 hybrids, suggest that fitness declines sharply in later generation hybrids. In contrast, the hybrid population of the two younger species had similar frequencies of F1 and > F1 hybrids. These differences are consistent with a model of accelerating post-mating incompatibility with time. Mitochondrial genotypes in hybrids, suggests indiscriminate mating by male S. perricois driving pre-zygotic breakdown, which may reflect the isolation of this endemic species in the TEP for millions of years and weak selection for conspecific mate recognition. Despite overlapping habitat use, high rates of hybridization, and evidence for historical gene flow, species boundaries are maintained by post-mating processes in this complex.

opencc-zeroDec 2014View details →

Data from: Reproductive isolation in a nascent species pair is associated with aneuploidy in hybrid offspring

Speciation may occur when the genomes of two populations accumulate genetic incompatibilities and/or chromosomal rearrangements that prevent inter-breeding in nature. Chromosome stability is critical for survival and faithful transmission of the genome, and hybridization can compromise this. However, the role of chromosomal stability on hybrid incompatibilities has rarely been tested in recently diverged populations. Here, we test for chromosomal instability in hybrids between nascent species, the 'dwarf' and 'normal' lake whitefish (Coregonus clupeaformis). We examined chromosomes in pure embryos, and healthy and malformed backcross embryos. While pure individuals displayed chromosome numbers corresponding to the expected diploid number (2n = 80), healthy backcrosses showed evidence of mitotic instability through an increased variance of chromosome numbers within an individual. In malformed backcrosses, extensive aneuploidy corresponding to multiples of the haploid number (1n = 40, 2n = 80, 3n = 120) was found, suggesting meiotic breakdown in their F1 parent. However, no detectable chromosome rearrangements between parental forms were identified. Genomic instability through aneuploidy thus appears to contribute to reproductive isolation between dwarf and normal lake whitefish, despite their very recent divergence (approx. 15–20 000 generations). Our data suggest that genetic incompatibilities may accumulate early during speciation and limit hybridization between nascent species.

opencc-zeroDec 2012View details →

Data from: Targeted sequence capture and resequencing implies a predominant role of regulatory regions in the divergence of a sympatric lake whitefish species pair (Coregonus clupeaformis)

Latest technological developments in evolutionary biology bring new challenges in documenting the intricate genetic architecture of species in the process of divergence. Sympatric populations of lake whitefish represent one of the key systems to investigate this issue. Despite the value of random genotype-by-sequencing methods and decreasing cost of sequencing technologies, it remains challenging to investigate variation in coding regions, especially in the case of recently duplicated genomes as in salmonids, as this greatly complicates whole genome resequencing. We thus designed a sequence capture array targeting 2773 annotated genes to document the nature and the extent of genomic divergence between sympatric dwarf and normal whitefish. Among the 2728 genes successfully captured, a total of 2182 coding and 10 415 noncoding putative single-nucleotide polymorphisms (SNPs) were identified after applying a first set of basic filters. A genome scan with a quality-refined selection of 2203 SNPs identified 267 outlier SNPs in 210 candidate genes located in genomic regions potentially involved in whitefish divergence and reproductive isolation. We found highly heterogeneous FST estimates among SNP loci. There was an overall low level of coding polymorphism, with a predominance of noncoding mutations among outliers. The heterogeneous patterns of divergence among loci confirm the porous nature of genomes during speciation with gene flow. Considering that few protein-coding mutations were identified as highly divergent, our results, along with previous transcriptomic studies, imply that changes in regulatory regions most likely had a greater role in the process of whitefish population divergence than protein-coding mutations. This study is the first to demonstrate the efficiency of large-scale targeted resequencing for a nonmodel species with such a large and unsequenced genome.

opencc-zeroDec 2011View details →

Data from: Experimental confirmation that body size determines mate preference via phenotype matching in a stickleback species pair

Mate choice by phenotype matching, whereby individuals prefer a mate whose phenotype is similar to their own, should facilitate speciation with gene flow. This is because the genes that control mate signal (the phenotype being matched) also determine the preferred mate signal ('mate preference'). Speciation is made even easier if phenotype matching is based on a trait under divergent natural selection. In this case, assortative mating should readily evolve as a by-product of divergent selection on the trait. Previous observational studies of assortative mating between sympatric, hybridizing threespine stickleback species (Gasterosteus aculeatus complex) suggested that phenotype matching might occur by body size, a trait under divergent natural selection. To test this we used experimental manipulation of body size to rule out the effects of confounding variables. We found that size-manipulated benthic and limnetic stickleback females prefer mates whose body size more closely matches their own. It is thus likely that assortative mating by phenotype matching has facilitated the origin and persistence of benthic and limnetic threespine sticklebacks in the face of gene flow.

opencc-zeroDec 2015View details →

Data from: Standing chromosomal variation in Lake Whitefish species pairs: the role of historical contingency and relevance for speciation

The role of chromosome changes in speciation remains a debated topic, although demographic conditions associated with divergence should promote their appearance. We tested a potential relationship between chromosome changes and speciation by studying two Lake Whitefish (Coregonus clupeaformis) lineages that recently colonized postglacial lakes following allopatry. A dwarf limnetic species evolved repeatedly from the normal benthic species, becoming reproductively isolated. Lake Whitefish hybrids experience mitotic and meiotic instability, which may result from structurally divergent chromosomes. Motivated by this observation, we test the hypothesis that chromosome organization differs between Lake Whitefish species pairs using cytogenetics. While chromosome and fundamental numbers are conserved between the species (2n = 80, NF = 98), we observe extensive polymorphism of subtle karyotype traits. We describe intrachromosomal differences associated with heterochromatin and repetitive DNA, and test for parallelism among three sympatric species pairs. Multivariate analyses support the hypothesis that differentiation at the level of subchromosomal markers mostly appeared during allopatry. Yet we find no evidence for parallelism between species pairs among lakes, consistent with colonization effect or postcolonization differentiation. The reported intrachromosomal polymorphisms do not appear to play a central role in driving adaptive divergence between normal and dwarf Lake Whitefish. We discuss how chromosomal differentiation in the Lake Whitefish system may contribute to the destabilization of mitotic and meiotic chromosome segregation in hybrids, as documented previously. The chromosome structures detected here are still difficult to sequence and assemble, demonstrating the value of cytogenetics as a complementary approach to understand the genomic bases of speciation.

opencc-zeroDec 2014View details →

Data from: Predator experience overrides learned aversion to heterospecifics in stickleback species pairs

Predation risk can alter female mating decisions because the costs of mate searching and selecting attractive mates increase when predators are present. In response to predators, females have been found to plastically adjust mate preference within species, but little is known about how predators alter sexual isolation and hybridization among species. We tested the effects of predator exposure on sexual isolation between benthic and limnetic threespine sticklebacks (Gasterosteus spp.). Female discrimination against heterospecific mates was measured before and after females experienced a simulated attack by a trout predator or a control exposure to a harmless object. In the absence of predators, females showed increased aversion to heterospecifics over time. We found that predator exposure made females less discriminating and precluded this learned aversion to heterospecifics. Benthic and limnetic males differ in coloration, and predator exposure also affected sexual isolation by weakening female preferences for colourful males. Predator effects on sexual selection were also tested but predators had few effects on female choosiness among conspecific mates. Our results suggest that predation risk may disrupt the cognitive processes associated with mate choice and lead to fluctuations in the strength of sexual isolation between species.

opennotspecifiedDec 2003View details →

FIGURES 12 in A sympatric species pair: Spogostylum ocyale (Wiedemann, 1828) and S. griseipenne Macquart, 1850 (Diptera: Bombyliidae)

FIGURES 12. Wings of Spogostylum species. 1. S. ocyale (Wiedemann). 2. S. griseipenne (Macquart).

opennotspecifiedDec 2010View details →

FIGURE 2 in Another new, diminutive Rock Gecko (Cnemaspis Strauch) from Peninsular Malaysia and a discussion of resource partitioning in sympatric species pairs

FIGURE 2. Dorsal (upper) and ventral (lower) view of holotype (ZRC 6695).

opennotspecifiedDec 2010View details →

FIGURE 1 in Another new, diminutive Rock Gecko (Cnemaspis Strauch) from Peninsular Malaysia and a discussion of resource partitioning in sympatric species pairs

FIGURE 1. Distribution of Cnemaspis shahruli sp. nov. in northwestern Peninsular Malaysia.

opencc-by-4.0Nov 2023View details →

Raw data associated to the paper "Analysis of species pair associations combined with functional traits reveals the effects of environmental filtering and biotic interactions in an unmanaged temperate forest"

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