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Fig. 5 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 5 Mean daily biting rates ± 1 standard error (SE) at the four collection sites based on three collection days each month. Biting rates were highest at the two riverside sites (Bayomen and Nyamongo I) and decreased with increasing distance from the river

Fig. 1 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 1 Map of the study area showing adult and larval blackfly collection sites and dissection stations in relation to the Mbam river. Grey arrows show the direction of river flow and the inset map shows the location of the study area (black star) in Cameroon

Fig. 2 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 2 Historical rainfall and river discharge for Bafia and the lower Mbam river. Bars show mean monthly rainfall (mm) ± 1 standard error (SE) at Bafia for years 1930–1994 [26]; dashed line shows mean monthly river discharge (m3/s) ± 1 standard error (SE) for years 1952–80 for the Goura gauge located on the Mbam river ≈25 km SE of Bafia (4.56703°N, 11.36740°E) [27]

Fig. 4 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 4 Polytene chromosomes of S. squamosum E2 and S. mengense showing a chromosome 1 of S. squamosum E2 with fixed inversions 1S-1 and 1L-3, and inversion 1L-57 which was fixed in the specimens examined, b part of chromosome 3 of S. squamosum E2 male showing sex-linked band dimorphism 3C-Sp and sex-linked heterozygous inversion 3L/82 present in 19/20 male specimens examined,'b'= blister, and c chromosome 1 of S. mengense showing expanded centromere 1CER

Fig. 7 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 7 Results of pool screening showing maximum likelihood estimate of the percentage of S. damnosum s.l. possessing L3 larvae in their heads (± 95% CI) based on black flies collected over the 12-month sampling period. The number above the bar denotes the maximum likelihood point estimate for each site

Fig. 3 in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 3 Head and thorax of late-instar larvae showing a S. squamosum E2, and b S. mengense with arrow pointing to tuft of hair-like scales on the anterior dorsum of the thorax

Fig. 6 Seasonal parasite transmission along the lower Mbam river showing a in ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM

Fig. 6 Seasonal parasite transmission along the lower Mbam river showing a combined parity and infection rates for flies dissected at Bayomen and Nyamongo I riverside sites (L1–L2 = percentage of flies infected with developing parasite stages only, L3H = percentage of flies containing L3 stages in the head), and b monthly transmission potentials at Bayomen, Nyamongo I, and Egona II estimated based on dissection data only. Ondouano not shown since no larvae were found in dissected flies

opencc-by-4.0Jun 2013View details →

Figure 1 in Cytotypes of Nannospalax xanthodon (Satunin, 1898) (Rodentia: Spalacidae) from western Anatolia

Figure 1. Map of study area in Turkey and distribution of N. xanthodon cytotypes determined. The numbers of localities are as in the Table.

Figure 1 in Heterochromatin distribution and localization of NORs in the 2n = 48 cytotypes of Nannospalax xanthodon and N. ehrenbergi

Figure 1. Collection sites of Nannospalax xanthodon (black square) and N. ehrenbergi (black triangle) in Turkey. The numbering of sampling localities corresponds to the data in the Table. The approximate ranges of both species are indicated after Kryštufek and Vohralík (2009).

Figure 4 in Heterochromatin distribution and localization of NORs in the 2n = 48 cytotypes of Nannospalax xanthodon and N. ehrenbergi

Figure 4. Standard karyotype (1), C-banded karyotype (2), and silver-stained karyotype (3) of Nannospalax ehrenbergi from Yayladağı. The heteromorphic chromosome pair is within the frame.

Figure 3 in Heterochromatin distribution and localization of NORs in the 2n = 48 cytotypes of Nannospalax xanthodon and N. ehrenbergi

Figure 3. Standard karyotype (1), C-banded karyotype (2), and silver-stained karyotype (3) of Nannospalax xanthodon from Malazgirt.

Figure 2 in Heterochromatin distribution and localization of NORs in the 2n = 48 cytotypes of Nannospalax xanthodon and N. ehrenbergi

Figure 2. Standard karyotype (1), C-banded karyotype (2), and silver-stained karyotype (3) of Nannospalax xanthodon from Şamanlı.

opencc-zeroAug 2020View details →

Strength in numbers? Cytotype frequency mediates effect of reproductive barriers in mixed-ploidy arrays.

When differentiated lineages come into contact, their fates depend on demographic and reproductive factors. These factors have been well-studied in taxa of the same ploidy, but less is known about sympatric lineages that differ in ploidy, particularly with respect to demographic factors. We assessed prezygotic, postzygotic, and total reproductive isolation in naturally-pollinated arrays of diploid-tetraploid and tetraploid-hexaploid population mixes of Campanula rotundifolia by measuring pollinator transitions, seed yield, germination rate, and proportion of hybrid offspring. Four frequencies of each cytotype were tested, and pollinators consistently overvisited rare cytotypes. Seed yield and F1 hybrid production were greater in 4X-6X arrays than 2X-4X arrays, while germination rates were similar, creating two distinct patterns of reproductive isolation. In 2X-4X arrays, postzygotic isolation was near-complete (3% hybrid offspring), and prezygotic isolation associated with pollinator preference is expected to facilitate the persistence of minority cytotypes. However, in 4X-6X arrays where postzygotic isolation permitted hybrid formation (44% hybrids), pollinator behavior drove patterns of reproductive isolation, with rare cytotypes being more isolated and greater gene flow expected from rare into common cytotypes. In polyploid complexes, both the specific cytotypes in contact and local cytotype frequency, likely reflecting spatial demography, will influence likelihood of gene exchange.

opencc-zeroJan 2024View details →

Data from: Plant-soil microbe feedbacks depend on distance and ploidy in a mixed cytotype population of Larrea tridentata

Premise of the study Theory predicts that mixed ploidy populations should be short-lived due to strong fitness disadvantages for the rare ploidy. However, mixed ploidy populations are common, suggesting that the fitness costs for rare ploidies are counterbalanced by ecological benefits that emerge when rare. We investigated whether differences in ecological interactions with soil microbes help to maintain a tetraploid-hexaploid population of Larrea tridentata (creosote bush) in the Sonoran Desert, California, USA, where prior work documented ploidy-specific root-associated microbes. Methods We used a plant-soil feedback (PSF) experiment to test whether host-specific soil microbes can alter the outcomes of intra-ploidy vs. inter-ploidy competition. Host-specific soil microbes can build up over time; thus, distance from a host plant can affect the fitness of nearby plants. Key results Seedlings grown in soils from near plants of a different ploidy produced greater biomass relative to seedlings grown in soils from near plants of the same ploidy. Moreover, seedlings grown in soils from near plants of a different ploidy produced greater biomass than those grown in soils from further away from plants of a different ploidy. This suggests the ecological consequences of PSF may facilitate the persistence of mixed ploidy populations. Conclusions This is the first evidence, to our knowledge, consistent with plant-soil microbe feedback as a viable mechanism to maintain the coexistence of multiple ploidy levels in a single population.

opencc-zeroJun 2022View details →

Variation in reproduction and gene flow between cytotypes in a polyploid complex: one size does not fit all

Whole-genome duplication is considered an important speciation mechanism in plants. However, its effect on reproductive isolation between higher cytotypes is not well understood. We used backcrosses between different ploidy levels and surveys of mixed-ploidy contact zones to determine how reproductive barriers differed with cytotype across a polyploid complex. We backcrossed F1 hybrids derived from 2X-4X and 4X-6X crosses in the Campanula rotundifolia autopolyploid complex, measured backcross fitness, and estimated backcross DNA cytotype. We then sampled four natural mixed-ploidy contact zones (two 2X-4X and two 4X-6X), estimated ploidy, and genotyped individuals across each contact zone. Reproductive success and capacity for gene flow was markedly lower for 2X-4X than 4X-6X hybrids. In fact, 3X hybrids could not backcross; all 2X-4X backcross progeny resulted from neotetraploid F1 hybrids. Further, no 3X individuals were found in 2X-4X contact zones, and 2X and 4X individuals were genetically distinct. By contrast, backcrosses of 5X hybrids were relatively successful, particularly when crossed to 6X individuals. In 4X-6X contact zones, 5X individuals and aneuploids were common and all cytotypes were largely genetically similar and spatially intermixed. Taken together, these results provide strong evidence that reproduction is low between 2X and 4X cytotypes, primarily occurring via unreduced gamete production, but that reproduction and gene flow are ongoing between 4X and 6X cytotypes. Further, it suggests whole genome duplication can result in speciation between diploids and polyploids, but is less likely to create reproductive barriers between different polyploid cytotypes, resulting in two fundamentally different potentials for speciation across polyploid complexes.

opencc-zeroAug 2019View details →

Data from: Are buffalograss (Buchloë dactyloides) cytotypes spatially and ecologically differentiated?

Premise of the study Although autopolyploidy is common among dominant Great Plains grasses, the distribution of cytotypes within a given species is typically poorly understood. This study aims to establish the geographic distribution of cytotypes within buffalograss (Buchloë dactyloides), and to assess whether individual cytotypes exhibit differing ecological tolerances. Methods A range-wide set of 578 B. dactyloides individuals was obtained through field collecting and sampling from herbarium specimens. The cytotype of each sample was estimated by observing allele numbers at thirteen simple sequence repeat loci, a strategy that was assessed by comparing estimated to known cytotype in 79 chromosome-counted samples. Ecological differentiation between the dominant tetraploid and hexaploid cytotypes was assessed with analyses of macro-climatic variables. Key results Simple sequence repeat variation accurately estimated cytotype in 89% of samples from which a chromosome count had been obtained. Applying this approach to samples of unknown ploidy established that diploids and pentaploids are rare, with the common tetraploid and hexaploid cytotypes generally occurring in sites to the north/west (tetraploid) or south/east (hexaploid) portions of the species range. Both MANOVA and niche modeling approaches identified significant but subtle differences in macro-climatic conditions at the set of locations occupied by these two dominant cytotypes. Conclusions Incorporating chromosome count vouchers and cytotype-estimated herbarium records allowed us to perform the largest study of cytotype niche differentiation to date. Buffalograss cytotypes differ greatly in frequency, the common tetraploid and hexaploid cytotypes are non-randomly distributed, and these two cytotypes are subtly ecologically differentiated.

publicAug 2020View details →

Strength in numbers? Cytotype frequency mediates effect of reproductive barriers in mixed-ploidy arrays.

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publicJan 2024View details →

Data from: Plant-soil microbe feedbacks depend on distance and ploidy in a mixed cytotype population of Larrea tridentata

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publicJun 2022View details →

Variation in reproduction and gene flow between cytotypes in a polyploid complex: one size does not fit all

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