FIGURE 1. Phylogenetic hypotheses of relationships of cypriniforms based on morphology. Higher-le... more FIGURE 1. Phylogenetic hypotheses of relationships of cypriniforms based on morphology. Higher-level taxon names follow Mayden et al. (2008); see Appendix I for name equivalencies with other studies. A. Phylogenetic relationships from Siebert (1987, Fig. 77). B. Conway & Mayden (2007, Fig. 5C). Psilorhynchus was considered a cyprinid by Siebert (1987). * represents the position of Vaillantella (Vaillantellidae).
FIGURE 2. Phylogenetic hypotheses of relationships of cypriniforms based on molecular data. A. Sa... more FIGURE 2. Phylogenetic hypotheses of relationships of cypriniforms based on molecular data. A. Saitoh et al. (2006); B. Mayden et al. (2008).
FIGURE 7. Diagrammatic view of the gill arches (dorsal view, anterior at top) showing possible sk... more FIGURE 7. Diagrammatic view of the gill arches (dorsal view, anterior at top) showing possible skeletal elements in cypriniform fishes, excluding pharyngobranchial 1. Dense stippling indicates cartilage; light or no stippling indicates bone.
FIGURE 3. Strict consensus of parsimony tree using Saitoh et al. (2006) outgroups (Appendix III) ... more FIGURE 3. Strict consensus of parsimony tree using Saitoh et al. (2006) outgroups (Appendix III) recovered from 2,817 equally parsimonious trees. Treelength=292; CI=0.304; RI=0.734. Nodal values indicate bootstrap support.
Formation of species generally occurs in a continuum from potentially intermixing populations to ... more Formation of species generally occurs in a continuum from potentially intermixing populations to independent entities isolated from other species by pre- and postzygotic barriers. Especially the establishment of hybrid sterility (HS) is a hallmark of speciation, which usually emerges at different rates between hybrid sexes. However, although HS is frequently observed, the underlying molecular mechanisms remain poorly understood. Here we report that speciation proceeds through a previously unnoticed stage at which gene flow is completely interrupted on side of both hybrid’s sexes, although only male hybrids are sterile, while female fertility is rescued due to a particular gametogenetic deviation leading to the formation of clonal gametes. Specifically, analysis of gametogenetic pathways in hybrids between fish species Cobitis elongatoides and C. taenia revealed that male HS resulted from extensive asynapses and crossover reduction among elongatoides-taenia chromosomal pairs followed...
Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, 2017
The diploid-polyploid populations of Cobitis distributed in Poland are usually composed of the sp... more The diploid-polyploid populations of Cobitis distributed in Poland are usually composed of the spined loach Cobitis taenia or, less often, the Danubian loach C. elongatoides and their triploid (females) and tetraploid hybrids (females and males). The aim of this study was to determine whether tetraploid males participate in the reproduction process by analyzing their testis ultrastructure and the process of spermatogenesis in comparison with diploid males of both parental species. Tetraploid loaches were obtained from three different diploid-polyploid populations distributed in Poland. The structure of Cobitis testes are typical for most Teleostei fish with cystictype spermatogenesis. The successive stages of developing germ cells are enclosed within cysts formed by the Sertoli cells. This paper morphologically describes the different germ cell stages of spermatogenesis (spermatogonia, spermatocytes, spermatids, and spermatozoa) of C. taenia and C. elongatoides and provides a pioneering ultrastructural analysis of tetraploid Cobitis testes which reveals their unusual structure for the first time. Thus, cysts with normal spermatogonia and spermatocytes (pachyten or leptoten stages) containing synaptonemal complexes were present and no spermatids or spermatozoa were observed. Moreover, in contrast to previously analyzed diploid species, single cells or all of the cells within the cysts displayed chromatin condensation and/or chromatin fragmentation. The obtained results clearly demonstrated that tetraploid males are sterile and diploids are fertile and are the only sperm donors in the reproduction processes of diploid-polyploid Cobitis populations.
Early development and post embryonic skeletal morphology of the progeny of Cobitis taenia (Teleos... more Early development and post embryonic skeletal morphology of the progeny of Cobitis taenia (Teleostei, Cobitidae) and its naturally occurring allotriploids. Folia Biologica (Kraków) 64: 153-162. Polyploid fishes of the genus Cobitis represent a valuable model system to study the origin and consequences of hybridization and polyploidization within vertebrates. These naturally accessible polyploids are an excellent subject to determine the advantages or disadvantages of polyploidy. We investigated the embryonic and larval development with skeletal morphology of diploid and polyploid Cobitis progeny, obtained from crosses between females and males of Cobitis taenia and between allotriploid Cobitis females and C. taenia males. Observations were made during first fourteen days post fertilization. The pattern of development of all investigated individuals was the same. However the diploids developed synchronically, achieving successive stages faster than the polyploid ones; hatching was observed at 50 and 63 hours post fertilization, respectively. Statistically significant differences in hatching success and survival rate between diploid and polyploid progeny were not observed. All newly hatched larvae were characterized by a large amount of yolk, forty myomeres, body pigmentation and four external gills. Skeletal elements of the chondrocranium in the first days post hatching consisted of the otic capsule, ethmoid plate, trabeculae cranii and Meckel's cartilage. In contrast to the diploids, the polyploid larvae were characterized by a higher number of deformities. This study gives new comparative data on the features of early development of diploid and polyploid Cobitis progeny.
The aim of this study was to determine and compare for the first time the size of eggs laid by C.... more The aim of this study was to determine and compare for the first time the size of eggs laid by C. taenia (2n=48) and its naturally occurring triploid (3n=74) hybrid females and the total length of offspring of these females obtained from experimental crosses, in the period from hatch to 22 days post hatch. The eggs laid by triploid females had an average diameter of 1.18 mm and were significantly larger than the eggs spawned by C. taenia females, which averaged 0.93 mm in diameter. The size of the triploid female eggs was associated with their level of ploidy. Similarly, the average total length of triploid female progeny from one to ten days post hatch was statistically significantly higher than the average total length of C. taenia offspring in the same period of life. After two weeks, the offspring of diploid and triploid females reached average total lengths of 13.27 mm and 13.60 mm, respectively, which was not a significant difference. The possible causes of triploid Cobitis female domination in diploid-polyploid populations in terms of egg size and other traits associated with polyploid functioning was also investigated.
FIGURE 1. Phylogenetic hypotheses of relationships of cypriniforms based on morphology. Higher-le... more FIGURE 1. Phylogenetic hypotheses of relationships of cypriniforms based on morphology. Higher-level taxon names follow Mayden et al. (2008); see Appendix I for name equivalencies with other studies. A. Phylogenetic relationships from Siebert (1987, Fig. 77). B. Conway & Mayden (2007, Fig. 5C). Psilorhynchus was considered a cyprinid by Siebert (1987). * represents the position of Vaillantella (Vaillantellidae).
FIGURE 2. Phylogenetic hypotheses of relationships of cypriniforms based on molecular data. A. Sa... more FIGURE 2. Phylogenetic hypotheses of relationships of cypriniforms based on molecular data. A. Saitoh et al. (2006); B. Mayden et al. (2008).
FIGURE 7. Diagrammatic view of the gill arches (dorsal view, anterior at top) showing possible sk... more FIGURE 7. Diagrammatic view of the gill arches (dorsal view, anterior at top) showing possible skeletal elements in cypriniform fishes, excluding pharyngobranchial 1. Dense stippling indicates cartilage; light or no stippling indicates bone.
FIGURE 3. Strict consensus of parsimony tree using Saitoh et al. (2006) outgroups (Appendix III) ... more FIGURE 3. Strict consensus of parsimony tree using Saitoh et al. (2006) outgroups (Appendix III) recovered from 2,817 equally parsimonious trees. Treelength=292; CI=0.304; RI=0.734. Nodal values indicate bootstrap support.
Formation of species generally occurs in a continuum from potentially intermixing populations to ... more Formation of species generally occurs in a continuum from potentially intermixing populations to independent entities isolated from other species by pre- and postzygotic barriers. Especially the establishment of hybrid sterility (HS) is a hallmark of speciation, which usually emerges at different rates between hybrid sexes. However, although HS is frequently observed, the underlying molecular mechanisms remain poorly understood. Here we report that speciation proceeds through a previously unnoticed stage at which gene flow is completely interrupted on side of both hybrid’s sexes, although only male hybrids are sterile, while female fertility is rescued due to a particular gametogenetic deviation leading to the formation of clonal gametes. Specifically, analysis of gametogenetic pathways in hybrids between fish species Cobitis elongatoides and C. taenia revealed that male HS resulted from extensive asynapses and crossover reduction among elongatoides-taenia chromosomal pairs followed...
Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, 2017
The diploid-polyploid populations of Cobitis distributed in Poland are usually composed of the sp... more The diploid-polyploid populations of Cobitis distributed in Poland are usually composed of the spined loach Cobitis taenia or, less often, the Danubian loach C. elongatoides and their triploid (females) and tetraploid hybrids (females and males). The aim of this study was to determine whether tetraploid males participate in the reproduction process by analyzing their testis ultrastructure and the process of spermatogenesis in comparison with diploid males of both parental species. Tetraploid loaches were obtained from three different diploid-polyploid populations distributed in Poland. The structure of Cobitis testes are typical for most Teleostei fish with cystictype spermatogenesis. The successive stages of developing germ cells are enclosed within cysts formed by the Sertoli cells. This paper morphologically describes the different germ cell stages of spermatogenesis (spermatogonia, spermatocytes, spermatids, and spermatozoa) of C. taenia and C. elongatoides and provides a pioneering ultrastructural analysis of tetraploid Cobitis testes which reveals their unusual structure for the first time. Thus, cysts with normal spermatogonia and spermatocytes (pachyten or leptoten stages) containing synaptonemal complexes were present and no spermatids or spermatozoa were observed. Moreover, in contrast to previously analyzed diploid species, single cells or all of the cells within the cysts displayed chromatin condensation and/or chromatin fragmentation. The obtained results clearly demonstrated that tetraploid males are sterile and diploids are fertile and are the only sperm donors in the reproduction processes of diploid-polyploid Cobitis populations.
Early development and post embryonic skeletal morphology of the progeny of Cobitis taenia (Teleos... more Early development and post embryonic skeletal morphology of the progeny of Cobitis taenia (Teleostei, Cobitidae) and its naturally occurring allotriploids. Folia Biologica (Kraków) 64: 153-162. Polyploid fishes of the genus Cobitis represent a valuable model system to study the origin and consequences of hybridization and polyploidization within vertebrates. These naturally accessible polyploids are an excellent subject to determine the advantages or disadvantages of polyploidy. We investigated the embryonic and larval development with skeletal morphology of diploid and polyploid Cobitis progeny, obtained from crosses between females and males of Cobitis taenia and between allotriploid Cobitis females and C. taenia males. Observations were made during first fourteen days post fertilization. The pattern of development of all investigated individuals was the same. However the diploids developed synchronically, achieving successive stages faster than the polyploid ones; hatching was observed at 50 and 63 hours post fertilization, respectively. Statistically significant differences in hatching success and survival rate between diploid and polyploid progeny were not observed. All newly hatched larvae were characterized by a large amount of yolk, forty myomeres, body pigmentation and four external gills. Skeletal elements of the chondrocranium in the first days post hatching consisted of the otic capsule, ethmoid plate, trabeculae cranii and Meckel's cartilage. In contrast to the diploids, the polyploid larvae were characterized by a higher number of deformities. This study gives new comparative data on the features of early development of diploid and polyploid Cobitis progeny.
The aim of this study was to determine and compare for the first time the size of eggs laid by C.... more The aim of this study was to determine and compare for the first time the size of eggs laid by C. taenia (2n=48) and its naturally occurring triploid (3n=74) hybrid females and the total length of offspring of these females obtained from experimental crosses, in the period from hatch to 22 days post hatch. The eggs laid by triploid females had an average diameter of 1.18 mm and were significantly larger than the eggs spawned by C. taenia females, which averaged 0.93 mm in diameter. The size of the triploid female eggs was associated with their level of ploidy. Similarly, the average total length of triploid female progeny from one to ten days post hatch was statistically significantly higher than the average total length of C. taenia offspring in the same period of life. After two weeks, the offspring of diploid and triploid females reached average total lengths of 13.27 mm and 13.60 mm, respectively, which was not a significant difference. The possible causes of triploid Cobitis female domination in diploid-polyploid populations in terms of egg size and other traits associated with polyploid functioning was also investigated.
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Papers by Alicja Boroń