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opennotspecifiedJun 2020View details →

FIGURE 3 in Description of a new species in the genus Bythotrephes Leydig, 1860 (Crustacea Cladocera: Onychopoda), supplements to selected species, and concluding remarks on the genus

FIGURE 3. Bythotrephes centralasiaticus sp. nov., females, Lake Kadysh (Tyva, Southern Siberia). A, distal part of mandible (a group of broken minute spinules is arrowed). B, anterior mandibular lobe (mandibular process). C, prominences of mandibular process. D, proximal part of tl II and tl III, outer side. E, apical end of pseudognathobase of tl II. F, the same one of tl III. Scale bars: 5µm (C), 10 µm (B, E, F), 25µm (A), 100 µm (D).

opennotspecifiedJun 2020View details →

FIGURE 5 in Description of a new species in the genus Bythotrephes Leydig, 1860 (Crustacea Cladocera: Onychopoda), supplements to selected species, and concluding remarks on the genus

FIGURE 5. Bythotrephes cederströmii, females of first generation hatched from resting egg, Lake Imandra (Kola Peninsula, Russia) (A-upper, B); B. lilljeborgi, females, Ålsjön (Kragered, Halland, Sweden) (A-lower, C–F). A, distal segments of tl I. B, postabdomen and caudal process. C–F, claws of postabdomen and caudal process.

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Data from: Genetic and maternal effects on tail spine and body length in the invasive spiny water flea (Bythotrephes longimanus)

Interest in the evolution of invasive species has grown in recent years, yet few studies have investigated sources of variation in invasive species traits experiencing natural selection. The spiny water flea, Bythotrephes longimanus, is an invasive zooplankton in the Great Lakes that exhibits seasonal changes in tail spine and body length consistent with natural selection. Evolution of Bythotrephes traits, however, depends on the presence and magnitude of quantitative genetic variation, which could change within or across years. Clonal analysis of wild-captured Bythotrephes indicated that variance components for distal spine length were variable among but not within years. Spine length was always heritable but was not always influenced by maternal effects. In contrast, variance components for body length varied both within and among years, but likewise body length was always heritable and not always influenced by maternal effects. Results indicate that important Bythotrephes traits have heritable variation comparable to native species and other invasive species that would enable an evolutionary response to natural selection. This evolutionary capacity could contribute to the widespread success and dramatic effects of Bythotrephes invasion in systems with diverse biotic and abiotic conditions.

opencc-zeroDec 2010View details →

FIGURE 7. Bythotrephes transcaucasicus Behning, 1941 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 7. Bythotrephes transcaucasicus Behning, 1941, parthenogenetic females, Lake Chaldyr (Turkey), 1879. A, general lateral view. B, antennule. C, upper antennal branch. D, lower antennal branch. E, apical end of upper antennal branch. F, apical end of lower antennal branch. G, thoracic limb of first pair (tl I). H, distal part of pseudognathobase of tl I. I, J, distal setae of first segment of endopodite of tl I. K, L, distal setae of second segment of endopodite of tl I. M, postabdomen and proximal part of caudal process. N, distal part of caudal process. O, apical setae of caudal process.

FIGURE 8. Bythotrephes transcaucasicus Behning, 1941 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 8. Bythotrephes transcaucasicus Behning, 1941, parthenogenetic females, Lake Chaldyr (Turkey), 1879. A, B, outer distal parts of protopodites of tl I–tl III (from right to left). C, thoracic limb of second pair (tl II). D, pseudognathobase of tl II, E, thoracic limb of third pair (tl III). F, pseudognathobase of tl III, G, thoracic limb of fourth pair (tl IV). H, pseudognathobase of tl IV. I, J, K, claws of postabdomen and caudal spine. L, posterior part of trunk with a line separating third abdominal segment and postabdomen (arrowed).

FIGURE 9 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 9. Geographical distribution of Bythotrephes arcticus (black circles with "?", localities with atypical specimens; SK, locality Sabanty-Kul in Northern Kazakhstan) and B. transcaucasicus (asterisk)

FIGURE 5 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 5. Bythotrephes arcticus Lilljeborg, adult parthenogenetic females (A, lake 1 (basin of the River Tchernaya, Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia); B, E, Lake Sabanty Kul, Akmolinskaya region (Kazakhstan); C, lake near village Puiko, Yamal Peninsula (Western Siberia, Russia); D, F, Forellenmägen (Norway); G, Pustozersk (Arkhangel'skaya region, North-East of European Russia); H, Råbosjön (Hls, Sweden); I, tundra near mouth of the River Pechera (Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia); J, K, Karabel'naya bay ("Karabella"), Kola Peninsula, Russia), Lake Dubovskoi (Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia)). A–K, variability of postabdominal claws and claws of caudal process. L, postabdomen and proximal part of caudal process with two sclerotized sections (dotted).

FIGURE 4 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 4. Bythotrephes arcticus Lilljeborg, adult parthenogenetic females, lake 1 (basin of the River Tchernaya, Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia). A, anterior seta of second segment of endopodite of thoracic limb of third pair (tl III) (C, see Fig. 2). B, proximal part of anterior terminal seta of tl III (D, see Fig. 2). C, armament of posterior subterminal seta of tl III (G, see Fig. 2). D, distal part of pseudognathobase of tl III (pore is arrowed). E, outer terminal seta of tl IV (L, see Fig. 2). F, inner terminal seta of tl IV. G, pseudognathobase of tl IV (pore is arrowed). H, distal part of mandible. I, "postabdomen" and proximal part of caudal process (abd = posterior abdominal segment, p/abd = postabdomen). J, mandibular maxillar process. K, papillae of maxillar process. Scale bars: I =250 µm; H = 50 µm; A, D, E = 25 µm; B, C, F, G =20 µm; J = 10 µm; K= 5 µm.

FIGURE 2 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 2. Bythotrephes arcticus Lilljeborg, adult parthenogenetic females, lake 1 (basin of the River Tchernaya, Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia). A, thoracic limb of second pair (tl II) (small letters indicate the respective type of setae). B, anterior lateral seta of first segment of endopodite of tl II. C, anterior distal seta of second segment of endopodite of tl II. D, anterior terminal seta of endopodite of tl II. E, anterior subterminal seta of endopodite of tl II. F, posterior terminal seta of endopodite of tl II. G, posterior subterminal seta of endopodite of tl II. H, thoracic limb of third pair (tl III). I, thoracic limb of fourth pair (tl IV) (inner view). J, distal seta of protopodite of tl IV. K, inner lateral seta of distal segment of tl IV. L, outer seta of distal segment of tl IV. M, outer distal parts of protopodites of tl I–tl III.

FIGURE 6 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 6. Bythotrephes arcticus Lilljeborg, males (A–I) and parthenogenetic female of first generation (J, K); (A, I, swamps of Kildin Island (Murmansk region, Russia); B, C, H, Lake Dubovskoi (Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia); D, Karesuando (Norrbotten, Sweden); E, Porsanger lake (Norway); F, Karabel'naya bay ("Karabella"), Kola Peninsula, Russia); G, Forellenmägen (Norway); J, K, Alexandrovsk (Kola Peninsula, Russia)). A, male, general lateral view. B, male's hook. C–G, claws of postabdomen and caudal spine. H, I, copulatory appendage. J, thoracic limb of first pair (tl I). K, postabdomen and caudal spine with claws.

FIGURE 1 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 1. Bythotrephes arcticus Lilljeborg, adult parthenogenetic females and juveniles. A–G, I, K–M: lake 1 (basin of River Tchernaya, Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia). H: Lake Yan (basin of the River Pur, Western Siberia), J: Forelenmägen (Norway). A, general lateral view. B, antennule. C, upper lip (labrum) with anterior process. D, apical end of lower antennal branch, outer side. E, apical end of upper antennal branch, inner side. F, seta on apical end of upper antennal branch, outer side. G, distal part of caudal process. H, terminal setae of caudal process (juvenile specimen). I, thoracic limb of first pair (tl I) (C, anterior setae, see Fig. 2). J, armament of first segment and second segment of endopodite of tl I. K, distal setae of first segment of endopodite of tl I. L, distal end of second segment of endopodite of tl I. M, the same (juvenile specimen).

FIGURE 3 in Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea: Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig

FIGURE 3. Bythotrephes arcticus Lilljeborg, adult parthenogenetic females, lake 1 (basin of the River Tchernaya, Bol'shezemelskaya tundra, Arkhangel'skaya region, North-Eastern European Russia). A, thoracic limbs, general view. B, pseudognathobase of thoracic limb of first pair (tl I). C, anterior lateral setae of first segment of endopodite of tl I (C, see Fig. 2). D, armament of anterior lateral seta of first segment of endopodite of tl I (C, see Fig. 2). E, armament of posterior distal seta of first segment of endopodite of tl I. F, armament of terminal seta of tl I. G, anterior and posterior lateral setae of first segment of endopodite of thoracic limb of second pair (tl II). H, armament of distal part of anterior lateral seta of endopodite of tl II (B, see Fig. 2). I, distal anterior seta of first segment of endopodite of tl II (C, see Fig. 2). J, anterior subterminal seta of tl II (E, see Fig. 2). K, proximal part of anterior terminal seta of tl II (D, see Fig. 2). L, distal part of pseudognathobase of tl II (pore is arrowed). Scale bars: A = 250 µm; G, J = 50 µm; B, C, F, I, K, L = 25 µm; D, E, H =10 µm.

opencc-zeroMay 2022View details →

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Evolutionary change in metabolic rate of Daphnia pulicaria following invasion by the predator Bythotrephes longimanus

Metabolic rate is a trait that may evolve in response to the direct and indirect effects of predator-induced mortality. Predators may indirectly alter selection by lowering prey densities and increasing resource availability or by intensifying resource limitation through changes in prey behaviour (e.g. use of less productive areas). In the current study we quantify evolution of metabolic rate in the zooplankton Daphnia pulicaria following an invasive event by the predator Bythotrephes longimanus in Lake Mendota, Wisconsin, US. This invasion has been shown to dramatically impact D. pulicaria, causing a ~60% decline in their biomass. Using a resurrection ecology approach, we compared the metabolic rate of D. pulicaria clones originating from prior to the Bythotrephes invasion with that of clones having evolved in the presence of Bythotrephes. We observed a 7.4% reduction in metabolic rate among post-invasive clones compared to pre-invasive clones, and discuss the potential roles of direct and indirect selection in driving this change.

FIGURE 14 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 14. Bythotrephes cederströmii Schödler, 1877. Female (A) and males (B‒G). A, F, G: Lake Vozhe (Russia). B: Lake Erne (Ireland). C, D: Lake Pozemskoye (Karelia, Russia). E: Karesuando (Sweden). A, postabdomen and proximal part of caudal process with claws. B, general lateral view. C, distal part of tl I with clasping hook. D, clasping hook. E, copulatory appendage. F, clasping hook of juvenile male. G, copulatory appendage of juvenile male.

FIGURE 13 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 13. Bythotrephes cederströmii Schödler, 1877, females. Lake Nizhnee Nilm-ozero (Karelia, Russia). A, bend of caudal process. B, denticles of a bend. Scale bars: 100 µm (A), 10 µm (B).

FIGURE 10 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 10. Bythotrephes cederströmii Schödler, 1877, females. A‒H: Lake Pozemskoye (Karelia, Russia). I, J: Lake Taiylaar (Yakutia, Russia). A, thoracic limb of second pair (tl II). B, thoracic limb of third pair (tl III). C, thoracic limb of fourth pair (tl IV). D, apical and subapical setae of tl III. E, anterior apical seta of third endopodital segment of tl II. F, anterior lateral seta of first endopodital segment of tl II. G, anterior subapical seta of third endopodital segment of tl II. H, anterior apical seta of first and second endopodital segments of tl II. I, distal part of tl I. J, postabdomen and proximal part of caudal process.

FIGURE 9 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 9. Bythotrephes cederströmii Schödler, 1877, females. Lake Nizhnee Nilm-ozero (Russia). A, labral papillae. B, distal part of mandible. C, D, papillae of mandibular process. E, pseudognathobase of tl I. F, armament of posterior seta of first endopodital segment of tl I. Scale bars: 50 µm (B), 25 µm (E), 10 µm (C), 5 µm (A), 3µm (D, F).

FIGURE 17 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 17. Geographical distribution of Bythotrephes brevimanus (black circles), B. cederstrӧmii (open circles), and B. lilljeborgi sp. nov. (crosses); i, regions of recent invasion of B. brevimanus,?—locality of B. cf. brevimanus requiring confirmation.

FIGURE 8 in Further revision of the genus Bythotrephes Leydig (Crustacea: Cladocera: Onychopoda): redescription of B. brevimanus Lilljeborg, reevaluation of B. cederströmii Schödler, and description of a new species of the genus

FIGURE 8. Bythotrephes cederströmii Schödler, 1877, females. Lake Pozemskoye (Karelia, Russia). A, general lateral view. B, endopodite of thoracic limb of first pair (tl I). C, D, E, proximal, middle, and distal part of caudal process, respectively. F, antennule. G, proximal part of upper antennal branch, inner view. H, tiny denticle near base of the branch (arrowed). I, short apical seta of second segment of the branch (arrowed). J, apical end of upper antennal branch, outer side. K, L, apical setae of first and second endopodital segments of tl I. M, apical setae of caudal process. N, O, inner and outer side of labrum, respectively. P, distal part of maxillule. Q, first (proximal) segment of endopodite of tl I. R, distal part of protopodites of tl I—tl III (from left to right), outer view.