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opennotspecifiedJan 2021View details →

FIGURE 2 in Two new aphid species of the genus Cryptomyzus Oestlund, 1922 (Hemiptera Aphididae) from Kazakhstan, and keys to apterous and alate viviparous females

FIGURE 2. Cryptomyzus karzhantavicus sp. n.: a—body; b—Third and 4th antennal segments; c—ultimate rostral segment; d—siphunculus; e—dorsal hair; f—cauda.

opencc-zeroDec 2011View details →

Data from: Experimental evidence of early costs of reproduction in conspecific viviparous and oviparous lizards

Reproduction entails costs, and disentangling the relative importance of each stage of the reproductive cycle may be important to assess the costs and benefits of different reproductive strategies. We studied the early costs of reproduction in oviparous and viviparous lizard females of the bimodal reproductive species Zootoca vivipara. Egg-retention time in oviparous females is approximately one third of the time in viviparous females. We compared the vitellogenesis and egg-retention stages which are common to both reproductive modes. Precisely, we monitored the thermoregulatory behaviour, the weight gain and the immunocompetence of the females. Moreover, we injected an antigen in half of the females (immune challenge) to study the trade-offs between reproductive mode and immune performance, and between different components of the immune system. Finally, we experimentally induced parturition in viviparous females at the time of egg-laying in oviparous females. Oviparous and viviparous females did not show strong differences in response to the immune challenge. However, viviparous females spent more time thermoregulating while partially hidden and gained more weight than oviparous females. The greater weight gain indicates that the initial period of egg-retention is less costly for viviparous than for oviparous females or that viviparous females are able to save and accumulate energy at this period. This energy may be used by viviparous females to cope with the subsequent costs of the last two thirds of the gestation. Such an ability to compensate the higher costs of a longer egg-retention period may account for the frequent evolution of viviparity in squamate reptiles.

opencc-zeroDec 2017View details →

Data from: A global test of the cold-climate hypothesis for the evolution of viviparity of squamate reptiles

Aim The evolution of viviparity in squamate reptiles has attracted considerable scientific attention since the beginning of last century. The cold climate hypothesis posits that cold regions favor viviparity (and therefore the incidence of viviparous squamates is increased in these regions) because viviparous females can use thermoregulatory behavior to shorten embryonic developmental time and to reduce exposure of embryos to stressful temperatures. However, a rigorous global-scale test of the impact of viviparity on the developmental time and viability of embryos is still absent. Recently developed biophysical models and climate databases enable us to conduct a mechanistic test of this hypothesis. Location Global Time period Summer Major taxa studied Squamata Methods We integrated global climate data, a biophysical model, and developmental functions to quantify the effects of temperature on embryo developmental time, developmental viability, and energy consumption of oviparous versus viviparous embryos. To examine the accuracy of our predictions, we calculated the percentage of squamate reptiles that were viviparous in each region and assessed developmental temperature of gravid females, latitude and elevation as predictors for the percentage of squamate reptiles. Results Compared with oviparous embryos, viviparous embryos develop faster in cold regions, and experience similar embryonic developmental viability. Across most latitudes and elevations, the total energetic cost of development is lower for viviparous embryos than for oviparous embryos. Cold regions contain a higher proportion of viviparous species than do hot regions. By comparing the distribution pattern of viviparity and temperature effects on embryonic development, we found that shortened development time provided the strongest benefit of viviparity. Main conclusions Our global and biophysical model based comparison generally supports the cold climate hypothesis. Moreover, viviparity in cold climates appears beneficial primarily by shortening developmental time.

opencc-zeroDec 2018View details →

Data from: Facultative oviparity in a viviparous skink (Saiphos equalis)

Facultative changes in parity mode (oviparity to viviparity, and vice versa) are rare in vertebrates, yet offer fascinating opportunities to investigate the role of reproductive lability in parity mode evolution. Here we report apparent facultative oviparity by a viviparous female of the bimodally reproductive skink Saiphos equalis- the first report of different parity modes within a vertebrate clutch. Eggs oviposited facultatively possess shell characteristics of both viviparous and oviparous S. equalis, demonstrating that egg coverings for viviparous embryos are produced by the same machinery as those for oviparous individuals. Since selection may act in either direction when viviparity has evolved recently, squamate reproductive lability may confer a selective advantage. We suggest that facultative oviparity is a viable reproductive strategy for S. equalis and that squamate reproductive lability is more evolutionarily significant than previously acknowledged.

opencc-zeroDec 2016View details →

Data from: Seasonal shifts along the oviparity-viviparity continuum in a cold-climate lizard population

Because squamate embryos require weeks of high temperature to complete development, cool climatic areas are dominated by viviparous taxa (in which gravid females can sun-bask to keep embryos warm) rather than oviparous taxa (which rely on warm soil to incubate their eggs). How, then, can some oviparous taxa reproduce successfully in cool climates – especially late in summer, when soil temperatures are falling? Near the northern limit of their distribution (in Sweden), sand lizards (Lacerta agilis) shift tactics seasonally, such that the eggs in late clutches complete development more quickly (when incubated at a standard temperature) than do those of early clutches. That acceleration is achieved by a reduction in egg size, and by an increase in the duration of uterine retention of eggs (especially, after cool weather). Our results clarify the ability of oviparous reptiles to reproduce successfully in cool climates, and suggest a novel advantage to reptilian viviparity in such conditions: by maintaining high body temperatures, viviparous females may escape the need to reduce offspring size in late-season litters.

opencc-zeroNov 2019View details →

Data from: Water availability and temperature induce changes in oxidative status during pregnancy in a viviparous lizard

<ol> <li>Reproduction involves considerable reorganization in an organism's physiology that incurs potential toxicity for cells (e.g., oxidative stress) and decrease in fitness. This framework has been the cornerstone of the so-called 'oxidative cost of reproduction', a theory that remains controversial and relatively overlooked in non-model ectotherms.</li> <li>Here, we used two complementary approaches in natural and controlled conditions to test whether altered access to climate conditions (water and temperature resources) alters oxidative status and mediates reproductive trade-offs in viviparous populations of the common lizard (<i>Zootoca vivipara</i>).</li> <li>First, we examined whether access to free standing water and differences in ambient temperature across 12 natural populations could be related with variation in oxidative status, reproductive effort and reproductive success. Second, we determined whether an experimental restriction to water triggers higher oxidative cost of reproduction and correlates with fitness measures (reproductive success, future survival rate and probability of future reproduction).</li> <li>Pregnant females exhibited higher sensitivity than males to natural or experimental limitations in temperature and water access. That is, in restricted environments, pregnant females with higher reproductive effort exhibited stronger oxidative damage despite enhanced non-enzymatic antioxidant capacity.</li> <li>Enhanced antioxidant defensive capacity in pregnant females was positively correlated with higher reproductive success, whereas elevated oxidative damage negatively correlated with offspring annual survival. </li> <li>Altogether, our results revealed a context-dependent oxidative cost of reproduction that was concomitant with a conflict in water demand from offspring. These new insights should be critical for understanding ectotherm responses to heat waves and summer droughts that are increasing in frequency and duration.</li> </ol>

opencc-zeroDec 2014View details →

Data from: Genetic and ecological data reveal species boundaries between viviparous and oviparous lizard lineages

Identification of cryptic species is an essential aim for conservation biologists to avoid premature extinctions of 'unrecognized' species. Integrating different types of data can undoubtedly aid in resolving the issue of species delimitation. We studied here two lineages of the common lizard Zootoca vivipara that display different reproductive mode (the viviparous Z. v. vivipara and the oviparous Z. v. carniolica) and that overlap their distributional ranges in the European Alps. With the purpose of delimiting species' boundaries, we analyzed their ecological, genetic and natural history features. More than 300 samples were collected and analyzed at cytochrome b and 11 microsatellites loci for investigating genetic variation, population structure, individual relatedness and evolutionary histories of the two lineages. Additionally, we compared their ecological niches using eight ecological variables. Genetic data showed contrasting patterns of genetic structure between the two lineages, different demographic dynamics and no hybridization events. Also strong ecological differences (such as temperature) emerged between the two lineages, and niche overlap was limited. Taken together, these results indicate that Z. v. vivipara and Z. v. carniolica should be recognized as two separate species, and particular conservation consideration should be given to the oviparous lineage that tends to live in areas threatened by increasing impact of human activities. However, recent and rapid climate warming might determine an increasing risk for the persistence of the viviparous lineage, being adapted to cold environments.

FIGURE 4 in A new viviparous species of asterinid (Echinodermata, Asteroidea, Asterinidae) and a new genus to accommodate the species of pantropical exiguoid sea stars

FIGURE 4. Aboral view of the gonads of C. hystera n. sp. filled with late stage juveniles just prior to leaving the parent, Juveniles about 500 µ m.

FIGURE 3. a in A new viviparous species of asterinid (Echinodermata, Asteroidea, Asterinidae) and a new genus to accommodate the species of pantropical exiguoid sea stars

FIGURE 3. a) Colour in life Cryptasterina hystera n.sp. (at left) and Cryptasterina pentagona (at right) Photograph. M Byrne. b) Statue Bay, central Queensland. Boulder and cobble beach. Type locality for C. hystera n. sp. Photograph. S McKillup.

FIGURE 2 in A new viviparous species of asterinid (Echinodermata, Asteroidea, Asterinidae) and a new genus to accommodate the species of pantropical exiguoid sea stars

FIGURE 2. Abactinal surface of holotype of Cryptasterina hystera sp.nov. (R= 10.2 mm) Emergent young visible in the interradius to left of image.

FIGURE 3 in Crossota millsae (Cnidaria: Trachymedusae: Rhopalonematidae), a new species of viviparous hydromedusa from the deep sea off California and Hawaii

FIGURE 3. Crossota millsae, sp. nov. a) Two of the juvenile paratype specimens representing different stages of early development, scale bar = 2.5 mm. b) Two of the juvenile paratype specimens representing later stages of development, same scale bar as in Fig 3a. c) Abscission zone at base of tentacles. ABS = abscission point, RC = ring canal, YIP = yellow iridescent pigment. d) Scanning electron micrograph of spermatids from testes of the male specimen shown in Fig. 1b. Three size classes of spermatids are noted, A ~10 µm, B ~5 µm and C ~2 µm. The smallest spermatids have developing flagella. Scale bar = 10 µm.

FIGURE 1 in Crossota millsae (Cnidaria: Trachymedusae: Rhopalonematidae), a new species of viviparous hydromedusa from the deep sea off California and Hawaii

FIGURE 1. Crossota millsae, sp. nov. a) Lateral view of female specimen. Scale bar = 9 mm. b) Lateral view of male paratype specimen. Note the exumbrellar furrows. Scale bar = 5 mm. c) Oral view of female shown in Fig 1a with developing juveniles. Scale bar = 9 mm. d) Aboral view of female with developing juveniles. Scale bar = 10 mm.

FIGURE 2 in Crossota millsae (Cnidaria: Trachymedusae: Rhopalonematidae), a new species of viviparous hydromedusa from the deep sea off California and Hawaii

FIGURE 2. In situ video frame of Crossota millsae sp. nov. taken off California from the Monterey Bay Aquarium Research Institute's ROV Tiburon. This is a female specimen with developing juveniles.

FIGURES 73–75 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 73–75. Procloeon (Oculogaster) album sp. n., male imago. 73–74, the same specimen at different light; 75, head and thorax of another specimen.

FIGURES 68–72 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 68–72. Procloeon (Oculogaster) album sp. n. 68, mature female larva (reddish paired hypodermal spots on abdominal terga IV, VII and VIII visible through cuticle); 69, subimaginal abdomen extracted from mature female larva (holotype); 70, mature male larva (reddish hypodermal markings on abdominal terga IV, VII and VIII visible through cuticle); 71, subimaginal abdomen extracted from this larva; 72, male imago.

FIGURES 65–67 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 65–67. Procloeon (Oculogaster) album sp. n. 65, genitals of male imago (at left half gonovectal muscles shown by interrupted lines, hidden part of penis shown by interrupted line and dotted, gonostylar muscle not shown; at right half gonostylar muscle shown by interrupted lines, gonovectal muscles not shown; median styligeral muscle shown by interrupted lines, areas of anterior attachment of median paraproctal muscles shown by dotted lines). 66, genitals of male subimago; 67, wing. Abbreviations: 1, 2, 3, segments of gonostylus; mIX-X, areas of anterior attachment of median paraproctal muscles (i.e., muscles going from sternum IX to common base of paraprocts); usg, unistyliger.

FIGURES 49–58 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 49–58. Procloeon (Oculogaster) album sp. n., larva. 49–55, tergalii I–VII; 56, fore leg, anterior view (fine setae not shown; dots show bases of fine setae forming regular rows on apical part of femur, proximal part of tibia and proximal part of tarsus); 57, claw; 58, paraproct (49–52, 54–55, 58, holotype).

FIGURES 43–48 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 43–48. Procloeon (Oculogaster) album sp. n., larva. 43, labrum, 44, 45, apices of left and right mandibles; 46, maxilla, dorsal view; 47, half of labium, ventral view; 48, the same, dorsal view. Abbreviations: ds1, ds2, ds3, dentisetae; in1, in2, in3, in4, denticles of incisor; in-V, ventral denticle of incisor; kd1, kd2, kd3, denticles of kinetodontium.

FIGURES 38–42 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 38–42. Procloeon (Oculogaster) cylindroculum, female imago. 38, head and prothorax in Canadian balsam with embryos visible inside; 39, enlarged embryo with focus on median ocellus and mandibles; 40, mature female imago free of embryos; 41, abdomen of female imago with embryos (black eyes and ocelli visible through integument); 42, embryo extracted from female imago (38, 39, 41, 42, from Uganda; 40, from Zambezi). Abbreviations: md, mandibles; oc, future facetted eye; ocl.l., lateral ocellus; ocl.m., median ocellus.

FIGURES 33–37 in A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae)

FIGURES 33–37. Procloeon (Oculogaster) cylindroculum. 33, 34, male imagoes; 35, subimaginal abdomen extracted from mature male larva; 36, subimaginal abdomen extracted from mature female larva; 37, subimaginal exuviae of postsubalar sclerite and lateropostnotal crest (33, 35–37, specimens from Zambia; 34, specimen from Uganda).