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175 results for “Viviparity”
Data from: Viviparity does not affect the numbers and sizes of reptile offspring
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Data from: Seasonal shifts along the oviparity-viviparity continuum in a cold-climate lizard population
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Data from: Do male fish prefer them big and colourful? Non-random male courtship effort in a viviparous fish with negligible paternal investment
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Data from: Conservation of sex-linked markers among conspecific populations of a viviparous skink, Niveoscincus ocellatus, exhibiting genetic and temperature-dependent sex determination
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Data from: Genetic and ecological data reveal species boundaries between viviparous and oviparous lizard lineages
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Data from: Climate and sex ratio variation in a viviparous lizard
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Data from: Comparative landscape genetics reveals the evolution of viviparity reduces genetic connectivity in fire salamanders
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Data from: Maternal food availability affects offspring performance and survival in a viviparous lizard
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Data from: A global test of the cold-climate hypothesis for the evolution of viviparity of squamate reptiles
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Data from: The genetics of egg retention and fertilization success in Drosophila: one step closer to understanding the transition from facultative to obligate viviparity
Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait. Here, we develop a novel microscope-based method for measuring egg retention in Drosophila females and determine the range of phenotypic variation in mated female egg retention in a subset of 91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the genetic basis of egg retention using a genome-wide association study (GWAS). Further, the scoring of more than 95,000 stained, staged eggs enabled estimates of fertilization success for each line. We found evidence that ovary- and spermathecae-related genes as well as genes affecting olfactory behavior, male mating behavior, male-female attraction and sperm motility may play a crucial role in post-mating physiology. Based on our findings we also propose potential evolutionary routes towards obligate viviparity. In particular, we propose that the loss of fecundity incurred by viviparity could be offset by benefits arising from enhanced mate discrimination, resource specialization, or modified egg morphology.
Data from: Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)
Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure, and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (FST range: 0.06 - 0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9,000 years ago. Our study provides evidence of rapid genetic differentiation among island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.
Data from: Sex-specific maternal effects in a viviparous fish
Mothers vary in their effects on their offspring, but studies of variation in maternal effects rarely ask whether differences between mothers are consistent for sons and daughters. Here, we analysed maternal effects in the mosquitofish Gambusia holbrooki for development time and adult size of sons and daughters, and a primary male sexual character (gonopodium length). We found substantial maternal effects on all traits, most notably for gonopodium length. There were significant correlations within each sex for maternal effects on different traits, indicative of trade-offs between development rate and adult size. By contrast, there was no evidence of any consistency in maternal effects on sons and daughters. This suggests that the evolution of maternal effects will follow independent trajectories dependent on sex-specific selection on offspring. Importantly, failure to recognize the sex-specific nature of maternal effects in this population would have substantially underestimated the extent of their variation between mothers.
Data from: Evolution of viviparity: a phylogenetic test of the cold-climate hypothesis in Phrynosomatid lizards
The evolution of viviparity is a key life-history transition in vertebrates, but the selective forces favoring its evolution are not fully understood. With >100 origins of viviparity, squamate reptiles (lizards and snakes) are ideal for addressing this issue. Some evidence from field and laboratory studies supports the "cold-climate" hypothesis, wherein viviparity provides an advantage in cold environments by allowing mothers to maintain higher temperatures for developing embryos. Surprisingly, the cold-climate hypothesis has not been tested using both climatic data and phylogenetic comparative methods. Here, we investigate the evolution of viviparity in the lizard family Phrynosomatidae using GIS-based environmental data, an extensive phylogeny (117 species), and recently developed comparative methods. We find significant relationships between viviparity and lower temperatures during the warmest (egg-laying) season, strongly supporting the cold-climate hypothesis. Remarkably, we also find that viviparity tends to evolve more frequently at tropical latitudes, despite its association with cooler climates. Our results help explain this and two related patterns that seemingly contradict the cold-climate hypothesis: the presence of viviparous species restricted to low-elevation tropical regions and the paucity of viviparous species at high latitudes. Finally, we examine whether viviparous taxa may be at higher risk of extinction from anthropogenic climate change.
Data from: Water restriction causes an intergenerational trade-off and delayed mother-offspring conflict in a viviparous lizard
1. Parenting is costly and because the relationship between the mother and embryos is not mutualistic, mother-offspring conflicts may exist whenever resource are scarce. However, intergenerational trade-offs and conflicts resulting from limited access to water, a vital and depreciable resource, remain largely overlooked. 2. In this study, we examined the physiological, reproductive and life history responses to water restriction in the European Common Lizard (Zootoca vivipara). We hypothesised that, under water-limited conditions, pregnant females experience both short-term and long-term physiological impacts (dehydration and stress) underlying an allocation trade-off for water between mothers and offspring. 3. Water restriction led to a decrease in body mass, and an increase in plasma osmolality (dehydration) and corticosterone concentration in both males and females. The extent of the dehydration was positively correlated with fecundity in females. This suggests a trade-off between maternal water balance and allocation of water to developing embryos during reproduction. 4. Water restriction had no immediate effect on reproductive output or offspring morphology at birth. Yet, water restriction in pregnant females enhanced their reproductive effort the following year but reduced the early life growth and annual survival of their second-year offspring. 5. These delayed fitness responses to water restriction in offspring and mothers suggest that water can trigger intergenerational conflicts as demonstrated for energy. Although the mediation of this conflict remains to be clarified, we hypothesized that it represents a selective force that influences reproductive strategies.
High-quality, chromosome-level reference genomes of the viviparous Caribbean skinks Spondylurus nitidus and S. culebrae
<p>Output files from the assembly of 2 reference genomes detailed in the publication Rivera et al. 2024. High-quality, chromosome-level reference genomes of the viviparous Caribbean skinks <em>Spondylurus nitidus</em> and <em>S. culebrae. Genome Biology and Evolution</em>, evae079.</p>
Figure 7 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489
Figure 7 - Foetal digestive system. Exceptional for an anuran foetus is the straight and differentiated gut, with an oesophagus, the transparent and the dark intestines (stomach) and a rectum, as well as the large liver lobes. Additionally, shown are small lungs (as well small in adults), the heart, kidney and gonads. Redrawn after Angel and Lamotte (1944a).
Figure 6 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489
Figure 6 - "Birthing posture" in Nimba toads. A: gestating Nimba toad; the grey shading indicates the size and position of the enlarged distal parts of the oviduct (uterus), B: shows the "birthing posture", in which females build a double W with their legs and increase pressure on their uteri. Compare the position of legs on the photograph on the right (C) of a female giving birth, showing likewise the double W, of the legs. A and B are redrawn after Vilter (1956a).
Figure 2 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489
Figure 2 - Rainy and dry season at Nimba. The rainy season (top) is characterised by persistent fog and rain, whereas the dry season (middle) is characterised by little rain, high temperature fluctuations and dry season fires. After dry season fires the grasses sprout very fast (bottom, © Nèma Soua Loua).
Figure 12 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489
Figure 12 - Summary of the temporal development of the foetus and male and female reproductive system. The outer layer gives the months as abbreviations and the seasons by colour (yellow: dry season, blue: rainy season). Toads mate between mid-September and mid-October on average, are going underground mid-October and emerge in mid-March from their dormancy sites. Juveniles are born in mid-June (pictograms). Spermatogenesis shows the development within the male reproductive system. Foetal growth gives the speed of development and growth. The uterus shows three phases: a proliferation phase in which the uterine epithelium develops, a secretion phase during the gestation and an apoptosis phase during which the uterine epithelium is completely exchanged (old one removed and new one built). The ovary has two phases: the follicles phase, characterised by follicle growth and the luteal phase characterised by the presence of corpora lutea. Within the female pituitary three cell types show variation within the annual cycle, the glycoprotein type 1 cells and the protein type 1 and type 2 cells. Within the male pituitary as well three cell types show variation (not shown), glycoprotein type 1 cells and glycoprotein type 2 cells in the same way as those of females, whereas protein type 2 cells are only present in July/ August.
Figure 4 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489
Figure 4 - Female and male cloaca of Nimba toads and a pair in amplexus. The female cloaca (top left) is close to the urostyle, whereas the male cloaca (top right) is ventrally oriented. During mating it swells and encloses the female cloaca. During the amplexus lumbalis the female is constantly horizontally swaying (bottom).
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