References of "Székely, Diana"
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See detailRandom size-assortative mating despite size-dependent fecundity in a Neotropical amphibian with explosive reproduction
Székely, Diana ULiege; Székely, Paul; Denoël, Mathieu ULiege et al

in Ethology (2018), 124(4), 218-226

Sexual selection theory predicts that, when body size is correlated with fecundity, there should be fitness advantages for mate choice of the largest females. Moreover, because larger males are expected ... [more ▼]

Sexual selection theory predicts that, when body size is correlated with fecundity, there should be fitness advantages for mate choice of the largest females. Moreover, because larger males are expected to monopolize the largest females, this should result in an assortative mating based on body size. Although such patterns could be expected in both explosive and prolonged breeders, non-assortative mating should be more widespread in species under time constraints. However, patterns of sexual selection are largely unexplored in explosive breeding species, and contrasting patterns have been found previously. We expect that the active choice of partners may be particularly risky when the time period during which sexual partners are available is severely limited. Therefore, to avoid missing an entire reproductive act, males and females should pair irrespective of traits, such as body size. We tested this hypothesis by investigating the mating patterns of the Pacific horned toad, Ceratophrys stolzmanni, a short-lived fossorial species inhabiting Neotropical dry forests. This species is particularly adequate to test our prediction because it reproduces explosively over the course of a single night per year. Although the number of eggs laid was proportional to the size of females, and individuals of both sexes showed variation in body size, there was no assortative mating based either on size, body condition or age of mates. Egg size was not influenced by either female size or clutch size. The larger body size of females compared to males is likely due to fecundity selection, i.e. the selective pressure that enhances reproductive output. Although we cannot dismiss the possibility that individuals could select their partners based on other criteria than those related to size or age, the results fit well our prediction, showing that the explosive breeding makes improbable an active choice of partners in both sexes and therefore favours a random mating pattern. [less ▲]

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See detailBreed fast, die young: demography of a poorly known fossorial frog from the xeric Neotropics
Székely, Diana ULiege; Szekely, Paul; Stanescu, Florina et al

in Salamandra (2018), 54(1), 37-44

We successfully used skeletochronology to provide the first detailed demographic data regarding Ceratophrys stolzmanni, a cryptic, fossorial amphibian inhabiting the xeric Neotropics. We observed a female ... [more ▼]

We successfully used skeletochronology to provide the first detailed demographic data regarding Ceratophrys stolzmanni, a cryptic, fossorial amphibian inhabiting the xeric Neotropics. We observed a female-biased sexual size dimorphism, but no differences in age parameters between the two sexes. Growth rate is accelerated during the first year of life, both before and after metamorphosis, followed by a rapid sexual maturation and a short lifespan. Both males and females reached sexual maturity before they were one year old, the mean age was two years, and longevity was low for both sexes, with only 2% of the tested individuals, all females, reaching the age of four years. We discuss the implications of the observed aging and growth patterns for the long-term survival and conservation of the species, comparing our results to other tropical species. [less ▲]

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See detailDryness affects burrowing depth in a semi-fossorial amphibian
Székely, Diana ULiege; Cogălniceanu, Dan; Székely, Paul et al

in Journal of Arid Environments (2018)

The fossorial life-history emerged as a response to hostile environmental conditions, such as extreme temperatures and dryness. It evolved independently in different lineages of amphibians, which are ... [more ▼]

The fossorial life-history emerged as a response to hostile environmental conditions, such as extreme temperatures and dryness. It evolved independently in different lineages of amphibians, which are particularly vulnerable to dehydration and require a continuous level of humidity because of their permeable skin. For the first time, we test the hypothesis that amphibians are able to adapt their fossorial behaviour to substrate humidity, using the Pacific horned frogs (Ceratophrys stolzmanni) from the Ecuadorian dry forest as a model. When exposed to dry substrate, the animals burrowed much deeper than the ones in wet soil. The capacity to excavate was particularly high in this species: frogs from the dry treatment could be found at more than one-meter depth after just a few hours. Our results reveal a conditional strategy that contributes to explain the persistence of amphibians in dry environments. [less ▲]

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See detailPond drying cues and their effects on growth and metamorphosis in a fast developing amphibian
Székely, Diana ULiege; Denoël, Mathieu ULiege; Székely, Paul et al

in Journal of Zoology (2017), 303(2), 129-135

The hydroperiod of breeding habitats imposes a strong selection on amphibians and pond-breeding species usually exhibit a high degree of plasticity in the duration of larval period. However, the potential ... [more ▼]

The hydroperiod of breeding habitats imposes a strong selection on amphibians and pond-breeding species usually exhibit a high degree of plasticity in the duration of larval period. However, the potential for phenotypic plasticity in fast developing species was investigated only in a small number of anurans, and the specific response to environmental cues such as low water versus decreasing water level, as well as the effects of such cues on particular developmental stages, are even less understood. In this context, we investigated the plastic response to pond desiccation in a neotropical species (Ceratophrys stolzmanni) by raising tadpoles in three water level treatments: constant high, constant low and decreasing. The growth rates were the highest reported for amphibian tadpoles (up to 0.3g/day) and the time to metamorphosis was short in all treatments, with the fastest developing tadpole metamorphosing in only 16 days after egg deposition. Individuals from the constant high water level treatment had a higher growth rate than those in the other two treatments, whereas decreasing and constant low water levels had similar effects on development, speeding up metamorphosis. In turn, this involved a cost as these tadpoles had a lower body size and mass at metamorphosis than the ones raised in constant high water levels. The final stages of metamorphosis, when tadpoles are the most vulnerable, were shorter in tadpoles exposed to a decreasing water level, allowing them to leave water quickly. Our experiment demonstrates that phenotypic plasticity is maintained even in environments devoid of permanent aquatic habitats. Ceratophryd tadpoles are able to shorten their developmental time when they perceive a risk of desiccation and react similarly to cues coming from the two unfavorable water conditions showing their adaptation to ephemeral and unpredictable breeding habitats. [less ▲]

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See detailBreed fast, die young - Demography of a Neotropical fossorial frog
Székely, Diana ULiege; Székely, Paul; Stănescu, Florina et al

Poster (2017, September 19)

Information regarding age- and size-related parameters is of paramount importance both to understanding the life-history of populations, and for designing effective conservation strategies; however, such ... [more ▼]

Information regarding age- and size-related parameters is of paramount importance both to understanding the life-history of populations, and for designing effective conservation strategies; however, such base-line data lacks for many species, especially for those inhabiting tropical habitats. Using skeletochronology, we provide the first detailed information regarding the demography of the Pacific horned frog, Ceratophrys stolzmanni, a vulnerable, fossorial amphibian, that lives in the Tumbesian dry-forests of Ecuador. The species shows an intense growth rate during the first activity season, both before and after metamorphosis. Sexual maturity is achieved by both sexes before the first year of life, after which growth rates abruptly decrease. Females are on average larger, but not older, than males, mean age being two years in both sexes. The rapid sexual maturation is associated with a short life-span, the observed maximum longevity being three years in males and four years in females. The short reproductive life-span, which offers few mating opportunities, might have important implications for the conservation of this species, that can be especially at risk in the case of prolonged droughts expected to affect its habitat. [less ▲]

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See detailOut of the ground: two coexisting fossorial toad species differ in their emergence and movement patterns
Székely, Diana ULiege; Cogalniceanu, Dan; Székely, Paul et al

in Zoology (2017), 121

Understanding the way species with similar niches can coexist is a challenge in ecology.The niche partitioning hypothesis has received much support, positing that species can exploit available resources ... [more ▼]

Understanding the way species with similar niches can coexist is a challenge in ecology.The niche partitioning hypothesis has received much support, positing that species can exploit available resources in different ways. In the case of secretive species, behavioural mechanisms of partitioning are still poorly understood. This is especially true for fossorial frogs because individuals hide underground by day and are active only during the night. We investigated the nocturnal activity and tested the niche partitioning hypothesis in two syntopic fossorial spadefoot toads (Pelobates fuscus and P. syriacus) by examining interspecific variation in emergence from the soil. We employed a night vision recording system combined with video-tracking analyses in a replicated laboratory setting to quantify individual movement patterns, a procedure that has not been used until now to observe terrestrial amphibians. Most individuals appeared on the surface every night and returned to their original burrow (about 60% of the times), or dug a new one around morning. There was a large temporal overlap between the two species. However, P. syriacus was significantly more active than P. fuscus in terms of total distance covered and time spent moving, while P. fuscus individuals left their underground burrow more frequently than P. syriacus. Consequently, P. fuscus adopted more of a sit-and-wait behaviour compared to P. syriacus, and this could facilitate their coexistence. The use of night video-tracking technologies offered the advantage of individually tracking these secretive organisms during their nocturnal activity period and getting fine-grain data to understand their movement patterns. [less ▲]

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See detailPhenotypic plasticity in a fossorial toad from a Pacific xeric forest (Ecuador)
Székely, Diana ULiege; Szekely, Paul; Denoël, Mathieu ULiege et al

Poster (2016, October 06)

For amphibians, optimal size at metamorphosis is determined by a trade-off between opportunities for growth and risks of mortality in aquatic and terrestrial habitats, and many species show a high degree ... [more ▼]

For amphibians, optimal size at metamorphosis is determined by a trade-off between opportunities for growth and risks of mortality in aquatic and terrestrial habitats, and many species show a high degree of plasticity in time and size at metamorphosis that allow them to adapt to unpredictable environments. We used as model a neotropical anuran species, the Pacific horned frog, Ceratophrys stolzmanni, that inhabits the Tumbesian dry forests of southwestern Ecuador, and lays its eggs in lentic habitats of variable size and unpredictable duration. We investigated (i) how tadpoles time their metamorphosis in order to escape a rapidly drying aquatic habitat, and (ii) the consequences of metamorphosis plasticity on the immediate and mid-term fitness of individuals. We conducted two experiments; in the first one we exposed 36 tadpoles to one of three water levels treatments: constant high, decreasing and constant low. Tadpoles that were raised in decreasing or low water level metamorphosed on average 13% and 10% faster than the ones from constant high water level, but at a lower body size and mass. Growth rates were among the highest recorded for tadpoles and individuals from the constant high water level treatment grew at a much faster rate than the others. In a second experiment, we sampled 72 freshly metamorphosed (Gosner stage 45) C. stolzmanni individuals of assorted sizes (SVL between 23.8 and 47.9 mm, body weight between 1.2 and 11.9 g). From this spectrum of sizes, we selected the 21 largest and 22 smallest individuals and evaluated the effects of body size at metamorphosis on trophic and locomotory performance parameters. We determined their growth rate and survival over the course of an activity season (i.e., two months). Our results show that bigger size at metamorphosis is correlated with better survival chances and performance. Larger individuals were more mobile, had bigger gape width and better survival rates (95% compared to 64% for small individuals). Growth rates were not correlated with initial size, and small individuals were capable of increasing their size at a higher rate. This indicates that, although size at metamorphosis has an immediate impact on fitness, smaller individuals are able to compensate with an increased growth rate. [less ▲]

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See detailWho are the winners in the race against desiccation – phenotypic plasticity in a fossorial toad
Székely, Diana ULiege; Székely, Paul; Denoël, Mathieu ULiege et al

Poster (2016, September 29)

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See detailBehavioral effects of exposure to salinity on tadpoles of two syntopic species of spadefoot toads (genus Pelobates)
Székely, Diana ULiege; Stanescu, Floriana; Székely, Paul et al

Poster (2015, September)

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See detailPELOBATES SYRIACUS (Syrian Spadefoot). CANNIBALISM
Székely, Diana ULiege; Szekely, Paul; Cogalniceanu, Dan

in Herpetological Review (2015), 46(1), 76-77

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See detailSALINITY TOLERANCE IN PELOBATES FUSCUS (LAURENTI, 1768) TADPOLES (AMPHIBIA: PELOBATIDAE)
Stanescu, Florina; Iosif, Ruben; Székely, Diana ULiege et al

in Travaux du Muséum National d’Histoire Naturelle «Grigore Antipa» (2013), 56(1), 103-108

We investigated the effect of salinity on larval development and survival rate to metamorphosis in the common spadefoot toad Pelobates fuscus (Laurenti, 1768). Our hypothesis was that higher salinity ... [more ▼]

We investigated the effect of salinity on larval development and survival rate to metamorphosis in the common spadefoot toad Pelobates fuscus (Laurenti, 1768). Our hypothesis was that higher salinity would decrease tadpole survival rate and body size at metamorphosis, and delay metamorphosis. The response of the tadpoles was evaluated through an experimental design with three salinity treatments of 2, 4, and 8‰ compared to a control (deionized water). Survival varied across the treatments: neither of the tadpoles in 8‰ salinity treatment survived the experiment, nor achieved metamorphosis. Salinity levels of 2 and 4‰ had no significant influence on the mean time to metamorphosis, body mass and SVL at metamorphosis. Our results suggest that P. fuscus tadpoles have a tolerance threshold for brackish water up to 4‰, above which survival is impaired. [less ▲]

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