Incubation time as an important influence on egg production and distribution into clutches for sauropod dinosaurs

Paleobiology ◽  
10.1666/13028 ◽  
2014 ◽  
Vol 40 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Graeme D. Ruxton ◽  
Geoffrey F. Birchard ◽  
D. Charles Deeming
Keyword(s):  
Predation Risk ◽  
Incubation Time ◽  
Egg Production ◽  
Adaptive Strategy ◽  
Finite Limit ◽  
Small Individual ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Production And Distribution ◽  
Long Time

Individual egg size and clutch size of the largest of the dinosaurs (the sauropods) are both smaller than might be expected for such large oviparous organisms. We suggest that these effects can be understood in the light of likely incubation times of sauropod eggs. Using allometric relationships from extant birds and crocodilians, we estimate that time from laying to hatching was likely to have been 65–82 days. If total predation risk varies with length of incubation time, there may be egg sizes above which the advantages of larger initial hatchling size are outweighed by the increased risk of predation during the egg stage. Also, in seasonal environments there will often be a finite limit to the period over which environmental temperatures are high enough for egg development. Thus incubation time may have been an important constraint explaining the small individual size of sauropod eggs. We further suggest that for sauropods spatial dispersal of eggs in small clutches was an adaptive strategy to mitigate this high predation risk associated with long time of exposure in the egg stage. Such a dispersive strategy brings several benefits. Thus, incubation time may also be key to explaining the surprisingly small clutch sizes.

scholarly journals Does Moonlight Increase Predation Risk for Elusive Mammals in Costa Rica?

2020 ◽  
Vol 13 ◽  
pp. 194008292095240
Author(s):  
Ryan T. Botts ◽  
Amy A. Eppert ◽  
Timothy J. Wiegman ◽  
Steven R. Blankenship ◽  
Abner Rodriguez ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Costa Rica ◽  
Predation Risk ◽  
Activity Patterns ◽  
Night Vision ◽  
Lunar Phase ◽  
Nocturnal Activity ◽  
Related Activity ◽  
Risk Of Predation ◽  
Increased Risk

An increasing body of evidence indicates that moonlight influences the nocturnal activity patterns of tropical mammals, both predators and prey. One explanation is that brighter moonlight is associated with increased risk of predation (Predation Risk hypothesis), but it has also been proposed that nocturnal activity may be influenced by the sensory ecology of a species, with species that rely on visual detection of food and danger predicted to increase their activity during bright moonlight, while species relying on non-visual senses should decrease activity (Visual Acuity hypothesis). Lack of an objective measure of “visual acuity” has made this second hypothesis difficult to test, therefore we employed a novel approach to better understand the role of lunar illumination in driving activity patterns by using the tapetum lucidum as a proxy for “night vision” acuity. To test the alternative predictions, we analyzed a large dataset from our long-term camera trap study in Costa Rica using activity overlap, relative abundance, and circular statistical techniques. Mixed models explored the influence of illumination factors (moonrise/set, cloud cover, season) and night vision acuity (tapetum type) on nocturnal and lunar phase-related activity patterns. Our results support the underlying assumptions of the predation risk and visual acuity models, but indicate that neither can fully predict lunar-related activity patterns. With diurnal human “super predators” forcing a global increase in activity during the night by mammals, our findings can contribute to a better understanding of nocturnal activity patterns and the development of conservation approaches to mitigate forced temporal niche shifts.

Increased risk of predation increases mobbing intensity in tropical birds of French Guiana

2015 ◽  
Vol 31 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Vallo Tilgar ◽  
Kadri Moks
Keyword(s):  
Predation Risk ◽  
French Guiana ◽  
Empirical Studies ◽  
Predator Species ◽  
Acoustic Stimuli ◽  
Risk Of Predation ◽  
Increased Risk ◽  
In The Wild ◽  
The Common ◽  
Animal Communities

Abstract:Stressful environments have been suggested to enhance cooperative behaviours in animal communities. Prey animals living in risky environments can also increase long-term benefits by cooperating with neighbours, such as collectively harassing predators. However, empirical studies have rarely tested this prediction in the wild. In this experimental study we explored whether the perceived predation risk influences cooperative mobbing behaviour in tropical forest birds in French Guiana. The predation risk was increased by 5-d-long presentation of visual and acoustic stimuli of pygmy-owls in 24 locations. In order to examine whether mobbing response can vary in relation to the abundance of local predators, we used the Amazonian pygmy-owl (Glaucidium hardyi) as a common predator and the ferruginous pygmy-owl (Glaucidium brasilianum) as a rare predator in the study area. Our results showed that repeated predator-presentations increased mobbing response over time for the rarer owl species, while this effect was not significant for the common owl species. No effect of repeated presentations of either pygmy-owl species was found on the latency of mobbing. Moreover, mobbing latency was shorter and mobbing response was stronger for the common predator species, the Amazonian pygmy-owl. This study provides experimental evidence that birds exhibit stronger mobbing responses when the predator is locally abundant, while repeated encounters can be perceived as more dangerous when the predator is rare.

The population dynamics of bite-sized predators: prey dependence, territoriality, and mobility

2018 ◽  
Author(s):  
Xavier Lambin
Keyword(s):  
Prey Species ◽  
Top Down ◽  
Predator Prey ◽  
Biological Barrier ◽  
Reciprocal Interactions ◽  
Demographic Rates ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Rodent Prey ◽  
Small Mustelids

The dependency of mustelid demographic rates on prey abundance has the potential to cause a strong coupling between predator-prey populations. Data on mustelid dynamics show that such strong reciprocal interactions only materialise in some restricted conditions. Bite-size mustelid predators searching for scarce, depleted prey expose themselves to increased risk of predation by larger predators of small mammal that are themselves searching for similar prey species. As voles or muskrats become scarcer, weasels and mink searching for prey over larger areas become increasingly exposed to intra-guild predation, unless they operate in a habitat refuge such as the sub-nivean space. Where larger predators are sufficiently abundant or exert year-round predation pressure on small mustelids, their impact on mustelids may impose biological barrier to dispersal that are sufficient to weaken the coupling between small mustelids and their rodent prey, and thus impose a degree of top down limitation on mustelids.

scholarly journals Risk Factors, and Clinical and Etiological Characteristics of Ischemic Strokes in COVID-19-Infected Patients: A Systematic Review of Literature

2021 ◽  
pp. 1-4
Author(s):  
Simone Vidale
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Clinical Features ◽  
Case Reports ◽  
Clinical Severity ◽  
Large Artery ◽  
Causal Association ◽  
Review Of Literature ◽  
Increased Risk ◽  
Long Time

<b><i>Background and Purpose:</i></b> Coronavirus disease 2019 (CO­VID-19) infection is an ongoing pandemic and worldwide health emergency that has caused important changes in healthcare systems. Previous studies reported an increased risk of thromboembolic events, including stroke. This systematic review aims to describe the clinical features and etiological characteristics of ischemic stroke patients with CO­VID-19 infection. <b><i>Method:</i></b> A literature search was performed in principal databases for studies and case reports containing data concerning risk factors, clinical features, and etiological characteristics of patients infected with COVID-19 and suffering from stroke. Descriptive and analytical statistics were applied. <b><i>Results:</i></b> Overall, 14 articles were included for a total of 93 patients. Median age was 65 (IQR: 55–75) years with prevalence in males. Stroke occurred after a median of 6 days from COVID-19 infection diagnosis. Median National of Institute of Health Stroke Scale (NIHSS) score was 19. Cryptogenic (Cry) strokes were more frequent (51.8%), followed by cardioembolic etiology, and they occurred a long time after COVID-19 diagnosis compared with large-artery atherosclerosis strokes (<i>p</i><sub>trend</sub>: 0.03). The clinical severity of stroke was significantly associated with the severity grade of COVID-19 infection (<i>p</i><sub>trend</sub>: 0.03). <b><i>Conclusions:</i></b> Ischemic strokes in COVID-19-infected patients were clinically severe, affecting younger patients mainly with Cry and cardioembolic etiologies. Further multicenter prospective registries are needed to better describe the causal association and the effect of COVID-19 infection on stroke.

The effects of moonlight on nocturnal activity in bushy-tailed wood rats (Neotoma cinerea)

1999 ◽  
Vol 77 (3) ◽  
pp. 480-485 ◽  
Author(s):  
Michael G Topping ◽  
John S Millar ◽  
James A Goddard
Keyword(s):  
Light Level ◽  
Intermediate Level ◽  
Nocturnal Activity ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Neotoma Cinerea ◽  
Two Measures ◽  
Males And Females ◽  
Rocky Outcrops ◽  
Breeding Seasons

The nocturnal activity of bushy-tailed wood rats (Neotoma cinerea) was monitored for two breeding seasons (1993 and 1994) in the Canadian Rockies. Radiotelemetry was used under three levels of moonlight to assess two measures of nocturnal activity: (i) the proportion of animals crossing rocky outcrops and entering the surrounding forest to forage, search for mates, or both, and (ii) the distance moved from the den site while in the forest. Males and females exhibited significant differences among moonlight levels, with greater activity on nights of intermediate-level moonlight and less activity on nights with bright or dark moonlight. There was no difference in the proportions of males and females active at any moonlight level. The distances moved from the den did not differ among moonlight levels for either males or females. Having traversed the rocks and entered the forest, individuals moved similar distances regardless of light level. These results suggest that wood rats respond to moonlight only when making the decision to cross rocks and enter the forest. This behaviour presumably serves to counteract the increased risk of predation on bright nights.

scholarly journals Renoprotective Effects of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin: A Review in Type 2 Diabetes

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Cristina Mega ◽  
Edite Teixeira-de-Lemos ◽  
Rosa Fernandes ◽  
Flávio Reis
Keyword(s):  
Type 2 Diabetes ◽  
Current Knowledge ◽  
Diabetic Patients ◽  
Dipeptidyl Peptidase 4 ◽  
Dipeptidyl Peptidase 4 Inhibitor ◽  
Increased Risk ◽  
Long Time ◽  
Stage Renal Disease ◽  
End Stage

Diabetic nephropathy (DN) is now the single commonest cause of end-stage renal disease (ESRD) worldwide and one of the main causes of death in diabetic patients. It is also acknowledged as an independent risk factor for cardiovascular disease (CVD). Since sitagliptin was approved, many studies have been carried out revealing its ability to not only improve metabolic control but also ameliorate dysfunction in various diabetes-targeted organs, especially the kidney, due to putative underlying cytoprotective properties, namely, its antiapoptotic, antioxidant, anti-inflammatory, and antifibrotic properties. Despite overall recommendations, many patients spend a long time well outside the recommended glycaemic range and, therefore, have an increased risk for developing micro- and macrovascular complications. Currently, it is becoming clearer that type 2 diabetes mellitus (T2DM) management must envision not only the improvement in glycaemic control but also, and particularly, the prevention of pancreatic deterioration and the evolution of complications, such as DN. This review aims to provide an overview of the current knowledge in the field of renoprotective actions of sitagliptin, namely, improvement in diabetic dysmetabolism, hemodynamic factors, renal function, diabetic kidney lesions, and cytoprotective properties.

Do changes in reef habitats influence relative predation risk on the juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875)?

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 839-856 ◽  
Author(s):  
J. Hesse ◽  
J. A. Stanley ◽  
A. G. Jeffs
Keyword(s):  
Predation Risk ◽  
Spatial Scales ◽  
Spiny Lobster ◽  
Habitat Type ◽  
Small Spatial Scale ◽  
Important Species ◽  
Early Juvenile ◽  
Risk Of Predation ◽  
Jasus Edwardsii ◽  
Commercially Important

Kelp habitats are in decline in many temperate coastal regions of the world due to climate change and expansion of populations of grazing urchins. The loss of kelp habitat may influence the vulnerability to predators of the juveniles of commercially important species. In this study relative predation rates for kelp versus barren reef habitat were measured for early juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875), on the northeastern coast of New Zealand using tethering methods. Variation in assemblages of predators over small spatial scales appeared to be more important for determining the relative predation of lobsters, regardless of habitat type. Therefore, the assessment of relative predation risk to early juvenile lobsters between kelp and barren habitats will require more extensive sampling at a small spatial scale, as well as a specific focus on sampling during crepuscular and nocturnal periods when these lobsters are most at risk of predation.

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

2010 ◽  
Vol 37 (4) ◽  
pp. 273 ◽  
Author(s):  
Karen Fey ◽  
Peter B. Banks ◽  
Hannu Ylönen ◽  
Erkki Korpimäki
Keyword(s):  
Baltic Sea ◽  
Predation Risk ◽  
Myodes Glareolus ◽  
The Baltic Sea ◽  
Short Term ◽  
Behavioural Responses ◽  
Alien Predator ◽  
Risk Of Predation ◽  
The Baltic ◽  
The Impact

Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis) and a recently invading alien predator, the American mink (Mustela vison), in laboratory. We also studied the short-term responses of free-ranging field voles and bank voles (Myodes glareolus) to simulated predation risk by alien mink on small islands in the outer archipelago of the Baltic Sea. Key results. In the laboratory, voles avoided odour cues of native weasel but not of alien mink. It is possible that the response to mink is a context dependent learned response which could not be induced in the laboratory, whereas the response to weasel is innate. In the field, however, voles reduced activity during their normal peak-activity times at night as a response to simulated alien-mink predation risk. No other shifts in space use or activity in safer microhabitats or denser vegetation were apparent. Conclusions. Voles appeared to recognise alien minks as predators from their odours in the wild. However, reduction in activity is likely to be only a short-term immediate response to mink presence, which is augmented by longer-term strategies of habitat shift. Because alien mink still strongly suppresses vole dynamics despite these anti-predator responses, we suggest that behavioural naiveté may be the primary factor in the impact of an alien predator on native prey. Implications. Prey naiveté has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naiveté whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.

Breeding behaviour of ectotherms at high latitudes: the case of the natterjack toad Epidalea calamita at its northern range limit

Behaviour ◽  
2021 ◽  
pp. 1-20
Author(s):  
Linda Saare ◽  
Riinu Rannap
Keyword(s):  
Climatic Conditions ◽  
Energetic Cost ◽  
Breeding Period ◽  
High Latitudes ◽  
Range Limit ◽  
Photo Identification ◽  
Breeding Behaviour ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Northern Range Limit

Abstract We explored the breeding behaviour of a threatened amphibian, the natterjack toad, at its northern range limit in Estonia, to determine the extent to which reproduction is affected by harsh and unstable climatic conditions. Using photo identification of specimens, we found that in optimal weather conditions males formed three breeding cohorts, while in adverse conditions only a single cohort occurred and under extreme conditions reproduction was skipped entirely. During the extended breeding season, larger males participated in reproduction throughout the breeding period, while smaller males appeared in later cohorts. Breeding success was related to the calling effort of a male, where larger males had greater mating success than smaller ones. We found that the natterjack toad males exhibit significant plasticity in reproductive behaviour at the northern range limit, which, given the energetic cost of reproduction and the increased risk of predation, allows them to increase their fitness at high latitudes.

scholarly journals Predation Risk by Gastronomic Boom - Case Peru

2018 ◽  
Vol 11 (1) ◽  
pp. 100-103
Author(s):  
Aldo Alvarez-Risco ◽  
Jaime Delgado-Zegarra ◽  
Jaime A. Yáñez ◽  
Santiago Diaz-Risco ◽  
Shyla Del-Aguila-Arcentales
Keyword(s):  
Natural Resources ◽  
Predation Risk ◽  
Environmental Sustainability ◽  
Natural Sources ◽  
Risk Of Predation ◽  
Significant Damage

Abstract The growth of tourism to Peru and the gastronomic boom with millions of people looking to taste Peruvian food is resulting in a risk of predation of natural sources necessary to make these dishes. The focus in only obtaining these ingredients can generate significant damage to the Peruvian biodiversity, so stakeholders need to develop strategies to avoid predation due to the gastronomic boom. Citizens and visitors need to play a role in protecting the natural resources and contributing to environmental sustainability.

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