Silky sifaka (Propithecus candidus) use sleep sites for thermoregulation, food access and predator avoidance

2021 ◽  
Author(s):  
Catriona Jade Mills ◽  
K.A.I. Nekaris ◽  
Marco Campera ◽  
Erik Patel
Keyword(s):  
Food Access ◽  
Linear Models ◽  
Ecological Factors ◽  
Generalised Linear Models ◽  
Predation Avoidance ◽  
Cryptoprocta Ferox ◽  
Risk Of Predation ◽  
Site Use ◽  
Number Of Individuals ◽  
Silky Sifaka

Primate sleeping site selection is influenced by multiple ecological factors including predation avoidance, thermoregulation, and food access. To test these hypotheses, we studied the sleeping trees used by a group of wild silky sifakas (Propithecus candidus) in Marojejy National Park, Madagascar. During this ten-month study, the group slept in 828 sleeping trees from approximately 35 genera. In support of thermoregulation, generalised linear models revealed that as temperature decreased, the number of individuals sleeping together significantly increased and they slept at further distances from the trunk. As rainfall increased, sleep site height significantly increased. Weinmannia was the most frequented tree genus, despite low abundance, accounting for 29% of all sleeping trees. In support of food access, 94.8% of sleeping trees were food trees. Weinmannia is among the most highly preferred food trees. The group slept at a mean height of 16.0 m near the top of tall trees which averaged 19.5 m. Sleep trees were significantly taller than trees in botanical plots within the sifaka’s home range. They never slept in the same trees on consecutive nights, and sleeping heights were significantly higher than daytime heights which is consistent with predation avoidance. Social sleeping in groups of two or three individuals (62.9%) was more common than solitary sleeping (37.1%). At such heights, huddling may increase vigilance and lessen the risk of predation by the fossa (Cryptoprocta ferox) while also reducing heat loss. These patterns suggest that silky sifaka sleep site choice is influenced by thermoregulation and food access in addition to predation avoidance. We suggest that understanding sleep site use can assist in conservation of species like silky sifakas by enabling researchers to find new groups, protect habitats with key tree species, and inform reforestation efforts.

Nonnull asymptotic distributions of three classic criteria in generalised linear models

Biometrika ◽  
1994 ◽  
Vol 81 (4) ◽  
pp. 709-720 ◽  
Author(s):  
GAUSS M. CORDEIRO ◽  
DENISE A. BOTTER ◽  
SILVIA L. DE PAULA FERRARI
Keyword(s):  
Linear Models ◽  
Asymptotic Distributions ◽  
Generalised Linear Models

scholarly journals Ecological preference of the diving bell spider Argyroneta aquatica in a resurgence of the Po plain (Northern Italy) (Araneae: Cybaeidae)

2016 ◽  
Vol 48 (1) ◽  
pp. 9 ◽  
Author(s):  
Stefano Mammola ◽  
Riccardo Cavalcante ◽  
Marco Isaia
Keyword(s):  
Ecological Study ◽  
Aquatic Vegetation ◽  
Linear Models ◽  
Prey Availability ◽  
Ecological Factors ◽  
Northern Italy ◽  
Aquatic Life ◽  
Po Plain ◽  
Ecological Importance ◽  
Positive Effect

The diving bell spider <em>Argyroneta aquatica</em> is the only known spider to conduct a wholly aquatic life. For this reason, it has been the object of an array of studies concerning different aspects of its peculiar biology such as reproductive behavior and sexual dimorphism, physiology, genetic and silk. On the other hand, besides some empirical observations, the autoecology of this spider is widely understudied. We conducted an ecological study in a resurgence located in the Po Plain (Northern Italy, Province of Vercelli) hosting a relatively rich population of <em>Argyroneta</em> <em>aquatica</em>, aiming at identifying the ecological factors driving its presence at the micro-habitat level. By means of a specific sampling methodology, we acquired distributional data of the spiders in the study area and monitored physical-chemical and habitat structure parameters at each plot. We analyzed the data through Bernoulli Generalized Linear Models (GLM). Results pointed out a significant positive effect of the presence of aquatic vegetation in the plot. In addition, the presence of <em>A. aquatica</em> was significantly associated with areas of the resurgence characterized at the same time by high prey availability and low density of predators. Considering the ecological importance and rarity of this species, we update and revise the data on the distribution of <em>A. aquatica</em> in Italy.

Second order asymptotics for score tests in generalised linear models

Biometrika ◽  
1995 ◽  
Vol 82 (2) ◽  
pp. 426-432 ◽  
Author(s):  
FRANCISCO CRIBARI-NETO ◽  
SILVIA L. P. FERRARI
Keyword(s):  
Linear Models ◽  
Second Order ◽  
Generalised Linear Models ◽  
Score Tests ◽  
Second Order Asymptotics

Intensification of future low-flow events in relation to projected changes in large-scale climate drivers due to climate change

2021 ◽  
Author(s):  
Pallavi Goswami ◽  
Arpita Mondal ◽  
Christoph Rüdiger ◽  
Tim J. Peterson
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Linear Models ◽  
Southern Oscillation ◽  
Value Theory ◽  
Extreme Value ◽  
Low Flow ◽  
Generalised Linear Models ◽  
Southeast Australia ◽  
The Future

&lt;p&gt;Large-scale climate processes such as the El Nino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Southern Annular Mode (SAM) influence the hydro-climatology of Southeast Australia (SEA). In the present study, we show that low-flow events in many catchments in SEA are significantly influenced by variability in these climate drivers. Extreme value distributions and Generalised Linear Models (GLMs) are used here to model low-flow characteristics such as intensity, duration and frequency with respect to these climate drivers. Further, we study how the future projections of ENSO, IOD and SAM are likely to evolve under climate change by examining the projected values of their representative indices and how they will impact low-flow events in the region. It is found that the future dry phases of these climate drivers are likely to be more dry than those in the historic period. This in turn is expected to lead to intensification of low-flow events in the future, resulting in lower availability of fresh water during occurrences of the dry phases of these climate drivers. Thus, climate change in the future is expected to significantly influence future low-flow events in the region thereby making it even more crucial for water managers to adequately manage and ensure water availability.&lt;/p&gt;&lt;p&gt;&lt;br&gt;Keywords: low-flows, ENSO, IOD, SAM, Extreme Value Theory, Generalised Linear Models, Southeast Australia, CMIP5, RCP8.5.&lt;/p&gt;

Integral projection models

2021 ◽  
pp. 181-196
Author(s):  
Edgar J. González ◽  
Dylan Z. Childs ◽  
Pedro F. Quintana-Ascencio ◽  
Roberto Salguero-Gómez
Keyword(s):  
Population Dynamics ◽  
Environmental Variables ◽  
Linear Models ◽  
Vital Rates ◽  
Matrix Population Models ◽  
Generalised Linear Models ◽  
Integral Projection Models ◽  
Integral Projection ◽  
Over Time

Integral projection models (IPMs) allow projecting the behaviour of a population over time using information on the vital processes of individuals, their state, and that of the environment they inhabit. As with matrix population models (MPMs), time is treated as a discrete variable, but in IPMs, state and environmental variables are continuous and are related to the vital rates via generalised linear models. Vital rates in turn integrate into the population dynamics in a mechanistic way. This chapter provides a brief description of the logic behind IPMs and their construction, and, because they share many of the analyses developed for MPMs, it only emphasises how perturbation analyses can be performed with respect to different model elements. The chapter exemplifies the construction of a simple and a more complex IPM structure with an animal and a plant case study, respectively. Finally, inverse modelling in IPMs is presented, a method that allows population projection when some vital rates are not observed.

scholarly journals Lifetime, 5-year and past-year prevalence of homelessness in Europe: a cross-national survey in eight European nations

BMJ Open ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. e033237 ◽  
Author(s):  
Owen Taylor ◽  
Sandrine Loubiere ◽  
Aurelie Tinland ◽  
Maria Vargas-Moniz ◽  
Freek Spinnewijn ◽  
...  
Keyword(s):  
Service Use ◽  
Linear Models ◽  
Pairwise Comparison ◽  
Response Rates ◽  
Computer Assisted ◽  
Generalised Linear Models ◽  
The Past ◽  
History Of ◽  
Nationally Representative ◽  
Difference Test

ObjectivesTo examine the lifetime, 5-year and past-year prevalence of homelessness among European citizens in eight European nations.DesignA nationally representative telephone survey using trained bilingual interviewers and computer-assisted telephone interview software.SettingThe study was conducted in France, Ireland, Italy, the Netherlands, Poland, Portugal, Spain and Sweden.ParticipantsEuropean adult citizens, selected from opt-in panels from March to December 2017. Total desired sample size was 5600, with 700 per country. Expected response rates of approximately 30% led to initial sample sizes of 2500 per country.Main outcome measuresHistory of homelessness was assessed for lifetime, past 5 years and past year. Sociodemographic data were collected to assess correlates of homelessness prevalence using generalised linear models for clustered and weighted samples.ResultsResponse rates ranged from 30.4% to 33.5% (n=5631). Homelessness prevalence was 4.96% for lifetime (95% CI 4.39% to 5.59%), 1.92% in the past 5 years (95% CI 1.57% to 2.33%) and 0.71% for the past year (95% CI 0.51% to 0.98%) and varied significantly between countries (pairwise comparison difference test, p<0.0001). Time spent homeless ranged between less than a week (21%) and more than a year (18%), with high contrasts between countries (p<0.0001). Male gender, age 45–54, lower secondary education, single status, unemployment and an urban environment were all independently strongly associated with lifetime homelessness (all OR >1.5).ConclusionsThe prevalence of homelessness among the surveyed nations is significantly higher than might be expected from point-in-time and homeless service use statistics. There was substantial variation in estimated prevalence across the eight nations. Coupled with the well-established health impacts of homelessness, medical professionals need to be aware of the increased health risks of those with experience of homelessness. These findings support policies aiming to improve health services for people exposed to homelessness.

Redefining the deviance objective for generalised linear models

2012 ◽  
Vol 17 (3) ◽  
pp. 491-509
Author(s):  
A. C. Lovick ◽  
P. K. W. Lee
Keyword(s):  
Linear Models ◽  
Patent Application ◽  
Generalised Linear Models ◽  
Number Of Factors ◽  
Efficient Calculation ◽  
Unseen Data ◽  
Data Points ◽  
New Material ◽  
Price Comparison Sites ◽  
Generalised Linear Modelling

AbstractThis paper defines the ‘Case Deleted’ Deviance - a new objective function for evaluating Generalised Linear Models, and applies this to a number of practical examples in the pricing of general insurance. The paper details practical approximations to enable the efficient calculation of the objective, and derives modifications to the standard Generalised Linear Modelling algorithm to allow the derivation of scaled parameters from this measure to reduce potential over fitting to historical data. These scaled parameters improve the predictiveness of the model when applied to previously unseen data points, the most likely being related to future business written. The potential for over fitting has increased due to number of factors now used, particularly in pricing personal lines business and the advent of price comparison sites which has increased the penalties of mis-estimation. New material in this paper has been included in a UK patent application No. 1020091.3.

Evolution of insect morphology in relation to plants

1991 ◽  
Vol 333 (1267) ◽  
pp. 257-264 ◽  
Keyword(s):  
Rapid Evolution ◽  
Ecological Factors ◽  
Handling Time ◽  
Short Review ◽  
Morphological Adaptations ◽  
Plant Chemical ◽  
Risk Of Predation ◽  
Two Factors ◽  
Concomitant Reduction ◽  
Plant Ecological

This short review points out some of the major physical problems faced by insects feeding on plants, and some of the kinds of morphological adaptations that have been noted to date. Major emphasis is given to two factors: the nature of the plant surface, and the difficulty of dealing with hard or tough food. The surface provides a great variety of terrains that require specialization for maximizing tenacity and agility, especially for small insects. It is suggested that natural enemies may provide significant selection for the relevant morphologies. The difficulty of feeding upon certain plant tissues is shown to be overcome in different ways by different herbivore groups. In the case of tough leaves for example, grasshopper mandible adaptations appear to have evolved to maximize efficiency of processing. On the other hand, in the case of caterpillars, mandible adaptations for tough food appear to be minimizing handling time with a concomitant reduction in risk of predation. Convergent evolution is shown in both grasshoppers and caterpillars for dealing with leaves of similar design and an example is given of rapid evolution of mouthpart morphology in response to differences in host characteristics. These examples are used to indicate the risks of using such characters in establishing phylogenetic relationships. Finally, it is pointed out that plant chemical qualities and plant ecological factors can influence insect morphological features.

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