Statistical Modelling of Platypus, Ornithorhynchus anatinus, Habitat Preferences Using Generalised Linear Models.

1998 ◽  
Vol 20 (2) ◽  
pp. 281
Author(s):  
B.A. Ellem ◽  
A. Bryant ◽  
A. O’Connor
Keyword(s):  
Linear Models ◽  
Habitat Preferences ◽  
River System ◽  
Statistical Modelling ◽  
Time Of Day ◽  
Seasonal Effects ◽  
Factors Affecting ◽  
Ordinal Response ◽  
Ordered Category ◽  
Ornithorhynchus Anatinus

Bryant (1993) collected extensive data on the habitat preferences of the platypus (Ornithorhynchus anatinus) measured in 36 pools in the upper Macquarie River system. Platypus presence or absence in these pools was measured on three occasions. Detailed modelling of the factors affecting pool preference was complicated by the scale of response being ordinal due to the inability of the observer to distinguish between repeated sightings of the same animal and several different animals. Initial modelling using logistic regression on a presence/absence index, collapsed from the ordinal response, discounted time of day and seasonal effects. These temporal simplifications allowed a binomial analysis of success rate based on the three visits, which identified an additional habitat factor not identified in the original analysis. Finally, a full ordinal regression of the proportions falling into each ordered category is presented as the ultimate modelling of platypus pooI preferences. The analysis indicated that length and depth of pools and the presence of overhanging vegetation were positively related to the observed presence of platypuses.

Habitat use by platypus (Ornithorhynchus anatinus) in a modified Australian Wet Tropics catchment, north-eastern Queensland

2009 ◽  
Vol 31 (1) ◽  
pp. 35 ◽  
Author(s):  
Michael Milione ◽  
Elaine Harding
Keyword(s):  
Woody Debris ◽  
Habitat Preferences ◽  
River System ◽  
Bare Soil ◽  
Large Woody Debris ◽  
Habitat Modification ◽  
Habitat Assessment ◽  
Ornithorhynchus Anatinus ◽  
North Eastern ◽  
Wet Tropics

The habitat affiliations of platypus (Ornithorhynchus anatinus) were investigated in the upper Barron River and its tributaries, a modified Wet Tropics catchment in north-eastern Queensland, Australia. A habitat assessment was carried out at 46 sites, and a visual monitoring survey was used to determine whether platypus were present at these sites. Habitat assessment of riparian and in-stream parameters included an evaluation of factors known to influence platypus populations: disturbance level, stream depth and width, riparian continuity, the amount of overhanging vegetation, bare soil along banks, large woody debris, weeds, pool and riffle area and substrate types. Sites where platypus sightings occurred were characterised by a minimum channel width of 3.8 m and slow-flowing pools with depths of 0.49–2.0 m. These findings concur with platypus habitat preferences as described in other regions, although some in-stream and riparian factors considered as important components of platypus habitat in other studies (riparian continuity, large woody debris, undercut banks and coarse stream substrate) were not associated with the presence of platypus in this study. This study represents the first investigation of the influence of human-induced habitat modification on platypus affiliations in an Australian Wet Tropics river system.

scholarly journals Factors affecting presence and relative abundance of the Endangered volcano rabbit Romerolagus diazi, a habitat specialist

Oryx ◽  
2021 ◽  
pp. 1-10
Author(s):  
Felipe Osuna ◽  
Roger Guevara ◽  
Enrique Martínez-Meyer ◽  
Raúl Alcalá ◽  
Alejandro Espinosa de los Monteros
Keyword(s):  
Sierra Nevada ◽  
Relative Abundance ◽  
Linear Models ◽  
Cattle Grazing ◽  
Patch Occupancy ◽  
Factors Affecting ◽  
Rock Cover ◽  
Volcanic Fields ◽  
Mountain Grasslands ◽  
Insight Into

Abstract Habitat specialists are particularly vulnerable to extinction when habitat conditions are altered. Information on the habitat use of such species is thus important because it provides insight into factors that influence distribution and abundance, which is crucial for conservation. Here, we aimed to identify factors that influence the patterns of presence and abundance of the Endangered volcano rabbit Romerolagus diazi, a rare leporid with a patchy distribution. Through exhaustive sampling of its range in the Sierra Chichinautzin and Sierra Nevada volcanic fields, Mexico, and using generalized linear models, we found that the probability of patch occupancy was higher where bunchgrass cover exceeded 75%, rock cover exceeded 5%, no cattle grazing was observed and human settlements were at least 7 km away. Patches with greater relative abundance were those with similar characteristics, but located at elevations > 3,600 m, and with rock cover < 15%. Cattle grazing was identified as a major threat to local populations of the volcano rabbit, particularly in the Sierra Chichinautzin. Because of the significance of bunchgrasses for this species, the protection of the mountain grasslands is required in both volcanic fields.

What Are the Factors Affecting Total Sleep Time During Video Polysomnography in Infants?

2020 ◽  
Author(s):  
Grace R. Paul ◽  
Don Hayes ◽  
Dmitry Tumin ◽  
Ish Gulati ◽  
Sudarshan Jadcherla ◽  
...  
Keyword(s):  
Total Sleep Time ◽  
Sleep Time ◽  
Time Of Day ◽  
Apnea Hypopnea Index ◽  
Clinical Factors ◽  
Initial Management ◽  
Factors Affecting ◽  
Modifiable Factors ◽  
Key Points ◽  
Medical Complexity

Objective The aim of the study is to investigate factors affecting total sleep time (TST) during infant polysomnography (PSG) and assess if <4 hours of TST is sufficient for accurate interpretation. Study Design Overall, 242 PSGs performed in 194 infants <6 months of chronological age between March 2013 and December 2015 were reviewed to identify factors that affect TST, including age of infant, location and timing of study, presence of medical complexity, and presence of nasal tubes. A continuum of apnea-hypopnea index (AHI) in relation to TST was reviewed. Data were examined in infants who had TST <4 hours and low AHI. Results Greater TST (p < 0.001) was noted among infants during nocturnal PSGs, at older chronological and post-menstrual ages, and without medical complexity. The presence of nasogastric/impedance probes reduced TST (p = 0.002). Elevated AHIs were identified even in PSGs with TST <4 hours. Short TST may have affected interpretation and delayed initial management in one infant without any inadvertent complications. Conclusion Clinical factors such as PMA and medical complexity, and potentially modifiable factors such as time of day and location of study appeared to affect TST during infant PSGs. TST < 4 hours can be sufficient to identify high AHI allowing physician interpretation. Key Points

Factors affecting pollinator visitation and reproductive success in Sonneratia caseolaris and Aegiceras corniculatum in a mangrove forest in India

2001 ◽  
Vol 17 (3) ◽  
pp. 431-447 ◽  
Author(s):  
SHALINI PANDIT ◽  
B. C. CHOUDHURY
Keyword(s):  
Reproductive Success ◽  
Mangrove Forest ◽  
Time Of Day ◽  
Pollinator Visitation ◽  
Aegiceras Corniculatum ◽  
Factors Affecting ◽  
Plant Reproductive Success ◽  
Sonneratia Caseolaris ◽  
Exclusion Experiments ◽  
Selfing Species

Pollinator visitation to, and the reproductive success of, Sonneratia caseolaris (Sonneratiaceae) and Aegiceras corniculatum (Myrsinaceae) was investigated in a mangrove forest in India. S. caseolaris was shown to be primarily outcrossed and A. corniculatum was shown to be a selfing species. The flowers of both plant species attracted several diurnal and nocturnal visitors. Earlier reports had indicated that S. caseolaris flowered for one night and was exclusively night-pollinated. But flowers of this species were found to be in bloom both at night and during the day, and diurnal visitors to the flowers were more diverse and frequent than nocturnal ones. This was related to the higher volume and energy value of nectar in the morning. The effects of time of day and temperature on visitation rates were quantified. The importance of visitors to plant reproductive success was investigated via controlled visitor-exclusion experiments. Pollinators were expected to be more important for the outcrossing species than for the selfing species, and this was confirmed by the results of the exclusion experiments. In S. caseolaris reproductive success was determined both by pollinator availability and the intensity of flower and fruit predation, while in A. corniculatum it is likely to be resource limited.

scholarly journals The habitat preferences of fishes from the Limpopo river system, Transvaal and Mocambique

Koedoe ◽  
1973 ◽  
Vol 16 (1) ◽  
Author(s):  
I.G. Gaigher
Keyword(s):  
Species Composition ◽  
Habitat Preferences ◽  
River System ◽  
Frequency Of Occurrence ◽  
Check List

The species composition of fishes in the Limpopo River system is described. The frequency of occurrence for eachhabitat type is expressed as a percentage of the habitats sampled. A check list of species is presented and the species can be grouped into five habitat preferences.

scholarly journals The Impacts of Flowering Time and Tillering on Grain Yield of Sorghum Hybrids across Diverse Environments

2019 ◽  
Author(s):  
Xuemin Wang ◽  
Colleen Hunt ◽  
Alan Cruickshank ◽  
Emma Mace ◽  
Graeme Hammer ◽  
...  
Keyword(s):  
Grain Yield ◽  
Flowering Time ◽  
Genetic Background ◽  
Linear Models ◽  
Genetic Correlations ◽  
Environment Interaction ◽  
Canopy Development ◽  
Factors Affecting ◽  
Sorghum Production ◽  
Relationship Of

Sorghum in Australia is grown in water-limited environments of varying extent, generating substantial genotype &times; environment interaction (GEI). Much of the yield variation and GEI results from variations in flowering time and tillering through their effects on canopy development. The confounding effects of flowering and tillering complicate the interpretation of breeding trials. In this study, we evaluated the impacts of both flowering time (DTF) and tillering capacity (FTN) on yield of 1741 unique test hybrids derived from three common female testers in 21 yield testing trials (48 tester/trial combinations) across the major sorghum production regions in Australia in three seasons. Contributions of DTF and FTN to genetic variation in grain yield were significant in 14 and 12 tester/trial combinations, respectively. The proportion of genetic variance in grain yield explained by DTF and FTN ranged from 0.2% to 61.0% and from 1.4% to 56.9%, respectively, depending on trials and genetic background of female testers. The relationship of DTF or FTN with grain yield of hybrids was frequently positive, but varied across the genetic background of testers. Accounting for the effects of DTF and FTN using linear models did not substantially increase the between trial genetic correlations for grain yield. The results suggested that other factors affecting canopy development dynamics and grain yield might contribute GEI and/or the linear approach to account for DTF and FTN on grain yield did not capture the complex non-linear interactions.

scholarly journals The Analysis of Reproduction in Population of the Slovak Spotted Dairy Cows

2019 ◽  
Vol 67 (6) ◽  
pp. 1419-1426
Author(s):  
Jozef Bujko ◽  
Juraj Candrák ◽  
Peter Strapák ◽  
Július Žitný ◽  
Cyril Hrnčár ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Fixed Effects ◽  
Linear Models ◽  
Correlation Coefficients ◽  
Calving Interval ◽  
Factors Affecting ◽  
Actual Computation ◽  
Reproduction Traits ◽  
Days Open ◽  
Basic Statistical Analysis

The aim of study was to analyse the reproduction and factors affecting on reproduction traits of dairy cows in population of Slovak Spotted cattle from 2007 to 2016 the results for 37,274 dairy cows: days to first service (DFS), days open (DO), number of inseminations per conception (NIC), age of first calving (AFC) and calving interval (CI). The basic statistical analysis were analysed using the SAS version 9.3. For the actual computation a linear models with fixed effects was used: For the actual computation a linear models with fixed effects was used: yijklm = μ + HYSi + BTj+ Fk+ Bl +eijklm. The linear model represents coefficients determination R2 = 0.452117% (P < 0.001) for DFS, R2 = 0.377715% (P < 0.001) for DO, R2 = 0.348442% (P < 0.001) for NIC and R2 = 0.317128% (P < 0.001) for CI with all fixed effects. Correlation coefficients among DFS with DO, NIC, AFC and CI were r = 0.37275, r = -0.06881, r = 0.06493 and r = 0.08348. These coefficients were highly statistically significant (P < 0.001).

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