scholarly journals Integrating the host plant phylogeny, plant traits, intraspecific competition and repeated measures using a phylogenetic mixed model of field behaviour by polyphagous herbivores, the leaf-cutting ants

2019 ◽  
Author(s):  
Manasee Weerathunga ◽  
Alexander S. Mikheyev
Keyword(s):  
Tree Species ◽  
Repeated Measures ◽  
Foraging Behaviour ◽  
Mixed Model ◽  
Plant Traits ◽  
Relative Role ◽  
Complex Investigation ◽  
Plant Phylogeny ◽  
Wide Range ◽  
Leaf Cutting

Herbivores use a wide range of factors to choose their host, including their own physiological states, physical characteristics of plants, and the degree of competition. Field observations of herbivores in their native habitats provide a means for simultaneously estimating the relative importance of these factors, but statistical analysis of all these factors may be challenging. Here we used a 7-wk dataset of leaf-cutting ant (Atta cephalotes) foraging in a diverse neotropical arboretum containing 193 tree species (822 trees) to examine the relative role of tree phylogeny, territoriality and tree functional characteristics using a phylogenetic generalized least squares (PGLS) model. We observed that 54 tree species (117 trees) were foraged by the ants. This pattern was not random, but reflected known features of leaf-cutting ant foraging behaviour, such as the preference for larger trees and the decreased likelihood of foraging at the periphery of a colony’s territory. However, random effects such as tree phylogeny, the identity of individual trees and colony-specific effects, explained most of the variation in foraging data. A significant phylogenetic effect on foraging likelihood (λ = 0.28), together with repeated measures of foraging on the same tree species, allowed estimation of relative palatability for each plant species. PGLS models can be flexibly scaled to include other covariates for even more complex investigation of foraging behaviour, and the link function can be modified to include the amount of plants foraged. As a result, PGLS can be used as a flexible framework for the study of LCA foraging.

scholarly journals Integrating host plant phylogeny, plant traits, intraspecific competition and repeated measures using a phylogenetic mixed model of field behaviour by polyphagous herbivores, the leaf-cutting ants

2020 ◽  
Vol 36 (2) ◽  
pp. 80-86
Author(s):  
Manasee Weerathunga ◽  
Alexander S. Mikheyev
Keyword(s):  
Tree Species ◽  
Repeated Measures ◽  
Foraging Behaviour ◽  
Mixed Model ◽  
Plant Traits ◽  
Relative Role ◽  
Complex Investigation ◽  
Plant Phylogeny ◽  
Wide Range ◽  
Leaf Cutting

AbstractHerbivores use a wide range of factors to choose their host, including their own physiological states, physical characteristics of plants and the degree of competition. Field observations of herbivores in their native habitats provide a means for simultaneously estimating the relative importance of these factors, but statistical analysis of all these factors may be challenging. Here we used a 7-week dataset of leaf-cutting ant (Atta cephalotes) foraging in a diverse Neotropical arboretum containing 193 tree species (822 trees) to examine the relative role of tree phylogeny, territoriality and tree functional characteristics using a phylogenetic generalized least squares (PGLS) model. We observed that 54 tree species (117 trees) were foraged by the ants. This pattern was not random, but reflected known features of leaf-cutting ant foraging behaviour, such as a preference for larger trees and the decreased likelihood of foraging at the periphery of a colony’s territory. However, random effects such as tree phylogeny, the identity of individual trees and colony-specific effects explained most of the variation in foraging data. A significant phylogenetic effect on foraging likelihood (λ = 0.28), together with repeated measures of foraging on the same tree species, allowed estimation of relative palatability for each plant species. PGLS models can be flexibly scaled to include other covariates for even more complex investigation of foraging behaviour, and the link function can be modified to include the amount of plants foraged. As a result, PGLS can be used as a flexible framework for the study of LCA foraging.

Size-related foraging behaviour of the leaf-cutting ant Atta colombica

1991 ◽  
Vol 69 (6) ◽  
pp. 1530-1533 ◽  
Author(s):  
Dave Shutler ◽  
Adele Mullie
Keyword(s):  
Body Size ◽  
Leaf Litter ◽  
Tree Species ◽  
Foraging Behaviour ◽  
Foraging Theory ◽  
Costa Rican ◽  
Leaf Cutting ◽  
Foraging Trail ◽  
Atta Colombica ◽  
Load Mass

In a Costa Rican forest adjacent to cattle pasture, larger individuals of the leaf-cutting ant Atta colombica carried heavier loads and foraged farther from the colony, as predicted by foraging theory. Counter to foraging theory, individual ants did not increase their load mass if they foraged farther from the colony. However, the colony avoided this apparent inefficiency by sending larger ants to more distant trees. The colony harvested simultaneously from several individuals of the same tree species, even though distant trees were twice as far from the colony as nearby trees. The reasons for this behaviour require further investigation. In a wide foraging trail, larger ants travelled faster than their smaller counterparts. In addition, ant velocity was reduced when loads were experimentally supplemented, and increased when loads were experimentally reduced. Ants using narrow trails in the leaf litter may all be constrained to travel at the same speed, irrespective of load or body size, simply because they get in each other's way.

Tone, Rhythm, and Timbre Perception in School-Age Children Using Cochlear Implants and Hearing Aids

2013 ◽  
Vol 24 (09) ◽  
pp. 789-806 ◽  
Author(s):  
Hamish Innes-Brown ◽  
Jeremy P. Marozeau ◽  
Christine M. Storey ◽  
Peter J. Blamey
Keyword(s):  
Hearing Loss ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
School Age Children ◽  
Impaired Hearing ◽  
School Year ◽  
Temporal Cues ◽  
Wide Range

Background: Children with hearing impairments, especially those using hearing devices such as the cochlear implant (CI) or hearing aid (HA), are sometimes not encouraged to attend music classes, as they or their parents and teachers may be unsure whether the child can perform basic musical tasks. Purpose: The objective of the current study was to provide a baseline for the performance of children using CIs and HAs on standardized tests of rhythm and pitch perception as well as an instrument timbre identification task. An additional aim was to determine the effect of structured music training on these measures during the course of a school year. Research Design: The Intermediate Measures of Music Audiation (IMMA) Tonal and Rhythmic subtests were administered four times, with 6 wk between tests. All children in the study were also enrolled in “Music Club” teaching sessions. Measures were compared between groups and across the four testing sessions. Study Sample: Twenty children from a single school in Melbourne, Australia, were recruited. Eleven (four girls) had impaired hearing, including six with a unilateral CI or CI and HA together (two girls) and five with bilateral HAs (two girls). Nine were normally hearing, selected to match the age and gender of the hearing-impaired children. Ages ranged from 9–13 yr. Intervention: All children participated in a weekly Music Club – a 45 min session of musical activities based around vocal play and the integration of aural, visual, and kinesthetic modes of learning. Data Collection and Analysis: Audiological data were collected from clinical files. IMMA scores were converted to percentile ranks using published norms. Between-group differences were tested using repeated-measures analysis of variance, and between-session differences were tested using a linear mixed model. Linear regression was used to model the effect of hearing loss on the test scores. Results: In the first session, normally hearing children had a mean percentile rank of ˜50 in both the Tonal and Rhythmic subtests of the IMMA. Children using CIs showed trends toward lower scores in the Tonal, but not the Rhythmic, subtests. No significant improvements were found between sessions. In the timbre test, children generally made fewer errors within the set of percussive compared to nonpercussive instruments. The hearing loss level partially predicted performance in the Tonal, but not the Rhythmic, task, and predictions were more significant for nonpercussive compared to percussive instruments. Conclusions: The findings highlight the importance of temporal cues in the perception of music, and indicate that temporal cues may be used by children with CIs and HAs in the perception of not only rhythm, but also of some aspects of timbre. We were not able to link participation in the Music Club with increased scores on the Tonal, Rhythmic, and Timbre tests. However, anecdotal evidence from the children and their teachers suggested a wide range of benefits from participation in the Music Club that extended from increased engagement and interest in music classes into the children's social situations.

scholarly journals Innovation in groups: does the proximity of others facilitate or inhibit performance?

Behaviour ◽  
2009 ◽  
Vol 146 (11) ◽  
pp. 1543-1564 ◽  
Author(s):  
Julie Morand-Ferron ◽  
Sarah Overington ◽  
Laure Cauchard ◽  
Louis Lefebvre
Keyword(s):  
Social Context ◽  
Food Processing ◽  
Repeated Measures ◽  
Feeding Behaviour ◽  
Foraging Behaviour ◽  
Alarm Calls ◽  
Direct Effects ◽  
Repeated Measures Design ◽  
Wide Range ◽  
Novel Behaviour

AbstractForaging innovation, in which an individual eats a novel food or uses a novel foraging technique, has been observed in a wide range of species. If other individuals are nearby, they may adopt the innovation, thus spreading it through the population. Much research has focused on this social transmission of behaviour, but the effect of social context on the emergence of novel behaviour is unclear. Here, we examine the effect of social context on innovative feeding behaviour in the Carib grackle (Quiscalus lugubris), an opportunistic, gregarious bird. We test the effect of the proximity of conspecifics, while eliminating the direct effects of interference, scrounging, or aggression. Using a repeated-measures design, we found that birds took significantly longer to contact novel foraging tasks when in the presence of others vs. alone, and during playbacks of alarm calls vs. a control sound. Further, performance of a food-processing behaviour decreased when birds were with others, and individuals adjusted their behaviour depending on their distance from conspecifics. Our results suggest that feeding in groups may slow down or inhibit innovative foraging behaviour in this species. We discuss the implications of a trade-off between feeding in groups and taking advantage of new feeding opportunities.

Spatial Distribution of a Tree Trunk Specialist Spider: Relative Role of Landscape Versus Microhabitat Drivers

2020 ◽  
Vol 49 (4) ◽  
pp. 963-973
Author(s):  
Michael L Draney ◽  
Jason C Doll ◽  
Lydia R Doerr ◽  
Christopher J Houghton ◽  
Patrick S Forsythe
Keyword(s):  
Spatial Distribution ◽  
Spatial Autocorrelation ◽  
Tree Species ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Random Effect ◽  
Species Selection ◽  
Model Parameters ◽  
Relative Role ◽  
Paper Birch

Abstract By completely censusing a 1 ha forest dynamics plot it was possible to identify the variables (spider mass, size, sex and tree species, size, and bark roughness) that influenced the spatial distribution of adult Drapetisca alteranda Chamberlin 1909 (Araneae: Linyphiidae), a sheet web spider that specializes in lower tree trunks in North American forests. To account for spatial autocorrelation, a conditional autoregressive random effect was included in the zero-inflated Poisson generalized linear mixed model. Parameters estimated were produced by Bayesian inference with vague prior probability distributions and the best of 16 models were selected using Watanabe-Akaike Information Criterion. The best model showed that larger diameter trees located at higher plot elevations were more likely to have D. alteranda present. Smooth bark tree species such as paper birch and American basswood tended to have the most spiders while rough bark species had the least. The relationship between tree diameter and D. alteranda abundance also varied by tree species. Paper birch and quaking aspen tend to produce a greater slope compared to the other species, indicating that as these trees get larger, the abundance of D. alteranda increases at a higher rate than on other tree species. Spider sex and size were not associated with height on the trunk or tree species selection, nor were they associated with microhabitats such as bark furrow depth. Landscape-level factors largely predict D. alteranda abundance and distribution, suggesting that spatial autocorrelation should be considered when modeling the abundance of even small organisms, such as spiders.

Effects of Aging on the Subcortical Encoding of Stop Consonants

2020 ◽  
Vol 29 (3) ◽  
pp. 391-403
Author(s):  
Dania Rishiq ◽  
Ashley Harkrider ◽  
Cary Springer ◽  
Mark Hedrick
Keyword(s):  
Older Adults ◽  
Repeated Measures ◽  
Mixed Model ◽  
Auditory Brainstem ◽  
Auditory Brainstem Responses ◽  
Aging Effects ◽  
Formant Frequency ◽  
Place Of Articulation ◽  
Second Formant ◽  
Effects Of Aging

Purpose The main purpose of this study was to evaluate aging effects on the predominantly subcortical (brainstem) encoding of the second-formant frequency transition, an essential acoustic cue for perceiving place of articulation. Method Synthetic consonant–vowel syllables varying in second-formant onset frequency (i.e., /ba/, /da/, and /ga/ stimuli) were used to elicit speech-evoked auditory brainstem responses (speech-ABRs) in 16 young adults ( M age = 21 years) and 11 older adults ( M age = 59 years). Repeated-measures mixed-model analyses of variance were performed on the latencies and amplitudes of the speech-ABR peaks. Fixed factors were phoneme (repeated measures on three levels: /b/ vs. /d/ vs. /g/) and age (two levels: young vs. older). Results Speech-ABR differences were observed between the two groups (young vs. older adults). Specifically, older listeners showed generalized amplitude reductions for onset and major peaks. Significant Phoneme × Group interactions were not observed. Conclusions Results showed aging effects in speech-ABR amplitudes that may reflect diminished subcortical encoding of consonants in older listeners. These aging effects were not phoneme dependent as observed using the statistical methods of this study.

Power of Modified Brown-Forsythe and Mixed-Model Approaches in Split-Plot Designs

Methodology ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Pablo Livacic-Rojas ◽  
Guillermo Vallejo ◽  
Paula Fernández ◽  
Ellián Tuero-Herrero
Keyword(s):  
Repeated Measures ◽  
Statistical Power ◽  
Mixed Model ◽  
Covariance Structure ◽  
Simulation Method ◽  
Future Research ◽  
Repeated Measures Design ◽  
Fixed And Random Effects ◽  
Split Plot ◽  
High Level

Abstract. Low precision of the inferences of data analyzed with univariate or multivariate models of the Analysis of Variance (ANOVA) in repeated-measures design is associated to the absence of normality distribution of data, nonspherical covariance structures and free variation of the variance and covariance, the lack of knowledge of the error structure underlying the data, and the wrong choice of covariance structure from different selectors. In this study, levels of statistical power presented the Modified Brown Forsythe (MBF) and two procedures with the Mixed-Model Approaches (the Akaike’s Criterion, the Correctly Identified Model [CIM]) are compared. The data were analyzed using Monte Carlo simulation method with the statistical package SAS 9.2, a split-plot design, and considering six manipulated variables. The results show that the procedures exhibit high statistical power levels for within and interactional effects, and moderate and low levels for the between-groups effects under the different conditions analyzed. For the latter, only the Modified Brown Forsythe shows high level of power mainly for groups with 30 cases and Unstructured (UN) and Autoregressive Heterogeneity (ARH) matrices. For this reason, we recommend using this procedure since it exhibits higher levels of power for all effects and does not require a matrix type that underlies the structure of the data. Future research needs to be done in order to compare the power with corrected selectors using single-level and multilevel designs for fixed and random effects.

Biscogniauxia (Hypoxylon) Canker or Dieback in Trees

EDIS ◽  
2017 ◽  
Vol 2017 (6) ◽  
Author(s):  
Claudia Paez ◽  
Jason A. Smith
Keyword(s):  
Water Stress ◽  
Tree Species ◽  
Soil Compaction ◽  
Urban Areas ◽  
Root Disease ◽  
Poor Health ◽  
Green Spaces ◽  
Opportunistic Pathogens ◽  
Wide Range ◽  
Quercus Spp

Biscogniauxia canker or dieback (formerly called Hypoxylon canker or dieback) is a common contributor to poor health and decay in a wide range of tree species (Balbalian & Henn 2014). This disease is caused by several species of fungi in the genus Biscogniauxia (formerly Hypoxylon). B. atropunctata or B. mediterranea are usually the species found on Quercus spp. and other hosts in Florida, affecting trees growing in many different habitats, such as forests, parks, green spaces and urban areas (McBride & Appel, 2009).  Typically, species of Biscogniauxia are opportunistic pathogens that do not affect healthy and vigorous trees; some species are more virulent than others. However, once they infect trees under stress (water stress, root disease, soil compaction, construction damage etc.) they can quickly colonize the host. Once a tree is infected and fruiting structures of the fungus are evident, the tree is not likely to survive especially if the infection is in the tree's trunk (Anderson et al., 1995).

Long-term seizure outcomes after pediatric temporal lobectomy: does brain MRI lesion matter?

2019 ◽  
Vol 24 (2) ◽  
pp. 200-208
Author(s):  
Ravindra Arya ◽  
Francesco T. Mangano ◽  
Paul S. Horn ◽  
Sabrina K. Kaul ◽  
Serena K. Kaul ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Hippocampal Sclerosis ◽  
Brain Mri ◽  
Temporal Lobectomy ◽  
Seizure Freedom ◽  
Seizure Onset

OBJECTIVEThere is emerging data that adults with temporal lobe epilepsy (TLE) without a discrete lesion on brain MRI have surgical outcomes comparable to those with hippocampal sclerosis (HS). However, pediatric TLE is different from its adult counterpart. In this study, the authors investigated if the presence of a potentially epileptogenic lesion on presurgical brain MRI influences the long-term seizure outcomes after pediatric temporal lobectomy.METHODSChildren who underwent temporal lobectomy between 2007 and 2015 and had at least 1 year of seizure outcomes data were identified. These were classified into lesional and MRI-negative groups based on whether an epilepsy-protocol brain MRI showed a lesion sufficiently specific to guide surgical decisions. These patients were also categorized into pure TLE and temporal plus epilepsies based on the neurophysiological localization of the seizure-onset zone. Seizure outcomes at each follow-up visit were incorporated into a repeated-measures generalized linear mixed model (GLMM) with MRI status as a grouping variable. Clinical variables were incorporated into GLMM as covariates.RESULTSOne hundred nine patients (44 females) were included, aged 5 to 21 years, and were classified as lesional (73%), MRI negative (27%), pure TLE (56%), and temporal plus (44%). After a mean follow-up of 3.2 years (range 1.2–8.8 years), 66% of the patients were seizure free for ≥ 1 year at last follow-up. GLMM analysis revealed that lesional patients were more likely to be seizure free over the long term compared to MRI-negative patients for the overall cohort (OR 2.58, p < 0.0001) and for temporal plus epilepsies (OR 1.85, p = 0.0052). The effect of MRI lesion was not significant for pure TLE (OR 2.64, p = 0.0635). Concordance of ictal electroencephalography (OR 3.46, p < 0.0001), magnetoencephalography (OR 4.26, p < 0.0001), and later age of seizure onset (OR 1.05, p = 0.0091) were associated with a higher likelihood of seizure freedom. The most common histological findings included cortical dysplasia types 1B and 2A, HS (40% with dual pathology), and tuberous sclerosis.CONCLUSIONSA lesion on presurgical brain MRI is an important determinant of long-term seizure freedom after pediatric temporal lobectomy. Pediatric TLE is heterogeneous regarding etiologies and organization of seizure-onset zones with many patients qualifying for temporal plus nosology. The presence of an MRI lesion determined seizure outcomes in patients with temporal plus epilepsies. However, pure TLE had comparable surgical seizure outcomes for lesional and MRI-negative groups.

scholarly journals Fungal-Fungal Interactions in Leaf-Cutting Ant Agriculture

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Sunshine A. Van Bael ◽  
Catalina Estrada ◽  
William T. Wcislo
Keyword(s):  
Plant Traits ◽  
Secondary Compounds ◽  
Future Research ◽  
Ecological Interactions ◽  
Tropical Plants ◽  
Symbiotic Relationships ◽  
Complex Interactions ◽  
Symbiotic Fungi ◽  
Leaf Cutting ◽  
Fungal Interactions

Many organisms participate in symbiotic relationships with other organisms, yet studies of symbioses typically have focused on the reciprocal costs and benefits within a particular host-symbiont pair. Recent studies indicate that many ecological interactions involve alliances of symbionts acting together as mutualistic consortia against other consortia. Such interacting consortia are likely to be widespread in nature, even if the interactions often occur in a cryptic fashion. Little theory and empirical data exist concerning how these complex interactions shape ecological outcomes in nature. Here, we review recent work on fungal-fungal interactions between two consortia: (i) leaf-cutting ants and their symbiotic fungi (the latter grown as a food crop by the former) and (ii) tropical plants and their foliar endophytes (the cryptic symbiotic fungi within leaves of the former). Plant characteristics (e.g., secondary compounds or leaf physical properties of leaves) are involved in leaf-cutting ant preferences, and a synthesis of published information suggests that these plant traits could be modified by fungal presence. We discuss potential mechanisms for how fungal-fungal interactions proceed in the leaf-cutting ant agriculture and suggest themes for future research.

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