scholarly journals Variation in predator species abundance can cause variable selection pressure on warning signaling prey

2012 ◽  
Vol 2 (8) ◽  
pp. 1971-1976 ◽  
Author(s):  
Janne K. Valkonen ◽  
Ossi Nokelainen ◽  
Martti Niskanen ◽  
Janne Kilpimaa ◽  
Mats Björklund ◽  
...  
Keyword(s):  
Variable Selection ◽  
Selection Pressure ◽  
Species Abundance ◽  
Predator Species

scholarly journals Trait evolution under multiple selection pressures: Prey responses to predictable and unpredictable variation

2019 ◽  
Author(s):  
Manvi Sharma ◽  
Kavita Isvaran
Keyword(s):  
Variable Selection ◽  
Predation Risk ◽  
Selection Pressure ◽  
Spatial And Temporal Variation ◽  
Rock Pools ◽  
Selection Pressures ◽  
Space And Time ◽  
Natural Settings ◽  
Oviposition Sites ◽  
Desiccation Risk

AbstractWhen a strong selection pressure, such as predation risk, varies widely in space and time, how should prey respond? When risk varies predictably, prey are hypothesized to respond in a risk-sensitive manner. It is less clear how prey should respond when risk varies unpredictably.Additionally, prey response may also depend on how predation risk interacts with other selection pressures. Our understanding of the complex action of multiple and variable selection pressures on prey traits is still comparatively poor. Here, we examine how predictable and unpredictable aspects of predation risk act together with another important selection pressure to influence prey behaviour in the rock pool breeding mosquito, Aedes vexans. Through the selection of sites for oviposition, female mosquitoes can influence the predation risk faced by their offspring. We tested how females select oviposition sites, when encountering pools that vary in larval predation risk and desiccation risk. We comprehensively quantified spatial and temporal variation in predation risk by measuring densities of predatory dragonfly nymphs in rock pools of different sizes, along the mosquito breeding season. We also measured hydroperiod length. We next conducted manipulative experiments in rock pools and measured female oviposition responses to variation in predation and desiccation risks. Predation risk varied widely in space and time. Desiccation risk only appeared important for the small pools. Ovipositing females appeared to respond to these multiple aspects of variation in selection pressures. Females seemed to respond to predictable variation by avoiding large pools that permanently harboured predators in natural settings. Female responses were more variable to medium-sized pools with naturally stochastic predator densities, highlighting the role of unpredictability in predation risk in shaping behaviour. Females did not clearly prefer small pools that were naturally devoid of predators but carried high desiccation risk, suggesting that they balance multiple risks – predation versus desiccation – when choosing oviposition sites. Our study suggests that wild populations may commonly experience multiple and variable selection pressures that can favour seemingly puzzling trait variation. We highlight the need to quantify variation in selection pressures and investigate how such variation, especially the unpredictable aspects, shapes prey traits.

Variable Selection Pressure for Different Levels of Resistance to Rhizoctonia Root Rot in Sugarbeet

1988 ◽  
Vol 25 (1) ◽  
pp. 63-69 ◽  
Author(s):  
E.G. Ruppel ◽  
R.J. Hecker
Keyword(s):  
Variable Selection ◽  
Root Rot ◽  
Selection Pressure ◽  
Rhizoctonia Root Rot ◽  
Different Levels

scholarly journals On the relation amongst limnological factors and fish abundance in reservoirs at semiarid region

2015 ◽  
Vol 27 (1) ◽  
pp. 24-38 ◽  
Author(s):  
Ronaldo César Gurgel-Lourenço ◽  
Carlos Alberto de Sousa Rodrigues-Filho ◽  
Ronaldo Angelini ◽  
Danielle Sequeira Garcez ◽  
Jorge Iván Sánchez-Botero
Keyword(s):  
Dissolved Oxygen ◽  
Chlorophyll A ◽  
Rainy Season ◽  
Activity Patterns ◽  
Species Abundance ◽  
Temporal Patterns ◽  
Abundant Species ◽  
Fish Abundance ◽  
Semiarid Region ◽  
Predator Species

Aim:To evaluate possible nycthemeral and seasonal temporal patterns in fish assemblage associated with limnological aspects and biotic factors in two reservoirs in semarid Northeastern Brazil.MethodsFish were sampled with gillnets in nycthemeral cycles throughout the dry and rainy season in two reservoirs (Paulo Sarasate/PS and Edson Queiroz/EQ). The stomach contents of the predator species were surveyed. The limnological variables were submitted to principal components analysis, while their relation to fish abundance was determined by canonical correspondence analysis. Temporal patterns in relative fish species abundance were detected with nMDS.ResultsTemperature and dissolved oxygen levels segregated the reservoirs physico-chemically. Turbidity and chlorophyll-a levels differed between seasons, and the relative abundance of species differed between the reservoirs. Predators were more abundant in PS, while detritivores were more abundant in EQ. Triportheus signatusand Plagioscion squamosissimus were the most abundant species in both reservoirs. In general, predator abundance was positively associated with high temperature and dissolved oxygen (PS>EQ) and negatively associated with turbidity. The activity patterns of P. squamosissimus could not be explained by fluctuations in environmental variables. Non-predators tended to cluster around the vectors chlorophyll-a, pH and turbidity. Predators had a more diversified diet in PS in accordance with food availability, while predators in EQ ate only fish and shrimp. Nycthemeral patterns varied for the same species depending on the reservoir. Generally, in PS predators were more active during daylight hours while non-predators were more active after dark. However, in EQ predators and non-predators displayed similar nycthemeral activity patterns. Regardless of the reservoir, predators were more abundant in the rainy season. No seasonal trend was observed for non-predators.ConclusionsLimnological differences between PS and EQ influenced temporal species abundance patterns. The species distribution was determined by predation conditions and physiological attributes.

Polarity and Variable Selection Heuristics for SAT-Based Anytime MaxSAT

2020 ◽  
Vol 12 (1) ◽  
pp. 17-22
Author(s):  
Alexander Nadel
Keyword(s):  
Variable Selection ◽  
Open Source ◽  
System Description

This paper is a system description of the anytime MaxSAT solver TT-Open-WBO-Inc, which won both of the weighted incomplete tracks of MaxSAT Evaluation 2019. We implemented the recently introduced polarity and variable selection heuristics, TORC and TSB, respectively, in the Open-WBO-Inc-BMO algorithm within the open-source anytime MaxSAT solver Open-WBO-Inc. As a result, the solver is substantially more efficient.

Patterns in diversity and composition of the microbenthos of subarctic intertidal beaches with different morphodynamics

2020 ◽  
Vol 648 ◽  
pp. 19-38
Author(s):  
AI Azovsky ◽  
YA Mazei ◽  
MA Saburova ◽  
PV Sapozhnikov
Keyword(s):  
Species Abundance ◽  
Abundance Ratio ◽  
Wave Action ◽  
Coarse Grained ◽  
Sediment Properties ◽  
Β Diversity ◽  
Α Diversity ◽  
Wide Range ◽  
Similar Mode ◽  
Abundance And Diversity

Diversity and composition of benthic diatom algae and ciliates were studied at several beaches along the White and Barents seas: from highly exposed, reflective beaches with coarse-grained sands to sheltered, dissipative silty-sandy flats. For diatoms, the epipelic to epipsammic species abundance ratio was significantly correlated with the beach index and mean particle size, while neither α-diversity measures nor mean cell length were related to beach properties. In contrast, most of the characteristics of ciliate assemblages (diversity, total abundance and biomass, mean individual weight and percentage of karyorelictids) demonstrated a strong correlation to beach properties, remaining low at exposed beaches but increasing sharply in more sheltered conditions. β-diversity did not correlate with beach properties for either diatoms or ciliates. We suggest that wave action and sediment properties are the main drivers controlling the diversity and composition of the intertidal microbenthos. Diatoms and ciliates, however, demonstrated divergent response to these factors. Epipelic and epipsammic diatoms exhibited 2 different strategies to adapt to their environments and therefore were complementarily distributed along the environmental gradient and compensated for each other in diversity. Most ciliates demonstrated a similar mode of habitat selection but differed in their degree of tolerance. Euryporal (including mesoporal) species were relatively tolerant to wave action and therefore occurred under a wide range of beach conditions, though their abundance and diversity were highest in fine, relatively stable sediments on sheltered beaches, whereas the specific interstitial (i.e. genuine microporal) species were mostly restricted to only these habitats.

Trophic position scales positively with body size within but not among four species of rocky reef predators

2020 ◽  
Vol 640 ◽  
pp. 189-200 ◽  
Author(s):  
AM Olson ◽  
A Frid ◽  
JBQ dos Santos ◽  
F Juanes
Keyword(s):  
Body Size ◽  
Trophic Position ◽  
Stomach Contents ◽  
Rocky Reef ◽  
Morphometric Traits ◽  
Predator Species ◽  
Predatory Fishes ◽  
Average Size ◽  
Interspecific Comparisons ◽  
Large Predators

Intra- and interspecifically, larger-bodied predators generally occupy higher trophic positions (TPs). With widespread declines in large predators, there is a need to understand their size-based trophic roles to predict ecosystem-level responses. In British Columbia, Canada, we examined size-based trophic interactions between predatory fishes—3 rockfish species (genus Sebastes) and lingcod Ophiodon elongatus—and their prey, converting predator δ15N signatures to TP and analyzing stomach contents. Intraspecifically, TP scaled positively with predator length and gape width, but the rates of change varied by species. Interspecifically, TP did not scale positively with the observed mean sizes or known maximum sizes of species. Lingcod TP was lower than that of yelloweye and quillback rockfishes, which were 51 and 37%, respectively, smaller than lingcod. Yellowtail rockfish had the smallest average size, yet their mean TP did not differ significantly from that of lingcod. Neither species differences in some morphometric traits known to influence body size-TP relationships nor phylogenetic history explained these results. Most prey consumed were <20% of the predator’s size, which might partially explain the lack of a size-based trophic hierarchy among species. Currently, large size classes of rockfishes are being lost due to fisheries and perhaps climate-driven changes. Our findings on intraspecific size-TP relationships indicate that fishery removals of large individuals may diminish trophic structures. Interspecific comparisons of TP suggest that, along with size, species remain an important factor in understanding trophic dynamics. In addition, smaller-bodied predator species may have significant ecological roles to be considered in ecosystem-based fisheries management.

Database-Driven Modeling based on Variable Selection using Random Forest and Its Application for Linear Air Fuel Ratio Sensor Output Prediction

2019 ◽  
Vol 139 (8) ◽  
pp. 850-857
Author(s):  
Hiromu Imaji ◽  
Takuya Kinoshita ◽  
Toru Yamamoto ◽  
Keisuke Ito ◽  
Masahiro Yoshida ◽  
...  
Keyword(s):  
Random Forest ◽  
Variable Selection ◽  
Sensor Output ◽  
Fuel Ratio

Increased Moraxella and Streptococcus Species Abundance After Severe Bronchiolitis Is Associated With Recurrent Wheezing

PEDIATRICS ◽  
2020 ◽  
Vol 146 (Supplement 4) ◽  
pp. S325.1-S325
Author(s):  
Alexandra Navard-Keck ◽  
Pooja Varshney
Keyword(s):  
Species Abundance ◽  
Recurrent Wheezing ◽  
Streptococcus Species
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