scholarly journals Game of webs: species and web structure influence contest outcome in black widow spiders

2019 ◽  
Vol 31 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Cameron Jones ◽  
Lea Pollack ◽  
Nicholas DiRienzo
Keyword(s):  
Individual Variation ◽  
Native Species ◽  
Interspecific Interactions ◽  
Population Level ◽  
Black Widow ◽  
Trait Variation ◽  
Web Structure ◽  
Contest Outcome ◽  
Black Widow Spiders ◽  
The Web

Abstract Population-level trait variation within species plays an often-overlooked role in interspecific interactions. In this study, we compared among-individual variation in web phenotype and foraging behavior between native black widows (Latrodectus hesperus) and invasive brown widows (Latrodectus geometricus). We staged repeated contests whereby native widows defended their webs against intruders of both species to 1) investigate how trait variation mediates web contest outcome among native widows and 2) see whether widow behavior differs in response to an invasive spider. In only one trait, the average number of foraging lines, did black widows differ from brown widows. Black widow residents that built more structural lines were more likely to successfully defend their webs from conspecific intruders (i.e., be the sole spider remaining on the web postinteraction). This association between web structure and contest outcome did not exist in trials between black widows and invasive brown widows; however, in interspecific interactions, these same residents were more likely to have intruders remain on the web rather than drive them away. Surprisingly, brown widows did not usurp black widows. Brown widows were never observed signaling, yet black widow residents signaled equally to intruders of both species. Our results suggest that among-individual variation among native species can influence the response toward invasive competitors and outcome of these interactions.

scholarly journals Foraging behavior and extended phenotype independently affect foraging success in spiders

2020 ◽  
Vol 31 (5) ◽  
pp. 1242-1249 ◽  
Author(s):  
N DiRienzo ◽  
H A Schraft ◽  
P O Montiglio ◽  
C T Bradley ◽  
A Dornhaus
Keyword(s):  
Prey Capture ◽  
Phenotypic Traits ◽  
Foraging Success ◽  
Black Widow ◽  
Live Prey ◽  
Correlational Selection ◽  
Web Structure ◽  
Functional Consequences ◽  
Black Widow Spiders ◽  
Insight Into

Abstract Multiple phenotypic traits often interact with each other to determine an individual’s fitness. Behavioral and extended phenotypic traits, such as architectural constructions, can contribute to fitness in an integrated way. The goal of this study was to understand how the interaction between behavioral and extended phenotypic traits can affect foraging success. We tested this question using black widow spiders, where spiders that are aggressive in a foraging context tend to build more gumfooted silk lines that aid in prey capture, while non-aggressive spiders build webs with fewer gumfooted lines. We repeatedly assessed behavior and web structure to quantify relationships between these traits, and then allowed spiders to forage for live prey on their own web or the web of a conspecific that differed in structure. Thus, we assessed how varying combinations of behavior and web structure affect foraging success, and if correlational selection might act on them. We confirmed that aggressiveness and number of gumfooted lines are positively correlated and found that capture success increased with both aggressiveness and the number of gumfooted lines. Yet, we did not find any evidence for correlational selection: aggressiveness and number of gumfooted lines appeared to affect foraging success independently of each other. These findings highlight that a correlation between traits that contribute towards the same ecological function does not necessarily imply correlational selection. Taking advantage of the experimental convenience afforded by extended phenotypic traits can provide insight into the functional consequences of phenotypic variation within and between individuals.

PAPER PHYSICS. The web structure in relation to the furnish composition and shoe press pulse profiles during wet pressing

2012 ◽  
Vol 27 (4) ◽  
pp. 798-805 ◽  
Author(s):  
Collin Hii ◽  
Øyvind W. Gregersen ◽  
Gary Chinga-Carrasco ◽  
Øyvind Eriksen ◽  
Kai Toven
Keyword(s):  
Porous Structure ◽  
Peak Pressure ◽  
Pulse Length ◽  
Pressure Profile ◽  
Steam Consumption ◽  
Web Structure ◽  
Wet Pressing ◽  
Solids Content ◽  
In The Beginning ◽  
The Web

Abstract This study shows that wet-pressing TMP and DIP with a shoe press pulse may yield similar afterpress solids, provided that an adequate shoe pulse length with similar pressure profile is applied. A wet web with more porous structure in the sheet dewatering (felt) layer seems to contribute to the increased dewatering during wet pressing. In addition, a shoe press pulse with high peak pressure at the end yields higher solids content after wet-pressing and higher bulk compared to a pulse with a peak pressure in the beginning. The increased dewatering during wet-pressing implies a reduction of steam consumption in the dryer.

scholarly journals Resource partitioning between kit foxes (Vulpes macrotis) and coyotes (Canis latrans): a comparison of historical and contemporary dietary overlap

2018 ◽  
Vol 96 (5) ◽  
pp. 497-504 ◽  
Author(s):  
P.A. Byerly ◽  
R.C. Lonsinger ◽  
E.M. Gese ◽  
A.J. Kozlowski ◽  
L.P. Waits
Keyword(s):  
Great Basin ◽  
Native Species ◽  
Dietary Diversity ◽  
Canis Latrans ◽  
Population Level ◽  
Relative Importance ◽  
Dietary Overlap ◽  
Kit Fox ◽  
Prey Diversity ◽  
Vulpes Macrotis

Range expansions by generalists can alter communities and introduce competitive pressures on native species. In the Great Basin Desert, USA, coyotes (Canis latrans Say, 1823) have colonized and are now sympatric with native kit foxes (Vulpes macrotis Merriam, 1888). Since both species have similar diets, dietary partitioning may facilitate coexistence. We analyzed coyote and kit fox diets, then compared our results to an earlier study. Because populations are dynamic, we expected that decreases in prey or increases in predator abundance could alter dietary patterns. We found no significant changes in population-level prey diversity for kit foxes or coyotes, but found high levels of dietary overlap between species. We did detect a significant decrease in the relative importance of leporids (family Leporidae) in the diets of both canids, but they remained important for coyotes. The relative importance of small mammals was greater for kit foxes than coyotes, but their importance had not changed significantly over time. We detected significant declines in prey diversity per sample (scat-level dietary diversity) for both canids, suggesting that during a foraging event, individuals may encounter less diverse prey now than historically. These findings suggested that kit foxes and coyotes were not limited by prey, despite high dietary overlap.

Condition-dependent foraging strategies in a coastal seabird: evidence for the rich get richer hypothesis

2018 ◽  
Vol 30 (2) ◽  
pp. 356-363 ◽  
Author(s):  
Brock Geary ◽  
Scott T Walter ◽  
Paul L Leberg ◽  
Jordan Karubian
Keyword(s):  
Individual Variation ◽  
Multiple Scales ◽  
Foraging Ecology ◽  
Population Level ◽  
Foraging Strategies ◽  
Significant Relationships ◽  
Fitness Consequences ◽  
Brown Pelicans ◽  
The Rich ◽  
Foraging Movements

Abstract The degree to which foraging individuals are able to appropriately modify their behaviors in response to dynamic environmental conditions and associated resource availability can have important fitness consequences. Despite an increasingly refined understanding of differences in foraging behavior between individuals, we still lack detailed characterizations of within-individual variation over space and time, and what factors may drive this variability. From 2014 to 2017, we used GPS transmitters and accelerometers to document foraging movements by breeding adult Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico, where the prey landscape is patchy and dynamic at various scales. Assessments of traditional foraging metrics such as trip distance, linearity, or duration did not yield significant relationships between individuals. However, we did observe lower site fidelity and less variation in energy expenditure in birds of higher body condition, despite a population-level trend of increased fidelity as the breeding season progressed. These findings suggest that high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand, consistent with a “rich get richer” scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. This work highlights the importance of considering behavioral variation at multiple scales, with particular reference to within-individual variation, to improve our understanding of foraging ecology in wild populations.

Black widow spiders in an urban desert: Population variation in an arthropod pest across metropolitan Phoenix, AZ

2011 ◽  
Vol 15 (3) ◽  
pp. 599-609 ◽  
Author(s):  
Patricia Trubl ◽  
Theresa Gburek ◽  
Lindsay Miles ◽  
J. Chadwick Johnson
Keyword(s):  
Population Variation ◽  
Black Widow ◽  
Black Widow Spiders ◽  
Arthropod Pest

scholarly journals Functional analysis of the food web of Bahia Magdalena, Baja California Sur, Mexico

2017 ◽  
Vol 41 (3) ◽  
pp. 519-544
Author(s):  
Víctor H. Cruz-Escalona ◽  
María V. Morales-Zárate ◽  
Andrés F. Navia ◽  
Juan M. Rguez-Baron ◽  
Pablo Del Monte-Luna
Keyword(s):  
Trophic Levels ◽  
Baja California Sur ◽  
Ecopath With Ecosim ◽  
Estuarine Ecosystem ◽  
Energy Control ◽  
Marine Communities ◽  
Web Structure ◽  
The World ◽  
The Web ◽  
Bahia Magdalena

In the present study we developed a trophic model (ECOPATH with ECOSIM), to describe the structure and functioning of Bahía Magdalena estuarine ecosystem. The model, constituted by 24 functional groups, indicates that one third of the total ecosystem biomass is produced by secondary and tertiary trophic levels. The magnitude of total flows in the system and the transfer efficiency among trophic levels, are similar to those observed in other tropical systems around the world. A large proportion of the total flows are directed to the maintenance of the trophic web structure. The value of the connectance index (CI) was 0.2, meaning that there is only 20% of realized connections within the web. Benthic primary producers contribute with 53% of the total ascendency. We believe that the energy control in this particular ecosystem is top-down type (through the main predators), suggesting that high-trophic level species negatively affect other groups in the system. This trophic model can be used for exploring different hypothesis concerning the biotic and abiotic mechanisms that modify the structure and functioning of the Bahía Magdalena ecosystem, with the ultimate goal of understanding how this attributes determine the resilience of marine communities.

The interactive effects of stream temperature, stream size, and non-native species on Yellowstone cutthroat trout

2021 ◽  
Author(s):  
Robert Al-Chokhachy ◽  
Mike Lien ◽  
Bradley B. Shepard ◽  
Brett High
Keyword(s):  
Native Species ◽  
Cutthroat Trout ◽  
Population Level ◽  
Stream Temperature ◽  
Interactive Effects ◽  
Oncorhynchus Clarkii ◽  
Wide Range ◽  
Yellowstone Cutthroat Trout ◽  
Stream Size ◽  
Native Salmonids

Climate change and non-native species are considered two of the biggest threats to native salmonids in North America. We evaluated how non-native salmonids and stream temperature and discharge were associated with Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) distribution, abundance, and body size, to gain a more complete understanding of the existing threats to native populations. Allopatric Yellowstone cutthroat trout were distributed across a wide range of average August temperatures (3.2 to 17.7ºC), but occurrence significantly declined at colder temperatures (<10 ºC) with increasing numbers of non-natives. At warmer temperatures occurrence remained high, despite sympatry with non-natives. Yellowstone cutthroat trout relative abundance was significantly reduced with increasing abundance of non-natives, with the greatest impacts at colder temperatures. Body sizes of large Yellowstone cutthroat trout (90th percentile) significantly increased with warming temperatures and larger stream size, highlighting the importance of access to these more productive stream segments. Considering multiple population-level attributes demonstrates the complexities of how native salmonids (such as Yellowstone cutthroat trout) are likely to be affected by shifting climates.

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