Experimental evidence that high humidity is an essential cue for web building in Pasilobus spiders

Behaviour ◽  
2017 ◽  
Vol 154 (7-8) ◽  
pp. 709-718 ◽  
Author(s):  
Tadashi Miyashita ◽  
Minoru Kasada ◽  
Akio Tanikawa
Keyword(s):  
Mechanical Property ◽  
Experimental Evidence ◽  
Foraging Behaviour ◽  
High Humidity ◽  
Web Building ◽  
Bolas Spiders

Spiders in the subfamily Cyrtarachninae, including bolas spiders, are moth specialists, and it has been suggested that these spiders initiate web-weaving under high humidity. Here we used Pasilobus hupingensis to experimentally test whether Cyrtarachninae spiders build webs exclusively under high humidity. The results showed that humidity, as well as temperature and prey feeding history, affected web-building probability, but humidity had a much stronger effect. Moreover, spiders never constructed webs at under <70% humidity. We suggest that a mechanical property in sticky materials derived from moth specialization; namely, unusually high, yet rapidly degrading stickiness, is likely to have promoted the evolution of plastic foraging behaviour that varies with humidity.

Foraging behaviour in tadpoles of the bronze frogRana temporalis: Experimental evidence for the ideal free distribution

2004 ◽  
Vol 29 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Dheeraj K. Veeranagoudar ◽  
Bhagyashri A. Shanbhag ◽  
Srinivas K. Saidapur
Keyword(s):  
Experimental Evidence ◽  
Foraging Behaviour ◽  
Ideal Free Distribution ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

scholarly journals THE ALCOHOL DEHYDROGENASE POLYMORPHISM IN POPULATIONS OF DROSOPHILA MELANOGASTER. I. SELECTION IN DIFFERENT ENVIRONMENTS

Genetics ◽  
1978 ◽  
Vol 90 (1) ◽  
pp. 161-191
Author(s):  
W van Delden ◽  
A C Boerema ◽  
A Kamping
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Experimental Evidence ◽  
Balancing Selection ◽  
Adult Survival ◽  
High Survival ◽  
High Humidity ◽  
Allozyme Polymorphism ◽  
Degree Of Dominance ◽  
Frequency Changes

ABSTRACT The allozyme polymorphism at the alcohol dehydrogenase locus in Drosophila melanogaster was studied in order to obtain experimental evidence about the maintenance of this polymorphism. Populations started with different initial allele frequencies from homozygous F and S lines showed a convergence of frequencies on regular food at 25°, leading to values equal to those in the base populations. These results were interpreted as due to some kind of balancing selection. In populations kept at 29.8°, a lower equilibrium F frequency was attained. Addition of ethanol and some other alcohols to the food gave a rapid increase in F frequency, and high humidity decreased the F frequency slightly. Combination or alternation of ethanol and high humidity had variable effects in the populations tested. For a further analysis of the allele-frequency changes, estimates were obtained for egg-to-adult survival under different conditions and for adult survival on ethanol-supplemented food. On ethanol food (both at regular and high humidity), egg-to-adult survival of SS homozygotes was considerably lower than that of the FF and FS genotypes. Under regular conditions of food, temperature and humidity, a tendency to heterozygote superiority was observed, while at high humidity a relative high survival of SS was noticed in some tests. Adult survival of SS was lower than that of FF, but FS was generally intermediate, though the degree of dominance differed between populations. The results are consistent with the hypothesis of the occurrence of selection at the Adh locus.

scholarly journals A comparison of morphology and web geometry between hypogean and epigean species of Metellina orb spiders (family Tetragnathidae)

2019 ◽  
Vol 32 ◽  
pp. 1-13 ◽  
Author(s):  
Thomas Hesselberg ◽  
Daniel Simonsen
Keyword(s):  
Life Style ◽  
Foraging Behaviour ◽  
Behavioural Flexibility ◽  
Permanent Record ◽  
Behavioural Adaptation ◽  
Web Geometry ◽  
Web Building

Studies on the behaviour of subterranean animals are rare, mainly due to the problems with collecting data in these inaccessible habitats. Web-building cave spiders, however, leave a semi-permanent record of their foraging behaviour, which can relatively easily be recorded. In this study, we compare size, leg lengths and web characteristics between hypogean populations of Metellina merianae with its close wood-inhabiting relative M. mengei. We confirm previous observations that M. merianae does not show any obvious morphological and behavioural adaptions to a subterranean life-style, although individuals of the cave species were significantly larger and had webs with relatively fewer radii and capture spiral turns than M. mengei. We were, however, not able to determine if these findings indicate a transition towards behavioural adaptation to caves or if they are a result of behavioural flexibility in response to the different humidity and temperature between caves and woodland. Finally, we did not find any effect of cave characteristics on either the number of radii or the area of the M. merianae web.

scholarly journals Nutrient balance affects foraging behaviour of a trap-building predator

2009 ◽  
Vol 5 (6) ◽  
pp. 735-738 ◽  
Author(s):  
David Mayntz ◽  
Søren Toft ◽  
Fritz Vollrath
Keyword(s):  
Foraging Behaviour ◽  
Prey Capture ◽  
Prey Availability ◽  
Capture Rate ◽  
Nutrient Balance ◽  
Nutrient Composition ◽  
Web Architecture ◽  
First Instar ◽  
Predator Foraging ◽  
Web Building

Predator foraging may be affected by previous prey capture, but it is unknown how nutrient balance affects foraging behaviour. Here, we use a trap-building predator to test whether nutrients from previous prey captures affect foraging behaviour. We fed orb-weaving spiders ( Zygiella x-notata ) prey flies of different nutrient composition and in different amounts during their first instar and measured the subsequent frequency of web building and aspects of web architecture. We found that both the likelihood of web building and the number of radii in the web were affected by prey nutrient composition while prey availability affected capture area and mesh height. Our results show that both the balance of nutrients in captured prey and the previous capture rate may affect future foraging behaviour of predators.

Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne

2014 ◽  
Vol 101 (7) ◽  
pp. 587-593 ◽  
Author(s):  
Yuki G. Baba ◽  
Miki Kusahara ◽  
Yasunori Maezono ◽  
Tadashi Miyashita
Keyword(s):  
High Humidity ◽  
Web Building

scholarly journals A comparison of morphology and web geometry between hypogean and epigean species of Metellina orb spiders (family Tetragnathidae)

2019 ◽  
Vol 31 ◽  
pp. 53-65 ◽  
Author(s):  
Thomas Hesselberg ◽  
Daniel Simonsen
Keyword(s):  
Life Style ◽  
Foraging Behaviour ◽  
Behavioural Flexibility ◽  
Permanent Record ◽  
Behavioural Adaptation ◽  
Web Geometry ◽  
Web Building

Studies on the behaviour of subterranean animals are rare, mainly due to the problems with collecting data in these inaccessible habitats. Web-building cave spiders, however, leave a semi-permanent record of their foraging behaviour, which can relatively easily be recorded. In this study, we compare size, leg lengths and web characteristics between hypogean populations of Metellina merianae with its close wood-inhabiting relative M. mengei. We confirm previous observations that M. merianae does not show any obvious morphological and behavioural adaptions to a subterranean life-style, although individuals of the cave species were significantly larger and had webs with relatively fewer radii and capture spiral turns than M. mengei. We were, however, not able to determine if these findings indicate a transition towards behavioural adaptation to caves or if they are a result of behavioural flexibility in response to the different humidity and temperature between caves and woodland. Finally, we did not find any effect of cave characteristics on either the number of radii or the area of the M. merianae web.

How do memory modules differentially contribute to familiarity and recollection?

2019 ◽  
Vol 42 ◽  
Author(s):  
Olya Hakobyan ◽  
Sen Cheng
Keyword(s):  
Recognition Memory ◽  
Experimental Evidence ◽  
Subjective Experience ◽  
Target Article ◽  
Memory Modules ◽  
Familiarity And Recollection ◽  
Memory Contents

Abstract We fully support dissociating the subjective experience from the memory contents in recognition memory, as Bastin et al. posit in the target article. However, having two generic memory modules with qualitatively different functions is not mandatory and is in fact inconsistent with experimental evidence. We propose that quantitative differences in the properties of the memory modules can account for the apparent dissociation of recollection and familiarity along anatomical lines.

Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

1997 ◽  
Vol 161 ◽  
pp. 437-442
Author(s):  
Salvatore Di Bernardo ◽  
Romana Fato ◽  
Giorgio Lenaz
Keyword(s):  
Experimental Evidence ◽  
Lipid Membranes ◽  
Energy Supply ◽  
Redox Reactions ◽  
Living Systems ◽  
Asymmetric Distribution ◽  
Conservation Of Energy ◽  
Asymmetrical Distribution ◽  
Energy Conserving ◽  
Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

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