DOCSLIB.ORG

Division of Labor Increases with Colony Size, Regardless of Group Composition, In

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Division of Labor Increases with Colony Size, Regardless of Group Composition, In bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 DIVISION OF LABOR INCREASES WITH COLONY SIZE, REGARDLESS OF GROUP COMPOSITION, IN 2 THE SOCIAL SPIDER STEGODYPHUS DUMICOLA 3 4 Authors: Colin M. Wright1*, James L. L. Lichtenstein2, C. Tate Holbrook3, Justin Pretorius2, Noa 5 Pinter-Wollman4 and Jonathan N. Pruitt2,5 6 7 1. Department of Biology, The Pennsylvania State University, University Park, PA 16801, 8 USA 9 2. Department of Ecology, Evolution and Marine Biology, University of California Santa 10 Barbara, Santa Barbara, CA 93106-2015, USA 11 3. Department of Natural Sciences, College of Coastal Georgia, Brunswick, GA 31520 12 4. Department of Ecology and Evolutionary Biology, University of California Los Angeles, 13 Los Angeles, CA, 90095-1606, USA 14 5. Department of Pyschology, Neurobiology & Behaviour, McMaster University, Hamilton, 15 ON, Canada L8S 4K1 16 17 *To whom correspondence should be addressed. 18 Email: [email protected] 19 bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 20 ABSTRACT 21 Division of labor (DOL) is a pattern of work organization where individual group members 22 specialize on different tasks. DOL is argued to have been instrumental for the success of eusocial 23 insects, where it scales positively with group size both within and across species. Here we evaluate 24 whether DOL scales positively with group size in a society of cooperative breeders (social spiders) 25 and whether this pattern is impacted by the behavioral composition of the group. To do this we 26 engineered experimental colonies of contrasting group sizes and behavioral compositions and 27 tracked individuals participation in two colony maintenance tasks: prey capture and web 28 construction. As with some eusocial insects, we found that larger groups exhibited DOL metrics 29 up to 10-times greater than smaller groups, conveying that individuals specialize on particular 30 tasks more in larger colonies. This scalar relationship did not differ by a groups behavioral 31 composition, though groups composed of only bold spiders exhibited reduced DOL relative to all- 32 shy or mixed groups. We also found that per capita participation in prey capture, but not web 33 construction, decreased as a function of group size. This suggests that individuals in larger groups 34 may save energy by reducing their involvement in some tasks. Together, our results convey that 35 similar scalar relationships between DOL and group size can emerge both inside and outside the 36 eusocial insects. Thus, theory developed for understanding DOL in eusocial societies may inform 37 our understanding of group function in a larger swath of animal social diversity than is broadly 38 appreciated. 39 40 41 42 43 bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 44 SIGNIFICANCE STATEMENT 45 46 Division of labor (DOL) has been a major area of research in the eusocial insects for 47 decades, and is argues to underlie their ecological success. Only recently have other social 48 arthropods, such as social spiders, been considered for studies concerning DOL. Given their 49 smaller colony sizes, and absence of morphological castes, DOL was not thought to be an 50 important facet of spider societies. However, we found that spider societies do indeed exhibit high 51 degrees of DOL that is positively correlated to colony size, as seen in many eusocial insects. These 52 findings suggest that the scalar relationship between group size and social organization seen in 53 social insects is likely generalizable to a larger diversity of social taxa, and that cooperative 54 breeders can show levels of division of labor equaling or exceeding those of eusocial systems 55 evaluated to date. 56 57 Keywords: division of labor, collective behavior, personality, sociality, spider, social behavior 58 59 60 bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 61 INTRODUCTION 62 63 The concept of Division of labor (DOL) was first articulated by the economist Adam Smith in his 64 book The Wealth of Nations (1776). In it, he described a process whereby workers can increase 65 group productivity and output by assigning different jobs to different individuals. The increase in 66 productivity and efficiency produced by DOL is attributed to several factors: (1) time saved by the 67 elimination or reduction of task switching, (2) reduced task learning costs, and (3) increased task 68 efficiency associated with practiced motor learning and dexterity. In many social taxa, including 69 humans, individuals often differ innately in their aptitudes for different tasks. Thus, DOL and 70 within-group behavioral variation can allow workforces to adaptively align individuals with 71 contrasting aptitudes with the tasks that they each perform best (Oster and Wilson 1978). Although 72 DOL was originally formulated in the context of the human factory and assembly-line workers, it 73 has since been recognized as a ubiquitous phenomenon in biological systems from cells to social 74 insect colonies (Szathmary and Smith 1995). Many examples have been identified across the 75 animal kingdom, where DOL is defined as a pattern of non-random association between individual 76 worker identities and the tasks that they perform (Michener 1974; Rypstra 1993; Duarte et al. 77 2011a; Jeanson 2013; Jeanne 2016). 78 While research on division of labor has traditionally focused on eusocial insects, which 79 exhibit reproductive DOL between queen and worker castes (Oster 1978), other animal societies 80 further divide non-reproductive labor among workers or group members. Interindividual variation 81 in task performance can be associated with differences in morphology (e.g., majors vs. minors) 82 (Wilson 1980; Holldobler and Wilson 1990; Kay and Rissing 2005), age (temporal polyethism) 83 (Wilson 1971; Seeley 1982), innate response thresholds (Bonabeau et al. 1996; Bonabeau et al. bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 84 1998; Beshers 2001; Jeanson 2013), reproductive state (social spiders: (Junghanns et al. 2017), or 85 consistent individual differences in behavioral tendencies (Dornhaus 2008; Holbrook et al. 2014; 86 Wright et al. 2014). This last element of individual variation can arise from a variety of 87 mechanisms including individual differences in genotype, gene expression, hormonal changes, and 88 learning/experience (Duarte et al. 2011b). In some cases, such differences can cause individuals 89 to perform better at some tasks than others (Oster 1978; Holldobler and Wilson 1990). 90 DOL, however, is not a simple, static trait. Rather, it is a dynamic emergent property of a 91 group. Within a species, for instance, DOL tends to increase with colony size (Holbrook et al. 92 2011). This social scaling effect is consistent with a general principal known as the size-complexity 93 rule (Bonner 2004) that applies to many biological entities, including human societies. This rule 94 states that, in general, larger collective entities have higher DOL than smaller entities, and these 95 “entities” can refer to individual organisms composed of various types of cells or cooperative 96 societies composed of various types of individuals. The scaling of DOL in functionally integrated 97 societies could be an evolved response that allows them to overcome logistical challenges 98 associated with increasing group size, and thus, helps to increase performance efficiency. 99 Alternatively, the positive relationship between DOL and group size could be an emergent 100 consequence of social dynamics, as predicted by self-organizational models (Gautrais et al. 2002; 101 Merkle and Middendorf 2004; Jeanson et al. 2007; Ulrich et al. 2018). This latter hypothesis has 102 received some support from empirical tests in forced associations of normally solitary ant 103 foundresses (Jeanson and Fewell 2008) and sweat bees (Holbrook et al. 2013). 104 The DOL index developed by Gorelick et al. (2004) and Gorelick and Bertram (2007) 105 provides researchers with a rigorous and generalizable method to measure DOL and make 106 comparisons across social groups and taxa. In short, their approach quantifies the degree to which bioRxiv preprint doi: https://doi.org/10.1101/652677; this version posted May 30, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 107 individuals specialize on a subset of tasks instead of dividing their time evenly across all tasks, 108 and the degree to which different individuals specialize on different tasks.
Load more

Recommended publications
  • Antimicrobial Compounds in the Volatilome of Social Spider Communities
    fmicb-12-700693 August 24, 2021 Time: 14:5 # 1 ORIGINAL RESEARCH published: 24 August 2021 doi: 10.3389/fmicb.2021.700693 Antimicrobial Compounds in the Volatilome of Social Spider Communities Alexander Lammers1,2*, Hans Zweers2, Tobias Sandfeld3, Trine Bilde4, Paolina Garbeva2, Andreas Schramm3 and Michael Lalk1* 1 Department of Cellular Biochemistry and Metabolomics, University of Greifswald, Greifswald, Germany, 2 Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands, 3 Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark, 4 Section for Genetics, Ecology and Evolution, Department of Biology, Aarhus University, Aarhus, Denmark Social arthropods such as termites, ants, and bees are among others the most successful animal groups on earth. However, social arthropods face an elevated risk of Edited by: infections due to the dense colony structure, which facilitates pathogen transmission. An Eoin L. Brodie, Lawrence Berkeley National interesting hypothesis is that social arthropods are protected by chemical compounds Laboratory, United States produced by the arthropods themselves, microbial symbionts, or plants they associate Reviewed by: with. Stegodyphus dumicola is an African social spider species, inhabiting communal Hongjie Li, Ningbo University, China silk nests. Because of the complex three-dimensional structure of the spider nest Martin Kaltenpoth, antimicrobial volatile organic compounds (VOCs) are a promising protection against Max Planck Institute for Chemical pathogens, because of their ability to diffuse through air-filled pores. We analyzed Ecology, Germany Michael Poulsen, the volatilomes of S. dumicola, their nests, and capture webs in three locations in University of Copenhagen, Denmark Namibia and assessed their antimicrobial potential. Volatilomes were collected using Nanna Vidkjær, University of Copenhagen, Denmark, polydimethylsiloxane (PDMS) tubes and analyzed using GC/Q-TOF.
    [Show full text]
  • Capture of a Functionally Active Methyl-Cpg Binding Domain by an Arthropod Retrotransposon Family
    Downloaded from genome.cshlp.org on September 23, 2021 - Published by Cold Spring Harbor Laboratory Press Research Capture of a functionally active methyl-CpG binding domain by an arthropod retrotransposon family Alex de Mendoza,1,2 Jahnvi Pflueger,1,2 and Ryan Lister1,2 1Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, 6009, Australia; 2Harry Perkins Institute of Medical Research, Perth, Western Australia, 6009, Australia The repressive capacity of cytosine DNA methylation is mediated by recruitment of silencing complexes by methyl-CpG binding domain (MBD) proteins. Despite MBD proteins being associated with silencing, we discovered that a family of arthropod Copia retrotransposons have incorporated a host-derived MBD. We functionally show how retrotransposon- encoded MBDs preferentially bind to CpG-dense methylated regions, which correspond to transposable element regions of the host genome, in the myriapod Strigamia maritima. Consistently, young MBD-encoding Copia retrotransposons (CopiaMBD) accumulate in regions with higher CpG densities than other LTR-retrotransposons also present in the genome. This would suggest that retrotransposons use MBDs to integrate into heterochromatic regions in Strigamia, avoiding poten- tially harmful insertions into host genes. In contrast, CopiaMBD insertions in the spider Stegodyphus dumicola genome dispro- portionately accumulate in methylated gene bodies compared with other spider LTR-retrotransposons. Given that transposons are not actively targeted by DNA methylation in the spider genome, this distribution bias would also support a role for MBDs in the integration process. Together, these data show that retrotransposons can co-opt host-derived epige- nome readers, potentially harnessing the host epigenome landscape to advantageously tune the retrotransposition process.
    [Show full text]
  • Tarantulas and Social Spiders
    Tarantulas and Social Spiders: A Tale of Sex and Silk by Jonathan Bull BSc (Hons) MSc ICL Thesis Presented to the Institute of Biology of The University of Nottingham in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy The University of Nottingham May 2012 DEDICATION To my parents… …because they both said to dedicate it to the other… I dedicate it to both ii ACKNOWLEDGEMENTS First and foremost I would like to thank my supervisor Dr Sara Goodacre for her guidance and support. I am also hugely endebted to Dr Keith Spriggs who became my mentor in the field of RNA and without whom my understanding of the field would have been but a fraction of what it is now. Particular thanks go to Professor John Brookfield, an expert in the field of biological statistics and data retrieval. Likewise with Dr Susan Liddell for her proteomics assistance, a truly remarkable individual on par with Professor Brookfield in being able to simplify even the most complex techniques and analyses. Finally, I would really like to thank Janet Beccaloni for her time and resources at the Natural History Museum, London, permitting me access to the collections therein; ten years on and still a delight. Finally, amongst the greats, Alexander ‘Sasha’ Kondrashov… a true inspiration. I would also like to express my gratitude to those who, although may not have directly contributed, should not be forgotten due to their continued assistance and considerate nature: Dr Chris Wade (five straight hours of help was not uncommon!), Sue Buxton (direct to my bench creepy crawlies), Sheila Keeble (ventures and cleans where others dare not), Alice Young (read/checked my thesis and overcame her arachnophobia!) and all those in the Centre for Biomolecular Sciences.
    [Show full text]
  • Climatic Variables Are Strong Predictors of Allonursing and Communal Nesting in Primates
    City University of New York (CUNY) CUNY Academic Works School of Arts & Sciences Theses Hunter College 2-1-2019 Climatic variables are strong predictors of allonursing and communal nesting in primates Alexandra Louppova CUNY Hunter College How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/hc_sas_etds/380 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] Climatic variables are strong predictors of allonursing and communal nesting in primates by Alexandra Louppova Submitted in partial fulfillment of the requirements for the degree of Master of Arts Anthropology, Hunter College The City University of New York 2018 Thesis Sponsor: Andrea Baden December 15, 2018 Date Signature of First Reader Dr. Andrea Baden December 15, 2018 Date Signature of Second Reader Dr. Jason Kamilar Table of Contents ACKNOWLEDGEMENTS ....................................................................................................................... ii LIST OF FIGURES ................................................................................................................................... iii LIST OF TABLES ..................................................................................................................................... iv ABSTRACT ................................................................................................................................................
    [Show full text]
  • Effect of Kleptoparasitic Ants on the Foraging Behavior of a Social Spider (Stegodyphus Sarasinorum Karsch, 1891)
    Zoological Studies 58: 3 (2019) doi:10.6620/ZS.2019.58-03 Open Access Effect of Kleptoparasitic Ants on the Foraging Behavior of a Social Spider (Stegodyphus sarasinorum Karsch, 1891) Ovatt Mohanan Drisya-Mohan*, Pallath Kavyamol, and Ambalaparambil Vasu Sudhikumar Centre for Animal Taxonomy and Ecology, Department of Zoology, Christ College, Irinjalakuda, Kerala, India. *Correspondence E-mail: [email protected] (Drisya-Mohan). E-mail (other authors): [email protected] (Kavyamol); [email protected] (Sudhikumar) Received 23 February 2018 / Accepted 23 December 2018 / Published 25 February 2019 Communicated by John Wang The term kleptoparasitism is used to describe the stealing of nest material or prey of one animal by another. Foraging and food handling behaviors of social spiders increase the vulnerability to klepto- parasitism. Kleptoparasites of the social spider Stegodyphus sarasinorum Karsch 1891 were identified based on the observations done in the field. Four species of spiders and two species of ants were observed as kleptoparasites and collected from the nest and webs of this social spider. The ants were found to be the most dominant among them. The influence of a facultative kleptoparasitic ant, Oecophylla smaragdina on the foraging behavior of S. sarasinorum was studied in laboratory conditions. The experiments suggested that the web building behavior of S. sarasinorum was influenced by the exposure to ants. However, exposure to ants caused no significant effect in the prey capture, handling time of prey and prey ingestion behaviors of the spider. Key words: Social spider, Ecology, Kleptoparasites, Ants, Prey capturing behavior. BACKGROUND 2000). Kleptoparasites depend on high-quality food and it is available to them due to prolonged handling Kleptoparasitism is a type of feeding behavior, (Giraldeau and Caraco 2000).
    [Show full text]
  • The Evolution of Sociality in Spiders
    ADVANCES IN THE STUDY OF BEHAVIOR, VOL. 37 The Evolution of Sociality in Spiders { Yael Lubin* and Trine Bilde *blaustein institutes for desert research, ben‐gurion university of the negev, sede boqer campus, 84990 israel {department of biological sciences, university of aarhus, denmark I. INTRODUCING SOCIAL SPIDERS A solitary lifestyle characterizes the vast majority of almost 40,000 known species of spiders (Platnick, 2007). Thus, the occurrence of group living in spiders begs the question: what is different about these species? Group living has arisen in spiders in basically two different forms. Cooperative or ‘‘non- territorial permanent‐social’’ species (sensu Avile´s, 1997;alsoreferredtoas ‘‘quasi‐social,’’ Buskirk, 1981) are the main focus of this chapter. These species have family‐group territories consisting of communal nests and cap- ture webs, which they inhabit throughout the entire lifetime of the individual, and colony members cooperate in foraging and raising young. In many ways, these species resemble the ‘‘primitively eusocial’’ wasps and bees and the cooperative breeders in vertebrate societies, where the family forms the basic unit of sociality (Brockmann, 1997; Whitehouse and Lubin, 2005). Another form of group living in spiders has been termed colonial or communal‐ territorial (Avile´s, 1997: ‘‘territorial permanent‐social’’ species). Colonial species occur in aggregations, but individuals in the colony generally forage and feed alone and there is no maternal care beyond the egg stage; thus, they lack the cooperative behaviors described below for nonterritorial permanent‐ social species (reviewed in Uetz and Hieber, 1997; Whitehouse and Lubin, 2005). Colonial species have been likened to foraging flocks of birds (Rypstra, 1979) and are described as ‘‘foraging societies’’ by Whitehouse and Lubin (2005).
    [Show full text]
  • Anthropod Community Associated with the Webs of the Subsocial Spider Anelosimus Studiosus
    Georgia Southern University Digital Commons@Georgia Southern Electronic Theses and Dissertations Graduate Studies, Jack N. Averitt College of Fall 2008 Anthropod Community Associated with the Webs of the Subsocial Spider Anelosimus Studiosus Sarah Natalie Mock Follow this and additional works at: https://digitalcommons.georgiasouthern.edu/etd Recommended Citation Mock, Sarah Natalie, "Anthropod Community Associated with the Webs of the Subsocial Spider Anelosimus Studiosus" (2008). Electronic Theses and Dissertations. 702. https://digitalcommons.georgiasouthern.edu/etd/702 This thesis (open access) is brought to you for free and open access by the Graduate Studies, Jack N. Averitt College of at Digital Commons@Georgia Southern. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Digital Commons@Georgia Southern. For more information, please contact [email protected]. THE ARTHROPOD COMMUNITY ASSOCIATED WITH THE WEBS OF THE SUBSOCIAL SPIDER ANELOSIMUS STUDIOSUS by SARAH N. MOCK (Under the Direction of Alan Harvey) ABSTRACT Anelosimus studiosus (Theridiidae) is a subsocial spider that has a diverse arthropod fauna associated with its webs. From south Georgia, I identified 1006 arthropods representing 105 species living with A. studiosus , and 40 species that were prey items from 250 webs. The arthropods seen in A. studiosus webs represented a distinct community from the arthropods on the tree. I found that Barronopsis barrowsi (Agelenidae) and Frontinella pyramitela was similar to A. studiosus in web structure and that B. barrowsi webs contained multiple arthropods. Also, previously known as asocial, B. barrowsi demonstrated sociality in having multiple adults per web. Lastly, the inquiline communities in the webs of A.studiosus and B.barronopsis contained many different feeding guilds, including herbivores, omnivores, generalist predators, kleptoparasites, and aranievores.
    [Show full text]
  • Widespread Retention of Ohnologs in Key Developmental Gene Families Following Whole Genome Duplication in Arachnopulmonates Ambe
    bioRxiv preprint doi: https://doi.org/10.1101/2020.07.10.177725; this version posted April 26, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Widespread retention of ohnologs in key developmental gene families following whole genome duplication in arachnopulmonates Amber Harper1, Luis Baudouin Gonzalez1, Anna Schönauer1, Ralf Janssen2, Michael Seiter3, Michaela Holzem1,4, Saad Arif1,5, Alistair P. McGregor1,5*, Lauren Sumner- Rooney6,* 1Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, United Kingdom. 2Department of Earth Sciences, Uppsala University, Geocentrum, Villavägen 16, 752 36 Uppsala, Sweden. 3Department of Evolutionary Biology, Unit Integrative Zoology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria. 4Division of Signalling and Functional Genomics, German Cancer Research Centre (DKFZ), Heidelberg, Germany and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany. 5Centre for Functional Genomics, Oxford Brookes University, Oxford, OX3 0BP, United Kingdom. 6Oxford University Museum of Natural History, University of Oxford, Oxford OX1 3PW, United Kingdom. *Corresponding authors: [email protected] (APM) and lauren.sumner- [email protected] (LSR). 1 Harper et al. bioRxiv preprint doi: https://doi.org/10.1101/2020.07.10.177725; this version posted April 26, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. ABSTRACT Whole genome duplications have occurred multiple times during animal evolution, including in lineages leading to vertebrates, teleosts, horseshoe crabs and arachnopulmonates.
    [Show full text]
  • Virgin Female Spiders Found Willing to Give Themselves up to Being Eaten Alive by Spiderlings 19 September 2017, by Bob Yirka
    Virgin female spiders found willing to give themselves up to being eaten alive by spiderlings 19 September 2017, by Bob Yirka they hatch, the little ones emerge and eat the mother alive by injecting chemicals into her body that dissolve her organs. Anecdotal evidence has suggested that the same fate may befall close female virgin relatives. To find out if this was, indeed, the case, the researchers collected approximately 200 female spiders, some of which were ripe for laying eggs. The researchers color- marked the two groups and then watched as events unfolded over a 10-week period. The researchers report that in 97 percent of cases, both mated and virgin spiders tended to the eggs The community nesting spider, Stegodyphus dumicola. and also to the spiderlings that eventually emerged. Credit: Wikipedia/CC BY-SA 2.0 They observed as the spiderlings proceeded to eat both the mothers and virgin adult females. The researchers suggest the behavior has evolved because of the difficulty in finding alternative food (Phys.org)—A team of researchers with Ernst Moritzfor the spiderlings in the very dry climate in which Arndt University in Germany and Aarhus University they live. in Denmark has found that female virgin velvet spiders (Stegodyphus dumicola) in addition to But there is still one major question to resolve—in assisting close relatives in raising their young, order for the young to eat the adults, the adults allow themselves to be eaten alive by the must first go through a physical process that makes spiderlings. In their paper published in the journal it possible for the young to eat them—rather like a Animal Behavior, the group describes their study of mammal changing to begin lactation.
    [Show full text]
  • Habitat Productivity Constrains the Distribution of Social Spiders Across Continents
    Majer et al. Frontiers in Zoology 2013, 10:9 http://www.frontiersinzoology.com/content/10/1/9 RESEARCH Open Access Habitat productivity constrains the distribution of social spiders across continents – case study of the genus Stegodyphus Marija Majer*, Jens-Christian Svenning and Trine Bilde Abstract Introduction: Sociality has evolved independently multiple times across the spider phylogeny, and despite wide taxonomic and geographical breadth the social species are characterized by a common geographical constrain to tropical and subtropical areas. Here we investigate the environmental factors that drive macro-ecological patterns in social and solitary species in a genus that shows a Mediterranean–Afro-Oriental distribution (Stegodyphus). Both selected drivers (productivity and seasonality) may affect the abundance of potential prey insects, but seasonality may further directly affect survival due to mortality caused by extreme climatic events. Based on a comprehensive dataset including information about the distribution of three independently derived social species and 13 solitary congeners we tested the hypotheses that the distribution of social Stegodyphus species relative to solitary congeners is: (1) restricted to habitats of high vegetation productivity and (2) constrained to areas with a stable climate (low precipitation seasonality). Results: Using spatial logistic regression modelling and information-theoretic model selection, we show that social species occur at higher vegetation productivity than solitary, while precipitation seasonality received limited support as a predictor of social spider occurrence. An analysis of insect biomass data across the Stegodyphus distribution range confirmed that vegetation productivity is positively correlated to potential insect prey biomass. Conclusions: Habitat productivity constrains the distribution of social spiders across continents compared to their solitary congeners, with group-living in spiders being restricted to areas with relatively high vegetation productivity and insect prey biomass.
    [Show full text]
  • Research Note Extended Nest Residence and Cannibalism in a Jumping Spider (Araneae, Salticidae)
    2000. The Journal of Arachnology 28:123±127 RESEARCH NOTE EXTENDED NEST RESIDENCE AND CANNIBALISM IN A JUMPING SPIDER (ARANEAE, SALTICIDAE) Keywords: Sociality, parental care, matriphagy, sub-social Menemerus bracteatus (L. Koch 1879) is a at least one clutch. A further seven nests large unidentate Australian salticid that nests found were from the previous season (evi- under the bark of eucalypt trees (Davies & dence: constructed on older bark attached to ZÇ abka 1989). During an earlier work (Rienks the shedding bark, and contained shed exo- 1992) several nests were found on the scribbly skeletons only). gum, Eucalyptus racemosa Cavanilles. While Description of nests.ÐNests were con- studying the microhabitats of a wide range of structed in the curve of the shedding bark and salticid species, it was noted that sometimes a had tough roof and outer walls which strongly single nest of this species was occupied by adhered to both the shedding bark and the tree numbers of large juveniles and the dead and trunk. Each nest had two reinforced entrances shrunken body of a conspeci®c adult female, with projecting lip-like ¯aps above and below possibly the mother. It is common for juvenile the entrance slit which may hinder access by salticids to remain with the mother for the ®rst predators and parasites. Nests were very instar after emerging from the postembryo strongly constructed and could be removed in- stage (Richman & Jackson 1992), but nest tact by carefully pulling the loose bark piece sharing by larger juveniles and an adult fe- away from the tree trunk. male is unusual.
    [Show full text]
  • The Innervation of the Male Copulatory Organ of Spiders (Araneae) – a Comparative Analysis Tim M
    Dederichs et al. Frontiers in Zoology (2019) 16:39 https://doi.org/10.1186/s12983-019-0337-6 RESEARCH Open Access The innervation of the male copulatory organ of spiders (Araneae) – a comparative analysis Tim M. Dederichs1*, Carsten H. G. Müller1, Lenka Sentenská2, Elisabeth Lipke3, Gabriele Uhl1* and Peter Michalik1* Abstract Background: Nervous tissue is an inherent component of the many specialized genital structures for transferring sperm directly into the female’s body. However, the male copulatory organ of spiders was considered a puzzling exception. Based on the recent discovery of nervous tissue in the pedipalps of two distantly related spider species, we investigated representatives of all major groups across the spider tree of life for the presence of palpal nerves. We used a correlative approach that combined histology, micro-computed tomography and electron microscopy. Results: We show that the copulatory organ is innervated in all species investigated. There is a sensory organ at the base of the sperm transferring sclerite in several taxa and nervous tissue occurs close to the glandular tissue of the spermophor, where sperm are stored before transfer. Conclusions: The innervation of the copulatory organ by the bulb nerve and associated efferent fibers is part of the ground pattern of spiders. Our findings pave the way for unraveling the sensory interaction of genitalia during mating and for the still enigmatic mode of uptake and release of sperm from the male copulatory organ. Keywords: Copulation, Intromittent organ, Sexual selection, Bulb nerve, Sensory organ, Pedipalp, Palpal organ, Copulatory mechanism, Spiders Background spiders, however, was considered a puzzling exception Animals with internal fertilization have evolved highly since no muscles, nerves and sense organs had been specialized and diverse genital structures for transfer- found in it [11–15].
    [Show full text]