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Male mating strategies to counter sexual conflict in spiders. Commun Biol 2022; 5:534. [PMID: 35655093 PMCID: PMC9163124 DOI: 10.1038/s42003-022-03512-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/20/2022] [Indexed: 12/04/2022] Open
Abstract
When sexual conflict selects for reproductive strategies that only benefit one of the sexes, evolutionary arms races may ensue. Female sexual cannibalism is an extreme manifestation of sexual conflict. Here we test two male mating strategies aiming at countering sexual cannibalism in spiders. The “better charged palp” hypothesis predicts male selected use of the paired sexual organ (palp) containing more sperm for their first copulation. The “fast sperm transfer” hypothesis predicts accelerated insemination when cannibalism is high. Our comparative tests on five orbweb spider species with varying levels of female sexual cannibalism and sexual size dimorphism (SSD) reveal that males choose the palp with more sperm for the first copulation with cannibalistic females and that males transfer significantly more sperm if females are cannibalistic or when SSD is biased. By supporting the two hypotheses, these results provide credibility for male mating syndrome. They, however, open new questions, namely, how does a male differentiate sperm quantities between his palps? How does he perform palp choice after assessing his cannibalistic partner? By conducting follow-up experiments on Nephilengys malabarensis, we reveal that it is sperm volume detection, rather than left-right palp dominance, that plays prominently in male palp choice. Male spiders make choices about how to maximise their mating success when at risk of cannibalisation by females.
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Kuntner M, Coddington JA. Sexual Size Dimorphism: Evolution and Perils of Extreme Phenotypes in Spiders. ANNUAL REVIEW OF ENTOMOLOGY 2020; 65:57-80. [PMID: 31573828 DOI: 10.1146/annurev-ento-011019-025032] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Sexual size dimorphism is one of the most striking animal traits, and among terrestrial animals, it is most extreme in certain spider lineages. The most extreme sexual size dimorphism (eSSD) is female biased. eSSD itself is probably an epiphenomenon of gendered evolutionary drivers whose strengths and directions are diverse. We demonstrate that eSSD spider clades are aberrant by sampling randomly across all spiders to establish overall averages for female (6.9 mm) and male (5.6 mm) size. At least 16 spider eSSD clades exist. We explore why the literature does not converge on an overall explanation for eSSD and propose an equilibrium model featuring clade- and context-specific drivers of gender size variation. eSSD affects other traits such as sexual cannibalism, genital damage, emasculation, and monogyny with terminal investment. Coevolution with these extreme sexual phenotypes is termed eSSD mating syndrome. Finally, as costs of female gigantism increase with size, eSSD may represent an evolutionary dead end.
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Affiliation(s)
- Matjaž Kuntner
- Evolutionary Zoology Laboratory, Department of Organisms and Ecosystems Research, National Institute of Biology, SI-1000 Ljubljana, Slovenia;
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0105, USA;
- Evolutionary Zoology Laboratory, Institute of Biology ZRC SAZU, SI-1001 Ljubljana, Slovenia
| | - Jonathan A Coddington
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0105, USA;
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Wolff JO, Paterno GB, Liprandi D, Ramírez MJ, Bosia F, Meijden A, Michalik P, Smith HM, Jones BR, Ravelo AM, Pugno N, Herberstein ME. Evolution of aerial spider webs coincided with repeated structural optimization of silk anchorages. Evolution 2019; 73:2122-2134. [DOI: 10.1111/evo.13834] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 07/11/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023]
Affiliation(s)
- Jonas O. Wolff
- Department of Biological SciencesMacquarie University Sydney New South Wales 2109 Australia
| | - Gustavo B. Paterno
- Departamento de Ecologia, Centro de BiociênciasUniversidade Federal do Rio Grande do Norte (UFRN) Lagoa Nova 59072–970 Natal Rio Grande do Norte Brazil
- Instituto de Ciências Biológicas, Programa de Pós‐Graduação em EcologiaUniversidade Federal de Juiz de Fora Rua José Lourenço Kelmer 36036–900 Juiz de Fora Minas Gerais Brazil
| | - Daniele Liprandi
- Laboratory of Bio‐Inspired and Graphene Nanomechanics, Department of CivilEnvironmental and Mechanical EngineeringUniversity of Trento Via Masiano 77 I‐38123 Trento Italy
| | - Martín J. Ramírez
- Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Av. Ángel Gallardo 470 C1405DJR Buenos Aires Argentina
| | - Federico Bosia
- Department of Physics and Nanostructured Interfaces and Surfaces Interdepartmental CentreUniversità di Torino Via P. Giuria 1 10125 Torino Italy
| | - Arie Meijden
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIOUniversidade do Porto Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão, Vila do Conde Porto 4485–661 Portugal
| | - Peter Michalik
- Zoologisches Institut und MuseumUniversität Greifswald Loitzer Str. 26 17489 Greifswald Germany
| | - Helen M. Smith
- Australian Museum 1 William St Sydney New South Wales 2010 Australia
| | - Braxton R. Jones
- Department of Biological SciencesMacquarie University Sydney New South Wales 2109 Australia
| | - Alexandra M. Ravelo
- Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Av. Ángel Gallardo 470 C1405DJR Buenos Aires Argentina
| | - Nicola Pugno
- Laboratory of Bio‐Inspired and Graphene Nanomechanics, Department of CivilEnvironmental and Mechanical EngineeringUniversity of Trento Via Masiano 77 I‐38123 Trento Italy
- School of Engineering and Materials ScienceQueen Mary University Mile End Rd London E1 4NS UK
- KET Labs, Edoardo Amaldi Foundation Via del Politecnico snc 00133 Rome Italy
| | - Marie E. Herberstein
- Department of Biological SciencesMacquarie University Sydney New South Wales 2109 Australia
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4
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Orb-web spiders as Bayesian learners. Naturwissenschaften 2019; 106:22. [DOI: 10.1007/s00114-019-1615-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/18/2019] [Accepted: 04/03/2019] [Indexed: 10/26/2022]
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5
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Piorkowski D, Blamires SJ, Doran NE, Liao CP, Wu CL, Tso IM. Ontogenetic shift toward stronger, tougher silk of a web-building, cave-dwelling spider. J Zool (1987) 2017. [DOI: 10.1111/jzo.12507] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- D. Piorkowski
- Department of Life Science; Tunghai University; Taichung Taiwan
| | - S. J. Blamires
- Evolution and Ecology Research Centre; University of New South Wales; Sydney NSW Australia
| | - N. E. Doran
- Bookend Trust and the School of Biological Sciences; University of Tasmania; Sandy Bay Tasmania Australia
| | - C.-P. Liao
- Department of Life Science; Tunghai University; Taichung Taiwan
| | - C.-L. Wu
- Center for Measurement Standards; Industrial Technology Research Institute; Hsinchu Taiwan
| | - I.-M. Tso
- Department of Life Science; Tunghai University; Taichung Taiwan
- Center for Tropical Ecology and Biodiversity; Tunghai University; Taichung Taiwan
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6
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Gregorič M, Kuntner M, Blackledge TA. Does body size predict foraging effort? Patterns of material investment in spider orb webs. J Zool (1987) 2015. [DOI: 10.1111/jzo.12219] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- M. Gregorič
- Institute of Biology Scientific Research Centre Slovenian Academy of Sciences and Arts Ljubljana Slovenia
- Department of Biology and Integrated Bioscience Program University of Akron Akron OH USA
| | - M. Kuntner
- Institute of Biology Scientific Research Centre Slovenian Academy of Sciences and Arts Ljubljana Slovenia
- Department of Entomology National Museum of Natural History Smithsonian Institution Washington DC USA
- College of Life Sciences Hubei University Wuhan Hubei China
| | - T. A. Blackledge
- Department of Biology and Integrated Bioscience Program University of Akron Akron OH USA
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Pasquet A, Marchal J, Anotaux M, Leborgne R. Does building activity influence web construction and web characteristics in the orb-web spider Zygiella x-notata (Araneae, Araneidae)? Zool Stud 2014. [DOI: 10.1186/1810-522x-53-11] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kuntner M, Arnedo MA, Trontelj P, Lokovšek T, Agnarsson I. A molecular phylogeny of nephilid spiders: evolutionary history of a model lineage. Mol Phylogenet Evol 2013; 69:961-79. [PMID: 23811436 DOI: 10.1016/j.ympev.2013.06.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/25/2013] [Accepted: 06/15/2013] [Indexed: 11/29/2022]
Abstract
The pantropical orb web spider family Nephilidae is known for the most extreme sexual size dimorphism among terrestrial animals. Numerous studies have made Nephilidae, particularly Nephila, a model lineage in evolutionary research. However, a poorly understood phylogeny of this lineage, relying only on morphology, has prevented thorough evolutionary syntheses of nephilid biology. We here use three nuclear and five mitochondrial genes for 28 out of 40 nephilid species to provide a more robust nephilid phylogeny and infer clade ages in a fossil-calibrated Bayesian framework. We complement the molecular analyses with total evidence analysis including morphology. All analyses find strong support for nephilid monophyly and exclusivity and the monophyly of the genera Herennia and Clitaetra. The inferred phylogenetic structure within Nephilidae is novel and conflicts with morphological phylogeny and traditional taxonomy. Nephilengys species fall into two clades, one with Australasian species (true Nephilengys) as sister to Herennia, and another with Afrotropical species (Nephilingis Kuntner new genus) as sister to a clade containing Clitaetra plus most currently described Nephila. Surprisingly, Nephila is also diphyletic, with true Nephila containing N. pilipes+N. constricta, and the second clade with all other species sister to Clitaetra; this "Nephila" clade is further split into an Australasian clade that also contains the South American N. sexpunctata and the Eurasian N. clavata, and an African clade that also contains the Panamerican N. clavipes. An approximately unbiased test constraining the monophyly of Nephilengys, Nephila, and Nephilinae (Nephila, Nephilengys, Herennia), respectively, rejected Nephilengys monophyly, but not that of Nephila and Nephilinae. Further data are therefore necessary to robustly test these two new, but inconclusive findings, and also to further test the precise placement of Nephilidae within the Araneoidea. For divergence date estimation we set the minimum bound for the stems of Nephilidae at 40 Ma and of Nephila at 16 Ma to accommodate Palaeonephila from Baltic amber and Dominican Nephila species, respectively. We also calibrated and dated the phylogeny under three different interpretations of the enigmatic 165 Ma fossil Nephila jurassica, which we suspected based on morphology to be misplaced. We found that by treating N. jurassica as stem Nephila or nephilid the inferred clade ages were vastly older, and the mitochondrial substitution rates much slower than expected from other empirical spider data. This suggests that N. jurassica is not a Nephila nor a nephilid, but possibly a stem orbicularian. The estimated nephilid ancestral age (40-60 Ma) rejects a Gondwanan origin of the family as most of the southern continents were already split at that time. The origin of the family is equally likely to be African, Asian, or Australasian, with a global biogeographic history dominated by dispersal events. A reinterpretation of web architecture evolution suggests that a partially arboricolous, asymmetric orb web with a retreat, as exemplified by both groups of "Nephilengys", is plesiomorphic in Nephilidae, that this architecture was modified into specialized arboricolous webs in Herennia and independently in Clitaetra, and that the web became aerial, gigantic, and golden independently in both "Nephila" groups. The new topology questions previously hypothesized gradual evolution of female size from small to large, and rather suggests a more mosaic evolutionary pattern with independent female size increases from medium to giant in both "Nephila" clades, and two reversals back to medium and small; combined with male size evolution, this pattern will help detect gross evolutionary events leading to extreme sexual size dimorphism, and its morphological and behavioral correlates.
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Affiliation(s)
- Matjaž Kuntner
- Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia; Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA; College of Life Sciences, Hubei University, Wuhan 430062, Hubei, China.
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Blamires SJ, Hou C, Chen LF, Liao CP, Tso IM. Three-dimensional barricading of a predatory trap reduces predation and enhances prey capture. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1493-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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10
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Optimal foraging, not biogenetic law, predicts spider orb web allometry. Naturwissenschaften 2013; 100:263-8. [PMID: 23354758 DOI: 10.1007/s00114-013-1015-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 10/27/2022]
Abstract
The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.
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11
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Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs. Sci Rep 2012; 2:833. [PMID: 23150784 PMCID: PMC3495280 DOI: 10.1038/srep00833] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/25/2012] [Indexed: 01/10/2023] Open
Abstract
Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers.
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12
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Agnarsson I, Gregorič M, Blackledge TA, Kuntner M. The phylogenetic placement of Psechridae within Entelegynae and the convergent origin of orb-like spider webs. J ZOOL SYST EVOL RES 2012. [DOI: 10.1111/jzs.12007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Ingi Agnarsson
- Department of Biology; University of Vermont; Burlington VT USA
- National Museum of Natural History; Smithsonian Institution; Washington DC USA
| | - Matjaž Gregorič
- Institute of Biology; Scientific Research Centre; Slovenian Academy of Sciences and Arts; Ljubljana Slovenia
| | - Todd A. Blackledge
- Department of Biology and Integrated Bioscience Program; University of Akron; Akron OH USA
| | - Matjaž Kuntner
- National Museum of Natural History; Smithsonian Institution; Washington DC USA
- Institute of Biology; Scientific Research Centre; Slovenian Academy of Sciences and Arts; Ljubljana Slovenia
- College of Life Sciences; Hubei University; Wuhan Hubei China
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14
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Năpăruş M, Kuntner M. A GIS model predicting potential distributions of a lineage: a test case on hermit spiders (Nephilidae: Nephilengys). PLoS One 2012; 7:e30047. [PMID: 22238692 PMCID: PMC3253118 DOI: 10.1371/journal.pone.0030047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 12/08/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Although numerous studies model species distributions, these models are almost exclusively on single species, while studies of evolutionary lineages are preferred as they by definition study closely related species with shared history and ecology. Hermit spiders, genus Nephilengys, represent an ecologically important but relatively species-poor lineage with a globally allopatric distribution. Here, we model Nephilengys global habitat suitability based on known localities and four ecological parameters. METHODOLOGY/PRINCIPAL FINDINGS We geo-referenced 751 localities for the four most studied Nephilengys species: N. cruentata (Africa, New World), N. livida (Madagascar), N. malabarensis (S-SE Asia), and N. papuana (Australasia). For each locality we overlaid four ecological parameters: elevation, annual mean temperature, annual mean precipitation, and land cover. We used linear backward regression within ArcGIS to select two best fit parameters per species model, and ModelBuilder to map areas of high, moderate and low habitat suitability for each species within its directional distribution. For Nephilengys cruentata suitable habitats are mid elevation tropics within Africa (natural range), a large part of Brazil and the Guianas (area of synanthropic spread), and even North Africa, Mediterranean, and Arabia. Nephilengys livida is confined to its known range with suitable habitats being mid-elevation natural and cultivated lands. Nephilengys malabarensis, however, ranges across the Equator throughout Asia where the model predicts many areas of high ecological suitability in the wet tropics. Its directional distribution suggests the species may potentially spread eastwards to New Guinea where the suitable areas of N. malabarensis largely surpass those of the native N. papuana, a species that prefers dry forests of Australian (sub)tropics. CONCLUSIONS Our model is a customizable GIS tool intended to predict current and future potential distributions of globally distributed terrestrial lineages. Its predictive potential may be tested in foreseeing species distribution shifts due to habitat destruction and global climate change.
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Affiliation(s)
- Magdalena Năpăruş
- Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia
- Tular Cave Laboratory, Kranj, Slovenia
| | - Matjaž Kuntner
- Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia
- National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
- College of Life Sciences, Hubei University, Wuhan, China
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Gregorič M, Agnarsson I, Blackledge TA, Kuntner M. How did the spider cross the river? Behavioral adaptations for river-bridging webs in Caerostris darwini (Araneae: Araneidae). PLoS One 2011; 6:e26847. [PMID: 22046378 PMCID: PMC3202572 DOI: 10.1371/journal.pone.0026847] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/04/2011] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Interspecific coevolution is well described, but we know significantly less about how multiple traits coevolve within a species, particularly between behavioral traits and biomechanical properties of animals' "extended phenotypes". In orb weaving spiders, coevolution of spider behavior with ecological and physical traits of their webs is expected. Darwin's bark spider (Caerostris darwini) bridges large water bodies, building the largest known orb webs utilizing the toughest known silk. Here, we examine C. darwini web building behaviors to establish how bridge lines are formed over water. We also test the prediction that this spider's unique web ecology and architecture coevolved with new web building behaviors. METHODOLOGY We observed C. darwini in its natural habitat and filmed web building. We observed 90 web building events, and compared web building behaviors to other species of orb web spiders. CONCLUSIONS Caerostris darwini uses a unique set of behaviors, some unknown in other spiders, to construct its enormous webs. First, the spiders release unusually large amounts of bridging silk into the air, which is then carried downwind, across the water body, establishing bridge lines. Second, the spiders perform almost no web site exploration. Third, they construct the orb capture area below the initial bridge line. In contrast to all known orb-weavers, the web hub is therefore not part of the initial bridge line but is instead built de novo. Fourth, the orb contains two types of radial threads, with those in the upper half of the web doubled. These unique behaviors result in a giant, yet rather simplified web. Our results continue to build evidence for the coevolution of behavioral (web building), ecological (web microhabitat) and biomaterial (silk biomechanics) traits that combined allow C. darwini to occupy a unique niche among spiders.
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Affiliation(s)
- Matjaž Gregorič
- Scientific Research Centre, Institute of Biology, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia.
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Kuntner M, Gregoric M, Li D. Mass predicts web asymmetry in Nephila spiders. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2011; 97:1097-105. [PMID: 21060982 DOI: 10.1007/s00114-010-0736-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 10/22/2010] [Accepted: 10/25/2010] [Indexed: 10/18/2022]
Abstract
The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such as the size limitation hypothesis and the biogenetic law.
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Affiliation(s)
- Matjaz Kuntner
- Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Novi trg 2, P. O. Box 306, SI-1001 Ljubljana, Slovenia.
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Pruitt JN, DiRienzo N, Kralj-Fišer S, Johnson JC, Sih A. RETRACTED ARTICLE: Individual- and condition-dependent effects on habitat choice and choosiness. Behav Ecol Sociobiol 2011. [DOI: 10.1007/s00265-011-1208-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kuntner M, Agnarsson I. Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys). Mol Phylogenet Evol 2011; 59:477-88. [PMID: 21316478 DOI: 10.1016/j.ympev.2011.02.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 01/19/2011] [Accepted: 02/02/2011] [Indexed: 10/18/2022]
Abstract
The origin of the terrestrial biota of Madagascar and, especially, the smaller island chains of the western Indian Ocean is relatively poorly understood. Madagascar represents a mixture of Gondwanan vicariant lineages and more recent colonizers arriving via Cenozoic dispersal, mostly from Africa. Dispersal must explain the biota of the smaller islands such as the Comoros and the chain of Mascarene islands, but relatively few studies have pinpointed the source of colonizers, which may include mainland Africa, Asia, Australasia, and Madagascar. The pantropical hermit spiders (genus Nephilengys) seem to have colonized the Indian Ocean island arc stretching from Comoros through Madagascar and onto Mascarenes, and thus offer one opportunity to reveal biogeographical patterns in the Indian Ocean. We test alternative hypotheses on the colonization route of Nephilengys spiders in the Indian Ocean and simultaneously test the current taxonomical hypothesis using genetic and morphological data. We used mitochondrial (COI) and nuclear (ITS2) markers to examine Nephilengys phylogenetic structure with samples from Africa, southeast Asia, and the Indian Ocean islands of Madagascar, Mayotte, Réunion and Mauritius. We used Bayesian and parsimony methods to reconstruct phylogenies and haplotype networks, and calculated genetic distances and fixation indices. Our results suggest an African origin of Madagascar Nephilengys via Cenozoic dispersal, and subsequent colonization of the Mascarene islands from Madagascar. We find strong evidence of gene flow across Madagascar and through the neighboring islands north of it, while phylogenetic trees, haplotype networks, and fixation indices all reveal genetically isolated and divergent lineages on Mauritius and Réunion, consistent with female color morphs. These results, and the discovery of the first males from Réunion and Mauritius, in turn falsify the existing taxonomic hypothesis of a single widespread species, Nephilengys borbonica, throughout the archipelago. Instead, we diagnose three Nephilengys species: Nephilengys livida (Vinson, 1863) from Madagascar and Comoros, N. borbonica (Vinson, 1863) from Réunion, and Nephilengys dodo new species from Mauritius. Nephilengys followed a colonization route to Madagascar from Africa, and on through to the Mascarenes, where it speciated on isolated islands. The related golden orb-weaving spiders, genus Nephila, have followed the same colonization route, but Nephila shows shallower divergencies, implying recent colonization, or a moderate level of gene flow across the archipelago preventing speciation. Unlike their synanthropic congeners, N. borbonica and N. dodo are confined to pristine island forests and their discovery calls for evaluation of their conservation status.
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Affiliation(s)
- Matjaž Kuntner
- Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Novi trg. 2, P.O. Box 306, SI-1001 Ljubljana, Slovenia.
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Novak T, Tkavc T, Kuntner M, Arnett AE, Delakorda SL, Perc M, Janžekovič F. Niche partitioning in orbweaving spiders Meta menardi and Metellina merianae (Tetragnathidae). ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2010. [DOI: 10.1016/j.actao.2010.07.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Harmer AMT, Blackledge TA, Madin JS, Herberstein ME. High-performance spider webs: integrating biomechanics, ecology and behaviour. J R Soc Interface 2010; 8:457-71. [PMID: 21036911 DOI: 10.1098/rsif.2010.0454] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks.
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Affiliation(s)
- Aaron M T Harmer
- Department of Biological Sciences, Macquarie University, Sydney 2109, Australia.
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Nakata K. Does ontogenetic change in orb web asymmetry reflect biogenetic law? Naturwissenschaften 2010; 97:1029-32. [DOI: 10.1007/s00114-010-0719-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Revised: 09/09/2010] [Accepted: 09/09/2010] [Indexed: 12/01/2022]
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