University of Vermont

The College of Arts and Sciences

Department of Biology

Faculty - Ingi Agnarsson

Ingi Agnarsson

Ingi Agnarsson,

Assistant Professor
  • Ph.D., George Washington University, 2004
  • Research Associate (2004-present) Smithsonian Institution
  • Assistant Professor (2008-2012) University of Puerto Rico
  • Assistant Professor (2012-present) University of Vermont
  • CV (PDF)
Area of expertise


Contact Information
Email: Ingi Agnarsson

Office Hours: Tue 2:15-4:00, or by appointment
Marsh Life Science Building, Rm 316
Phone: (802) 656-0460

Dr. Agnarsson's LAB

Island Biogeography Link


I’m an evolutionary biologist working on various fronts. My main research applies phylogenetics, and population genetics to address evolutionary questions with a focus on spiders. Current topics include evolution of sociality in spiders, evolutionary biomechanical of spider silk, and a large project on the biogeography of the Caribbean and the role of dispersal in diversification.

Selected Publications

  • Liu J, May-Collado LJ, Pekar S, Agnarsson I. 2016.  A revised and dated phylogeny of cobweb spiders (Araneae, Araneoidea, Theridiidae): a predatory Cretaceous lineage diversifying in the era of the ants (Hymenoptera, Formicidae). Molecular Phylogenetics and Evolution 94: 658-675 [3.92; 10/46 (Evolutionary Biology)].
  • Agnarsson I, Levi HW. 2016. Theridiidae. In Ubick D, Cushing PE, Paquin P (eds) Spiders of North America: an identification manual. American Arachnological Society, chapter 62, p. xxx-xxx.
  • Agnarsson I, Gotelli NJ, **Agostini D, Kuntner M. 2016. Limited role of character displacement in the coexistence of congeneric Anelosimus spiders in a Madagascan montane forest. Ecography 39: xxx-xxx, Early View [4.77; 16/145 (Ecology)].
  • *Xu X, Liu F, Chen J, Ono H, Agnarsson I, Li D, Kuntner M. 2016. Pre-Pleistocene geological and climatic events shaping diversification and distribution of primitively segmented spiders on East Asian Margins. Journal of Biogeography 43: xxx-xxx, Early View [4.59; 19/144 (Ecology)]
  • May-Collado LJ, Zambrana-Torrelio CM, Agnarsson I. 2015. Global spatial analyses of phylogenetic conservation priorities for aquatic mammals. In Crandcolas P, Pellens R (eds), Topics in Biodiversity and Conservation, Springer, forthcoming.
  • **Dziki A, Binford GJ, Coddington JA, Agnarsson I. 2015. Spintharus flavidus in the Caribbean – a 30 million year biogeographical history and radiation of a ‘widespread species’. PeerJ 3:e1422; DOI 10.7717/peerj.1422 [2.11; 13/57 (Multidisciplinary sciences)]
  • Lopez-Osorio F, Perrard A, Pickett KM, Carpenter JM, Agnarsson I. 2015. Phylogenetic tests reject Emery’s rule in the evolution of social parasitism in yellowjackets and hornets (Hymenoptera: Vespidae, Vespinae). Royal Society Open Science 2, 150159.
  • Esposito LA, **Bloom T, **Caicedo L, **Alicia-Serrano A, **Sánchez-Ruíz J, Laura J. May-Collado, Binford G, Agnarsson I. 2015. Islands within islands: diversification of tailless whip spiders (Amblypygi, Phrynus) in Caribbean caves. Molecular Phylogenetics and Evolution 93: 107-117 [3.92; 10/46 (Evolutionary Biology)].
  • Kuntner M, Agnarsson I, Li D. 2015. The eunuch phenomenon: Adaptive evolution of genital emasculation in sexually dimorphic spiders. Biological Reviews 90: 279–296 [9.67; 1/85 (Biology)].
  • *Ruch J, Riehl T, May-Collado LJ, Agnarsson I. 2015. Multiple origins of subsociality in crab spiders (Thomisidae). Molecular Phylogenetics and Evolution 82: 330-340 [3.92; 10/46 (Evolutionary Biology)]
  • Dines J, Mesnick SL, Ralls K, May-Collado LJ, Agnarsson I, Dean MD. 2015. A tradeoff between precopulatory and postcopulatory trait investment in male cetaceans. Evolution 69: 1560-1572. [4.61; 8/46 (Evolutionary Biology)]
  • May-Collado LJ, Kilpatrick WC, Agnarsson I. 2015. Mammals from ‘down under’: a multi-gene species-level phylogeny of marsupial mammals (Mammalia, Metatheria) PeerJ 3:e805; DOI 10.7717/peerj.805. [2.11; 13/57 (Multidisciplinary Sciences)]
  • Agnarsson I, **Jencik BB, **Veve GM, *Hanitriniaina S, **Agostini D, *Goh SP, Pruitt J, Kuntner M. 2015. A radiation of subsocial Anelosimus spiders on Madagascar: remarkable local richness and endemism. Zookeys 509: 13-52. [0.93; 86/154 (Zoology)]
  • Gregorič M, Agnarsson I, Blackledge TA, Kuntner M. 2015. Phylogenetic position and composition of Zygiellinae and Caerostris with new insight into orb-web evolution and gigantism. Zoological Journal of the Linnean Society 175: 225-243. [2.72; 14/154 (Zoology)]
  • Marshall SA, Borkent A, Agnarsson I, Otis GW, **Fraser L, **d'Entremont D. 2015. New observations on a neotropical termite-hunting theridiid spider: opportunistic nest raiding, prey storage, and ceratopogonid kleptoparasites. Journal of Arachnology 43: 419-421. [0.62; 62/92 (Entomology)]
  • *Velez-Zuazo X, Alfaro-Shigueto J, Mangel J, Papa R, Agnarsson I. 2015. What barcode sequencing reveals about the shark fishery in Peru. Fisheries Research 161: 34-41 [1.90; 11/52 (Fisheries)].
  • *Gregorič M, Blackledge TA, Agnarsson I, Kuntner M. 2015. A molecular phylogeny of bark spiders reveals new species from Africa and Madagascar (Araneae: Araneidae: Caerostris). Journal of Arachnology 43: 293-312. [0.62; 62/92 (Entomology)]
  • Agnarsson I, Cheng R-C, Kuntner M. 2014. A multi-clade test supports the intermediate dispersal model of biogeography. PLoS One9(1) e86780.
  • Rheims CA, Agnarsson I, Alayón Garcia G. 2014. Description of the male of Yabisi guaba (Araneae: Eresoidea: Hersiliidae). Zoologia 31: 405-407.
  • Cala-Riquelme F, Agnarsson I. 2014. New species of Otiothops MacLeay (Araneae: Palpimanidae: Otiothiopinae) from Cuba. Arachnology 16: 193-194.
  • Bloom T, Binford G, Alayon G, Esposito L, **Peterson I, **Nishida A, **Loubet-Senear K, Agnarsson I. 2014. Discovery of two new species of eyeless spiders within a single Hispaniola cave. Journal of Arachnology 42: 148-154. [0.73; 43/74 (Entomology)]
  • Bond JE, *Garrison NL, *Hamilton CA, Godwin RL, Hedin M, Agnarsson I. 2014. Phylogenomics resolves a spider backbone phylogeny and rejects a prevailing paradigm for orb web evolution. Current Biology 24: 1765–1771. [9.49; 19/289 (Biochemistry and Molecular Biology)].
  • Agnarsson I. 2014. Félagslyndar köngulær á þróunarfræðilegum blindgötum. Náttúrufræðingurinn 84: 132-140. [invited peer-reviewed public science paper, in Icelandic with English abstract: ‘Social spiders on evolutionary blind alleys’]
  • Lopez-Osorio, Pickett KM, Carpenter JM, Ballif BA, Agnarsson I. 2014. Phylogenetic relationships of yellowjackets inferred from nine loci (Hymenoptera: Vespidae, Vespinae, Vespula and Dolichovespula). Molecular Phylogenetics and Evolution73: 190-201
  • McHugh A, Yablonsky A, Binford G, Agnarsson I. 2014. Molecular phylogenetics of Caribbean Micrathena (Araneae: Araneidae) suggests multiple colonization events and single island endemism. Invertebrate Systematics, OnlineEarly.
  • Agnarsson I, Rayor L. 2013. A molecular phylogeny of the Australian huntsman spiders (Sparassidae, Deleninae): implications for taxonomy and social behaviour. Molecular Phylogenetics and Evolution 69: 895-905
  • Majer M, Agnarsson I, Svenning JC, BildeT. 2013. Social species in the spider genus Anelosimus occur in wetter, more productive habitats than non-social species. Naturwissenschaften 100:1031-1040
  • Kuntner M, Arnedo M, Trontelj P, Lokovšek T, Agnarsson I. 2013. A molecular phylogeny of nephilid spiders: Evolutionary history of a model lineage. Molecular Phylogenetics and Evolution 69: 961-979
  • Peng P, Blamires SJ, Agnarsson I, Lin HC, Tso I-M. 2013. A colour-mediated mutualism between two arthropod predators. Current Biology 23: 1-5
  • Agnarsson I, Coddington JA, Kuntner M. 2013. Systematics – progress in the study of spider diversity and evolution. In: Spider Research in the 21st Century (Ed. Penney D) chapter 2, pp 58-111.
  • Agnarsson I, Avilés L, Maddison WP. 2013. Loss of genetic variability in social spiders: genetic and phylogenetic consequences of population subdivision and inbreeding. Journal of Evolutionary Biology 26: 27-37
  • Agnarsson I, Gregorič M, Blackledge TA, Kuntner M. 2013. The phylogenetic placement of Psechridae and the convergent origin of orb-like spider webs. Journal of Zoological Systematics and Evolutionary Research 51: 100-106
  • Grinsted L, Agnarsson I, Bilde T. 2012. Mixed-species colonies of theridiid spiders show extended maternal care and interspecific brood adoption. Naturwissenschaften­ 99: 1021-1030
  • Blackledge TA, Kuntner M, Agnarsson I. 2012. Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs. Scientific Reports 2: 833
  • Agnarsson I, Kuntner M. 2012. The Generation of a Biodiversity Hotspot: Biogeography and Phylogeography of the Western Indian Ocean Islands. In Kesara Anamthawat-Jonsson (Ed.): Current Topics in Phylogenetics and Phylogeography of Terrestrial and Aquatic Systems. Rijeka: In Tech Publishers, pp. 33-82. ISBN 978-953-51-0217-5
  • Agnarsson I. 2012. Systematics of new subsocial and solitary Australasian Anelosimus species (Araneae, Theridiidae). Invertebrate Systematics 26: 1-16.
  • Agnarsson I, Kuntner M, Blackledge TA. Darwin’s bark spider. 2012. In: McGraw-Hill Encyclopedia of Science and Technology. V. 11. New York, McGraw-Hill, pp. 52-54.
  • Blackledge TA, Kuntner M, Agnarsson I. 2011. The form and function of spider orb webs: evolution from silk to ecosystems. In Jérôme Casas, editor: Advances in Insect Physiology 41: 175-262, Burlington: Academic Press.
  • Kuntner M, Agnarsson I. 2011. Phylogeography of a successful aerial disperser: the golden orb spider Nephila on Indian Ocean islands. BMC Evolutionary Biology 11: 119.
  • May-Collado LJ, Agnarsson I. 2011. Phylogenetic analysis of conservation priorities for aquatic mammals and their terrestrial relatives. PLoS One 6(7): 1-10, e22562. doi:10.1371/journal.pone.0022562
  • Kuntner M, Agnarsson I. 2011. Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys). Molecular Phylogenetics and Evolution 59: 477-488
  • Agnarsson I, Zambrana-Torrelio CM, Flores Saldaña NP, May-Collado LJ. 2011. A time-calibrated species-level phylogeny of bats (Chiroptera, Mammalia). PLoS Currents: Tree of Life. Version 44. 2011 Jan 4 [revised 2011 Feb 4]. Available from:
  • Gregorič M, Agnarsson I, Blackledge TA, Kuntner M. 2011. Darwin's bark spider: giant prey in giant orb webs (Araneidae: Caerostris darwini)? Journal of Arachnology 39: 287-295. *Featured in Nature 479: 152-153
  • Kuntner M, May-Collado L, Agnarsson I. 2011. Phylogeny and conservation priorities of afrotherian mammals (Afrotheria, Mammalia). Zoologica Scripta 40: 1-15.
  • Vélez-Zuazo X, Agnarsson I. 2011. Shark tales: A molecular species level phylogeny of sharks (Selachimorpha, Chondrichthyes). Molecular Phylogenetics and Evolution 58: 207-217
  • Agnarsson I, Avilés L, Maddison WP. 2010. Complete separation along matrilines in a social spider metapopulation inferred from hypervariable mitochondrial DNA region. Molecular Ecology 19: 3052-3063
  • Agnarsson I, Kuntner M, May-Collado LJ. 2010. Dogs, cats, and kin: a molecular species-level phylogeny of Carnivora. Molecular Phylogenetics and Evolution 54: 726–745
  • Agnarsson I, Kuntner M, Blackledge TA. 2010. Bioprospecting finds the toughest biological material: extraordinary silk from a giant riverine orb. PLoS One 5(9): 1-9. *Featured in Science 330: 21.
  • Martén-Rodríguez S, Fenster CB, Agnarsson I, Skog LE, Zimmer EA. 2010. Evolutionary breakdown of pollination specialization in a Caribbean plant radiation. New Phytologist 188: 403-417
  • Sensenig A, Agnarsson I, Blackledge TA. 2010. Behavioral and biomaterial coevolution in spider orb webs Journal of Evolutionary Biology 23: 1839-1856