Table S1. A sampler of hybrid zones in which position appears to be determined by climate or environment.
Hybrid zone / Taxa / Structure / Gradient / ReferencesAllonemobius fasciatus x A. socius / ground crickets / mosaic / north/south, elevation / Britch et al. 2001
Aponomma hydrosauri x A. limbatum / ticks / clinal / north/south / Bull & Burzacott 2001
Aquilegia formosa x A. pubescens / columbine / clinal / elevation / Hodges and Arnold 1994
Artemisia tridentate spp. / mountain and basin big sagebrush / bounded hybrid superiority / elevation, moisture / Miglia et al. 2005, Freeman et al. 1991, Wang et al. 1997
Bombina bombina x B. variegata / fire-bellied toads / mosaic / habitat / Vines et al. 2003; Catriona et al. 1998
Caledia captiva / Australian grasshopper chromosomal races / clinal / temperature and precipitation / Kohlmann et al. 1988
Callipepla californica x C. gambelii / California and Gambel’s quail / clinal / precipitation / Gee 2003, 2004
Colaptes auratus spp / yellow and red-shafted flickers / clinal / east/west / Moore and Price 1993
Colias eurytheme x C. eriphyle / Colias butterflies / mosaic / temperature / Jahner et al. 2012
Corvus cornix x C. corone / hooded and carrion crow / clinal / east/west, north/south / Cook 1975, Poelstra et al. 2014
Fraxinus agustifolia x F. excelsior / ash trees / clinal / temperature and precipitation / Gérard et al. 2013
Geomys bursarius x G. lutescens / pocket gophers / clinal / soils / Heaney and Timm 1985
Glaucomys volans x G. sabrinus / flying squirrels / clinal / north/south / Garroway et al. 2010, 2011
Gryllus firmus x G. pennsylvanicus / field crickets / mosaic / north/south, costal/inland, soils / Larson et al. 2013, Harrison et al 1985, Rand and Harrison 1989
Heliconius erato x H. melpomene / Heliconius butterflies / clinal / precipitation / Rosser et al. 2014
Hippolais icterina x H. polyglotta / icterine and melodious warblers / clinal / north/south / Engler et al. 2013
Icterus bullockii x I. galbula / Bullock’s and Baltimore orioles / clinal / temperature / Carling et al. 2011, Swenson 2005, Swenson and Howard 2005
Iris fulva x I. brevicaulis / Louisiana irises / mosaic / habitat / Johnston et al. 2007.
Limenitis arthemis astyanax x L.a. arthemis / admiral butterflies / clinal / north/south / Mullen et al. 2008
Litoria ewingii x L. paraewingi / Australian treefrog / clinal / north/south / Smith et al. 2012
Mytilus spp. / European mussels / mosaic / temperature / Fly et al. 2015, Hilbish et al. 2012, Fraïsse et al. 2014
Papilio canadensis x P. glaucus / swallowtail butterflies / clinal / north/south / Scriber 2011, Kunte et al. 2011, Scriber et al. 2014,
Passerina cyanea x P. amoena / indigo and lazuli buntings / clinal / east/west, temperature / Carling and Brumfield 2008, Carling and Zuckerberg 2011, Swenson 2005, Swenson and Howard 2005
Pheucticus melanocephalus x P. ludovicianus / black-headed and rose-breasted grosbeaks / clinal / east/west, temperature / Mettler and Spellman 2009, Swenson 2005, Swenson and Howard 2005
Picea sp. / white, Engelmann and Sitka spruce / bounded hybrid superiority / costal/inland, elevation / Hamilton et al. 2013a,b, 2014, De La Torre et al. 2014, 2015
Poecile atricapillus x P. carolinensis / black-capped and Carolina chickadees / clinal / north/south / Curry 2005, Taylor et al. 2014
Polyommatus lineages / brown argus butterflies / clinal / north/south / Mallet et al. 2011
Radix lineages / freshwater snails / clinal / precipitation / Patel et al. 2015
Rubus palmatus x R. grayanus / raspberries / clinal / north/south / Mimura et al. 2014
Senecio aethnensis and S. chrysanthemifolius / ragworts / clinal / elevation / Abbott and Brennan 2014; Brennan et al. 2009
Solea aegyptiaca x S. senegalensis / marine fish (soles) / clinal / east/west / Ounes et al. 2011
Vermivora chrysoptera x V. cyanoptera / blue-winged and golden-winged warblers / mosaic / latitude and elevation / Vallender et al. 2007a,b, Gill 1997, 2004
Table S1 References
Abbott, R.J. and Brennan A.C. (2014) Altitudinal gradients, plant hybrid zones, and evolutionary novelty. Phil Trans R Soc B 369, 20130346
Brennan, A.C. et al. (2009) Adaptation and selection in the Senecio (Asteraceae) hybrid zone on Mount Etna, Sicily. New Phytol 183, 702–717
Britch, S.C. et al. (2001) Spatio-temporal dynamics of the Allonemobius fasciatus- A. socius mosaic hybrid zone: a 14-year perspective. Mol Ecol 10, 627–638
Bull, C.M. and Burzacott, D. (2001) Temporal and spatial dynamics of a parapatric boundary between two Australian reptile ticks. Mol Ecol 10, 639–648
Carling M.D., and Brumfield R.T. (2008) Haldane’s rule in an avian system: using cline theory and divergence population genetics to test for differential introgression of mitochondrial, autosomal, and sex-linked loci across the Passerina bunting hybrid zone. Evolution 62, 2600-2615
Carling M.D., and Zuckerberg B. (2011) Spatio-temporal changes in the genetic structure of the Passerina bunting hybrid zone. Mol Ecol 20, 1166-1175
Carling et al. (2011) Using historical DNA to characterize hybridization between Baltimore orioles (Icterus galbula) and Bullock’s orioles (I. bullockii). The Auk 128, 61-68
Catriona, J (1998) Habitat preference in the Bombina hybrid zone in Croatia. Evolution 52, 227-239
Cook, A. (1975) Changes in the carrion/hooded crow hybrid zone and the possible importance of climate. Bird Study 22, 165-168
Curry, R.L. (2005) Hybridization in chickadees: much to learn from familiar birds. The Auk 122, 747-758
De La Torre, A.R. et al. (2014a) Adaptation and exogenous selection in a Picea galuca x Picea engelmannii hybrid zone: implications for forest management under climate change. New Phytol 201, 687-699
De La Torre, A.R. et al. (2015) Genetic architecture and genomic patterns of gene flow between hybridizing species of Picea. DOI: 10.1038/hdy.2015.19
Engler, J.O. et al. (2013) Species distribution models contribute to determine the effect of climate and interspecific interactions in moving hybrid zones. J. Evol Biol 26, 2487-2496
Fly, E.K. et al. (2015) Physiology and biogeography: the response of European mussels (Mytilus spp.) to climate change. Am Mala Bull 33, 136-149
Fraïsse C. et al. (2014) Gene-flow in a mosaic hybrid zone: is local introgression adaptive? Genetics 197, 939-951
Freeman, D.C. et al. (1991) Characterization of a narrow hybrid zone between two subspecies of Big sagebrush (Artemisia tridentata: Asteraceae). Am. J. Bot. 78, 805–815
Garroway, C.J. et al. (2010) Climate change induced hybridization in flying squirrels. Glob Change Biol 16, 113-121
Garroway, C.J. et al. (2011) The genetic signature of rapid range expansion by flying squirrels in response to contemporary climate warming. Glob Change Biol 17, 1760-1769
Gee J.M. (2003) How a hybrid zone is maintained: behavioral mechanisms of interbreeding between California and Gambel’s quail (Callipepla californica and C. gambelii). Evolution 57, 2407-2415
Gee J.M. (2004) Gene flow across a climatic barrier between hybridizing avian species, California and Gambel’s quail (Callipepla californica and C. gambelii). Evolution 58, 1108-1121
Gérard, P.R. et al. (2013) Chilled but not frosty: understanding the role of climate in the hybridization between Mediterranean Fraxinus agistifolia Vahl and the temperate Fraxinus excelsior L. (Oleaceae) ash trees. J Biogeog 40, 835-846
Gill, F.B. (1997) Local cytonuclear extinction of the Golden-winged warbler. Evolution 51, 519-525
Gill F.B. (2004) Blue-winged warblers (Vermivora pinus) versus golden-winged warbles (V. chrysoptera). The Auk 121, 1014-1018
Hamilton, J.A. et al. (2013a) Genomic and phenotypic architecture of a spruce hybrid zone (Picea sitchensis × P. glauca). Mol Ecol 22, 827–841
Hamilton, J.A. et al. (2013b) Differential introgression reveals candidate genes for selection across a spruce (Picea sitchensis x P. glauca) hybrid zone. New Phytol 197, 927-938
Hamilton, J.A. et al. (2014) Fine-scale environmental variation contributes to introgression in a three-species spruce hybrid complex. Tree Genet Genome 11, 1-14
Harrison, R.G. (1985) Barriers to gene exchange between closely related cricket species. II. life-cycle variation and temporal isolation. Evolution 39, 244–259
Heaney, L.R. and Timm R.M. (1985) Morphology, genetics, and ecology of pocket gophers (genus Geomys) in a narrow hybrid zone. Biol J Linn Soc 25, 301-317
Hilbish, T.J. et al. (2012) Change in stasis in marine hybrid zones in response to climate warming. J Biogeog 39, 676-687
Hodges, S.A. and Arnold M.L. (1994) Floral and ecological isolation between Aquilegia Formosa and A. pubescens. PNAS 91, 2493-2496
Jahner J. P. et al. (2012) Drivers of hybridization in a 66-generation record of Colias butterflies. Evolution 66, 818-830
Johnston, J.A. et al. (2008) Intimately linked or hardly speaking? The relationship between genotype and environmental graidents in a Louisiana iris hybrid population. Mol Ecol 10, 673-681
Kohlmann, B. et al. (1988) Environmental predictions and distributional limits of chromosomal taxa in the Australian grasshopper Caledia captiva (F.). Oecologia 75, 483–493
Kunte, K. et al. (2011) Sex chromosome mosaicism and hybrid speciation among tiger swallowtail butterflies. PLoS Genet 7, e1002274–14
Larson, E.L. et al. (2013) Structure of a mosaic hybrid zone between the field crickets Gryllus firmus and G. pennsylvanicus. Ecol Evol 3, 985-1002
Mallet J. et al. (2011) Hybridization and climate change: brown argus butterflies in Britain (Polymmatus subgenus Aricia). Insect Conserv Diver 4, 192-199
Mettler R.D. and Spellman, G.M. (2009) A hybrid zone revisited: molecular and morphological analysis of the maintenance, movement, and evolution of a Great Plains avian (Cardinalidae: Pheucticus) hybrid zone. Mol Ecol 18, 3256-3267
Miglia K.J. et al. (2005) Nine-year reciprocal transplant experiment in the gardens of the basin and mountain big sagebrush (Artemisia tridentate: Asteraceae) hybrid zone of Salt canyon Creek: the importance of multiple-year tracking of fitness. Biol J Linn Soc 86, 213-225
Mimura M. et al. (2014b) Range shift and introgression of the rear and leading populations in two ecologically distinct Rubus species. BMC Evol Biol 14, 209
Moore W.S. and Price J.T. (1993) Nature of selection in the northern flicker hybrid zone and its implications for speciation theory. In Hybrid zones and the evolutionary process, ed Harrison R.G. Pages 196-225
Mullen S.P. et al. (2008) Hybrid zone origins, species boundaries, and the evolution of wing-pattern diversity in a polytypic species complex of North American admiral butterflies (Nymphalidae: Limenitis). Evolution 62, 1400-1417
Ouanes K. (2011) Expanding hybrid zone between Solea aegyptiaca and S. senegalensis: genetic evidence over two decades. Mol Ecol 20, 1717-1728
Patel S. et al. (2015) Characterizing a hybrid zone between a cryptic species pair of freshwater snails. Mol Ecol 24, 643-655
Polestra et al. (2014) The genomic landscape underlying phenotypic integrity in the face of gene flow in crows. Science 20, 1410-1414.
Rand D.M. and Harrison R.G (1989) Ecological genetics of a mosaic hybrid zone - mitochondrial, nuclear, and reproductive differentiation of crickets by soil type. Evolution 43, 432–449
Rosser N. et al. (2014) Stable Heliconius butterfly hybrid zones are correlated with a local rainfall peak at the edge of the Amazon basin. Evolution 68, 3470-3484
Scriber, J.M. (2011) Impacts of climate warming on hybrid zone movement: Geographically diffuse and biologically porous “species borders.” Insect Sci 18, 121-159
Scriber, J.M. et al. (2014) Adaptations to “thermal time” constraints in Papilio: latitudinal and local size clines differ in response to regional climate change. Insects 5, 199-226
Smith K.L. et al. (2012) Spatio-temporal changes in the structure of an Australian frog hybrid zone: A 40 year perspective. Evolution 67, 3442-4354
Swenson N.G. (2005) Gis-based niche models reveal unifying climatic mechanisms that maintain the location of avian hybrid zones in a North American suture zone. J Evol Biol 19, 727-725
Swenson N.G. and Howard D.J. (2005) Clustering of contact zones, hybrid zones, and phylogeographic breaks in North America. Am Nat 166, 581-591
Taylor, S.A. et al. (2014) Climate-Mediated Movement of an Avian Hybrid Zone. Curr Biol 24, 671-676
Vallender R. et al. (2007) Complex hybridization dynamics between golden-winged and blue-winged warblers (Vermivora chrysoptera and Vermivora pinus) revealed by AFLP, microsatellite, and mtDNA markers. Mol Ecol 16, 2017-2029
Vallender et al. (2007) Paternity and performance of golden-winged warblers (Vermivora chrysoptera) and golden-winged X blue-winged warbler (V. pinus) hybirds at the leading edge of a hybrid zone. Behav Ecol Sociobiol 61, 1797-1807
Vallender R. et al. (2009) Extensive range-wide mitochondrial introgression indicates substantial cryptic hybridization in the golden-winged warbler (Vermivora chrysoptera). Avian Cons Ecol 4, 4
Vines T.H. et al. (2003) The maintenance of reproductive isolation in a mosaic hybrid zone between the fire-bellied toads Bombina bombina and B. variegata. Evolution 57, 1876-1888
Wang H et al. (1997) Narrow hybrid zone between two subspecies of big sagebrush (Artemisia tridentata: Asteraceae). IV. Reciprocal transplant experiments. Evolution 51, 95–102