Jordon-Thaden IE, Al-Shehbaz IA, Koch MA* Species richness of a globally distributed
, arctic-alpine polyploid genus, Draba
L. (Brassicaceae). Alpine Botany.
*correspondence: University of Heidelberg, Center for Organismal Studies (COS), Department of Biodiversity and Plant Systematics, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany.
Draba Distributions in Detail
This description of Draba distributions is a textual narrative of the species matrix that can be found in ESM 2. Here, we make connections between shared species between the different levels of ecoregions (I, II, III, and IV) and categories of shared species (narrow, medium, wide, and large). The species occurring in the different ecoregions are indicated, and endemic species are highlighted when known. Biogeographical correlations are made when appropriate.
Eastern North America
The Eastern North American region is defined here as all areas east of the Greater Rocky Mountain ranges in Canada and United States to the Atlantic coast, and south of the Canadian Tundra. The Level I region of Eastern North America region has 7 species combined. Eastern North America is divided into two major regions, those of the Eastern North American Hardwood Forests ecotype, and those in the Great Plains. The Eastern Canadian species that are in the tundra are more akin to the species in the arctic and are discussed within that section below. The group that is mostly in the United States is the eastern North American hardwood forests and has 5 species: D. arabisans, D. cana, D. glabella, D. incana, and D. ramossisma. This region was divided into three smaller regions: the Great Lakes forests (D. arabisans, D. cana, D. glabella, D. incana), Appalachian mixed forests (D. ramossisma), and the remainder of the central U.S. hardwood forests (D. ramossisma). The remainder of the Eastern North American groups represents very few species: the Great Plains (D. aurea, D. cana, D. ruaxes).
Draba arabisans is found in the Central Canadian forests and in the area around the Great Lakes, and continues to the Atlantic coast of Canada. Draba aurea, a strongly Canadian species is also found in the High Great Plains. This is also true for D. cana, except it is also more circum-north in its distribution and can also be found in Siberia. The mostly circum-north species, D. incana and D. glabella, reach into the Great Lakes region, but go no further south. This leaves D. ramosissima as the only Core Draba species to not be found in the arctic and exclusively found in the central forests of the Appalachia in the United States. Draba ruaxes is also found in the Great Plains, but is found again in the Cascades and Columbia River Valley all the way to Alaska, skipping over the Central Rocky Mountains. It is important to mention here many of the lowland annual species that were formally defined to be Draba are in the eastern United States and some of those also are shared with the southwest of North America. However, these species are now recognized as Abdra and Tomostima species (Abdra aprica, Abdra brachycarpa, Tomostima cuneifolia, Tomostima platycarpa, Tomostima sonorae,and Tomostima reptans) and are not considered in the species richness data within this manuscript (Jordon-Thaden et al. 2010; Al-Shehbaz 2012).
Western North America
The Western portion of North America includes the North American Cordillera of the Western Hemisphere and consists of the many mountain ranges either closely associated with the Continental Divide or even as far west as the mountains of California (the Southern American Cordillera is in South America and consists of the Andes and is discussed next), and as far east as eastern Wyoming. The Level I region North American Cordillera has a total of 102 Draba species, most of which have a narrow distribution within the different mountain ranges. This North American Cordillera is divided here into three Level II Ecoregions: Northern North American Cordillera (26), Central North American Cordillera (58), and Southern North American Cordillera (41).
The Northern North American Cordillera is divided into two Level III Ecoregions. The north-central Canadian Tiaga, having 22 species, many of which are also found in the Central North American Cordillera and the arctic. The Pacific Northwest and Northern California coastal forests have five species: D. albertina, D. aureola, D. cinerea, D. howellii, and D. petrosperma. Two of these species, D. aureola and D. howellii, have a distribution that includes the forests of Northern California, into the Cascades and Columbia River Valley. Only two other species, D. carnosula and D. pterosperma, have a narrow distribution in coastal Northern California only.
The Central North American Cordillera consists of one Level III region and is sub-divided into four Level IV regions, one of which has a very high species number. The Central Rocky Mountains holds one of the highest numbers of Draba species (49). The Northern Rocky Mountains hold 21 species, most of which also occur in the Central Rockies except with the addition of D. cinerea, D. corymbosa, D. glabella, D. grandis, and D. ruaxes. There are 33 species missing from the Northern Rockies that are only found in the Central Rockies. Five of species have a wide southerly distribution and grow both in the Central and Southern Rockies. Two of these species, D. fladnizensis and D. porsildii, have a Central Rocky Mountain distribution shared with Northern Canadian Tiaga and the North American Beringia areas.
The Cascades and Columbia River Valley have 14 species. Draba cusickii has a medium range distribution that includes the Oregon Cascades and the Snake and Columbian River valleys and steppe. Draba cyclomorpha is the only species with a narrow distribution in northeastern forests of Oregon. Draba ruaxes has a disjunct distribution and is found within the Columbia River Valley, Great Plains, and Alaska.
The Colorado Plateau, the last of the four regions within the Greater Rocky Mountains, has four species: D. rectifructa, D.aurea, D. albertina, and D. abajoensis. None of these species are endemic to the Colorado Plateau. Draba abajoensis and D. rectifructa are found also in the southwestern forests of Arizona. Draba albertina and D. aurea are more widespread North American Cordilleran species.
The Southern North American Cordillera is divided into three Level III ecoregions. The Sierra Nevada, Great Basin, and southwestern forests of Arizona group into one region (40), the southwestern American Deserts (9), and the third region is Mexico (8). Nine species have a narrow distribution in the Sierra Nevada: D. asterophora, D. breweri, D. cruciate, D. incrassata, D. lemmonii, D. longisquamosa, D. monoensis, D. scharsmithii, and D. sierrae. Eight species, D. arida, D. incrassata, D. kassii, D. paucifructa, D. pedicellata, D. pennellii, D. serpentina, and D. sphaeroides, are narrowly distributed in the Great Basin. Only 2 species, D. subumbellata and D. californica, are found in both the Sierra Nevada and the Great Basin. The remaining 11 species in this region are found in other regions of the Central Rocky Mountains. The southwestern forests of Arizona have 7 widely distributed species and 4 narrowly distributed species which are D. asperella, D. bifurcate, D. petrophila, and D. mogollonica. Draba spectabilis is found both in the southwestern forests of Arizona and the Central Rocky Mountains. While D. abojoensis is similar to D. spectabilis, except is not found in the Rockies, but the Colorado Plateau instead. Three species, D. demareei, D. corrugata and D. saxosa, have a narrow distribution in the southwest American deserts and do not grow outside of these regions. Draba demareei is endemic to Baja California in particular.
Draba helleriana and D. viridis have a distribution that is Southern Cordilleran, which includes the deserts of southwestern North America, the southern portion of the Central Rocky Mountains, and into Mexico in the xeric matorral forests and Sierra Madre Oriental. Draba nivicola and D. hidalgensis are exclusively Central American species; they are found throughout the dry forests of Mexico and small areas in Guatemala, including the Sierra Madre Oriental and the Trans Mexican volcanic Belt. Four species, D. standlei, D. jorullensis, D. implexa, and D. rubicaulis, are found in the broadly defined Mexican and Central American dry mountains that include the southwestern deserts straddling the border of Mexico and USA. These mountain ranges include the Sierra Madre Occidental and Oriental, and the Trans Mexican volcanic belt.
Some North American Cordilleran species share distribution ranges with either other parts of North America, Arctic Canada, or Siberia. Some North American Cordilleran species like, D. praealta, D. albertina, D. densifolia, D. grandis, D. porsildii, D. macounii, D. oligosperma, D. stenoloba, D. ruaxes, and D. lonchocarpa, have more in common with Beringia than other areas of North America. Also differentiating between North American and Beringia, D. albertina, D. densifolia, D. porsildii, and D. grandis are Cordilleran and only on the North American side of Beringia. Similarly, D. macounii, D. stenoloba, and D. incerta, also are Cordilleran and stay on the North American side of Beringia, but continue into the Canadian Arctic Archipelagos. As mentioned above, D. ruaxes has a unique distribution, occurring from North American Beringia, throughout the North American Cordillera, excluding the Central Rockies, into the mountains of the Cascades and Columbia Valley, then again in the high portion of the Great Plains. Draba lonchocarpa is similar to other Cordilleran and North American Beringian species, except that it is also found in Asian Beringia and partly into continental Siberia.
The North American Cordilleran species with the largest distribution is D. oligosperma, which extends from the Yukon to southern Colorado and from Eastern California to Eastern Wyoming and has the largest altitudinal range of ~7000 to 10,000 ft. Draba aurea and D. crassifolia are the most widely distributed Draba species in all of North America. Their distribution includes all of arctic Canada, Greenland, and Beringia, throughout the North American Cordillera going as far south as the southwestern forests of Arizona, excluding only Mexico and Eastern United States.
South American Draba can be described as occurring in the entire Andes chain from Western Venezuela to Chile, the Patagonian Steppe and the dry grasslands of Eastern Argentina. There are 73 species currently described in all of South America. The Northern Andes has 48 species, the Central Andes with 26, and the Southern Andes with 6. Not a single species is distributed throughout the entire South American continent. However, a few species are shared between the regions. Below is described the species distribution for the three major regions.
The Northern Andes, which consists of the high mountains of Venezuela, Colombia and Ecuador, was not divided into any smaller groups for this analysis. There are 42 species that are growing only in the Northern Andes, most of which are narrow to possibly endemic (48 total). Six species occur in both the North and Central Andes: D. alyssoides, D. depressa, D. hallii, D. matthioloides, D. schusteri, and D. wurdackii. None of the Northern Andes species occur throughout the entire region. Draba hallii has the widest distribution and occurs in numerous administrative states in the Northern Andes. The region near Quito has the most number of species, with 12 species occurring there.
The Central Andes region, with 26 species, is described here as most of Peru, the western portion of Bolivia, and the very northern parts of Chile and Argentina. Compared to the Northern Andes, there are fewer endemic species, but still mostly narrowly distributed species. Nineteen species are only found in the Central Andes. Draba brackenridgei is the most commonly distributed species in the Central Andes. One species, D. tucumanensis, is shared between the Central and Southern Andes. Draba araboides is now Tomostima araboides and is not included here in these counts (Jordon-Thaden et al. 2010; Al-Shehbaz 2012).
Southern Andes and Patagonia
Southern South America species distribution for Draba is quite uniform. The Southern Andes with 6 species, were divided into 3 smaller groups: Chilean Mountains, South American southern dry shrubs/grasslands, and the Patagonia Steppe (which includes the Falkland Islands). A unique ecosystem is defined here as the southern South American dry shrubs and grasslands region, found in the dry areas of northern Argentina, southern Paraguay and most of Uruguay and is home to only D. pusilla. There are 6 species in the southern portion of South America: D. magellanica, D. pusilla, D. funiculosa, D. thalspiformis, D. gillesii, and D. tucumanensis. The Chilean Mountains and Patagonia Steppe have three shared species, D. funiculosa, D. gilliesii, and D. magellanica, which are found throughout. Only D. pusilla and D. magellanica are found on the Falkland Islands. Two species, D. thlaspiformis and D. tucumanensis are found only within the Chilean Mountains, but as mentioned above, D. tucumanensis is found in the southern reaches of the Central Andes. D. pusilla is the only species found in all three southern regions (but not on the Falkland Islands). Draba australis is now Tomostima australis, and is distributed in the entire southern portion of South America where other Draba species are also growing, but is not included in these counts here (Jordon-Thaden et al. 2010; Al-Shehbaz 2012).
Europe to Iran
There are 70 total species that occur in regions within non-arctic Europe to the mountains of Morocco to Iran. This area of distribution has been divided into three major Level I Ecoregions: Central Europe (28), Mediterranean (34), and Turkey/Caucasus/Iran (31). There are numerous species distributions within and between these regions and are further described below.
This region is defined here to include Europe proper and the neighboring Russian provinces that have forested ecosystems similar to most of Europe. It also includes most of southern Sweden, but the Amphi-Atlantic region (incl. Norway) is considered partially separate and more related to the arctic group. Further discussion about the Amphi-Atlantic species is in the arctic section of this text.
There are 28 species in the Central European region as defined here. Most of those species (25) occur in the major alpine regions that are the Alps, Carpathians, and Pyreenes. The non-alpine forest dwelling and non-Mediterranean species of Europe are distributed from Eastern France to the western border of the Southern Ural Mountains, some of which also occur in alpine areas: D. aizoides, D. aspera, D. cupsidata, D. incana, D. lactea, D. lasiocarpa, D. nemorosa, D. siberica, D. simonkaiana, D. tomentosa, and D. verna. The only European species that do not occur in alpine regions and are considered only non-alpine are Draba cuspidata, D. lactea, D. sibirica and D. simonkaiana. Very few European species have a narrow distribution. Draba cuspidata is known only to be found on Crimea. Draba simokaiana is known only from the non-alpine regions of Romania. Only 2 of the most common out of the 11 species non-alpine species continue all the way to the Urals: D. lactea and D. sibirica. Two species are weeds that can be found globally both in alpine and non-alpine habitats: D. nemorosa and D. verna.
There are a total of 25 species found within the alpine regions of Europe. Five species, D. dolomitica, D. hoppeana, D. ladina, D. sauteri, and D. stellata, are only found in the Alps, but 19 species can be found within its boundaries, with only 3 being found only in the Austrian Alps: D. dolomitica, D. sauteri, and D. stellata. Draba ladina is the only species endemic to the Swiss Alps. Draba hoppeana is found in all of the Alps, but not elsewhere. The Carpathians have 14 species and three are endemic: D. dorneri, D. haynaldii, and D. kotschyi. One species is found only in the Alps and the Carpathians: D. pacheri. The Pyreenes have no narrowly distributed species, but have 10 that are also found in either the other European alpine, non-alpine or Mediterranean regions. Eleven European species grow both in and outside the alpine regions, and have rather large distributions and are discussed either below in relation to neighboring regions or in the arctic section of the results. These are: D. aizoides, D. dubia, D. fladnizensis, D. muralis, D. nemorosa, D. verna, D. lasiocarpa, D. siliquosa, D. tomentosa, D. aspera, and D. incana. After the analysis from the phylogeny of Draba, D. muralis is now recognized as its own monotypic genus, Drabella muralis, and the counts are not considered here (Jordon-Thaden et al. 2010; Al-Shehbaz 2012). Draba nemorosa, D. sibirica, and D. verna grow throughout the entire region as well as all neighboring regions.
There are 34 species throughout the entire Mediterranean region, and most are in the eastern part. There are 29 species in the Eastern Mediterranean region, which is divided into two regions. Fourteen are in the Italian and Balkan peninsulas. Nineteen are from Greece, Aegean Sea, western Turkey, and southern Anatolia. Only 9 species are in the Western Mediterranean region.
Draba lacaitae, D. laconica, and D. korabensis are exclusively found in the Eastern Mediterranean. Eastern Mediterranean regions defined here include West Anatolia, the Taurus Mountains, the islands of the Aegean Sea, and the Balkan and Italian peninsulas. Two species have a narrow distribution within the Balkan and Italian peninsulas: D. bertiscea and D. loiseleurii. Seven species, D. strasseri, D. parnassica, D. acualis, D. elegans, D. cretica, D. haradjianii, and D. laconica, have a narrow distribution in the Aegean Sea and South Anatolia regions. Draba loiseleurii is an endemic from Corsica. Draba vesicaria is narrowly distributed in Lebanon, Israel, and Syria. The high mountains of Morocco, Algeria and Tunisia have 5 of the 9 Western Mediterranean species: D. hederifolia, D. hispanica, D. lutescens, D. oreadum, and D. verna. Draba hederifolia and D. oreadum have a narrow distribution in the Moroccan Atlas Mountains, while D. lutescens is in both the Moroccan Atlas and Spain. Draba hispanica is the probably the most characteristic Western Mediterranean species and is known from the Moroccan, Algerian, and Tunisian Atlas Mountains and woodlands and the whole of Spain, including the Pyreenes. Draba aizoides and D. cantabriae (European to Arctic), D. dedeana (Amphi-Atlantic), and D. dubia (Mediterranean and Europe) are the remaining Western Mediterranean species and occur in Spain and beyond, but not Africa. The only species that occurs in Portugal, is the most common European species, D. verna.
Caucasus and Iranica
The Caucasus region includes the Caucasus mountain range, but here we also have added the Eastern Anatolian and Pontic Mountains of Turkey. The Iranica region is defined here as including the Zagros and Elburz Mountains, which are mostly in Iran and the northern part of Iraq. The region has been divided into three Level IV regions and has a total of 31 species. The Caucasus and Northeastern Turkey has the most species (28). The Zagros and Elburz Mountains of Iran and Iraq have 9 species in common with Caucasus and NE Turkey: D. brunifolia, D. huetii, D. minima, D. nemorosa D. pulchella, D. rosularis, D. siliquosa, D. thomasii, and D. verna. The third region Central Turkey has 6 species, but none of them are endemic to this region: D. brunifolia, D. cappadocica, D. huetii, D. polytricha, D. rigida, and D. verna.
Only one species, D. rosularis occurs entirely within the Caucasus and Iranica defined boundaries. Draba bruniifolia and D. minima also cover this region completely, but continue into the Eastern Mediterranean. Draba siliquosa and D. thomasii cover the same region as D. bruniifolia, but also continue into the alpine mountains of Europe. Draba subnivalis has a disjunct distribution that is reported from the Caucasus and then again in alpine Europe. Three species are exclusively found in Caucasus to Central Turkey: D. cappadocica, D. polytricha, and D. rigida. Twelve species have a narrow distribution in the Caucasus and northeastern Turkey, including the northern Anatolian mountains. These are D. araratica, D. elisabethae, D. hispida, D. imeretica, D. incompta, D. longisiliqua, D. mingrelica, D. mollissima, D. ossetica, D. scabra, D. subsecunda, and D. thylacocarpa. Only one species, D. pulchella, is narrowly distributed in the Zagros and Elburz Mountains. Draba heterocoma has a large distribution that goes from the Caucasus to all of the Mediterranean.
Three species share distributions with those in the Central Asian Mountains. Draba aucheri is found in the Zagros, Elburz, Alai, Pamir, and Tian Shan. Draba nuda has a larger distribution starting from the Eastern Mediterranean, through the Zagros and Elburz, and in most of the Central Asian Mountains. Draba huetii is similar, but it also grows into Caucasus and only in the Tian Shan, as well as the Zagros and Elburz.
Ties between Iranica, Mediterranean and Europe
Only one species has been able to colonize almost the entire distribution range of Draba except for South America, and that is true annual D. verna. It is considered only naturalized in North America and was therefore not included in the counts for any North American regions. Draba verna is currently thought to originate somewhere between the European and Caucasus regions, but no population level studies have been attempted. There are other European species that have varied distribution patterns into the Mediterranean, Caucasus, and Iranica regions.
Four species, D. bruniifolia, D. heterocoma, D. minima, and D. siliquosa, are found from Eastern Mediterranean to the mountains of Iran and Iraq. Draba siliquosa is also found in the alpine forests of Europe, as well as being distributed in East Mediterranean and Iranica. Draba dubia, D. lasiocarpa, D. aspera, and D. tomentosa are exclusively European and Mediterranean, but they do not go into Scandinavia, Iranica, Caucasus or the Atlantic coastal regions. Draba aizoides and D. cantabriae are distributed throughout Europe and the Mediterranean regions, including the Atlantic European forests, non-alpine and alpine Europe, and the West and East Mediterranean regions. Draba compacta has a wide distribution that ranges from the Balkan and Italian peninsulas and continues into other alpine regions of Europe, while D. subnivalis and D. thomasii are distributed in alpine Europe and the Caucasus and northeastern Anatolia regions.
Transition from Europe to Russia and the Arctic
These species are found throughout European Russian regions, but mostly are shared with circum-north species: D. verna, D. lactea, D. incana, D. glabella, D. cinerea, D. nemorosa, D. alpina, D. nivalis, D. norvegica, D. oxycarpa, D. insularis, and D. sibirica. Draba insularis is the only species that has a narrow distribution in the northern central Russian Tundra, growing only in the Kola Peninsula and Karelia regions.
Central Asian Mountains
The region which is described here as the Central Asian Mountains includes the following 5 Level II regions: Altai/Sayan/Baikal/Mongolian, Alai/Pamir/Tian Shan, Tibet/Chinese Forests, West Himalaya/Karakoram/Afghanistan/Pakistan Mountains, and the East Himalaya. There are a total of 99 Draba species found throughout this greater region. The region with the most species is the Tibetan Plateau and Chinese Forests (54).
The Altai, Sayan, Baikal, and Mongolian tundra and mountains have 27 species, with 4 species being endemic: D. baicalensis, D. dasycarpa, D. kodarica, and D. primuloides. The Alai, Pamir, and Tian Shan mountain ranges share 33 species, with the Alai and Pamir having the most in common. The Alai and Pamir consist of 29 species, and have six endemic species: D. arseniewii, D. darwasica, D. hissarica, D. odudiana, D. pamirica, and D. vvedenskyii. The Tian Shan has all of the Alai and Pamir species except these endemics and with the addition of D. koeiei and D. korschinskyi. The Tian Shan is also home to D. fladnizensis, D. ochroleuca, and D. talassica.
The Central Asian Mountain region with the most species is in the Tibetan Plateau and southwestern Chinese Forests (52). Only 9 of these species are found in the Eastern Chinese Forests as well: D. eriopoda, D. ladyginii, D. lasiophylla, D. mongolica, D. nemorosa, D. oreades, D. sekiyana, D. subamplexicaulis, and D. ussuriensis. The Eastern Chinese mountains have one endemic species: D. sekiyana. While the Tibetan Plateau and SW Chinese forest have 19 endemic species, for example D. jiulongensis.
The Western Himalaya, Karakoram, Afghanistan and Pakistan mountains have a shared distribution of species (38), with relatively low endemism. This region has the endemic Draba hystrix Hook. f. & Thomson, but is now defined as Pseudodraba hystrix (Kook.f & Thomson) Al-Shehbaz, D. German & M.A.Koch, from the Afghanistan and Pakistan mountains and is not included here in the species counts (Jordon-Thaden et al. 2010; Al-Shehbaz et al. 2011; Karl et al. 2012; Koch et al. 2012). The only other endemic species in the Western Himalaya is Draba alshehbazii from Jammu and Kashmir. The Eastern Himalaya (28) share most of the species with the Western Himalaya, and have 2 species endemic to Eastern Himalaya: D. bagmatiensis and D. sherriffii.
Large and Disjunct Distributions
Draba lanceolata has a large distribution that occurs from the Afghanistan and Pakistan highlands continuously into the Asian side of Beringia, including all the major mountain ranges in Central Asia. Draba minima also shows a large distribution from Greece, Turkey, Caucasus to the Tian Shan and Alai and Pamir. A disjunctive distribution is seen for D. koeiei where it grows in the mountains of Yunnan, then in the Pamir and into the Afghanistan and Pakistan highlands. Draba nuda has a unique distribution that goes from the eastern Mediterranean, through Iranica, excluding Caucasus, and continuously into the Himalayas and the Tian Shan. Draba huetii is recorded from the Aegean Sea continuously into the Tian Shan, but stays north of Karakorum and the Himalayas. Draba aucheri has a large distribution that spans from the Tian Shan, Pamir, and Alai of Central Asia and also in Iran and Iraq mountainous areas. Draba alajica stays south of the Altai and alternatively grows in the Alai, Pamir, Tian Shan into Tibet and the southwestern mountains of China, but excludes the Himalayas. Draba tibetica also is distributed throughout Central Asia, including the Himalayas and Afghanistan and Pakistan highlands, but omitting the Altai, Sayan, and Mongolian mountains and the forests of eastern China.
Draba stenocarpa is distributed throughout the entire mountain range that creates a circle within Central Asia that surrounds the dry ecosystems such as the Gobi desert. Draba eriopoda is distributed almost similar to D. stenocarpa, but is not in the Alai, Pamir, and Tian Shan. Similar to Draba stenocarpa and D. eriopoda, D. parviflora is distributed throughout the entire mountain range circle of Central Asia, but excludes the Himalayas. Draba oreades is distributed throughout all of Central Asian mountains, including Afghanistan and Pakistan highlands. Draba lasiophylla grows in the entire Greater Asian mountain region, including eastern China, but does not venture into the highlands of Afghanistan and Pakistan. Similar to D. lasiophylla, D. olgae also is distributed throughout most of Central Asian mountains, but on the other hand it excludes eastern China and is found in the Afghanistan and Pakistan highlands. Draba alticola grows continuously from the highlands of Afghanistan and Pakistan into the Alai, Pamir, and Tian Shan, across Tibet and into southwestern China.
The Related Tian Shan, Pamir, Alai and Highlands of Pakistan and Afghanistan
Five species, D. pamirica, D. hissarica, D. darwasica, D. odudiana, and D. vvedenskyii, are exclusively found in the Alai and Pamir mountain ranges. While two other species also are found in the Tian Shan as well: D. albertii and D. physocarpa. Continuing south into the highlands of Afghanistan and Pakistan, D. melanopus is also found in all four regions. Draba arseniewii is distributed exclusively from the Alai all the way to the Sayan Mountains. The Tian Shan has one narrowly distributed species: D. talassica.
Eastern Himalaya, Chinese Forests, and Tibet
Surprisingly enough, only two species, D. bagmatiensis and D. sherriffii, are exclusively found in the Eastern Himalaya. Draba altaica has a wide distribution throughout the entire Central Asian mountains, but does not grow into eastern China. Draba sekiyana is the only species that has a narrow distribution for the eastern Chinese forests, and is also restricted to the high elevations in Taiwan. Six species have a wide distribution of eastern Himalaya, Tibet and the southwestern mountains of China: D. elata, D. bhutanica, D. polyphylla, D. lichiangensis, D. cholaensis, and D. humillima. Although the distribution region for D. ussuriensis seems relatively small compared to the above-mentioned super regions, it is the only species that shares the distribution range only from the eastern Chinese forests to the Russian province of Okhotsk.
The Tibetan Plateau has 11 species in common with the southwestern Chinese forests. These 11 species are not found in the Himalayas or other mountains neighboring the Tibet Plateau. One species in particular, D. ladyginii, covers the entire range of Chinese forests as well as Tibet. Draba mongolica has an even wider distribution as it also grows into the Altai, Sayan and Mongolian mountains, as well as Tibet and the Chinese forests. Draba subamplexicaulis is yet even wider with its distribution going into the Tian Shan as well. The Tibetan Plateau has six species with a narrow distribution: D. nylamensis, D. mieheorum, D. jucunda, D. linearifolia, D. kongboiana, and D. sunhangiana.
Himalayas and its Neighbors
Draba glomerata also has a wide distribution growing from the southwestern Chinese mountains, Tibet, completely in the Himalayas and Karakorum and continuing into the highlands of Afghanistan and Pakistan. Draba korschinskyi has similar distribution to D. glomerata, but also continues into the Alai and Pamir. Draba gracillima and D. ellipsoidea share a distribution from the southwestern mountains of China, through Tibet, the Himalayas and Karakoram. Three species, D. affghanica, D. stenobotrys, and D. falconeri, occur from the Himalayas, Karakoram, expanding into greater Kashmir, and into the Hindu Kush and other Afghanistan and Pakistan highland mountains. Six species are exclusively distributed only in the Himalayas proper: D. alshehbazii, D. amoena, D. macbeathiana, D. poluniniana, and D. staintonii. Draba radicans is the only species that grows exclusively only in the Himalayas and Karakoram. Draba sikkimensis is the only species that exclusively grows in the Himalayas, Tibet, and the southwestern mountains of China. The ecosystem that includes the western Himalayas and Karakoram shares the distribution range with the highlands of Afghanistan and Pakistan. For example, D. trinervis has this distribution, while D. setosa and D. winterbottomii also continue into Tibet and southwestern China, but not in the eastern Himalaya. Alternatively, D. involucrata and D. cachemirica have a similar distribution, but excluding the highlands of Afghanistan and Pakistan. Three species are exclusively found only in the Western Himalaya and Karakoram: D. himachalensis, D. aubrietiodes, and D. tenerrima.
Altai, Sayan and Mongolian Mountains and Going North
The Altai and Sayan mountain ranges seem to be a mixing point for Central Asian species and Arctic and Siberian ones (see circum-north section). Draba chamissonis uniquely grows in a large distribution from the Altai and Sayan into central Siberia then continuously into Chukchi and into Alaska. Two species, D. kusnetzowii (or D. kuznetsovii) and D. pygmaea, have a large distribution from the Altai and Sayan and Mongolian mountains into central Siberia. Draba ochroleuca has a large distribution range that spans from the Tian Shan, into Siberia, both arctic and non-arctic, across the Altai, Sayan and Mongolian mountains and into the Chukchi Peninsula. Three species have a narrow distribution from the Altai, Sayan and into the Mongolian mountains: D. baicalensis, D. kodarica, and D. primuloides.
The region with the species distribution that is the greatest in overall geographic coverage is the circum-north or panarctic (83 species). For the purposes of this study, it was decided that circum-north meant any regions that are around the 60° latitude, but still including the British Iles within the subsection Amphi-Atlantic and Japan as part of the greater Beringia ecosystems. This is different than the traditionally described “arctic” or panarctic in that it includes areas that are not considered arctic per se, but have tundra which stays frozen below the seasonally thawed surface, or colder rocky coastal-cliff areas. The Panarctic Flora checklist by Elven et al. (2007) also found defining this region difficult. It is in these tundra and coastal ecosystems where Draba grows, as well as the high mountains found within these areas. Circum-north was used to describe the species distribution if occurred throughout this entire area. This region is divided into three major Level I Ecoregions: Circum-North America/Asia (57), Beringia (60), and Amphi-Atlantic (27). The circum-north North America/Asia was divided into four Level III Ecoregions: North American Arctic Coastal Tundra (40), Asian Arctic Coastal Tundra (34), and non-arctic Siberia and Scandinavia tundra/taiga (21), and east-central coastal Canada (15).
These sections will be discussed in the following paragraphs.
Arctic Coastal Tundra
This region essentially covers all regions bordering and above the Arctic Circle. The number of ecological niches is high in this region, but still enough uniformity exists that it can be grouped into one region. There was a significant difference between the Asian and North American species distribution. The arctic Asian portion, which includes the Level IV Ecoregions of Kola Peninsula Tundra (7 species), Arctic Svalbard and neighboring islands (14), and Arctic Siberia (33), has 34 species combined. The North American portion, which includes Canadian Arctic Archipelagos (28) and most of Greenland (22), also has 40 species when combined. The following species that are in the North American arctic coastal tundra are not found in the Asian Arctic Coastal Tundra: D. arabisans, D. aurea, D. crassifolia, D. densifolia, D. incerta, D. macounii, D. murrayi, D. ogliviensis, D. oligosperma, D. palanderiana, D. porsildii, D. praealta, D. ruaxes, D. simmonsii, D. stenoloba, and D. stenopetala. Of these, the only one is not found throughout the North American arctic coastal tundra is the central-eastern-coastal Canadian D. arabisans. Draba simmonsii is narrowly distributed in the Canadian Archipelagos.
All the Asian Arctic Coastal Tundra species are shared with the North American species except: D. eschscholtzii, D. glacialis, D. ochroleuca, D. parvisiliquosa, D. pohlei, D. prozorvskii, D. simmonsii, and D. taimyrensis. The non-arctic Siberia and Scandinavia ecoregion shares many species with the arctic coastal tundra except has the following unique species: D. chamissonis, D. insularis, D. kusnetzowii, D. lanceolata, and D. pygmaea. Some Siberian Arctic species have narrow ranges within a large area, but do not grow in continental Siberia. These include D. barbata, D. glacialis, D. prozorovskii, D. pohlei, D. sambukii, D. subfladinzensis, and D. taimyrensis. Draba parvisiliquosa is the only species that grows only throughout the entire central Siberian area, including both arctic and continental Siberia.
Non-Arctic Siberia and Scandinavia
This group is mostly circum-north in similarity of species, but has enough unique patterns to separate it from the other Arctic regions despite the fact it is not a true arctic ecological region. This groups shares species with the Arctic Coastal Tundra, Europe, circum-north, Central Asian Mountains, Iranica and Caucasus regions, and has 21 species. It seems to be a mixing point for arctic and non-arctic Draba. The regions within this area are divided into four Level IV Ecoregions. The first is the Scandinavian and Russian Tundra and Taiga (13), second are the Ural Mountains (8), third is the Western Siberian Taiga and Forests (5), and fourth is the Central Siberian Taiga (14). Draba cinerea, D. nemorosa and D. sibirica are common throughout this entire region. Draba parvisiliquosa is the only species that is found only from the arctic to non-arctic Central Siberia. As discussed in the European section, Draba insularis is the only species that has a narrow distribution in the northern central Russian Tundra.
East-central coastal Canada
The area surrounding the Hudson Bay and other eastern Canadian forests and taiga form three Level IV Ecoregions: the Central Canadian Forests (6), Eastern Canada and Hudson Bay taiga and forests (15), and the Northeastern Atlantic Coastal Forests (8). The six Central Canadian Forest Draba species are: D. arabisans, D. aurea, D. cana, D. glabella, D. incana and D. pycnosperma. The Eastern Canada and Hudson Bay taiga and forests consist of those six species with the addition of D. alpina, D. cinerea, D. crassifolia, D. fladnizensis, D. incerta, D. lactea, D. nivalis, D. norvegica, and D. subcapitata. The Northeastern Atlantic Coastal Forests have similar common species: D. arabisans, D. aurea, D. cana, D. glabella, D. incana, D. nivalis, D. norvegica, and D. pycnosperma.
The Draba species of Beringia also show a significant difference between the North American and Asian areas and share a total of 60 species at the Level II Ecoregions, making it a region of high species richness as the Greater Rocky Mountains, with 58 species. The Asian side of Beringia is divided into four Level IV Ecoregions: one which includes Japan, part of Korea, the Kuriles, and Okhotsk region (16 species); a second that includes the Chukchi and Kamchatka Peninsulas (27); the third is Wrangel Island (20), and fourth is the Cherskii and Kolyma Mountain tundra (15); all together, the Asian Beringian region has 43 species.
The North American portion is divided also into four Level IV Ecoregions: the Aleutian Islands and Alaskan Peninsula (32) and western coast of Alaska (29), Central and Southern Alaska and the Yukon taiga and tundra (35), and Arctic Alaska which includes the Brooks Mountains and the Yukon (30). Together the North American Beringia region has 39 species.
Draba aleutica is the only species that is exclusively Beringian, growing both on the North American and Asian sides, but not outside of this boundary. Four species, D. japonica, D. sakuraii, D. shiroumana, and D. kitadekensis, have a narrow distribution on the islands of Japan. Japan has a unique group of species that are endemic to the high mountains of the islands. Draba sachalinensis is found both in Japan and on the Kruiles. Draba cardaminiflora has a narrow distribution growing only in the Okhotsk region. Draba supravillosa and D. magadanensis are found only in the Magadan region, and D. tichomirovii in the Chukotski.
Despite the high number of ecosystem types in Alaska, there are still six species, D. ogilviensis, D. mulliganii, D. murrayi, D. scotteri, D. stenopetala, and D. palanderiana, which are distributed throughout the region. Draba ogilviensis and D. murrayi also continue into the Yukon, while D. stenopetala is also covering the entire North American Beringian area. Draba palanderiana covers most of northern North America going from Alaska, Yukon and the arctic of Canada. There are two species known only from Kluanei National Park in the Yukon: D. kluanei and D. yukonensis. Draba ventosa has a wide distribution that is mainly Cordilleran, which continues from the Yukon to the Central Rocky Mountains. Draba oligosperma has the largest Cordilleran distribution (as mentioned above) with the northern most distribution in St. Elias mountain ranges in Kluanei National Park.
Draba grandis was often identified as Draba hyperborean Desv. or Nesodraba grandis Greene or N. megalocarpa Greene. Draba grandis Langsdorf in de Candolle is now the accepted taxon for this Beringian species (Al-Shehbaz et al. 2010). Draba hyperborea Desv. actually refers to the previously named Schivereckia andrzejowski ex de Candolle, which was shown to be a true Draba in the phylogenetic analysis of the genus (Jordon-Thaden et al. 2010; Al-Shehbaz et al. 2010), and is included in the non-arctic Siberian counts, but is not yet officially recognized as Draba hyperborea.
The Amphi-Atlantic region includes the following smaller regions: Greenland (22 species), North Atlantic Islands (9), Atlantic European Forests (which includes the British Isles) (6), coastal Norway (10), and Lappland (18). The entire Amphi-Atlantic region has 27 Draba species. This is different from Hultén’s (1958) inclusion of 6 Draba species in his treatment of Amphi-Atlantic plants. However, here we include species that also have other distribution areas outside of the Amphi-Atlantic 'borders'. Since Hultén’s (1958) first description of the Amphi-Atlantic flora, much work has been done and the region is far better understood (see Brochmann 2003, Brochmann et al. 2004, Jørgensen et al. 2012) - especially due to the strong geological evidence of the Amphi-Atlantic land bridge (reviewed in Brochmann 2003). However, fossil evidence indicating that the current lineages of plants have survived there in situ has not been found. Brochmann (2003) explains that this region has been migrated into and across much more recently from the neighboring areas even when the mode has not been identified (i.e. dispersal across bodies of water). In fact the region seems to be better defined as one of constantly changing habitats containing highly hybridizing, self-fertilizing polyploids, and apomictic or highly asexual species that have survived in one place or another.
Greenland has the most species in the Amphi-Atlantic region and the species are mostly shared with circum-north distributions (22). The North Atlantic Islands has 9 species: D. alpina, D. arctogena, D. glabella, D. incana, D. lactea, D. nivalis, D. norvegica, D. oxycarpa, and D. verna. The coast of Norway and Lappland are similar in both having the following species: D. alpina, D. cacuminum, D. fladnizensis, D. glabella, D. incana, D. lactea, D. nivalis, D. norvegica, and D. oxycarpa. Lappland also has D. arctica, D. acrtogena, D. cinerea, D. corymbosa, D. micropetala, D. nemorosa, D. pauciflora, and D. subcapitata, all of which are also found in Greenland. The Atlantic European coastal species are D. aizoides, D. cantabriae, D. dedeana, D. incana, D. norvegica, and D. verna.
Within this data analysis, there are many different distribution patterns for the Draba species that occur in the Amphi-Atlantic region. Most of these species also have circum-north distribution, but some are also distributed in either western or eastern North America, and others are also in Central and Southern Europe. These patterns are similar to most Amphi-Atlantic plants. There are no Draba species that have a narrow distribution in the Amphi-Atlantic region. Draba incana and D. lactea are largely Amphi-Atlantic and circum-north species with a range that continues into Siberia and Europe and the northeastern portions of North America. But there are many other Amphi-Atlantic species, including 12 other species (D. alpina, D. arctica, D. arctogena, D. cinerea, D. corymbosa, D. crassifolia, D. nivalis, D. micropetala, D. norvegica, D. oxycarpa, D. pauciflora, and D. subcapitata), of which some extends their ranges into the Russian Far East (and therefore circum-north), whereas others have ranges only into Greenland and northeastern Canada. Draba cacuminum has a narrow distribution to the Lappland and Norwegian coastline.
The difference in distribution between the Atlantic coastal forests of Europe and the British Isles is slight. Draba aizoides and D. verna are known on the British Isles and also in mainland Europe and the Mediterranean. Draba aizoides is also a commonly found alpine and sub-alpine European species found in all major mountain ranges within and as far west as the Carpathians, and also into the Mediterranean.
The Amphi-Atlantic species have an interesting distribution which is a merging point between arctic, European and western Mediterranean groups. For example, D. dedeana is known from both the Atlantic coast of Europe and West Mediterranean. The Atlantic Ocean European coast is home to D. hispanica which is found throughout the western Mediterranean, including the Atlas and neighboring mountains of Africa as well as in the Pyreenes. However, unlike D. aizoides and D. dedeana, D. hispanica does not venture out of its Mediterranean climates further into the other Amphi-Atlantic areas. The Pyreenes often share species with other European Alpine species, and not arctic ones. The remaining species that are in this region are discussed within the following section due to their greater distribution patterns within the arctic and beyond.
Comments on Circum-North and Beyond
Six species, D. arctica, D. arctogena, D. micropetala, D. oblongata, D. pauciflora, and D. subcapitata, are exclusively circum-north. Other circum-north species have further distributions into neighboring regions. Draba oxycarpa has an extremely large distribution that ranges from the Aegean and southern Anatolian mountains, throughout arctic and non-arctic Siberia, most Amphi-Atlantic regions including Greenland, and across Beringia into Central Alaska. While D. norvegica has similar distribution range as D. oxycarpa, it does not continue south beyond Scotland, but instead reaches the majority of the Canadian forests. Three species, D. corymbosa, D. borealis, and D. juvenilis, are completely circum-north and Cordilleran. Draba fladnizensis, has a similar distribution but goes even further into Siberia and as far south as the Tian Shan, and the alpine regions of Europe. Similar to D. fladnizensis, D. nivalis is found throughout the circum-north, Cordilleran, and Siberian regions, but only goes as far south as the Altai and Sayan mountains and instead of the Tian Shan. It also extends into most of the Canadian forests. Another extremely large distribution is that of D. nemorosa and D. sibirica. These two species range from most regions in Iranica, Anatolia, Caucasus, and the mountains of Central Asia, into Siberia and Europe and Scandinavia and ultimately circum-north and Beringian. Draba pilosa is the only species that occurs in all of the circum-north regions, but it does not occur in Greenland. Four species occur in all areas except South America, Europe, and the Iranica and Caucasus regions: D. alpina, D. cana, D. cinerea, and D. glabella.