I couldn't find a thread dedicated to this topic, so I figured one was due! It's a subject of great interest to me and I'd like to hear different views and opinions on it. Anything relating to it could be discussed here, but at the moment I'm looking for thoughts on the deliniation of different realms/regions, and if applicable, sub-regions/provinces/whatever your preferred term is. I'm working on an educational piece on animal distributions intended for general audiences & children, and am debating over how to categorize everything, which species should represent which regions, etc. Zoogeographic regions make much more sense to me than simple continental borders in this regard - Asia north of the Himalayas has much more in common with Europe than tropical Asia, North Africa is more akin to southwest Asia than tropical Africa, etc. And I still struggle with considering Central America part of North America because of this!
Wallace's classification is still the most widely used even today, 142 years later. An update from last year of WWF's original ecoregions map still adheres to it (although no sub-regions are delineated), with a few differences such as more of the Arabian Peninsula belonging to the Palearctic rather than Afrotropical, and the Australasian region being partially split into the Oceanian region.
Wallace's original map: https://upload.wikimedia.org/wikipedia/commons/2/2c/Wallace03.jpg
2017 ecoregion map (click on 'Realms' in the upper left): Ecoregions 2017 ©
There have been several variations and attempts to more properly define everything since, but I'm seeing more and more mention of a recent proposal from 2012, however, which overhauls Wallace's map significantly using phylogenetic data: https://www.researchgate.net/public..._Wallace's_Zoogeographic_Regions_of_the_World (the supplementary material at the bottom is also really interesting)
Five new regions have been split from others, many of which have been considered "transitional zones" before:
- Panamanian from the Neotropics (Caribbean & Central America; southern Florida now belongs fully to the Nearctic)
- Madagascan from Afrotropical (which has been proposed several times before)
- From the Palearctic, Saharo-Arabian (North Africa, Arabian Peninsula & Southwest Asia) and Sino-Japanese (Japan, most of China, including Tibet, and the northern Himalayas). Europe & Russia, Central Asia, Mongolia, and Korea still belong to the Palearctic, which also now encompasses all of the Arctic including Greenland and northernmost North America.
- Oceanian from Australian (another more common split that's taken various incarnations, but here includes New Guinea, Melanesia and Polynesia. Hawaii now belongs to the Nearctic)
And the subregions are as follows:
- Nearctic: North American and Mexican (more or less split along the national borders, interestingly; Hawaii belongs to the North American sub-region)
- Neotropical: Amazonian and South American (Peruvian Andes, Paraguay, Chile and Argentina)
- Afrotropical: African and Guineo-Congolian (Congo Basin & rainforest region of West Africa)
- Palearctic: Eurasian and Arctico-Siberian (Arctic Circle and northern Russia/Siberia)
- Sino-Japanese: Japanese, Chinese & Tibetan
- Indo-Malayan: Oriental (India, Sri Lanka & most of mainland Southeast Asia) and Indo-Malayan (Malay Peninsula, Sunda Islands, Sulawesi & Philippines)
- Australian: Australian and Novozelandic (New Zealand)
- Oceanian: Papua-Melanesian and Polynesian
- Panamanian, Madagascan and Saharo-Arabian have no sub-regions.
This version is gaining some traction but isn't anywhere near widely-accepted, and remains controversial to many. Zoogeography has always been tetrapod-centric, but the study's reliance on only mammalian, avian and amphibian phylogenies (with the absence of data necessary to consider reptiles as well) as well as its focus on phylogeny in general have been criticized. I'm no expert and for the most part it makes sense to me - Madagascar for sure should be seperate, the sub-regions seem mostly about right, and I've always considered 'Wallacea' much closer to Indo-Malaya than Australasia - but I'm not completely convinced by some of it. The splitting of the Palearctic could be justified but it's hard to say if it's necessary (although Saharo-Arabia definitely is somewhat of a gray area between its three (four?) bordering regions), however the Neotropical splitting does seem a little gratuitous to me - Central America's and northern South America's fauna seem so similar to me but I might be missing something.
Of course there have been several different twists on Wallace's regions over the years. Here are a few regions I've seen pop up in more than one different classification excluding the 2012 study:
- Andean (southern S. America, essentially the 'South American' subregion of the 2012 study)
- Mediterranean (most of 'Saharo-Arabia' and Mediterranean Europe)
- Western and Eastern Palearctic (often used by birders, the split usually being in between Kazakhstan and Mongolia)
- The Palearctic and Nearctic, particularly farther north, have definite affinities and are often referred to collectively as the Holarctic, but some maps consider the Holarctic to be a proper region in itself.
I've also seen India and New Guinea designated as their own seperate regions at least once.
Nature obviously doesn't adhere to strict borders, but finding the areas where there are definite shifts in fauna is really fascinating to me. I have a love of categorization in general, though
Wallace's classification is still the most widely used even today, 142 years later. An update from last year of WWF's original ecoregions map still adheres to it (although no sub-regions are delineated), with a few differences such as more of the Arabian Peninsula belonging to the Palearctic rather than Afrotropical, and the Australasian region being partially split into the Oceanian region.
Wallace's original map: https://upload.wikimedia.org/wikipedia/commons/2/2c/Wallace03.jpg
2017 ecoregion map (click on 'Realms' in the upper left): Ecoregions 2017 ©
There have been several variations and attempts to more properly define everything since, but I'm seeing more and more mention of a recent proposal from 2012, however, which overhauls Wallace's map significantly using phylogenetic data: https://www.researchgate.net/public..._Wallace's_Zoogeographic_Regions_of_the_World (the supplementary material at the bottom is also really interesting)
Five new regions have been split from others, many of which have been considered "transitional zones" before:
- Panamanian from the Neotropics (Caribbean & Central America; southern Florida now belongs fully to the Nearctic)
- Madagascan from Afrotropical (which has been proposed several times before)
- From the Palearctic, Saharo-Arabian (North Africa, Arabian Peninsula & Southwest Asia) and Sino-Japanese (Japan, most of China, including Tibet, and the northern Himalayas). Europe & Russia, Central Asia, Mongolia, and Korea still belong to the Palearctic, which also now encompasses all of the Arctic including Greenland and northernmost North America.
- Oceanian from Australian (another more common split that's taken various incarnations, but here includes New Guinea, Melanesia and Polynesia. Hawaii now belongs to the Nearctic)
And the subregions are as follows:
- Nearctic: North American and Mexican (more or less split along the national borders, interestingly; Hawaii belongs to the North American sub-region)
- Neotropical: Amazonian and South American (Peruvian Andes, Paraguay, Chile and Argentina)
- Afrotropical: African and Guineo-Congolian (Congo Basin & rainforest region of West Africa)
- Palearctic: Eurasian and Arctico-Siberian (Arctic Circle and northern Russia/Siberia)
- Sino-Japanese: Japanese, Chinese & Tibetan
- Indo-Malayan: Oriental (India, Sri Lanka & most of mainland Southeast Asia) and Indo-Malayan (Malay Peninsula, Sunda Islands, Sulawesi & Philippines)
- Australian: Australian and Novozelandic (New Zealand)
- Oceanian: Papua-Melanesian and Polynesian
- Panamanian, Madagascan and Saharo-Arabian have no sub-regions.
This version is gaining some traction but isn't anywhere near widely-accepted, and remains controversial to many. Zoogeography has always been tetrapod-centric, but the study's reliance on only mammalian, avian and amphibian phylogenies (with the absence of data necessary to consider reptiles as well) as well as its focus on phylogeny in general have been criticized. I'm no expert and for the most part it makes sense to me - Madagascar for sure should be seperate, the sub-regions seem mostly about right, and I've always considered 'Wallacea' much closer to Indo-Malaya than Australasia - but I'm not completely convinced by some of it. The splitting of the Palearctic could be justified but it's hard to say if it's necessary (although Saharo-Arabia definitely is somewhat of a gray area between its three (four?) bordering regions), however the Neotropical splitting does seem a little gratuitous to me - Central America's and northern South America's fauna seem so similar to me but I might be missing something.
Of course there have been several different twists on Wallace's regions over the years. Here are a few regions I've seen pop up in more than one different classification excluding the 2012 study:
- Andean (southern S. America, essentially the 'South American' subregion of the 2012 study)
- Mediterranean (most of 'Saharo-Arabia' and Mediterranean Europe)
- Western and Eastern Palearctic (often used by birders, the split usually being in between Kazakhstan and Mongolia)
- The Palearctic and Nearctic, particularly farther north, have definite affinities and are often referred to collectively as the Holarctic, but some maps consider the Holarctic to be a proper region in itself.
I've also seen India and New Guinea designated as their own seperate regions at least once.
Nature obviously doesn't adhere to strict borders, but finding the areas where there are definite shifts in fauna is really fascinating to me. I have a love of categorization in general, though