Biogeographic realm

Earth has many large areas.

Plants and animals live in these spots. They grow in special ways. These places are often far apart. Oceans or high mountains keep them separate. This helps them grow in their own way.

Some areas have many different types of life. These spots are not the same as biomes. Biomes are based on the weather and soil. Realms are based on how life grew over time. It is fun to see how life changes.

Earth is divided into very large areas. We call these biogeographic realms.

These realms group life by how it grew. Animals and plants evolve in these spots over a long time. Large barriers keep them apart. These barriers can be oceans or big deserts. High mountains also act as walls. This helps life change in its own way in each spot.

Realms are not the same as biomes. A biome is a type of habitat. Biomes are based on things like weather and soil. One realm might have many different biomes. For example, a forest in one realm may look like a forest in another. But the animals there have different histories.

Scientists use different systems to name these areas. One man named Miklos Udvardy made a famous list. Another group called the World Wildlife Fund has a system too. They name many realms. The Palearctic covers much of Eurasia. The Nearctic includes most of North America. The Neotropic covers South America. The Afrotropic includes parts of Africa.

Earth has many very large areas called biogeographic realms.

These realms are the biggest ways we divide land. They group living things based on where they live. Animals and plants in one realm often share a history. They evolved in these areas over a very long time. Natural barriers keep these groups apart. These barriers can be wide oceans or large deserts. High mountain ranges also act as walls. These walls stop animals from moving to new places.

Realms are different from what scientists call biomes. A biome is a type of habitat. Biomes are based on things like weather and soil. A realm might contain many different biomes. For example, a forest in Central America is a biome. A forest in New Guinea is also a biome. They might look very similar to each other. However, the animals in them have different histories. The plants and fungi in each realm evolved separately. This is because of how landmasses moved over time.

Many people have worked to name these areas. Philip Sclater created a system with six regions. Later, Alfred Russel Wallace expanded his work in 1872. He was an expert who studied birds. Another scientist named Miklos Udvardy made a famous system. His system used the types of living things to define realms. The World Wildlife Fund also has its own system. Their system is similar to Udvardy's work. But they draw the lines for the Australasia realm differently.

There are many specific realms to learn about. The Palearctic covers most of Eurasia and North Africa. The Nearctic includes Greenland and most of North America. The Neotropic covers South America and the Caribbean. The Afrotropic includes parts of Africa, Madagascar, and Arabia.

The Indomalaya realm includes Southeast Asia and southern China. The Australasia realm includes Australia and New Zealand.

Some scientists even group the Palearctic and Nearctic together. They call this combined area the Holarctic realm.

Understanding realms helps us see how life works. It shows us how the Earth's history shapes nature. The movement of land shapes where life can go. This is linked to plate tectonics. Plate tectonics is how the Earth's surface moves.

These large areas help us study how life changes. We can see how different groups grow in isolation. It is a way to map the story of life. This story is written across the whole world.

A biogeographic realm is the largest way to divide the Earth's land surface. These realms group living things together based on where they are found. Scientists use these divisions to show patterns in how organisms are distributed across the globe.

Within these large realms, there are smaller areas called bioregions. These are then broken down even further into smaller units called ecoregions. Sometimes, people use the term "ecozone" to talk about these realms. This helps researchers organize the vast complexity of life on our planet.

How do these realms form? They develop because organisms evolve in relative isolation for very long periods. Natural barriers prevent animals and plants from migrating to new areas. These barriers might be wide oceans or very large deserts. High mountain ranges can also act as walls that stop movement. Because of these barriers, life in one realm develops a unique evolutionary history. This makes the organisms in one realm different from those in another, even if they live in similar weather.

It is important to distinguish realms from biomes. A biome is a major habitat type. Biomes are defined by life forms and how they adapt to specific conditions. These conditions include climate, soil types, and other environmental factors. Biomes are often characterized by their climax vegetation, which is the stable plant community in an area. A single biogeographic realm can contain many different biomes. For example, a tropical moist broadleaf forest in Central America and one in New Guinea might share the same biome type. However, they belong to different realms because their plants and animals have very different evolutionary histories.

History shows how our understanding of these areas has grown. In 1872, Alfred Russel Wallace developed a system of zoogeographic regions. He was an ornithologist, which is a scientist who studies birds. He expanded upon an earlier system created by Philip Sclater. Sclater had originally defined six regions. Later, Miklos Udvardy created a system of biogeographic realms based on taxonomic composition. Taxonomy is the science of naming and classifying living things. The World Wildlife Fund (WWF) also uses a scheme that is broadly similar to Udvardy's work. The main difference is how they define the Australasian realm.

There are several major terrestrial realms to identify. The Palearctic realm covers most of Eurasia and North Africa. The Nearctic realm includes Greenland and most of North America. Sometimes, scientists group the Palearctic and Nearctic together as the Holarctic realm. The Afrotropic realm includes Trans-Saharan Africa, Madagascar, and Arabia. In South America, the Neotropic realm covers the continent, Central America, the Caribbean, South Florida, and the Falkland Islands.

The Indomalaya realm includes the Indian subcontinent, Southeast Asia, and southern China.

The Australasia realm is a large area that includes Australia, New Zealand, and many islands like New Guinea and New Caledonia. The way this realm is drawn depends on which system you use. In Udvardy's system, New Zealand was part of the Antarctic realm. In the WWF system, it is part of Australasia. The Antarctic realm includes Antarctica and several surrounding islands like South Georgia.

There are also transition zones where different realms meet. Examples include the Mexican transition zone and the Chinese transition zone. These zones sit between two different realms.

The distribution of life across these realms is tied to the movement of the Earth. Plate tectonics, the study of how Earth's large plates move, has shaped the distribution of landmasses over geological history. As landmasses move, they create or destroy the barriers that define realms. This connection shows that the history of the Earth's physical structure is directly linked to the history of life. By studying biogeographic realms, we can see how the physical world and the biological world change together over millions of years.