Biodiversity refers to the variety of life on Earth, including the diversity of species, genetic diversity within species, and diversity of ecosystems. Biodiversity patterns refer to the distribution of species and ecosystems across the planet, and are influenced by a variety of factors such as climate, topography, geology, and human activities. Global biodiversity hotspots are areas of the world that are particularly rich in biodiversity but are also under threat from human activities.
Biodiversity patterns can be examined at different scales, ranging from global to local. At the global scale, biodiversity is not evenly distributed, with some regions of the world having much higher levels of biodiversity than others. This variation in biodiversity is influenced by a variety of factors, such as latitude, climate, geology, and history. For example, the tropics are known for their high levels of biodiversity, with rainforests and coral reefs being particularly important ecosystems.
At smaller scales, biodiversity patterns can be influenced by a range of factors, such as topography, soil, water availability, and human activities. For example, mountainous regions tend to have high levels of biodiversity due to the diversity of microclimates and habitats that are found at different elevations. Similarly, wetlands and river systems are often important habitats for a wide range of species.
Global Biodiversity Patterns
At the global scale, biodiversity is not evenly distributed, with some regions of the world having much higher levels of biodiversity than others. This variation in biodiversity is influenced by a variety of factors, such as latitude, climate, geology, and history.
One of the most well-known patterns of global biodiversity is the latitudinal gradient, which describes the trend of decreasing biodiversity from the equator towards the poles. The tropics, particularly rainforests and coral reefs, are known for their high levels of biodiversity, while the poles and deserts have much lower levels. This pattern is thought to be driven by a combination of factors, including climate stability, productivity, and speciation rates.
Another global pattern of biodiversity is the relationship between biodiversity and habitat heterogeneity. Areas with a variety of habitats, such as mountains or river systems, tend to have higher levels of biodiversity than areas with homogenous habitats, such as deserts or grasslands. This pattern is thought to be driven by the availability of a range of ecological niches and the ability of species to adapt to different habitats.
At the global scale, biodiversity patterns can also be influenced by historical factors such as glaciation and continental drift. For example, the separation of South America from Africa allowed for the evolution of unique species such as the platypus and marsupials in Australia.
Regional Biodiversity Patterns
At smaller scales, biodiversity patterns can be influenced by a range of factors, such as topography, soil, water availability, and human activities. In some regions, the influence of these factors can create unique biodiversity patterns.
For example, the Appalachian Mountains in North America are known for their high levels of plant diversity, with over 3,000 species of plants found in the region. This is thought to be driven by the range of ecological niches provided by the diverse topography and soil types in the region.
Similarly, the Mediterranean region is known for its high levels of plant diversity, with over 20,000 plant species found in the region. This is thought to be driven by a combination of factors, including the region’s climate, which has a mild winter and dry summer, as well as the region’s history of human activity, which has led to the development of unique agricultural practices such as terraced farming.
Local Biodiversity Patterns
At the smallest scales, biodiversity patterns can be influenced by microhabitat variations, such as soil moisture, pH, and light levels. These factors can create unique niches for different species, leading to high levels of biodiversity in small areas.
For example, the forest floor is often much more diverse than the canopy of a forest, due to the range of microhabitats created by fallen leaves, logs, and other debris. Similarly, small patches of wetland habitat within a larger landscape can support a diverse range of species adapted to wetland conditions.
Global Biodiversity Hotspots
Global biodiversity hotspots are areas of the world that are particularly rich in biodiversity but are also under threat from human activities. These areas have been identified as priorities for conservation efforts, as they contain a large proportion of the world’s plant and animal species, many of which are found nowhere else in the world. The concept of biodiversity hotspots was first introduced by Norman Myers in the 1980s, and has since become an important tool for conservation planning.
To be considered a biodiversity hotspot, an area must meet two criteria: it must contain at least 1,500 species of vascular plants (> 0.5% of the world’s total) that are endemic (i.e., found nowhere else in the world), and it must have lost at least 70% of its original habitat. Using these criteria, a total of 36 biodiversity hotspots have been identified around the world, which collectively cover only 2.3% of the Earth’s land surface but contain over half of the world’s plant species and 43% of all bird, mammal, reptile, and amphibian species.
Examples of biodiversity hotspots include the Tropical Andes in South America, which is home to over 45,000 plant species and a variety of unique ecosystems such as cloud forests and high-altitude grasslands, but is also under threat from deforestation, mining, and agricultural expansion. Another example is the Western Ghats in India, which is one of the world’s eight “hottest hotspots” due to its high levels of biodiversity and endemism, but is also threatened by habitat loss, fragmentation, and invasive species.