Several patterns of biodiversity can occur within various species, communities, regions, habitats, biomes, ecosystems and the entire Earth. We can get species-area relationships with the study of biodiversity.
It is the variety in organisms (plants/animals/microorganisms) that are found at every level of biological organization in the environment. Ecologists have studied and observed a regular pattern in which diversity was distributed over the environment.
Ecologists observed that species vary at global level as well as locally; also, species vary over time.
Species Varying Globally - Global pattern of biodiversity has been observed; here, species living in similar habitats are found in different parts of the world are distantly related and act in a similar way. Examples are Emus that are found in Australia, Rheas found in South America, Ostriches found in Africa, all are flightless birds.
Species Varying Locally - An example is the Galapagos islands that consist of a group of islands that are relatively close to each other but comprise different atmospheres with different climates. So, each island comprises its own species of tortoise and finch that adapt to respective islands.
Species Varying Over Time - An example that we can cite is modern-day armadillo and the fossil remains of glyptodont that resemble each other.
Latitude: It is a determinant of the angular distance of a place with respect to the equator, which ranges from 0° at the Equator to 90° (North or South) at the poles.
Gradient: "direction and rate of fastest increase".
Latitudinal gradients in species diversity explains the diverse existence of species on Earth (Biodiversity) and it varies with change in altitude or latitude. And we can observe an increase in biodiversity when we move from high latitude to the low latitude.
We can also say that diversity of species decreases when we move from equator towards poles.
The temperate regions having severe climate will have short growing periods for plants whereas the tropical regions will have favourable climate for the plants growth throughout the year. Therefore, a rich biodiversity exists in tropical regions because of the favourable environmental conditions that supports speciation and enables a larger number of species to grow and flourish.
For example, in tropical rainforests, the vascular species per 0.1 ha sampe area or the mean number ranges from 118-236 whereas it is only in the range of 21-28 for the temperate regions.
This type of correlation that exists between diversity and latitude can be observed in a number of taxonomic groups such as butterflies, ants, moths and birds.
Tropical latitudes (near the equator) were undisturbed for areas as compared to temperate latitudes (near the poles) i.e. they have higher collection of species or living organisms whereas the latter are disturbed by glaciers.
Tropical latitudes have a suitable environment for niche and living organisms. In polar or temperate regions, climate changes are unpredictable and the atmosphere is not suitable for living organisms to adapt to the changes. As a result, organisms migrate from those places or die.
Tropical regions organisms will sustain high because of the high availability of more solar energy as compared to the temperate zones.
A relationship between species diversity and the area.
Species diversity is the richness of species, i.e. how many different species exist in one area. Also, it describes species evenness, i.e. how evenly the species are distributed in one particular area. Species richness and species evenness constitute species biodiversity. It increases with increase in explored areas. When species explore other areas than initially found one, they expand their habitat and thus, biodiversity increases. However, there are other factors that govern it such as climatic factors and availability of food to sustain organisms.
Therefore, species diversity will be directly proportional to the explored area. It can be represented in the form of an equation:
logS= log C + Z logA
S is species richness/evenness.
C is a constant.
Z is regression coefficient or slope of the curve (can be understood with the help of a graph drawn below).
A is Explored or Particular Area.
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1. How do you Find the Species Richness and Area Relationship?
Ans. We can find it with the help of an equation: Log S= Log C + Z Log A
Where, S is the species, C is constant, A signifies the area.
It helps to predict the number of species found in a particular area or region.
A rough estimation is found to know the number of species.
2. What is Biodiversity Pattern in Species?
Ans. Biodiversity pattern in species is understanding that the number of species found on Earth vary globally, locally as well as with time. Many variations can be present within species, biomes, ecosystems and a particular area.
3. What are the Two Concepts that Help us to Understand the Variegation of Biodiversity or Patterns of Biodiversity?
Ans. The two important concepts that help us understand the pattern of biodiversity in Science are:
Species Area Relationships
4. How do you Explain Biodiversity Patterns in India?
Ans. The four biodiversity hotspots in India include Eastern Himalayas, Western Ghats, Western Himalayas and Andaman and Nicobar Islands.