Chapter 6 Practical 4
Aim:
To visualize and analyze the distribution of a species across both spatial and temporal dimensions using secondary data from the Global Biodiversity Information Facility (GBIF).
Principle:
Species distribution is not static. It changes across space (geographic location, altitude, habitat type) and time (seasonal migration, long-term shifts due to climate change, evolutionary history). Modern biodiversity databases aggregate millions of species occurrence records from museums, scientific studies, and citizen scientists. By mapping these records, we can reconstruct a species' geographic range (space) and analyze how its presence in certain areas has changed over decades or centuries (time).
Materials Required:
Computer with internet access.
Web browser to access the GBIF website (www.gbif.org).
(Optional) Spreadsheet software for data analysis.
Procedure:
Step 1: Selecting a Target Species
Choose a species with a well-documented history and a distribution likely to show change. Good examples include:
Climate Indicator Species: The Asian Elephant (Elephas maximus), whose range has fragmented over time.
Migratory Species: The Amur Falcon (Falco amurensis), to show seasonal distribution.
Invasive Species: Lantana (Lantana camara), to show rapid range expansion.
Species affected by human activity: The Indian Vulture (Gyps indicus), to show range contraction.
For this practical, we will use the Indian Peafowl (Pavo cristatus).
Step 2: Data Retrieval from GBIF
Go to the GBIF website.
Click on "Explore" and then "Species".
Search for your target species (e.g., "Pavo cristatus").
On the species page, click "Download" to get occurrence data.
Under "Download format," select "Simple" and then "CSV". This will generate a list of all recorded sightings with coordinates and dates.
Step 3: Analyzing Spatial Distribution
GBIF will automatically generate an interactive map showing all occurrence points.
Observe the spatial pattern:
What is the geographic extent of the points? (This defines the species' range).
Are the points clustered (e.g., around water sources, forests) or widespread?
Are there obvious gaps in the distribution? (e.g., absent from high-altitude regions like the Himalayas).
This map depicts the species' distribution across space.
Step 4: Analyzing Temporal Distribution
To see distribution across time, we need to filter the data by year.
On the GBIF occurrence page, use the "Filters" option.
Filter the data by time. For example:
Period 1 (Historic): 1900 - 1950
Period 2 (Recent): 2000 - Present
Download the CSV data for each time period separately.
Compare the two maps:
Has the overall range expanded or contracted?
Have new populations appeared in new areas? (e.g., peafowl moving into urban areas).
Have populations disappeared from previous areas?
Step 5: Creating a Composite Map (Visualization)
On a single printed map of India: (This can be hand-sketched in your notebook).
Plot the data points from Period 1 (1900-1950) using a blue pen.
Plot the data points from Period 2 (2000-Present) using a red pen.
This composite map will visually show how the species' distribution has changed over time.
Observations:
1. Target Species: Indian Peafowl (Pavo cristatus)
2. Spatial Distribution (All Time):
The occurrence points are predominantly distributed across the Indian subcontinent.
The points are clustered in specific regions: along river valleys, forest edges, and agricultural areas.
A clear gap in distribution is observed in the high-altitude regions of the Himalayas and the dry, arid regions of the Thar Desert.
3. Temporal Distribution (Comparison):
| Feature | Period 1 (1900-1950) | Period 2 (2000-Present) | Inference |
|---|---|---|---|
| Overall Range | Mostly confined to natural habitats: forests, grasslands. | Significant expansion. Now found in urban and suburban areas. | Range has expanded due to adaptation. |
| Distribution Density | Lower number of records. Clusters are less dense. | Higher number of records. Clusters are much denser. | Population may have increased or recording effort improved. |
| Notable Change | Absent from major cities like Delhi and Mumbai. | Numerous records from within major cities. | Successfully colonized urban ecosystems. |
4. Composite Map:
(A hand-drawn map of India would be here)
Blue dots (1900-1950) are concentrated in central and peninsular India.
Red dots (2000-Present) show the same clusters but are more numerous and also appear in new areas, particularly around northern cities (e.g., Delhi, Chandigarh) and deeper into agricultural zones.
Result:
The analysis of GBIF data for the Indian Peafowl (Pavo cristatus) shows that:
Spatially, its distribution is clustered in specific habitats and absent from extreme environments.
Temporally, its geographic range has expanded significantly from the early 20th century to the present day, particularly into human-dominated landscapes like urban areas.
Discussion:
Reason for Spatial Pattern: Peafowl prefer habitats that provide food (grains, insects), water, and roosting trees. They avoid deserts (no water) and high mountains (harsh climate).
Reason for Temporal Expansion:
Adaptation: Peafowl have adapted to feed on agricultural crops and food waste in urban areas.
Protection: Their cultural and religious significance in India offers them protection from hunting.
Habitat Modification: Human expansion has created new suitable habitats (e.g., city parks, golf courses) while destroying natural ones.
Limitations: GBIF data can have biases. Older records are scarce, and modern records are more numerous due to easier data collection methods (e.g., citizen science apps like iNaturalist). This can create an illusion of expansion where there is merely better recording.
Conclusion:
This practical demonstrates that species distribution is a dynamic phenomenon. Using open-access biodiversity databases like GBIF, we can effectively visualize and analyze how a species occupies space and how its range shifts over time in response to environmental and anthropogenic pressures. The Indian Peafowl serves as an excellent example of a species that has successfully expanded its range by adapting to human-modified environments.
Viva Voce Questions:
What does GBIF stand for and what is its purpose?
Global Biodiversity Information Facility. It is an international network and data infrastructure providing open-access biodiversity data.
Name one factor that could cause a species' range to contract over time.
Habitat destruction, hunting/poaching, disease, or competition from an invasive species.
What is the difference between a species' "range" and its "habitat"?
Range is the broad geographic area where a species is found. Habitat is the specific type of environment within that range where it lives (e.g., forest, grassland).
Why is it important to study species distribution over time?
It helps us understand the impacts of climate change, habitat loss, and other anthropogenic activities, which is crucial for conservation planning and policy-making.
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