noc19-bt09 Lecture 06-Biodiversity-II

Biodiversity: Understanding Hotspots and Evolutionary Processes

Introduction to Biodiversity

• The lecture begins with a focus on biodiversity, specifically discussing biodiversity hotspots—regions with high species richness and endemism.

• Hotspots are critical as they contain unique species that, if lost, have no backup elsewhere. They also face significant threats from various factors.

Factors Influencing Species Richness

• A key question arises regarding why some regions exhibit high species richness while others do not.

• Areas between the Tropic of Cancer and the Tropic of Capricorn show greater biodiversity compared to polar regions like the Arctic and Antarctic.

Hypotheses on Biodiversity Variation

• Several hypotheses explain variations in biodiversity, combining evolutionary and ecological processes. Current understanding remains hypothesis-driven rather than theory-based.

Evolutionary Speed Hypothesis

• This hypothesis posits that biodiversity is influenced by the time available for evolution and the speed at which it occurs.

• Older areas tend to have more species due to longer evolutionary timescales; rapid evolution can occur in environments with shorter generation times or higher mutation rates.

Examples Illustrating Evolutionary Concepts

• An example contrasts new volcanic islands (with zero evolutionary time) against older islands rich in biodiversity due to millions of years of evolution.

Importance of Generation Time

• Shorter generation times lead to more rapid evolution. For instance:

• Bacteria like E.coli reproduce every 20 minutes, leading to quick population growth.

• In contrast, larger animals like tigers have longer generational periods (around 7 years), resulting in slower population increases.

High Mutation Rates and Evolution

The Role of Environmental Factors in Mutation Rates

• High mutation rates can occur in areas with increased background radiation, such as near uranium mines, or in regions contaminated with heavy metals or chemicals.

• These environmental factors contribute to rapid evolution due to the accelerated rate of genetic changes.

Geographical Area Hypothesis

• The geographical area hypothesis posits that larger and more complex habitats support greater biodiversity by providing more ecological niches for organisms.

• For example, a small island may have limited habitats (e.g., sand and water), while a larger island can host diverse environments like hills, plains, forests, and swamps.

• Larger islands are likely to support a wider variety of species adapted to different habitats compared to smaller islands.

Interspecific Interactions and Biodiversity

Understanding Interspecific Interactions

• The interspecific interactions hypothesis suggests that biodiversity increases in areas where competition among species occurs, influencing niche partitioning.

• Competition leads species to adapt by specializing in different roles within the same habitat, which enhances overall biodiversity.

Niche Partitioning Through Competition

• When two bird species share the same tree but face low competition, they can occupy the same niche (e.g., both feeding on fruits).

• As competition increases (with more bird species), some birds may adapt by shifting their diets from fruits to less nutritious parts like leaves or bark.

Biodiversity and Its Influencing Factors

Evolution and Adaptation

• The evolution of species, such as birds, leads to adaptations that enhance their ability to consume specific food sources like fruits or leaves, increasing biodiversity.

• Competition among species drives the number of bird species upward; more competition results in greater biodiversity.

Role of Predation

• In a pond with three fish species (purple, red, green), the most competitive species (red) could dominate without predation, leading to extinction of others.

• Introducing a predator (like a crocodile) maintains balance by controlling the population of the dominant fish, thus promoting biodiversity.

• Predation prevents any single fish species from outcompeting others excessively, allowing for coexistence and increased diversity.

Ambient Energy Hypothesis

• The ambient energy hypothesis posits that regions with higher energy availability (e.g., sunlight) support greater biodiversity due to favorable living conditions.

• Areas near the equator receive abundant sunlight and water, fostering diverse ecosystems compared to polar regions where low sunlight limits plant growth.

Disturbance and Biodiversity

• The intermediate disturbance hypothesis suggests that areas experiencing high levels of disturbance have lower biodiversity due to frequent extinctions.

Understanding Biodiversity and Disturbance

The Role of Disturbances in Ecosystems

• Areas with low or infrequent disturbances can lead to competitive equilibrium, resulting in the loss of species with low competitive ability. For example, without a crocodile's disturbance in a pond, dominant species may outcompete others, reducing biodiversity.

• A curve representing species richness versus disturbance levels shows that both very low and very high disturbances correlate with fewer species. In contrast, intermediate levels of disturbance promote higher biodiversity.

• This phenomenon is known as the intermediate disturbance hypothesis, which posits that moderate disturbances create conditions favorable for diverse species to thrive.

Examples of Intermediate Disturbance

• An example includes an area densely populated by trees. If some trees are removed (disturbance), sunlight reaches the ground, allowing grasses and herbs to grow alongside remaining trees.

• The creation of varied habitats (e.g., grasslands and forests) leads to more complex ecosystems. Ecotones—areas where different habitats meet—support unique species due to their diverse environmental conditions.

Importance of Biodiversity

• Understanding why biodiversity matters is crucial. Questions arise about the consequences of losing certain species (e.g., cheetahs or tigers). Some argue extinction does not collapse ecosystems; however, this perspective overlooks broader ecological impacts.

• To address these concerns, we must explore the economic value derived from biodiversity. This includes understanding both use values (benefits from resource utilization) and non-use values (benefits even when resources aren't directly used).

Economic Value of Biodiversity

• Total economic value is categorized into use value and non-use value:

• Use value arises from direct interaction with resources.

• Non-use value reflects benefits derived without direct usage.

• Use value further divides into:

• Direct Value: Benefits obtained through consumption.

• Indirect Value: Benefits provided by ecosystem services.

• Option Value: Potential future uses of resources.

Direct Value Explained

• Direct value encompasses consumptive and non-consumptive benefits:

• Consumptive values refer to resources consumed by humans (e.g., timber).

• Non-consumptive values include benefits like recreation or aesthetic enjoyment that do not deplete resources.

Understanding Consumptive vs. Non-Consumptive Resources

Differentiating Resource Types

• The discussion begins with the distinction between consumptive and non-consumptive resources, highlighting that non-consumptive values include recreation, ecotourism, education, and research.

• An example illustrates non-consumptive use: observing a tiger in its habitat does not diminish its value; both the observer and future visitors can enjoy this experience.

• In contrast, consumptive use (e.g., killing a tiger for a trophy) eliminates the resource for others, demonstrating the impact of different usage types on biodiversity.

Importance of Biodiversity Conservation

• Conserving biodiversity ensures access to direct values such as medicinal plants found in forests; examples include cinchona bark used against malaria.

• Indirect values are also crucial; these include watershed benefits like soil conservation and groundwater recharge that support agricultural productivity without direct extraction.

Ecosystem Services and Their Economic Value

Waste Assimilation Example

• A case study near Agra shows how municipal wastewater can be treated naturally by planting trees along channels to absorb nutrients before they enter rivers.

• This method serves as an ecosystem service known as waste assimilation, providing a cost-effective alternative to expensive treatment plants while maintaining water quality.

Addressing Global Warming

• Forest ecosystems play a vital role in carbon sequestration by absorbing CO2 from the atmosphere, which is essential in combating global warming effects.

Exploring Option Value in Biodiversity

Future Potential of Biodiversity

• Option value refers to preserving biodiversity for potential future benefits; keeping forests intact may yield undiscovered medicinal compounds or other resources later on.

Understanding the Value of Biodiversity

Option Value in Biodiversity

• The concept of option value is introduced, where a person pays to keep options open for future decisions regarding land purchase. This reflects the idea of preserving choices for potential future benefits.

• In biodiversity, option value signifies the potential future benefits derived from conserving biological resources, allowing for decisions to be made later.

Existence Value

• Existence value refers to the satisfaction gained from knowing that certain species exist, even if one does not interact with them directly.

• An example is provided where individuals feel happiness from the existence of African lions and sadness at their extinction, illustrating how existence value operates without direct utilization.

Altruistic Value

• Altruistic value arises from awareness that others benefit from natural resources. For instance, Kaziranga National Park provides employment opportunities to locals through tourism.

• The speaker emphasizes deriving happiness from knowing that fellow countrymen gain economic benefits from biodiversity conservation efforts.

Bequest Value

• Bequest value represents the desire to preserve biodiversity for future generations. Individuals may choose not to exploit resources like tigers today to ensure they remain available for descendants.

• The discussion highlights a moral dilemma between immediate financial gain and long-term ecological preservation for future enjoyment.

Importance of Biodiversity Valuation

• Various values (direct, indirect, bequest, existence, altruistic) collectively underscore the significance of biodiversity and its conservation.

• The need for ecological studies is emphasized as essential in understanding and preserving these diverse values associated with biodiversity.

Methods of Valuation

Market Valuation of Forests and Biodiversity

Market Price Method

• The market price method calculates the market value of a forest by multiplying the volume of timber extracted annually by its price, indicating that a forest can generate significant revenue (e.g., 20 crores of rupees per year).

Hedonic Pricing Method

• This method assesses the happiness derived from biodiversity, exemplified by property prices differing based on views (e.g., sea-facing apartments are valued higher due to aesthetic pleasure).

• Hedonic pricing highlights how exposure to biodiversity can influence real estate values compared to areas lacking such features.

Travel Cost Method

• The travel cost method evaluates the number of visitors to natural reserves (like Kanha tiger reserve) and their expenditures, providing insight into the economic value derived from these locations.

• It assumes that visitors perceive greater value than what they pay; for instance, if someone pays 10,000 rupees, their perceived benefit must exceed this amount.

Damage Cost Avoided Method

• This valuation approach estimates potential damages avoided by preserving forests. For example, cutting trees could lead to increased sediment in rivers causing floods or fish deaths.

• It quantifies costs associated with potential damages like flood management and loss of soil productivity if forests were removed.

Replacement Cost Method

• This method considers expenses incurred if forests are replaced with alternative structures (e.g., geo fabrics and filters), calculating how much it would cost to mitigate damage caused by deforestation.

Contingent Valuation Method

Contingent Valuation Method and Biodiversity Insights

Understanding the Contingent Valuation Method

• The contingent valuation method involves surveying individuals to determine how much they are willing to pay for environmental preservation, such as forests.

• Participants may provide varying amounts they would pay annually, which are then aggregated to estimate the total value of the forest.

• This method reflects public perception of environmental value based on monetary willingness, highlighting its significance in economic assessments of biodiversity.

Insights into Biodiversity

• The lecture delves into biodiversity, exploring why certain areas exhibit higher levels compared to others.

• Various hypotheses are discussed that explain the disparities in biodiversity across different regions.