BRIEF OVERVIEW OF PREVIOUS CLASS (5:21 PM)

• Faculty revised aquatic ecosystems and wetlands.
• General discussion on how to approach prelims from now-onwards. 

WETLAND (5:25 PM)

• Difference between Lakes and Wetlands:

• Characteristic	Lake	Wetland (Shallow Lake)
  Origin	Largest due to tectonic forces i.e. geomorphic	Mostly fluvial and residual lakes
  Water	Permanent	Permanent to Temporary
  Water level changes	Relatively small	Relatively large
  Vertical mixing	Thermally regulated	Wind regulated
  Thermal Stratification	Yes	No
  Dominant	Phytoplankton	Macrophytes
  Food chain	Grazing Pathway	Detritus Pathway
  Productivity	Low	High
  Trophic status	Oligotrophic	Mostly eutrophic
  Flood control	Less significant	Significant
  Waste treatment	No	Yes

• Significance:
• Wetlands are called kidneys of the Environment as it helps in filtering sediments and pollutant and purify the water. 
• It helps in nutrient recycling as it helps in the conversion of waste and organic biomass through the food chain. 
• It helps in groundwater recharge as it slows down the water percolates into the lower layer. 
• They provide drinking water and food to people as well as cattle for grazing. 
• It provides habitat and supports a large diversity of life. 
• It helps in disaster control such as controlling floods as well as droughts. 
• It helps in controlling soil erosion. 
• It helps in climate mitigation as it helps in maintaining ecological balance and keeping the environment cool. 
• Cultural and Eco-tourism
• Issues:
• Wetlands in urban areas are encroached and converted due to rapid urbanisation. For example- Banglore, Chennai, Mumbai and Hyderabad etc 
• Increased water pollution fue to excessive release of sewage and industrial waste or agriculture. 
• Excessive fertiliser usage in urban areas causes eutrophication and algal blooms.
• Deforestation 
• Overgrazing 
• Land degradation 
• Over-fishing 
• The release of methane from wetlands and paddy fields contributes to global warming. For example: Balandur lake catches fire due to the release of methane.
• Usage of antibiotics in aquaculture 
• Note: we will study separately all the acts and rules related to wetlands. 

BIODIVERSITY (6:19 PM)

• As per the United Nations Earth Summit, Biodiversity is defined as the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.
• Types of biodiversity:
• 
• Genetic diversity: It is the number of genetic diversity in the genetic make-up of a species and naturally occurring genetic differences among individuals of the same species. The higher genetic diversity enables a species to survive hard conditions. 
• Species diversity: It is the number of species found in an ecosystem. For example- a rainforest ecosystem has higher species diversity than a coniferous ecosystem
• Ecosystem diversity: It is the variation in ecosystems within a larger geographical area or habitat. For example- different types of ecosystems are found in equatorial rainforests. 
• Species diversity:
• It considers two main factors while measuring diversity:
• 1. Richness: It is a number of different species present in an ecosystem. 
• 2. Evenness: It is the number of individuals per species and their relative abundance.
• Species Richness
• 
• It can be divided into three types i.e. alpha, beta and gamma diversity.
• i. Alpha (α) diversity refers to diversity within a particular area, community or ecosystem and is measured by counting the number of taxa(usually species) within the ecosystem. 
• ii. Beta (β) diversity is species diversity in the ecosystem; this involves comparing the number of taxa that are unique to each of the ecosystems. 
• iii. Gamma (γ) diversity is a measurement of overall diversity for different ecosystems within a region. 
• Biodiversity in an ecosystem brings stability.
• A stable system does not show too much variation in productivity. 
• It shows resistance or resilience to occasional disturbances 
• The India State of the Forest report by the Forest Survey of India featured the Shannon-Wiener Index, providing data on species diversity and abundance in regions.

ENDEMISM (7:37 PM)

• It is an ecological state of species being unique to a defined geographic location. 
• Importance of endemism in ecosystems:
• It is an indicator of the richness of biodiversity. 
• It acts as an indicator species of ecosystems. 
• It contributes to the stability and resilience of ecosystems.
• Protecting these species helps in preserving their unique diversity and niche. 
• It also helps in understanding the unique adaptation and evolution process. 
• Note: 
• The species can classified into native and alien species.
• Native Species: These are species that naturally occur and have evolved in a specific region without human intervention
• It can be further classified into endemic and non-endemic.
• Endemic: Species that are native and unique to a specific geographical area or region.
• Non-Endemic: Native species that exist in a particular region but are not exclusive to that region and might be found elsewhere within their native range.
• Alien/Invasive Species: These species are introduced to a region by human activities, intentionally or unintentionally
• These can be further classified into invasive and non-invasive.
• Invasive: Species introduced to a region where they are not native and cause harm to the environment, economy, or human health.
• Non-Invasive: Species introduced to a region but do not cause significant harm to the environment or other species in that area.

DISTRIBUTION OF BIODIVERSITY (7:44 PM)

• Biogeographic realm: 
• It is any of the large special regions of the earth's land surface with ecosystems sharing similar biological evolutionary history and distributional patterns of terrestrial organisms. 
• There are 8 terrestrial biogeographic realms which share similar processes and major vegetation types. 
• 
• The Paleartic realm (Himalayas) and Indo-Malaya realm (rest of India).
• Megadiverse countries: 
• It is a group of countries which account for at least 70% of the planet, terrestrial biological diversity within 10% of Earth's surface. 
• There are 17 such countries.
• 
• Conditions: 
• 1. It must have at least 5000 endemic plants. 
• 2. Marine ecosystem within its borders. 

The Topic for the next class: Biodiversity (Continuation)