Week 2 – Evolution and Extinction; Environmental Resources (Water, Land, Energy)

how evolution and extinction shape life, then survey environmental resources water, land, and energy with Pakistan-specific examples, threats, and sustainable solutions.

Evolution & Adaptation

• Evolution: change in heritable traits in populations over generations.
• Mechanisms: natural selection, mutation, gene flow, genetic drift.
• Adaptation: trait that increases fitness (e.g., xerophytic leaves in Thar Desert shrubs).
• Speciation: formation of new species (allopatric along altitudinal gradients in the Himalaya).

Extinction

• Background extinction: continuous, low rate.
• Mass extinction: global, many taxa; today’s biodiversity crisis is human-driven.
• Drivers (Pakistan examples):
  • Habitat loss/fragmentation: river regulation affecting Indus River Dolphin.
  • Over-exploitation: rangeland overgrazing in Balochistan.
  • Pollution: agro-chemicals in canal command areas.
  • Invasive species: mesquite (Prosopis juliflora) in Sindh rangelands.
  • Climate change: glacier retreat influencing alpine endemics.

Why it matters: Extirpations reduce ecosystem resilience and services (fisheries, pollination, water purification).

Environmental Resources Overview

• Renewable: replenished naturally (surface water, groundwater if managed, soils with proper stewardship, solar/wind/hydro).
• Non-renewable: form slowly (fossil fuels, some aquifers, mineral soils).
• Resource triad this week: Water, Land, Energy strongly coupled through agriculture and cities.

Lecture 1- Environmental Biology Introduction, Scope, Biosphere, Biomes, Ecosystems & Biodiversity

Water Resources (Pakistan focus)

Stocks: Indus River system (glaciers–snowmelt–monsoon), reservoirs (Tarbela, Mangla), canals, wetlands; aquifers in alluvial plains.
Pressures: seasonal variability, high conveyance losses, salinity/sodicity, industrial/agri pollution, groundwater over-abstraction in Lahore Faisalabad Multan corridor.

Sustainable actions

• Demand management: shift to high-efficiency irrigation (drip/sprinkler), laser land-levelling, crop calendars matched to water budgets.
• Supply & storage: recharge wells, managed aquifer recharge (MAR), small check dams in foothills.
• Quality: buffer strips, constructed wetlands near drains, enforcement of effluent standards.
• Ecosystem flows: maintain environmental releases for deltaic mangroves and fisheries.

Land Resources

Assets: arable alluvium, loess plains, mountain terraces, rangelands, forests, coastal belts.
Degradation drivers: erosion, salinization, waterlogging, urban sprawl, mining, improper tillage.

Best practices

• Soil conservation: contour bunds, terraces, vegetative strips on slopes of KP/GB.
• Salinity management: gypsum + drainage + salt-tolerant varieties in Indus Basin.
• Agroforestry: shelterbelts in wind-eroded Thal/Cholistan.
• Urban planning: protect floodplains/ wetlands; enforce land-use zoning.

Energy Resources

Conventional: natural gas, oil, coal (Thar lignite) security vs emissions trade-off.
Renewables (high potential):

• Hydropower: run-of-river + storage; sediment handling critical.
• Solar PV: high insolation in south Punjab, Sindh, Balochistan; rooftop + agrivoltaics.
• Wind: Gharo–Jhimpir corridor.
• Biomass/biogas: livestock hubs; manage air quality and residue burning.

Just transition: prioritize grid upgrades, distributed solar for schools/clinics, and hybrid solutions for desert and mountain communities.

Summary

Evolution produces biodiversity; mismanaged water, land, and energy undermine that diversity and human wellbeing. A resource strategy that saves water, heals soils, and accelerates renewables reduces extinction drivers and strengthens climate resilience.

The approach followed at E Lectures reflects both academic depth and easy-to-understand explanations.

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