Animal Ecology and Evolution

Modern zoology rests on two integrated pillars: ecology (interaction of animals with environment) and evolution (descent with modification from common ancestors).

Darwin and Wallace

• Charles Darwin (1809–1882) — On the Origin of Species (24 November 1859); voyage of HMS Beagle (1831–36), Galápagos finches.
• Alfred Russel Wallace (1823–1913) — letter to Darwin from Ternate (1858) prompted joint Linnean Society paper.

Four pillars of natural selection:

1. Variation exists in populations.
2. Variation is heritable.
3. Overproduction of offspring — struggle for existence.
4. Differential survival/reproduction of better-adapted individuals.

Evidence for evolution

• Fossil record — Archaeopteryx (bird-dinosaur link), whale evolution series (Pakicetus discovered in Pakistan!), horse evolution.
• Comparative anatomy — homologous structures (tetrapod limb), analogous structures (wings of bat vs insect), vestigial organs.
• Comparative embryology — von Baer's law.
• Biogeography — Wallace's Line, Galápagos finches.
• Molecular — universal genetic code, conserved genes (cytochrome c, HOX genes), DNA phylogeny.

Pakistan-specific fossil: Pakicetus (~50 million years old, Punjab/Kala Chitta hills) — earliest known whale ancestor, transitional between artiodactyls and modern cetaceans.

Modes of speciation

• Allopatric — geographic isolation drives divergence.
• Sympatric — speciation in same geographic area (polyploidy, host-shift).
• Parapatric — partial isolation along environmental gradient.
• Peripatric — small peripheral population becomes isolated (Mayr's founder effect).

Modern synthesis & beyond

Microevolution mechanisms:

• Natural selection — directional, stabilising, disruptive.
• Genetic drift — random allele frequency change; strong in small populations.
• Gene flow — migration.
• Mutation — ultimate source of variation.
• Non-random mating (assortative).

Hardy–Weinberg principle (1908): in absence of evolutionary forces, allele frequencies remain constant; p² + 2pq + q² = 1.

Neutral theory (Kimura 1968) — most molecular evolution is neutral, not adaptive.

Population ecology

• Population growth:
  • Exponential: dN/dt = rN.
  • Logistic: dN/dt = rN(1 – N/K), where K is carrying capacity.
• Life-history strategies:
  • r-selected — many offspring, little parental care (most fish, insects).
  • K-selected — few offspring, much parental care (elephants, primates).
• Demography — age structure, survivorship curves (I, II, III).

Community ecology

• Trophic levels — producers, primary consumers, secondary, tertiary.
• Keystone species — disproportionate impact (sea otters, wolves).
• Foundation species — physical structure (corals, trees).
• Ecological niche — Gause's competitive exclusion principle.

Behaviour (ethology)

Founders: Konrad Lorenz, Niko Tinbergen, Karl von Frisch — Nobel 1973.

• Innate behaviour — fixed action patterns (FAPs).
• Imprinting — Lorenz's goslings.
• Learning — habituation, classical conditioning (Pavlov), operant (Skinner), insight learning.
• Bee dance — von Frisch decoded the waggle dance for communication of food source distance/direction.
• Altruism — kin selection (Hamilton 1964: rB > C), reciprocal altruism (Trivers 1971).

Wildlife conservation in Pakistan

Flagship species

• Snow leopard (Panthera uncia) — vulnerable; Bishkek Declaration 2013; PSL & WCS programmes.
• Markhor (Capra falconeri) — national animal; trophy hunting funds community conservation in Gilgit-Baltistan.
• Houbara bustard (Chlamydotis macqueenii) — overhunted by Gulf falconers; CMS-listed.
• Indus river dolphin (Platanista minor) — endangered; ~2,000 left.
• Marine turtles (green, olive ridley) — nest at Hawksbay/Sandspit; Sindh Wildlife Department.
• Gharial (Gavialis gangeticus) — locally extinct in Indus.
• Asiatic black bear, Himalayan brown bear — endangered.

Protected area network

• 27 national parks (Khunjerab, Deosai, Margalla, Hingol, Chitral Gol, Lal Suhanra).
• ~120+ wildlife sanctuaries and game reserves.
• Trophy hunting — community-managed scheme since the 1990s; revenues fund local conservation.

Conservation legislation

• Pakistan Wildlife Acts (provincial; e.g. Punjab Wildlife Act 1974, Sindh Wildlife Ordinance 2020, KP Wildlife Act 1975 amended 2015).
• CITES — ratified 1976.
• CMS Convention on Migratory Species (1979).
• Ramsar Convention — Pakistan has 19 Ramsar wetland sites.

Major extinctions

The "Big Five" mass extinctions: end-Ordovician, late Devonian, end-Permian (largest), end-Triassic, end-Cretaceous (dinosaurs). Scientists now talk of a sixth, anthropogenic extinction.

Behaviour ecology applied

• Trophy hunting in Pakistan provides a textbook incentive-based conservation example.
• Markhor populations in Chitral Gol and Tushi-Shasha conservancies have rebounded since the 1990s under regulated trophy hunting.