Thomas Malthus
Argued that populations grow geometrically while food supply grows more slowly, so growth is always checked.
Why it matters: Inspired both Darwin and Wallace's idea of a struggle for existence.
📄 Malthus TR. An Essay on the Principle of Population. London, 1798.
Alexander von Humboldt
Mapped how vegetation changes with altitude and climate on the Andes (Chimborazo), linking life to physical conditions.
Why it matters: Founded biogeography and the idea of nature as an interconnected whole.
📄 Humboldt A, Bonpland A. Essai sur la géographie des plantes. Paris, 1807.
Pierre-François Verhulst
Growth slows as a population approaches a ceiling — later called the carrying capacity.
Why it matters: The S-shaped curve used in the predator–prey model in this lab.
📄 Verhulst PF. Correspondance mathématique et physique 10:113 (1838).
Ernst Haeckel
Coined Oekologie: the science of the relations of organisms to their environment.
Why it matters: Named the field.
📄 Haeckel E. Generelle Morphologie der Organismen. Berlin, 1866.
Svante Arrhenius
Calculated that halving or doubling atmospheric CO₂ would change Earth's temperature by several degrees. (Eunice Foote had shown CO₂ traps heat in 1856.)
Why it matters: The first estimate of climate sensitivity.
📄 Arrhenius S. Philosophical Magazine 41:237 (1896); Foote E. Am. J. Sci. 22 (1856).
Frederic Clements
Described how plant communities change step by step after disturbance toward a stable 'climax'. Gleason (1926) argued species respond individually — the debate shaped the field.
Why it matters: Ecological succession is still a core idea.
📄 Clements FE. Plant Succession. Carnegie Institution, 1916.
Alfred Lotka; Vito Volterra
Independently wrote equations in which predator and prey numbers rise and fall in linked cycles.
Why it matters: The model behind the Predator & prey module.
📄 Lotka AJ. Elements of Physical Biology, 1925; Volterra V. Nature 118:558 (1926).
Charles Elton
Introduced food chains, the pyramid of numbers and the niche as an animal's role in its community.
Why it matters: Organised ecology around who eats whom.
📄 Elton C. Animal Ecology. London, 1927.
Georgii Gause
Two Paramecium species competing for the same food could not coexist; one always won.
Why it matters: Two species cannot share exactly the same niche.
📄 Gause GF. The Struggle for Existence. Baltimore, 1934.
Arthur Tansley
Coined 'ecosystem': living things and their physical environment as one system.
Why it matters: The central unit of ecology.
📄 Tansley AG. Ecology 16:284 (1935).
Raymond Lindeman
Measured energy passing through trophic levels of Cedar Bog Lake; only a small fraction moves up each level.
Why it matters: Basis of the energy pyramid and the ~10% rule.
📄 Lindeman RL. The trophic-dynamic aspect of ecology. Ecology 23:399 (1942).
Charles David Keeling
Began precise continuous CO₂ measurements at Mauna Loa, revealing the yearly 'breathing' of plants and a steady rise.
Why it matters: The key evidence that human CO₂ is building up.
📄 Keeling CD. Tellus 12:200 (1960).
Rachel Carson
Documented how pesticides such as DDT build up in food chains (biomagnification) and harm birds.
Why it matters: Launched the modern environmental movement; DDT was banned for farm use in the US in 1972.
📄 Carson R. Silent Spring. Boston, 1962.
Robert Paine
Removing the sea star Pisaster from a rocky shore let mussels take over and diversity collapsed.
Why it matters: Some species hold whole communities together.
📄 Paine RT. Am. Nat. 100:65 (1966).
Robert MacArthur & E. O. Wilson
Species number on an island balances immigration (higher near the mainland) and extinction (higher on small islands).
Why it matters: Guides the design of nature reserves.
📄 MacArthur RH, Wilson EO. The Theory of Island Biogeography. Princeton, 1967.
Farman, Gardiner & Shanklin
British Antarctic Survey measurements showed a seasonal collapse of ozone over Antarctica, caused by CFCs.
Why it matters: Led to the Montreal Protocol (1987) — a global environmental success.
📄 Farman JC et al. Nature 315:207 (1985).
UN Earth Summit, Rio
Countries agreed to conserve biodiversity, use it sustainably and share its benefits.
Why it matters: The framework for global conservation targets.
📄 Convention on Biological Diversity, 1992.
US National Park Service
Grey wolves were reintroduced after 70 years; elk numbers and behaviour changed.
Why it matters: A famous real-world trophic cascade — how strongly it affected plants is still debated.
📄 Ripple WJ, Beschta RL. Biol. Conserv. 145:205 (2012); Hobbs NT et al. (2024).
Johan Rockström and colleagues
Proposed nine Earth-system limits (climate, biodiversity, nitrogen…) for a safe operating space for humanity.
Why it matters: A whole-planet view of ecology; a 2023 update judged six of nine crossed.
📄 Rockström J et al. Nature 461:472 (2009); Richardson K et al. Sci. Adv. 9 (2023).
IPBES
Estimated around 1 million animal and plant species are threatened with extinction, many within decades.
Why it matters: The most comprehensive review of the state of nature.
📄 IPBES Global Assessment Report on Biodiversity and Ecosystem Services, 2019.
UN Biodiversity Conference (COP15)
Countries agreed targets including protecting 30% of land and sea by 2030 ('30×30').
Why it matters: The current global plan for nature.
📄 Kunming–Montreal Global Biodiversity Framework, CBD COP15, 2022.