Synthesis of Ecology
Ecology – study of relationships between living organisms and their natural environment. Includes: life
processes,. The term “ecology” – coined by the German biologist Ernst Haeckel, zoologist, artist, writer.
Applications of ecology: Conservation biology, wetland management, natural resource management
(agriculture, forestry, agro-forestry, fisheries), city planning, community health, economics, basic and
1) Community ecology – study of the interactions among species in the same geographic area. Ex:
community connections between plants and the decomposers (e.g., fungi and bacteria); or the
predator-prey dynamics in amphibian biomass.
2) Behavioural ecology – the study of an organism’s behavior in its environment and its ecological
and evolutionary implications. Ethology is the study of observable movement or behavior in
animals. Closely related to – Social ecology – the study of social behaviors among and between
species; such as altruism.
3) Ecosystem ecology – Ecosystems are habitats within biomes that form an integrated whole, with
both physical and biological complexes. Categorized as terrestrial, freshwater, atmospheric, or
marine. Recent addition – techno-ecosystems, which are affected by or primarily the result of
> Ecosystems – organisms, the communities, environment.
4) Human ecology – an interdisciplinary study into the ecology of our species. “Human ecology
may be defined: (1) bio-ecological standpoint – study of man as the ecological dominant in plant
and animal communities and systems; (2) bio-logical standpoint – simply another animal
affecting and being affected by his physical environment; and (3)human standpoint – able to
interact and affect ecological environments in a distinctive and creative way.
5) Metapopulation ecology – study of movement of populations. Migrating organism – emigrants
(when they leave a region) or immigrants (when they enter a region). A site – places where
ecologists sample populations, such as a pond or part of a forest. Sources – productive sites that
are a source of emigrants;
6) Molecular ecology – study of the relationship between ecology and genetic inheritance.
7) Population ecology – studies the dynamics of species populations and how these populations
interact with the environment. A population consists of individuals of the same species that live,
interact and migrate through the same niche and habitat.
Holism – a school of thought which emphasizes that an ecosystem cannot be predicted or understood by a
simple summation of the parts. Ecological studies are holistic as opposed to reductionistic.
Relation to evolution – Ecology and evolution are considered sister disciplines. Natural selection, life
history, development, adaptation, populations, and inheritance are all in ecological and evolutionary
theory. There is no sharp boundary.
Sinks are unproductive sites that only receive immigrants.
N A T U R E
(1) Atmosphere (air) – it contains the oxygen we breathe and protects the earth from radiation;
(2) Lithosphere (land) – which includes the crust and uppermost mantle;
(3) Hydrosphere (water) – is made up of the water elements on the earth;
(4) Biosphere – the part of the earth where plants and animals live.
Environment – includes the physical world, the social world of human relations and the built world of
human creation. The term “environment” has different conceptual meanings and overlaps with the
concept of “nature. The environment of ecosystems includes both physical and biotic attributes.
The physical environment is external – abiotic factors such as temperature, radiation, light, chemistry,
climate and geology. The biotic environment includes genes, cells, organisms, members of the same
species and other species that share a habitat.
Sunlight is the primary input of energy into the planet’s ecosystems.. Radiant energy from the sun
generates heat, provides photons of light measured as active energy in the chemical reactions of life, and
also acts as a catalyst for genetic mutation. Plants, algae, and some bacteria absorb light and assimilate the
energy through photosynthesis.
Physical environments: fire, gravity, pressure, soil, water, wind.
1) Fire – is a natural or man-made disturbance which consumes oxygen, releases CO2, and affects living
organisms is a catastrophic way.
2) Gravity – influences the shape and movement of tectonic plates (earthquakes) and erosion. Gravity
affects plant and fungal growth (gravitropism), animal migrations, and the biomechanics and size of
animals. The cardiovascular systems of animals are functionally adapted to overcome pressure and
3) Pressure – Climatic and osmotic pressure places physiological constraints on organisms, especially
those that fly and respire at high altitudes, or dive to deep ocean depths.
4) Soils – the top layer of mineral and organic dirt; of critical importance in agricultural science and
ecology. Dead organic matter give soils minerals and nutrients for plants. Plants convert carbon
dioxide into biomass and emit oxygen into the atmosphere Plants feed living organisms –
microorganisms, insects, animals, man. The whole of the planet’s soil ecosystems is called the
pedosphere where a large biomass of the Earth’s biodiversity organizes into trophic levels.
5) Water – the key to life; the transformation of water from one state to another is called the
hydrologic cycle. Water is greatly involved in climatic conditions. Oceans, rivers and wetlands are
host to vital physical, biological, and chemical processes.
6) Wind and turbulence – influence heat, nutrient, and biochemical profiles of ecosystems. wind create
thermally layered zones, affecting how fish, algae, and other parts of the aquatic ecology are
structured. Wind speed and turbulence also influence evapo-transpiration rates.
L I F E
Biosphere – was coined by geologist Eduard Suess in 1875, which he defined as: “The place on Earth’s
surface where life dwells.” In ecology, it is the largest scale of ecological organization, the total sum of
ecosystems on the planet.
Biodiversity – varieties of species in ecosystems and their ecological interactions. Biodiversity plays an
important role in ecological health. Preventing species extinctions is one way to preserve biodiversity.
Biogeochemistry – study of how six major elements relate to biological cycles, processes and climate;
Six major elements (hydrogen, carbon, nitrogen, oxygen, sulfur, and phosphorus; H, C, N, O, S, and P)
Biome – a large community of plants and animals that occupies a distinct region. Terrestrial biomes,
typically defined by their climate and dominant … large portions of an ecosystems such as tropical
rainforest, desert, ice caps, oceans. It is a larger unit for the specific specie. Microbiomes are those
inhabited by microbial organisms. Ex: the human body is a biome for a microbe.
Biotic/Abiotic – Biotic – of, related to or caused by living organisms; its opposite is Abiotic – which
means not associated with or derived from living organisms.
Biogeography (an amalgamation of biology and geography) – is the comparative study of the geographic
distribution of organisms and the corresponding evolution of their traits in space and time.
Disturbance – any process that removes biomass from a community – fire, flood, drought, or predation.
These are both the cause and product of natural fluctuations in death rates, species assemblages, and
biomass densities within an ecological community.
Corals – living marine plants that form calcium carbonate skeletons. This provides growing conditions
for future generations and forms a habitat for many other species.
Food webs – the network in an ecosystem pertaining to the movement of nutrients to sustain life;
Food chain – simplified linear feeding path from a basic species to a top consumer. Example: Plants
capture solar energy and use it to synthesize simple sugars during photosynthesis. Plants are eaten by
grazing herbivores, etc..
Gaia hypothesis – states that there is an emergent feedback loop generated by the metabolism of living
organisms that maintains the temperature of the Earth and atmospheric conditions.
Habitat – the environment over which a species is known to occur and the type of community that is
formed as a result. Types: aquatic, terrestrial.
Malthusian growth model – a population will grow (or decline) exponentially as long as the environment
experienced by all individuals in the population remains constant. Variables: death, birth, immigration,
Metabolism – the rate at which energy and material resources are taken up from the environment,
transformed within an organism, and allocated to maintenance, growth and reproduction – is a
fundamental physiological trait.
Niche – the preferred habitat or environment of a specie. The habitat plus the niche is called the ecotope,
which is defined as the full range of environmenta l and biological variables affecting an entire species.
Species – categorized as Autotrophs ( primary producers), Heterotrophs (consumers), and Detritivores
(decomposers). Autotrophs produce their own food by photosynthesis.Heterotrophs feed on others; subdivided
into – primary consumers (strict herbivores), secondary consumers (carnivorous predators that
feed exclusively on herbivores) and tertiary consumers (predators that feed on a mix of herbivores and
predators). Omnivores do not fit neatly into a functional category because they eat both plant and animal
tissues. Detritivores are organism that decompose organic matter, such as fungi and bacteria.
Keystone species – a species that is connected to a large number of other species in the foodweb,
thus needed to sustain other communities. The loss of a keystone species alters trophic
dynamics, and can cause the extinction of other species.
Symbiosis – a physical relationship of dependency between species in nature. Classified broadly into a
host and an associate relationship. A host is any entity that harbours the associate. Relationships that are
mutually or reciprocally beneficial are called mutualisms. Can also include –parasitism.; where the
associate lives in the host.
Trophic – (from Greek troph, τροφή, trophē, meaning “food” or “feeding”); organisms are organized
into trophic levels – the position it occupies in a food chain. Links in food webs primarily connect feeding
relations or trophism among species. Biomass is the estimated total dry weight in a trophic level. Plants
have the greatest biomass.
Human modifications to the planet’s ecosystems – disturbance, biodiversity loss, agriculture,
urbanization, industrialization – cause of rising atmospheric greenhouse gas levels resulting in melting
glaciers, ice caps, rising sea levels; higher planet temperature, extreme fluctuations in weather, alteration
of species distributions, and increased extinction rates.
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