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A Cross-Cultural Introduction to Bioethics
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B1. Ecology and Life
Chapter objectives.
Ecology is the biological science of living relationships.
This chapter aims to:
1. Introduce ecology and how life is defined.
2. Show how life is categorised and organised.
3. Explain living systems, processes & interactions.
B1.1. Ecology - basic ingredients
Biology is the scientific study of life. Ecology is the branch of biology which investigates living
relationships - the science of organization and interaction between different organisms, living
systems they inhabit and their physical environments. There is much less research into the
large-scale systems of ecology compared to the small-scale systems of molecular biology. As we
see the fragility of our world, the future of life depends on human understanding of this subject.
We need more ecologists if we are to manage the many predictions
of global ecological crisis.
Of particular concern are the abundance of life and the
distribution of life. Three primary subjects studied by ecology are:
1. Organisms
2. Interactions
3. Communities
To these traditional areas of discussion in ecology must be added a
fourth major concern, since life cannot be considered in isolation
from the impacts and pressures placed on it by relentless forces of
global change, industrial technology and the expansion of
human-dominated ecosystems:
4. Ecological ethics
Q1.
What other areas of knowledge do you think are important for a young
ecologist to have a working knowledge of, beyond 'natural' ecosystem
interactions?
Q2. Are the soil, water and sky parts of the ecological community?
.
Collaborating author: Morgan Pollard, Australia
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B1.2. Ecology - the cast of characters
Life is defined by science to have particular characteristics: birth, metabolism (synthesis of
energy from the environment), growth, replication (capacity for reproduction), hereditary
variation, adaptation (evolution by natural selection), inner program (DNA, genetics), organic
(carbon-based) chemistry in an aqueous medium, systems behaviour (self-organization,
feedback) and complexity (emergent properties like consciousness). Also relevant to the future of
life are systems which display most of the above characteristics and behaviours, having their own
ways of 'living'. These include viruses, ideas (the 'meme'), human institutions, technologies,
software (e.g. 'genetic' algorithms), and possible future developments in artificial intelligence
and nanotechnology.
The classification of living organisms into a logical hierarchy of groups is called taxonomy.
Biology subdivides life in the following manner: Kingdom, Phylum, Class, Order, Family, Genus
and Species. A commonly used five-kingdom system is Animalia, Plantae, Fungi, Protista and
Monera (bacteria). Communities are assemblages of species in the same habitat. Species are one
of the fundamental units of biology (along with genes, organisms and communities), referring to
a genetically and anatomically distinctive groups of organisms capable of breeding. Species are
written down in italics with a capitalised genus name followed by the species name (e.g. the
human species is Homo sapiens).
Habitat is the home or environmental space in which an organism lives and grows. Examples
shown in Table 1 are large-scale habitats, but boundaries typically merge. Habitats range down in
size to a particular forest community, leaf, pond or the specific localised conditions of
microhabitat. Each species has its ecological niche, or the tactics or role to play in the
community as defined by its food, shelter, foraging habitat, mating season and interactions with
other individuals and species. Keystone species play key roles, linking together community and
ecosystem structure (e.g. the dominant vegetation type of a habitat, specialised micro-organisms
etc.), making them essential conservation targets. An ecosystem is the collected cast of
characters, connected in a balanced performance of networked systems, subsystems, processes,
flows and cycles. Conservation effort is most effectively directed at larger-scale units such as
communities, habitats, ecosystems and vulnerable biodiversity hotspots (Figure 1).
Biodiversity refers to the variety of life, and is studied at the scales of genetic diversity, species
diversity and ecosystem diversity. There have been around 1.8 million species so far described,
but the majority of invertebrates and micro-organisms remain undiscovered. Estimating the total
number of species uses extrapolation from ecological models, scaling up a well known region or
taxon to the global level. Most estimates range from 10 to 50 million, but perhaps even up to 100
million species alive on Earth. Around 13,000 new species are catalogued each year. There are so
many kinds of insects that a young ecologist on a trip to the Amazon could easily discover and
name a new species of beetle. The inventory of life is the most exotic unmapped territory
remaining to science.
Q3. Where does the human species fit into the above cast of characters?
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Table 1: Large scale communities and habitats (also called ecotypes or biomes)
Polar (Arctic):
Coniferous Forest:
Deciduous Forest:
Montane:
Temperate Rainforest:
Tropical Rainforest:
Coral Reefs:
Oceans:
Riparian:
Estuarine:
Sclerophyll Forest:
Savannah:
Deserts:
Polar (Antarctic):
Figure 1:
Land of the polar bear
Northern cold-temperate pine forest (also called boreal forest or taiga)
Distinctly seasonal forests which shed their leaves in winter
High-altitude (cold-adapted) mountain ecosystems
Mid-latitude moist closed-canopy evergreen forest
Warm moist closed forest containing Earth's greatest biodiversity
Tropical coral reef containing the greatest marine biodiversity
Littoral (shallow), neritic (continental shelf) & oceanic (deepwater)
Rivers, lakes and deltas, the essential fresh water habitats
Intertidal bays & river mouths essential as fish nursery-grounds
Mainly hard-leaved (dry-adapted) forests such as Eucalyptus
Dry grasslands with widely-dispersed trees, such as the African plains
Arid (low rainfall) environment with little permanent vegetation
Land of the penguin
Biodiversity Hotspots (known forest & heath habitats only)
Source: E.O. Wilson (1992) The Diversity of Life p.250-251
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B1.3. Ecology - the action
How do organisms and communities change and arrange, and how have the
characteristics and diversity of life changed over the long term? This is the
subject of evolution, and the discovery by Charles Darwin (On The Origin of
Species by Means of Natural Selection, 1859) of a mechanism by which a
lineage can adapt into greater complexity through a series of incremental
changes to suit its environment. Natural selection is the 'survival of the fittest'
idea, where evolutionary success in the struggle for life goes to those
replicators (e.g. genes, organisms) best adapted to reproduce descendants in
competition with other living forms. Small genetic changes which are adaptive
to the environment will bestow competitive advantage, and aid the manoeuvre of the lineage into
new niches.
In building up civilizations, the human species has also designed its institutions around models
of competition and the struggle for fitness (witness major historical activities such as warfare,
economics and politics). Almost forgotten in all this competitive activity has been the more
fundamental interaction exemplified by ecology: namely cooperation.
Fundamentally, the functioning of ecosystems is a broadly cooperative enterprise. A base
framework of cooperation must underlie competitive surface activity; for example even ruthless
business competition must rely upon adherence to a cooperative framework of financial and
trade regulations. Models of cooperation (e.g. open-source software, multilateral agreements) are
increasingly recognised as necessary models for the future.
Close cooperation between two or more species is referred to as
symbiosis, or a symbiotic relationship. It's called mutualism
when both species benefit from the association, commensalism
when only one species gains advantage, and parasitism when
damage is done to the host. Specialised cooperation increases
dependence of one species on the evolutionary success of the
other. In some sense, the whole plant and animal kingdoms are in
broad mutual symbiosis, with animal respiration involving
conversion of oxygen into carbon dioxide, and plant
photosynthesis involving conversion of sunlight and carbon
dioxide into energy and oxygen (which is why tropical
rainforests are the 'lungs of the Earth'). Fungi and bacteria are
decomposers, creating life after death by recycling dead nutrients into a form usable by plants.
Another example of mutual symbiosis is plants and their pollinators, a delicate evolutionary
dance between nectar-producing flowers and pollen-transporting insects.
Q4.
The human species is constantly interacting with natural ecosystems of the
Earth. What kind of symbiotic relationships do we have? Does human
activity generally seem to be in cooperation with, or in competition with
nature?
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B1.4. Ecosystems - structure and function
Commoners' laws of ecology ('Ecology for Beginners')
a) everything is connected to everything else
b) everything must go somewhere
c) nature knows best
d) there's no such thing as a free lunch.
As the name implies, an ecosystem is a type of complex system, the structure and
function of which can be described by systems theory. The difference between a system and a
bundle of parts is that the elements of a system are functioning together as an interconnected
whole. At its simplest, a system is a web or
network, a model highlighting the intersection
points (nodes) and flow routes (links). For example,
a food web is a network flow diagram with a series
of links between predators and their prey. Flows
may be one-way or both ways along a link, and
matter or energy are often transformed at a node.
Analysis of how factors change with time is the
study of system dynamics. System dynamics are driven by a series of operations called
processes. Examples of ecological processes include chemical transformation, genetic exchange
and mass transfer, and actions at such micro-scales have impacts at the scale of organisms and
communities.
Complexity theory is the study of natural information patterns and the predictability of systems.
Just because a system is complex (which means unpredictable) doesn't imply that it's
complicated (which means difficult to understand). Actually, one of the amazing things about
systems is that they have common features and follow similar general rules across many different
scales and levels of organisation. Knowledge of systems and complexity allows connections
between many different disciplines to become apparent.
Systems are composed of many subsystems 'nested' hierarchically within them. Complex
interactions and cybernetic feedback (flows of changes which are self-reinforcing or
self-regulating) in the subsystems result in unpredictable collective behaviours in large-scale
systems called emergent properties - the emergence, at a certain level, of new order and
simplicity from a sea of complexity. For example, science tries to 'explain' life as an emergent
property of interacting molecular subsystems. In any case, the
important thing is that when nodes or links are altered or
removed, a system must find stability by rearranging itself into
a new structure. The dilemma for ecology is that human
rearrangement of its parts, towards and beyond unknown
thresholds (breaking-points), is likely to cause life-threatening
non-linear dynamics (dramatic changes or phase shifts) in the
stability and habitability of the entire global ecosystem.
Q5. Compare and contrast any two systems of your choice.
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Student Activity:
This simple natural scene could be from your local backyard or park. Draw a quick
sketch or network flow diagram showing hidden ecological interactions (e.g.
predator-prey relations) and cycles (e.g. energy, matter). Involve other important
nodes (e.g. micro-organisms, soil) beyond the existing sun, bird, lizard, caterpillar,
and plants (represented here by Bodhi leaves).
© Eubios Ethics Institute
Bioethics for Informed Citizens across Cultures
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