This course presents the principles of evolution and ecology for citizens and students interested in studying biology and environmental sciences. It discusses major ideas and results. Recent advances have energised these fields with evidence that has implications beyond their boundaries: ideas, mechanisms, and processes that should form part of the toolkit of all biologists and educated citizens.
Major topics covered by the course include fundamental principles of ecology, how organisms interact with each other and their environment, evolutionary processes, population dynamics, communities, energy flow and ecosystems, human influences on ecosystems, and the integration and scaling of ecological processes through systems ecology.
This course will also review major ecological concepts, identify the techniques used by ecologists, provide an overview of local and global environmental issues, and examine individual, group and governmental activities important for protecting natural ecosystems. The course has been designed to provide information, to direct the student toward pertinent literature, to identify problems and issues, to utilise research methodology for the study of ecology and evolution, and to consider appropriate solutions and analytical techniques.
Needed Learner Background: general biology and a good understanding of English.
This course has the following expectations and results:
1) covers the theoretical and practical issues involved in ecology and evolution,
2) conducting surveys and inventories in ecology,
3) analyzing the information gathered,
4) and applying their analysis to ecological and conservation problems.
De la lección
Module 3. Energy in Ecological Systems
In this module, we will discuss some fundamental ecological processes, such as those must be present in any Gaian planet. We will consider the Gaian effects of parasites and predators, biodiversity and hypercycles and we will see how these processes regulates our planet. Finally, we will consider the global ecological role of biomass, photosynthesis and carbon sequestration.
Ph.D., Associate Professor in Ecology and Biodiversity Biological Diversity and Ecology Laboratory, Bio-Clim-Land Centre of Excellence, Biological Institute
Hi learners! Welcome to the 13th lesson on my course Ecology: from cells to Gaia.
Today we will talk about biodiversity, hypercycles, and Gaia.
The diversity of nature is exemplified by what Darwin called the Entangled Bank.
Darwin said that an entangled bank is clothed with many plants of many kinds,
with birds singing on the bushes,
with various insects flitting about,
with worms crawling through the damp earth,
and to reflect that these elaborately constructed forms,
so different from each other,
and dependent on each other in
so complex manner have been produced by laws acting around us.
So I have two main question for you: What do all these species do,
and why they are so many?
These have implication for conservation biology.
If some species have limited ranges,
then our action could cause their extinction
much more easily than if the ranges are global.
Without tradeoffs, the rule of species reach guilds could be
filled by single taxa such as a perfected photosynthetic plant.
These species are so-called Darwinian demons.
A good definition of tradeoff by David Wilkinson
is an evolutionary dilemma whereby genetic change
conferring increased in fitness in one circumstance
inescapably involve sacrifice of fitness in another.
What processes lead to specialization by organism enhanced
biodiversity and would be expected to operate in all conceivable ecologies?
Tradeoffs prevent an organism from being
good at everything and so outrule out persistent planetary ecology
based on a single species.
Tradeoffs, also preventing one species outcompeting all others,
are therefore a good candidate for
the most fundamental reason for the development of biodiversity.
However, they clearly do not explain all the diversity of life on Earth.
Rare organisms could be crucial in allowing
communities to cope with climate and other changes.
As species rich community with more rare ones,
is more likely to contain species with the correct attributes to sweet new conditions.
James Lovelock, in discussing the rule of biodiversity in Daisyworld models,
developed to confute criticism against Gaia theory wrote "destroying
biodiversity will reduce the reservoir of apparently redundant or rare species.
Amongst these, may be those able to flourish and
sustain the ecosystem when the next perturbation occurs."
Tradeoffs are a fundamental aspect of
biodiversity as they prevent one or two species from monopolizing the planet.
Because of they allow speciation on any hypothetical planet with life,
we would expect to see a range of taxa.
The resulting biodiversity will have a positive Gaian effect that is the time to make
an ecological community or
a planetary ecosystem more stable than if it was composed of a smaller number of species.
Hypercycles as tradeoff are fundamental for biodiversity.
An example of ecological hypercycle comes from Darwin's Worm book.
The worms modify their environment in a way that
is beneficial to future generation of worms and
an implicit description of the positive and negative feedback loops between
the worms and the biotic and the abiotic environment is provided in this book.
One of the main applications of hypercycles in biology is being considering
the autocatalytic effects in cycles of
self-replicating molecules during the original life.
However, they are clearly also relevant to ecosystems.
In a paper published in Ecological Modelling,
I and my colleague,
Wim Hordijk and Stuart Kauffman,
proposed that indeed biodiversity is autocatalytic.
We suggested that biodiversity can be considered a system of autocatalytic sets,
and that this view offers a possible answer to
the fundamental question why so many species can co-exist in the same ecosystem.
The concept of hypercycle is still a useful aid to ecological thought,
even if difficult to describe in a quantitative manner.
The idea that life can have an autocatalytic quality is of great importance in
understanding the ecological history of
hypothetical planet or real planet such as the Earth.
Once autotrophs and decomposers have evolved,
then the simple hypercycle autotroph decomposer will exist.
These autocatalytic hypercycles could quickly
lead to life covering much of the planet as the presence of
life catalyzed the production of more life as I
explained with the biodiversity related issues differentiation theory.
Lovelock argued that planets will tend to have either loss of life or no life at all.
One of the reasons why conservationists worry about small populations is that they are
prone to extinction brought about by demographic and environmental stochasticity.
Demographics stochasticity is when
a chance fluctuation in demographic parameters such as birth and death rate,
sex ratio, population growth rate,
in a small population can lead to extinction.
Ideas of environmental stochasticity and catastrophes
are very different being potentially much more
relevant to arguments that
persistent restricted ecologies do not survive for geological periods of time.
The idea that spatially restricted ecologies are unlikely to survive is true.
Then it raises an interesting question about the end of life on the planet.
The potential long tale to microbial life on the planet will make
the moment of death of all life on our planet impossible to identify.
The exceptions to our long time span for
the extinction of life on the planet will be catastrophic events,
such as the massive asteroid or comet impact suffered by the earth in
its early history or a potential little flocks of cosmic rays from the nearby supernova.
Even in these cases it may be very difficult to kill
every last microbe living deep within the planet rock.
At the end of this lesson I have two questions for you.
First, what are the most evi-human impacts on ecosystem?
And second, will our species destroy all life on earth?
Roberto Cazzolla GattiPh.D., Associate Professor in Ecology and Biodiversity
