Lecture 1 - Introduction to Ecology.pdf

8/19/2019 Lecture 1 - Introduction to Ecology.pdf

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Introduction

to Ecology


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1.1 INTERACTIONS BETWEEN SPECIES DETERMINEWHERE ORGANISMS LIVE AND HOW MANY LIVE THERE

Ecology is the scientific study of the interactions

that determine the distribution and abundance

of organisms.

Interactions:

between species (predator – prey interactions);between organisms and the physical

environment (temperature and precipitation).


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Ecological System

o Ecology is the science that examines therelationships between all the animals,

plants, fungi and microbes on Earth.o These organisms interact in ecological

systems, which include all the organisms inan area as well as their non-living (abiotic)environment.


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Ecological System

The essential message of ecology is thatchanging one component in an

ecological system usually changes others.

The science of ecology can be thought ofas finding out the details.


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Examples of questions ask by Ecologists aboutspecies Abundant and Distribution

Distribution (where organisms are found);

Abundance (how many organisms live in agiven place).

The distribution and abundance of manyspecies vary in space. For example, the redkangaroo is common in north-eastern New

South Wales, but they are rare in WesternAustralia and absent altogether from most ofnorthern Australia (Figure 1.1).


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Distribution (where organisms are found);

Abundance (how many organisms live in agiven place).

The distribution and abundance of manyspecies vary in space. For example, the redkangaroo is common in north-eastern New

South Wales, but they are rare in WesternAustralia and absent altogether from most ofnorthern Australia (Figure 1.1).


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Examples of questions ask by Ecologists aboutspecies Abundant and Distribution

What accounts for this pattern ofabundance?

Why is this species less abundant towardthe edges of its geographic range?

What limits the western and northernextension of its range?

Will red kangaroos change in distributionas the climate warms?


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Assignment 1 (Group)

Find the same case (can be plant oranimal species) in Indonesia.

Group Presentation


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Ecology and Environmentalism

The word ecology was first used by theGerman zoologist Ernst Haeckel in 1866.

Ecology was not widely recognized as animportant science until the 1960s, whenecologists expressed concern about thecontinuing increase in the human

population and the associated destructionof natural environments by pesticides andpollutants.


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Ecology and Environmental Study

Ecology deals with the interrelations of allorganisms. While it includes humans as a

very significant species by virtue of theirimpacts, ecology is not solely concernedwith humans.

Environmental study is the analysis of humanimpacts on the physical, chemical andbiological environment of Earth.


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1.2 ECOLOGY’S FOUNDATION IN NATURAL HISTORY GOES BACK MORE THAN2000 YEARS

The Balance of Nature

- Pest outbreaks!

Wereng batang coklat (Nylaparvata lugens)


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1.2 ECOLOGY’S FOUNDATION IN

NATURAL HISTORY GOES BACK MORE THAN2000 YEARS

The Balance of Nature

- Pest outbreaks!

Each species had a special place in nature, andextinction did not occur because it would disrupt thebalance and harmony in nature.

Today, in the midst of a major extinction crisis, thebalance of nature idea seems naive, and the questionof how modern extinctions will affect the functioning ofnatural ecological systems is an important topic ofstudy for ecologists.


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Applied Ecology. Ecology developed from the applied fields ofagriculture and fisheries, long before the word ecology wascoined.

For example, Insect pestscontrol with introducedpredators. In 1762, themynah bird was broughtfrom India to the island ofMauritius to control the redlocust, and by 1770 locustswere a negligible problemon the island.


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Predatory ants were introduced fromthe mountains of south-western Arabiainto datepalm orchards to controlother species of ants.

An increasing knowledge of insectparasitism and predation led to manysuch introductions all over the world in

efforts to fight agricultural pests — abranch of applied ecology we nowcall biological control.


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Applied Ecology

Fisheries have been an important sourceof food for centuries, but over-fishing has

led to declines in many freshwater andmarine fish species.


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John Cabot returned to England fromthe Grand Banks of Newfoundland and

wrote about the extraordinaryabundance of northern cod in thesewaters:

‘…the sea is covered with fish which are

caught not merely with nets but withbaskets, a stone being attached tomake the baskets sink with the water…’


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1.3 ECOLOGISTS STUDY BIOLOGICAL

INTERACTIONS FROM THE LEVEL OF THEINDIVIDUAL TO THE ENTIRE BIOSPHERE

Biological systems can be analysed atdifferent levels, ranging from molecules to

ecosystems, defined largely by size.


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Level of Integration Populations are groups of individuals of a single species,

such as the emperor penguins of Adelie Land.

Communities are groups of species that live in the same

area, so they include many populations.

Ecosystems consist of communities and their physicalenvironment — Lake Michigan is a large aquatic ecosystem,but even a small pond can be considered an ecosystem.

Landscapes are groups of ecosystems typically at a largerspatial scale, such as the Everglades of Florida.

Landscapes can be aggregated to include the whole-Earth ecosystem, or biosphere, which is sometimes calledthe ecosphere.


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Each level of integration involves a separateand distinct set of attributes and problems.

A population has a density (the number ofindividuals per unit area or volume) — aproperty that cannot be attributed to asingle individual.

A community has biodiversity (the numberof species) — an attribute without meaningat the population level.


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In general, a scientist who deals with one level ofintegration seeks explanations from the lower

levels of integration.

For example, to understand why emperorpenguin populations have decreased in Adelie

Land during the last 50 years, an ecologist wouldstudy the numbers of births and the causes ofdeath of individual penguins.

This approach to science is said to bereductionist , because it reduces a problem atone level of integration to a series of problems atlower levels.


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Alternative approach to science is holistic ,encompassing higher levels.

An ecologist employing the holisticapproach to study the decline of emperorpenguin populations might analyze theconsequences of this decline on thecommunity in which the penguins live,

including the fish on which the penguinsfeed and the predators that feed on thepenguins.


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Which approach is better?

The example of dealing with AIDS (acquiredimmunodeficiency syndrome) shows why

both approaches are important and shouldbe embraced. To develop a vaccine, wemust understand the action of the virusresponsible for AIDS (reductionism); to stopthe spread of AIDS, we must understand thesocial and behavioral factors that affecttransmission of the virus (holism).


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Much of modern biology is highlyreductionist, trying to work out the chemical

basis of life. We know an enormous amount about the

molecular and cellular levels of organisms,and we know very much about organs,organ systems, and whole organisms.

However, we know relatively little aboutpopulations and even less aboutcommunities and ecosystems.


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A good example of this disparity is theHuman Genome Project. This expensive

and highly targeted research programhas sequenced all the genes on humanchromosomes, yet we do not know howmany species of beetles live on Earth or

how many species of trees there are inthe Amazon basin.


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1.4 LIKE OTHER SCIENTISTS, ECOLOGISTS

MAKE OBSERVATIONS, FORM HYPOTHESES,AND TEST PREDICTIONS

The essential features of the scientificmethod are the same in ecology as in

other sciences


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1.5 LYME DISEASE ILLUSTRATES THECOMPLEX INTERACTIONS IN ECOSYSTEMS

Lyme disease. First described in 1977 inConnecticut, Lyme disease is now

spreading from east to west across NorthAmerica.

The disease is caused by the transmissionof bacteria, called spirochetes, from ticks

to humans.


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Acaridae


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Lecture 1 - Introduction to Ecology.pdf

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