ECOLOGY, POLLUTION AND ENVIRONMENTAL HEALTH

BY

CASWELL MAVIMBELA

ECOLOGY

Learning outcomes

At the end of this lesson, you should be able to:

• Define term ecology

• Understand the historical context of the development of ecology

• Be able to synthesize meaning of the definition of ecology from its component contextual parts

• Understand the scope and levels of organisation of ecology

• Be familiar with basic fundamental questions characteristic of ecological investigation

Key concepts: Ecology; biotic; abiotic; habitat; population; community; ecosystem, biosphere etc.

Introduction to Ecology

• How do you know you are talking to a real ecologist? They always answer any question the same way.

Caswell Mavimbela

Introduction to Ecology

• How do you know you are talking to a real ecologist? They always answer any question the same way.

• “Well it depends…”

Caswell Mavimbela

Ecology is:

• A science of dependency

• A probabilistic science

The first ecologists?

Two Founders of Ecology

Ernst Haeckel Eugene Warming

Definitions of Ecology

• The word ecology was coined by a German zoologist Ernst Haeckel in 1866 derived from two Greek words namely “oikos” = home or house, and “-ology” = study of.

• Haeckel – 1870 – By ecology we mean the body of knowledge concerning the economy of nature – the investigation of the total relations of the animal both to its inorganic and organic environment.

• Tansley – 1904 – (Ecology is) Those relations of plants, with their surroundings and with one another, which depend directly upon differences of habitat among plants.

• Elton – 1927 – Ecology is the new name for a very old subject. It simply means scientific natural history.

• The term evolved, in 1927 Charles Elton described it as the study of animals and plants in relation to their habits and habitats. Shortfalls (fungi, protists, bacteria have their own kingdoms which are of equal importance)

Definitions of Ecology cont’d

• Andrewartha – 1961 – Ecology is the scientific study of the distribution and abundance of organisms.

• Krebs – 1972, 2008 – Ecology is the scientific study of the interactions that determine the distribution and abundance of organisms.

• Ecologist study the patterns of distribution and abundance of organism in nature and how these patterns are maintained in the short run, and how they change during the course of evolution (Arms and Camp 1987)

• Ecology is a branch of biology that examines the interactions of organisms with their environments

• Townsend et al. 2003 – Ecology is the scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance.

• Ecology, is defined by Begon et al (2006) as; the scientific study of the distribution and abundance of life and the interactions between organisms and their natural environment.

Some Definitions of Terms

• environment - biotic and abiotic factors that influence organisms

• organism - individual living thing

• population - many individuals of one species living close enough to each other to potentially interbreed

• community - all interacting populations in a particular habitat - includes plants, animals, decomposer microbes - pond or forest community - in practice often used when 2 or more species discussed

Some Definitions of Terms

• habitat - place where microbe, plant or animal lives

• ecosystem - community plus abiotic factors - nutrients, water, soil, etc. - pond ecosystem

• biosphere - the earth • autecology - relation of individual organism to

environment

• synecology - relation of populations or species to other populations or species

Intro. Continues…

• The natural environment of an organisms includes its physical properties or factors, which can be described as the sum of local abiotic, chemical and biotic factors

• Abiotic factors (e.g. sunlight, temperature, water and soil)

• Chemical factors (e.g. composition of air, soil, and substances dissolved in water)

• Biotic factors (e.g. other living organisms sharing a habitat)

Levels of ecological organisation (LEO)

Hierarchical

system

Biosphere Ecosystem

Community Population

Habitat Individual

2.1 Individual level

• Ecology can be studied at a wide range of levels from a small scale to large one (Mader, 1998).

• Individual level = lowest scale

• Ecologist studies how an individual organism is adapted to its immediate environment

• Example 1: new born ungulate calf learn how to walk in few minutes, adapt (outrun predators) or die (fall to prey/sausage)

• Example 2: famous peppered moths observational study; behavioural ecology etc.

2.2 Habitat level

• A habitat in this case refers to a place where an organism lives (Arms and Camp 1987) and reproduces in its environment.

• Each species/individual occupies a particular position in the community = habitat

• Spatial (where it resides) and functional sense (what role it plays)

• What are the practical examples of a habitat? Forest floor, ocean edge or streams etc.

• Every habitat is unique, characterised by particular ranges of temperatures, humidity, soil, vegetation structure, food type, competitors, predators and other factors that make up the organisms environment (Mader, 1998)

• The functional sense (the role an organisms plays) brings about the concept of ecological niche of an organism

• Ecological niche of an organism is the role the organism plays in its community including its habitat and its interactions with other organisms, includes the resources an organism uses to meet its energy and nutrients requirements and survival demands

• Niche is affected by both abiotic (climate and habitat) and biotic factors (competitors, parasites, predators)

2.3 Population level (stop)

• A population is defined by Mader (1998) as the existence of all organisms of the same species within a specified area.

• An emphasis is based on the factors that affect growth and regulation of population size.

• Ecology = studies factors affecting growth + regulations of populations size and distribution of organisms (where & why in a particular place at a particular time)

2.3.1 Characteristics of Populations

• At any one point in time, populations have a certain size

• So, population size is defined as the number of individuals contributing to the population’s gene pool