Ecology -Biodiversity: Introduction.

Key Definitions.

Biodiversity: Variety amongst species and other biological elements such as alleles and gene complexes, populations, ecosystems, communities, landscapes, the biosphere and biogeographical regions.

Genetic Diversity: Variation of genes within a species.

Species Diversity/Richness: Variation of number and evenness of a species within a region.

Ecosystem Diversity: The broad range of ecosystems and types of habitats.

Levels of Organisation:

1. Atoms - the smallest unit of an element with the chemical properties. All matter is composed of this.

2. (Macro)/molecules - Atoms bond together to form molecules, many of these bonded to form a polymer are macromolecules (nucleic acids, macronutrients etc.)

3. Cells - (macro)/molecules associate with each other, forming larger structures such as membranes of a cell (the simplest unit of life), which is also composed of other varieties of (macro)molecules.

4. Tissues - In plants and animals, multiple cells associate with each other to form different types of tissue (e.g. muscle tissue).

5. Organs - Organs are composed of at least two different types of tissue in complex multicellular organisms. Examples are the nervous, connective and muscle tissue.

6. Organisms - Biologists classify organisms belong to a particular species each, species being a related group of organisms sharing a distinctive form and set of attributes in nature, all members of the species are closely related genetically.

7. Populations - Group of organisms of the same species occupying the same environment.

8. Communities - all of the populations of different species assembled, the special range being determined by the environment as well as the interactions between each species.

9. Ecosystems - the Interactions between communities of organisms and their physical environment.

10. Biosphere - Includes all of the places on earth where living organisms exist; the soil, air, oceans and land!

Crisis and Conservation:

• Species loss --> diminished biodiversity on all levels (genetic and local scales to global and regional ones) --> ecosystem complexity diminishes, so do the inter-relationships.
• There's an ethnic responsibility to conserve biodiversity as well as potential benefits from organisms to gain. Preserving essential services from ecosystems such as air and water is also crucial.
•  The Linnean shortfall demonstrates how underestimated biodiversity loss is occurring even though there is little doubt how human activity has negatively impacted earth's life support systems leading to the current crisis.

Organismal Ecology.

• Study of how individual organisms meet the challenge of (a)/biotic environments - physiological ecology (how they physiologically adapt to an environment and how that affects the distribution) and behavioural ecology (how they behave and how that affects their survival and reproductive outcomes).

Population Ecology.

The main goal is to understand the factors affecting the growth of a population and determine its density and size, therefore lessen species endangerment, prevent extinction and control invasive species. Although the main focus of this area is usually on one species and its population, special interactions such as predation, parasitism and competition are taken into account as interactions between other species do affect the density and size of the main focus's abundance.

Community Ecology.

How Populations of species interact with each other and form functional communities, e.g. in a forest with trees, shrubs, herbs, grasses, herbivores that eat plants and the carnivores that prey on the herbivores.

It investigates why population size varies between different areas of a particular species (being species-rich/poor), there is a clear link between species richness and functionality of a community, hence ecologists are interested in species-richness. Species-rich communities are said to function better than those that are species-poor with more species increasing a community's stability and its resistance to disturbances such as an introduction of a new species.

Ecosystem Ecology.

Focuses on flows of energy and cycling of chemicals which both necessitate an understanding of the food chains and its trophic levels. Many food chains interconnect to form complex food webs.

In each energy transformation, free energy is reduced therefore heat is lost and the entropy of the system increases. This means a unidirectional flow of energy occurs through an ecosystem with energy dissipated at every step. a recurring input of energy, such as the Sun, is needed to sustain the ecosystem's energy flows. Chemicals, such as nitrates, are a different matter - as they don't dissipate and are constantly cycled between (a)/biotic components in the environment.