4.1: Species, communities & ecosystems

Species Defined as: groups of organisms that can potentially interbreed to produce fertile offspring Interbreeding: between members of the same species Crossbreeding: between members of different species (frequently offspring are infertile)

Populations Defined as: Members of a species maybe reproductively isolated into separate populations. A population is members of the same species, able to successfully interbreed, in the same place at the same time.

Species have either an autotrophic or heterotrophic method of nutrition. Autotroph – can make their own organic molecules. Auto – automatically make molecules (food) Heterotroph – cannot make their own organic molecules. Sheep eating grass, example of a heterotroph feeding on an autotroph

Task Is this an example of populations of the same species or is it describing two separate species? 1: An earthquake causes members of the same species to separate. Over time, one group is able to swim, the other cannot.

Consumers Defined as: heterotrophs that feed on living organisms by ingestion e.g. mosquito biting a human, lion eating a gazelle. Consumers ingest undigested materials from other organisms.

Detritivore – eats non living organic matter Saphrotrophs – live in or on non living organic matter, secrete enzymes.

Consumer Detritivore Either ingests by endocytosis (no cell wall) or has a gut. START Cell wall present. No ingestion, no gut. SaphrotrophAutotroph

Communities Defined as: Populations of different species living together and interacting with one another. Is it possible for a species to live in total isolation?

Quadrat sampling Many uses in ecology, one is for testing association between two species using the chi-squared test. Chi-squared ecology activity.

Ecosystems A community forms an ecosystem by interacting with the abiotic environment. Although organisms are affected by abiotic factors, organisms also have an effect on the abiotic features of an environment.

Inorganic nutrients Autotrophs and heterotrophs obtain inorganic nutrients from the abiotic environment. Including: -carbon, oxygen, hydrogen -Nitrogen, phosphorous Other elements are also required, but in smaller amounts.

Sustainability of ecosystems Something is sustainable if it can continue indefinitely. The main requirements for a sustainability include: - Nutrient availability -Detoxification of waste products -Energy availability