4.1 Why are there so many different species? Flashcards
Species
A species is a group of similar organisms which are able to breed together to produce fertile offspring. There are obvious differences between horses and donkeys. They can breed together but the offspring are sterile. Clearly, horses and donkeys belong to separate species. There are examples, however, where it is much more difficult to decide whether two organisms belong to separate species.
Species definition
A group of organisms with similar morphology, physiology and behaviour, which can interbreed to produce fertile offspring and which are reproductively isolated (in place, time or behaviour) from other species
Habitat
The particular place where a community of organisms is found. Peat bogs, coral reefs and cultivated fields are all habitats for particular communities of organisms.
Population
A group of individuals belonging to one species. Members of a population are generally found in one place at a particular time and are able to breed with one another. Daisy plants on a sports field or frogs in a pond are examples of populations.
Community
All the living organisms – animals, plants and microorganisms – found in a particular place at a particular time. The community found on a coral reef, for example, consists of the corals themselves and the algae that live within their cells, together with all the other different species of animals – the fish and worms and crabs – as well as the bacteria.
Niche
A description of the precise role of an organism in its environment. In simple terms, an organism’s niche is where it lives and what it does there. The niche of the two-spot ladybird would be described in terms of the abiotic aspects of its habitat such as the temperature range it can tolerate. A full description would also cover the biological aspects of its ecology such as the size of its aphid prey. An important biological principle is that no two different species have exactly the same ecological niche.
Endemic
Only found in a particular location
A species which is endemic is native to
a particular region and found nowhere else. The
Galapagos Islands have a very high proportion
of endemic species such as the marine iguana.
These species are found only on the Galapagos
Islands
Adaptation
Any features of an organism that make it well suited to survive in its environment. Adaptations can be anatomical, physiological or behavioural.
Co-adaptation
When two speceis are adapted so they come to depend on each other for their survival.
Biodiversity
The variety in living organisms. Biodiversity has three main components. These are: 1) species or organism diversity; many different species are found in tropical forests and on coral reefs – these places have high biodiversities; 2) genetic diversity – diversity within a species; animals such as tigers which live in small isolated populations often have low genetic diversity; 3) ecosystem diversity; a wide range of different habitats in an area will result in a much greater species diversity.
Evolution
The process by which there is a gradual change in the genetic make-up of species over time, including long periods of time. Evolution can give rise to new species if sufficient change occurs.
Natural selection
A process in which individuals that are fitter (better adapted to their environment) are more likely to survive and pass on their genes to future generations. Natural selection drives evolutionary change
Behavioural adaptation
Any actions by an organism that help them to survive or reproduce.
Physiological adaptation
Features of the internal workings of an organism that help them to survive or reproduce
Anatomical adaptations
The structures we can see when we observe or dissect an organism
