Topic 4 Biodiversity And Natural Resources Flashcards
What is a Species?
A species is a group of organisms with a 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.
What is a habitat?
A habitat can be thought of literally as the place with a distinct set of conditions where an organism lives.
What is a population?
Each population is a group of interbreeding individuals of the same species found in an area.
What is a community?
The various populations in a habitat make up a community.
What is a niche?
Two species sharing the same habitat tend to not be in competition with each other. Each species occupies a particular niche , often referred to as an ecological niche.
A niche can be defined as ‘the way an organism exploits (uses) its environment’.
If two species species live in the same habitat and have exactly the same role within the habitat- the same food source, the same time of feeding, the same shelter site and so on- they occupy the same niche and they will compete directly with each other. The better-adapted organisms will out-complete the other and exclude it from the habitat.
What is endemic?
Endemic is the only place a Species is found.
What are adaptations?
Being adapted means being specialised to suit the environment in which an organism lives. Features that enable organisms to survive are called adaptations.
Adaptations can be classified as behavioural , physiological or anatomical .
What are behavioural adaptions?
Behavioural adaptations are any actions by organisms that help them survive or reproduce.
When agouti Bury Brazil nuts, this a behaviour that will aid their survival by providing a future food source.
What are physiological adaptations?
Physiological adaptations are features of internal workings of an organism that help it survive and reproduce.
Danish scurvy grass is formly found near the sea on icy roads, but it has spread inland with increasing use of salt on icy roads. The plant has a physiological adaptation allowing it to tolerate high salt concentrations. It has therefore been able to occupy a newly created niche unavailable to other inland plants.
What are anatomical adaptations?
Anatomical adaptations are the structures we see when we dissect an organism.
For example, the bodies of bumblebees show adaptations used to collect nectar and pollen. Each has a long tongue through which it can suck nectar (sugar solution) from flowers. Within a habitat, some bumblebee species have longer tongues than others, so they are specialised to feed from different flowers.
What is co-adaptation?
In the Brazil nuts tree example, the plant and pollinator become dependent on each other, and more and more closely adapted. This is called co-adaptation.
Why did organisms become do well adapted? : Natural Selection
As a population increases in size a greater proportion of individuals will die or fail to reproduce owing to competition for resources, such as food and space. Disease and environmental conditions may cause the death of dome individuals. This striving for survival is known as the ‘struggle for existence’.
In this struggle there will be winners and losers. Winners are by chance those surviving individuals who, by chance, possessed some characteristic that gave them an advantage over others. This differential survival is natural selection, sometimes called survival of the fittest. In the case of orchid bees it might be the possession of a slightly longer tongue, which improves their ability to compete for food. They have a selective advantage over other orchid bees, and are more likely to survive and reproduce, passing on the alleles for a longer tongue to their offspring. Individuals with a longer tongue will be more common in the next generation. The average tongue length on the next generation will be slightly greater. Such a change in form (or behaviour or physiology) over generations is called ** evolution** by natural selection.
Natural selection is a mechanism by which species change over time.
Evolution by natural selection
Evolution is more precisely defined as ‘a change in allele frequency over time (generations). In our orchid bee example, there has been a change (increase) in the relative frequency of alleles for longer tongue.
The emphasis on alleles reminds us that for natural selection to lead to evolution, there must be some genetic variation in the population. An allele can be selectively neutral ( has no advantage or disadvantage) but suddenly becomes selectively advantageous when the environment changes. The allele frequency will then increase over time.
Summarise evolution by natural selection:
- A population has some naturally occurring variation with new alles created through mutations.
- A change in the environment causes a change in selection pressures acting on the population.
- An allele of no particular advantage now becomes favourable.
- Organisms with the allele are more likely to survive reproduce and so produce offspring.
- Their offspring are more likely to have the allele and the allele becomes more common in the population.
What is a gene pool?
A gene pool consists of all the allele of all the genes present in a population.
