Unit 5 Test Flashcards
Biodiversity
a broad concept encompassing total diversity which includes diversity of species, genetic diversity and habitat diversity
Species diversity
is a product of two variables, the number of species (richness) and their relative proportions (evenness).
The variation in diversity varies from habitat to habitat
Genetic diversity
is the range of genetic material present in a gene pool or population of a species.
Not all species have the same amount of genetic diversity
Humans can alter genetic diversity by artificially breeding or genetically engineering populations with reduced variation in their genotypes or even identical genotypes - clones.
Habitat diversity
is the range of different habitats per unit area in a particular system or biome
biodiversity hotspot
is a region with a high level of biodiversity that is under threat from human activities.
natural selection
those more adapted to their environment have an advantage and flourish and reproduce but those less adapted do not survive long enough to reproduce.
“Survival of the Fittest”
Summary of the theory of evolution
Each individual is different due to their particular set of inherited genes and to mutations
Each will be slightly differently adapted to its environment
Resources are limited for any population and there will be competition for these resources (eg for food, light, space, water)
Over time these changes show and the whole population gradually changes
Speciation
the formation of new species when populations of a species become isolated and evolve differently.
Isolation of Populations
can be caused by environmental changes forming barriers such as mountain building, changes in rivers, sea level change, climatic change or plate movements.
Mass extinctions
have been caused by a combination of factors such as tectonic movements, super-volcanic eruption, climatic changes, and meteor impact all of which resulted in new directions in evolution and therefore increased biodiversity.
Physical Barriers
When the same species, develops into two new species because of a physical barrier (e.g. mountain range or ocean)
Land Bridges
Allow species to invade new areas
Result from lowering sea levels
Destroyed by continental drift
Continental Drift
When continents move to different climatic zones
Food supply forces species to adapt to the new environment - increasing biodiversity
Lithosphere
7 main plate boundaries that move 50-100 mm per year
Where plates meet, they may…
Slide past each other
Diverge (this could cause the physical separation of populations)
Converge (Collide and both be forced upwards as mountains. This creates physical barriers // Collide and one sinks underneath lighter continental plate)
Geological Timescale
4.6 billion years ago = Earth formed
4 billion years ago = Bacteria cells (thought to be first life forms)
65 million years ago = Dinosaur extinction
200,000 years ago = Humans
Natural Extinction
1 species per 1 million species per year
Causes of Extinction
Climate Change
Natural Disaster
Human Activities
Adaptive Radiation
Species adapt to fill a niche but in turn leave one open
Weedy Species
species that have adapted to survive in the newly created environments by humans
Anthropogenic Extinction Causes
Transforming the environment
Overexploitation
Alien species introduction
Pollution
Current extinction rate
100 species per million species per year
Factors used to determine the conservation status of a species include:
- Population size
- Degree of specialization
- Distribution
- Reproductive potential and behaviour
- Geographic range and degree of fragmentation
- Quality of habitat
- Trophic level and the probability of extinction
Complexity of the Ecosystem
The more complex a food web, the more resilient it is to the loss of one species or reduction in its population size.
If one type of prey or food source or predator is lost, the others will fill the gaps left.
