Biodiversity Flashcards
Which three scales does biodiversity exist on?
- Ecosystem/Habitat: variety of ecosystems within a region
- Species: a variety of species within an ecosystem
- Genetic: a variety of genes among individuals of a species
How does genetic diversity affect its ability to respond to environmental stressors?
The more genetically diverse a population is, the better it can respond to environmental stressors.
Mutation
random change in genetic code produced by a mistake in the copying process, can improve an organism’s chances of survival or reproduction (will be passed on to next generation)
Allopatric speciation
process of speciation that occurs with geographic isolation
Geographic isolation
Physical separation of a group of individuals from others of the same species
Sympatric speciation
evolution of one species into two, without geographic isolation
Reproductive isolation
result of two populations within a species evolving separately to the point that they can no longer interbreed & produce viable offspring
Fitness
individual’s ability to survive & reproduce
Adaptation
trait that improves an individual’s fitness.
How does mutation cause evolution?
As the number of mutations accumulates in a population over time, evolution occurs.
How does gene flow cause evolution?
process by which individuals move from one population to another & thereby alter the genetic composition of both populations.
The arrival of individuals from adjacent populations alters the frequency of alleles in the population.
- nonadaptive, random process.
How does Genetic Drift cause evolution?
change in the genetic composition of a population over time as a result of random mating.
- nonadaptive, random process.
Bottleneck effect
reduction in the genetic diversity of a population caused by a reduction in its size
- Reduced population numbers means reduced genetic variation.
- Low genetic variation in a population can cause
- Increased risk of disease & low fertility.
- The bottleneck effect means species are less able to adapt to future environmental changes.
- Resulting low diversity can lead to decline & extinction.
Founder effect
A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals.
Background extinction rate
Average rate at which species become extinct over the long term.
Resilience
The rate at which an ecosystem returns to its original state after a disturbance.
Range of tolerance
- limits to abiotic conditions that an individual or species can tolerate
Fundamental niche
- suite of abiotic conditions under which a species can survive, grow & reproduce (full range of conditions, includes extremes)
Realized niche
- range of abiotic & biotic conditions under which a species actually lives (thrives)
Distribution
- areas of the world in which a species lives.
What are generalists? When do generalists do well?
Niche generalist - species that can live under a wide range of abiotic or biotic conditions.
- Niche generalists fare better under changing conditions because they have a number of alternative habitats and food sources available; however under stable conditions generalists may be outcompeted by specialists.
What are specialists? When do specialists do well?
Niche specialist - species that is specialized to live in a specific habitat or to feed on a small group of species.
- Niche specialists do well when environmental conditions remain relatively constant; however loss of a favored habitat or food source leaves them with few alternatives for survival.
How do natural disruptions to an ecosystem affect an ecosystem?
- Make major changes to swathes of habitats
- Force species to adapt, perish or migrate
Earth systems processes operate on a range of scale in terms of time. Processes can be:
- periodic (ie. spring rain leading to flooding & deposition of sediment),
- episodic (ie. earthquake causing landslides & soil erosion), or
- random (ie. tornado causing downed trees).
