Biological Diversity Flashcards
Examples of Biotic selection pressures
- Predation
- Introduced species
- Food availability
- Competition
- Diseases
Examples of Abiotic selection pressures
- Temperature
- Access to sunlight
- Water availability
- Gases
- Soil pH and mineral content
What is Cohesion-Tension theory? And how does it work?
Cohesion-tension theory refers to the upward movement of materials in the xylem (transpiration).
This process works due to two main forces: the cohesion of water molecules to each other, and the adhesive forces between the water molecules and the walls of the xylem vessel.
The theory states that the cohesive forces that cause water molecules to attract and stick together, and the adhesive forces between water molecules and the walls of the xylem vessel work together to pull the water up the sides of the xylem.
Explain Structural Adaptations and provide an example
A structural adaptation is to do with how the organism is built or structured, and how this aids their survival in their natural habitat. Structural adaptations are physical features.
Example: A giraffe’s long neck, adapted to help them browse food in high trees.
Explain Behavioural Adaptations and provide an example.
Behavioural adaptations refer to those actions performed by an organism in response to a stimulus that improves its chance of survival. Behavioural adaptations are actions.
Example: Penguins huddle together during winter to preserve body heat and survive cold winds.
Explain Physiological Adaptations and provide an example.
A Physiological adaptation is an internal body process carried out to regulate and maintain homeostasis for an organism to survive the environment in which it exists. Physiological adaptations refer to internal functions such as breathing, and are not consciously controlled by the organism.
Example: the production of venom in snakes, and poison found on poison dart frogs.
Describe Darwin’s theory of Phyletic Gradualism
Charles Darwin’s model of Phyletic Gradualism states that evolution occurs gradually at a constant pace, an accumulation of many small changes that happen over a long period of time due to environmental pressures and external factors.
What is Convergent Evolution?
Convergent evolution occurs when two unrelated organisms living in similar environments develop similar structural features. For example, sharks and dolphins.
- Different ancestor
- Converge to produce analogous structures
- Species’ appearance becomes more similar over time
- Species are unrelated (genetically different)
What is Divergent Evolution?
Divergent evolution occurs when one species speciates (splits off) to continue to evolve into two seperate species throughout evolution.
- Common ancestor
- Diverge to produce homologous structures
- Species appearance becomes more different over time
- Species are closely related (genetically similar)
Define Speciation
Speciation is the evolutionary process through which new biological species form, seperate from the rest of a population.
Speciation occurs when populations of a single species become isolated— geographically, behaviourally, or genetically— leading to the development of distinct traits over time.
Define Adaptive Radiation
Adaptive radiation is a rapid increase in the number of species with a common ancestor and increasing diversity
Evolution of an animal into a wide variety of types, adapted to specialise modes of life.
Widespread adaptions occuring
Describe Eldridge and Gould’s theory of Punctuated Equilibrium
Eldridge and Gould’s Punctuated Equilibrium model states that evolution doesn’t necessarily happen at a constant pace but rather has numerous geologically long periods of stasis during which little to no evolution occurs. This era of stability is periodically disrupted by or ‘punctuated’ by geologically short periods of rapid evolution, frequently triggered by sudden and significant environmental change.
State the theory of Evolution by Natural Selection
Darwin and Wallace proposed that species change over time in response to selection pressures in their environment.
The reproductive success of the members of a population best adapted to the environment.
Natural selection requires variation within a species or population.
