Species Diversity Index (SDI)
What two factors does the SDI take into account?
Answer: Species richness and evenness
What is mutualism?
A relationship where both species benefit
Name one tool used to monitor ecosystem health.
SDI, transects, remote sensing, species counts, etc.
What is ecological succession?
A natural process of change in the structure and species composition of an ecosystem over time.
What is a niche?
The role and position a species has in its environment, including how it obtains resources and interacts with other organisms.
What does a higher SDI indicate about an ecosystem?
It has higher biodiversity and greater resilience
Give an example of parasitism.
Tapeworm living in a dog’s intestine
What does a declining SDI over time suggest?
A possible decline in ecosystem health or biodiversity
What type of succession occurs on bare rock after a volcanic eruption?
Primary succession
How does competition influence the niche a species occupies in an ecosystem?
Competition can limit a species to a smaller realised niche by restricting the resources it can access or the habitat it can occupy.
Which would likely have a higher SDI: a forest with 20 evenly distributed species or one with 3 dominant species?
The forest with 20 evenly distributed species
What type of biotic interaction occurs when two species compete for the same food source?
Competition
What is the purpose of long-term monitoring in ecology?
To track changes in biodiversity and detect trends over time
Name one difference between primary and secondary succession.
Primary occurs where there is no soil; secondary occurs in areas where soil remains after a disturbance.
What is the purpose of classifying organisms in biology?
To organise species based on shared characteristics and evolutionary relationships, making it easier to study and communicate about biodiversity.
A researcher calculates an SDI of 0.85 for an ecosystem. What does this suggest about the species distribution?
Species are relatively evenly distributed; the ecosystem is diverse
How can predation help maintain species diversity in an ecosystem?
By preventing one species from dominating, allowing others to persist
How can invasive species impact the results of biodiversity monitoring?
They can decrease native species abundance, reducing SDI
Why does biodiversity typically increase during succession?
As conditions become more favourable, more species can colonise and establish, increasing biodiversity.
Two different species share a similar niche in the same ecosystem. What is likely to happen over time?
Competitive exclusion may occur, where one species outcompetes the other, or resource partitioning may evolve to reduce competition.
Why might two ecosystems with the same species richness have different SDIs?
They differ in species evenness; one might be dominated by one or two species
Explain how commensalism could indirectly influence SDI in an ecosystem.
By allowing one species to thrive without affecting another, it may help maintain or increase diversity
Describe how climate change could affect SDI and biotic interactions over time.
It may alter species distributions, disrupt mutualisms, increase extinctions, and reduce SDI
Describe how species interactions (e.g., mutualism or competition) influence the progression of succession.
Mutualism can help new species establish (e.g., nitrogen-fixing plants improve soil), while competition may exclude others, influencing which species dominate in later stages.
Explain how taxonomic classification reflects evolutionary relationships and niche similarities.
Organisms classified closely (e.g., same genus) tend to share structural traits, evolutionary history, and similar niches, indicating common ancestry and potential ecological roles.