Biodiversity and Human Impact on Lakes

Question 1

What are the 3 ways of measuring biodiversity?

Answer 1

• Species Richness = Number of species
  ○ Alpha diversity – the number of species found at the local scale (e.g., in one lake)
  ○ Beta diversity – species turnover; a measure of the difference in species composition between two or more lakes within a region
  ○ Gamma diversity – regional species pool; the number of species in lakes across a region
  • Evenness = Relative abundance of different species
  • Species Diversity = Take into account both richness and evenness
    ○ Shannon Index
    Simpson Index

Question 2

How many freshwater fish are native to California?

Answer 2

129

Question 3

What are the major threats to freshwater fish? (name 2)

Answer 3

Climate change
Large dams
Agriculture
Invasive species

Question 4

What is the species-area relationship?

Answer 4

Larger lakes contain more species than smaller lakes

Question 5

In Island Biogeography which factors affect immigration and extinction?

Answer 5

What aspects of a lake impacts immigration rate?
1. Lake size
2. Distance to source (another lake)

What aspects of a lake impacts extinction rate?
1. Lake size
Bigger lake = higher carrying capacity

Question 6

In Island Biogeography when is the immigration at is highest? When is the extinction at is highest?

Answer 6

Immigration: In the beginning the immigration is high because there is less competition, so when there is less number of species in a lake the immigration rate is higher.

Extinction: In the end (when number of species is high) the extinction rate is highest because not all species that immigrated to the lake make it. It can be because of more competition for nutrients.

Question 7

What is the effect of productivity on biodiversity? Draw a graph with species richness on y-axis and productivity on x-axis.

Question 8

Name the 4 factors that impact the species richness and diversity in a lake.

Answer 8

1) Lake size
2) Distance from other lakes
3) Lake age and depth
4) Productivity

Question 9

Why does biodiversity enhance ecosystem function?

Answer 9

1) Niche Complimentarity Effect – species use different niches, niche complimentarity enhance ecosystem function

2) Sampling Effect – species differ in their intrinsic performance, larger samples mean greater chance to get the best performers Larger samples: larger chance of getting really good gracerd (key stone species)

Question 10

What are keystone species?

Answer 10

Species that have
disproportionately large ecological effects
relative to their abundance