Practical 3 - daphnia

Question 1

Name 2 ways populations can respond to a strong selection pressure?

Answer 1

Phenotypic plasticity or via genetic evolution

Question 2

What is transgenerational plasticity?

Answer 2

When phenotypic plasticity persists across generations (non-genetic inheritance)

Question 3

What are Daphnia good model organisms?

Answer 3

Reproduce clonally, short generation time, key ecological role in shallow freshwater (key for food chain)

Question 4

What is are benefits of using mesocosms for studies?

Answer 4

Combine realistic ecological environments with the possibility to control aspects of population make-up, environment and interacting species as well as being big enough to host a realistic population size

Question 5

What did we change in each mesocosm?

Answer 5

The mesocosms were temperature controlled and so we were able to induce a heatwave in each

Question 6

Temperature size rule for ectotherms

Answer 6

Organisms grow to smaller body sizes at higher temperatures

Question 7

Metabolic theory for ectotherms

Answer 7

Metabolic rates (e.g. growth rates) increase at higher temperatures

Question 8

Temperature size rule and metabolic theory

Answer 8

Counteract each other and final outcome (e.g. age and size at maturity) depends on species and how responsive they are to temperature

Question 9

What life history details should you collect before in a life history assay?

Answer 9

Juvenile growth rate. age and size at maturity (and size of clutch (fecundity))

Question 10

Difference between genetic changes and phenotypic plasticity

Answer 10

Genetic changes stay over time whereas phenotypic plasticity dissipates over time

Question 11

How did the genetic change in the Daphnia occur?

Answer 11

Evolution by natural selection

Question 12

During the winter period we expect

Answer 12

Organisms grow to greater sizes

Question 13

During the summer period we expect

Answer 13

A much earlier maturation of organisms