BIO220 Lecture 17

Question 1

define: continuous traits

Answer 1

= quantitative traits

= phenotypes that vary continuously, determined by many genes, and are affected by the environment

Question 2

define: Mendelian traits

Answer 2

= discrete qualitative traits

= controlled by 1 gene, no environmental influence

Question 3

Rule of thumb/equation for quantitative traits

Answer 3

P = G + E + GE

Question 4

Mendelian traits allow us to infer many things. What are they?

Answer 4

infer phenotype from genotype

Question 5

How do we understand the evolution of continuous traits?

Answer 5

use statistical descriptions

Question 6

How do we calculate the strength of selection (s)?

Answer 6

current mean - past mean

Question 7

how do we interpret s?

Answer 7

neg: selecting down (smaller size, etc.)
pos: selecting up (bigger size, etc.)

Question 8

TRUNCATION SELECTION

Answer 8

strong form of directional selection

- individuals with phenotype above threshold die, and those below live

Question 9

how to measure intensity of truncation selection?

Answer 9

s = z* - z

z* = mean of population after selection
z = mean of population before selection

Question 10

How do we track the evolution of quantitative traits, given that environment also plays a huge part?

Answer 10

1. measure environmental factors and account for it statistically
2. track genetic changes explicitly

Question 11

what are 2 things that have experienced harvest-induced evolution?

Answer 11

1. Atlantic cod

2. Sheep (trophy hunting)

Question 12

At the _____ Fishery, Atlantic __ and __ were declining

Answer 12

Gulf of St. Lawrence Fishery;
abundance;
size

Question 13

avg size of cod was reduced by…

Answer 13

15-25 cm

Question 14

If cod had density dependent population growth, low density should promote…

Answer 14

• faster population growth

- larger sizes of individuals

Question 15

fish grow best under what temp?

Answer 15

warmer temperatures promote better fish growth

Question 16

what was the observed data regarding fish growth & temperature?

Answer 16

colder temperatures = higher densities of fish

warmer temp = lower densities of fish

Question 17

“natural” selection favoured __ sized fish due to ___

Answer 17

smaller or same;

fishing

Question 18

ecological forces select for __ sized fish due to ____

Answer 18

larger;

temperature & density-dependence

Question 19

Taking into account both ecological & evolutionary forces, what is happening to cod size?

Answer 19

No net change in fish size;

the 2 forces oppose each other

Question 20

What does R^2 mean?

Answer 20

How well the model explains the data

e.g. R^2 = 0.6
60% of the variation in the data can be explained by the model

Question 21

female size positively correlates with…

Answer 21

fecundity

Question 22

what are the implications for a recovering fishery (ecological vs. selection forces)?

Answer 22

• female fish will be small
• small fish = less fecundity
• less offspring produced
• slow recovery of population size

Question 23

Economic pressures usually lead to ___ harvesting than ____.

Answer 23

more;

MSY