W1 L2 evolutionary theory T

Question 1

Natural Selection

Answer 1

the mechanism of evolution
* differential mortality and/or fecundity between individuals with different traits

Question 2

The premise of Evolution by natural selection

Answer 2

a there is variation in the trait within a population
b the trait is heritable
c more individuals are born than can possibly survive

Question 3

Calculation of survival in natural selection

Answer 3

T is generation
N is number of individual
B is fecundity
K is survival
Nt x B x K= N at t+1

Question 4

What is fitness

Answer 4

Fitness is the average contribution to the gene pool of the next generation, made by individuals of the specified genotype or phenotype.
Fitness will be different in different selective environments
Fitness is a property, not of an individual, but a class of individuals (e.g. homozygous for allele A)

Question 5

What does selection act upon

Answer 5

• acts on phenotype ( individual ) not between species or groups

Question 6

Biological species concept

Answer 6

“species are groups of actual or potentially interbreeding
natural populations which are reproductively isolated from
other such groups.” (Ernst Mayr 1963)

Question 7

Obvious exception of Mayr definition of species

Answer 7

• inter-species hybridization: not common among animals, but frequent among plants and fungi — how much gene flow between populations can the biological species concept
  tolerate to retain its meaning? Are plants not species?
• asexual organisms: is each clone a different species?
  bacteria: horizontal gene transfer

Question 8

Speciation Process

Answer 8

genetic separation: splitting one gene pool into two or more largely separated gene pools
phenotypic differentiation: diversification of one biological form into two or more phenotypically different form

Question 9

Two method of speciation

Answer 9

Allopatric speciation
starts when populations become geographically isolated — Darwin’s finches
Sympatric speciation
populations not completely isolated — host shifts in phytophagous insects

Question 10

Isolating barriers of sympatric speciation

Answer 10

Geographic: extrinsic properties of landscape that prevent gene flow
Temporal: reproduction at different times
Reproductive: features of organisms that prevent interbreeding