Lecture 8: Problem of diveristy

Question 1

disturbance delays competitive exclusion, in itself does…

Answer 1

not prevent exclusion

Question 2

Lots-Volterra model for competition between 2 species:

Answer 2

used t understand when competitive exclusion occurs

Question 3

neutral dynamics:

Answer 3

• if all species were identical
• nothing to decide which species should be the winner
• species or individual indent is irrelevant
• add randomness we can’t predict the outcome

Question 4

neutral competition a __ model=

Answer 4

NONEQUILIBRIUM

• does not explain diversity, except that rate of elimination is v slow
• in the end in a finite environment we would end up with just one species

Question 5

tow scales of organisation

Answer 5

• local community
• – a set of species in a give location
• meta-community
• –a pool of species from which local communities are formed

Question 6

dynamics of the meta-community are much ___ than those of the local community

Answer 6

slower

Question 7

example of a meta-community

Answer 7

amazon rain forest

Question 8

Hubbels neutral theory: model for local community

Answer 8

• Think of the community as consisting of a series of ‘sites’
• Each site is large enough to support one tree
• J trees in the community: this number is constant, i.e. the community is assumed to be saturated with individuals
• All individuals are ecologically identical: i.e. occupy the same space and have the same rates of death and reproduction
• Competition occurs when individuals die
• gap formation and competition for gap occupancy = gap dynamics
• -allows a lot of species to persist for long time
• but eventually random extinction will lead to just one species remaining
• so need new source of new diversity

Question 9

Hubbels neutral Theory: meta-community

Answer 9

• Individuals migrate from the meta community to the local community
• Provides an input of new species
• This compensates for the loss of species in the local community through local extinction
• This is a wider community from which individuals may immigrate to local communities
• Is of size J individuals
• Dynamics of the species pool is governed by speciation-extinction dynamics
• Speciation occurs at a rate V