EE Lecture 39: Global Diversity Patterns

Question 1

what diversity gradient do birds show

Answer 1

latitudinal diversity gradient

Question 2

what evidence is there that the latitudinal diversity gradient hypothesis is correct

Answer 2

`for birds, number of species in tropics is far greater than N/S hemispheres

Question 3

why are there more species in the tropics

Answer 3

tropics act as a cradle -> faster speciation
tropics act as a museum -> lower extinction, longer time
higher carrying capacity: more niches, larger niches
larger land surface area

Question 4

how do the tropics act as a cradle

Answer 4

faster speciation

Question 5

how do the tropics act as a museum

Answer 5

lower extinction

longer time

Question 6

what is the result of the tropics having a higher carrying capacity

Answer 6

more niches

larger niches

Question 7

what are the main hypotheses for global diversity patterns

Answer 7

area
energy
time for speciation
niche conservatism

Question 8

discuss the area hypothesis for global diversity patterns

Answer 8

shown by SAR (species area relationships)
big tropical regoin, likely that theres more species there
SAR exlpains 7% of variation in flowering plant species richness

Question 9

give an example of SAR relationships in flowering plants

Answer 9

SAR explains 7% variation in flowering plant species richness
300,000 sp of plants -> high species richness

Question 10

what are the core predictors of species richness

Answer 10

potential evapotranspiratoin
number wet days per year
measurements of topographical and habitat heterogeneity

Question 11

discuss the residual differences across the major floristic kingdoms

Answer 11

the residual differences across the major floristic kingdoms, after accounting for enviro effects are minor - with the exception of Cape Region (v. diverse)

Question 12

discuss the species energy relationship hypothesis - what does it involve

Answer 12

energy in the form of potential evapotranspiration
more energy (spesh@tropics) = more species as can accumlate more biomass therfore increased carrying capacity

Question 13

what is the strongest single climate predictor

Answer 13

evapotranspiration

Question 14

why in terms of energy/evapotranspiration are there more species at equator

Answer 14

direct insulation at equator - get 2.5 times more energy than at the poles - more concentrated therefore more energy converted into biomass

Question 15

how much of the variation in plants is eplained by temperature and evpotranspiation

Answer 15

25%

Question 16

what are the main places where mammalian species richness is high

Answer 16

where its warm,wet and mountainous

where N/S biomes join up

Question 17

what causes the affect of SER (species energy relationship)

Answer 17

faster evoln - mutation rates, shorter lifespan, faster speciation
more biomass - high carrying capacity

Question 18

what are the problems faced by trying to generalise global biodiversity patterns

Answer 18

the lack of fit of plant diversity compared with the model shows a spatial
pattern
clades differ in where they are in the world

Question 19

what is the time for speciation hypothesis

Answer 19

glaciation wiped high latitudes clean
most tropical regions have been more stable
temperate speciation rates might now be high

Question 20

what is the tropical niche conservatism hypothesis

Answer 20

tropics are easier to adapt to due to less seasonal variation
seasonality is difficult to overcome, so if you can, you can radiate
predict high temperature speciation rates
assumes adaptation t high latitude is difficult
molecular phylogenies of New World birds and mammals say temperate rates of speciation and extinction are higher
predict highrates of speciation in temperate clades and predicts temperature clades wll be nested within tropical clades

Question 21

why are tropics easier to adapt to

Answer 21

due to less seasonal variatoin

Question 22

what does the tropical niche conservatism hypothesis predict

Answer 22

high rates of speciatoin in temperate climates and that temperate clades will be nested within tropical clades

Question 23

what do molecular phylogenies of New World birds and mammals show about temperate rates

Answer 23

there are far greater temperate rates of speciation and extinction in New World birds

Question 24

what are the three main aspects of biodiversity

Answer 24

functional
structural
compositional

Question 25

what was the traditional view of microbial biodiversit

Answer 25

organisms

Question 26

how are microbes distributed

Answer 26

wind
rain
but the environment seleces

Question 27

what seems to be a key determining factor for bacterial biogeography

Answer 27

pH - espesh in British soils - possibly due to latitudes

Question 28

how are we discovering the true diversity of fungi/protists/proKs

Answer 28

by using environmental DNA sequencing

Question 29

what are the main considerations of host associated microbes

Answer 29

species area
productivity
ph
oxygen levels