Tropical forests 1: Cradles or Arks

Question 1

Describe biogeography

Answer 1

The study of the distribution of organisms and genetic diversity across the Earth, in both time and space

Question 2

How is biogeography studied?

Answer 2

The analysis of spatial distribution of organisms and the identification of the factors that influence the distribution.

Question 3

Give examples of factors that are considered in biogeography

Answer 3

Ecological factors (control present distribution patterns) and historical factors (understanding how these ecological factors came to be)

Question 4

How can biogeographic data be presented?

Answer 4

Biogeographic maps

Question 5

What did ARW use to determine biogeographic realms?

Answer 5

Distributions and taxonomic relationships of particular vertebrate families

Question 6

Describe the updated version of ARW’s realms by Holt et al. (2013).

Answer 6

20 zoogeographic regions within 11 larger realms

Question 7

What is used to quantify biogeographic uniqueness of terrestrial zoogeographic regions?

Answer 7

Pairwise phylogenetic beta biodiversity (measures phylogenetic distance)

Question 8

Name the three major types of biogeographic distributions

Answer 8

Cosmopolitan, endemic, disjunct

Question 9

Describe a cosmopolitan biogeographic distribution

Answer 9

The state of being found almost anywhere around the world

Question 10

What is the result of humans being cosmopolitan?

Answer 10

Species that are associated with humans are also endemic e.g. house dust mite

Question 11

Describe an endemic biogeographic distribution and give an example

Answer 11

Unique to a defined geographic location e.g. lemurs in Madagascar

Question 12

Describe a disjunct biogeographic distribution and give an example

Answer 12

Distribution with gaps e.g. alligators in North America and China

Question 13

Define ecological niche

Answer 13

The space an individual species is able to occupy

Question 14

Define fundamental niche space

Answer 14

The set of environmental and biotic conditions necessary for the existence of a species

Question 15

Define realised environmental space

Answer 15

The set of conditions actually available within the resource space

Question 16

What is phylogenetic niche conservatism?

Answer 16

The tendency of closely related species to occupy niches that are more similar than those of their more distant relatives

Question 17

What is species number in a region related to?

Answer 17

Species number is correlated with the time since diversification in that region.

Question 18

Name three historical factors that can affect geographic distributions

Answer 18

Extinction, dispersal, vicariance

Question 19

Describe how extinction can affect geographic distributions

Answer 19

Either of some populations of a species or some species of a higher/lower taxon. e.g. Equidae spread from N.Am but then became extinct there

Question 20

Describe how dispersal can affect geographic distributions

Answer 20

Range expansion into a favourable habitat or jump dispersal across an unfavourable habitat.

Question 21

Give an example of a recent dispersal

Answer 21

Great American Interchange at the formation of the Isthmus of Panama

Question 22

Give three examples of dispersal pathways

Answer 22

Corridors, filter routes (favours species over others), sweepstakes (hazardous e.g. island hopping)

Question 23

Give three examples of things that can be dispersed by air currents

Answer 23

Seeds, spores, small animals

Question 24

Give three examples of things that can be dispersed by ocean currents

Answer 24

Seeds, plankton, larvae

Question 25

Describe vicariance

Answer 25

The splitting of a taxon’s range by barriers

Question 26

Give three examples of causes of a barrier that leads to vicariance

Answer 26

Geology, climate, habitat

Question 27

What can vicariance lead to?

Answer 27

Divergence and speciation

Question 28

What are the four tropical forest classifications?

Answer 28

Tropical moist broadleaf forests, tropical moist deciduous forest, tropical dry forests, tropical/subtropical coniferous forests

Question 29

Describe tropical moist broadleaf forests

Answer 29

Tropical rainforests, high levels of rainfall (>2,000mm/yr), low variability in annual temp, high biodiversity

Question 30

Describe tropical moist deciduous forests

Answer 30

Monsoon forests, low variability in annual temp, 3-6mo dry season, 1,000-2,000mm/yr, mostly deciduous and semideciduous. Heavily impacted by teak logging in SE Asia

Question 31

Describe tropical dry forests

Answer 31

5-8mo dry season, 1,000-1,500mm/yr, dominated by deciduous trees, sensitive to burning

Question 32

Describe tropical/subtropical coniferous forests

Answer 32

Found at high altitudes, lower biodiversity by high endemism

Question 33

What is the Latitudinal Biodiversity Gradient?

Answer 33

The pattern on having lots of species at the equator and fewer towards the poles

Question 34

What are the three main hypotheses to explain the LBG?

Answer 34

Cradle, Ark, Out of the Tropics

Question 35

Describe the Cradle Hypothesis to explain the LBG

Answer 35

There are higher rates of speciation at the tropics

Question 36

Describe the Ark Hypothesis to explain the LBG

Answer 36

There is less extinction at the tropics

Question 37

Describe the Out of the Tropics Hypothesis to explain the LBG

Answer 37

Speciation is high and extinction is low at the tropics. Species migration out of the tropics is high.

Question 38

Was the LBG present in the late Cretaceous?

Answer 38

There was no relationship between biodiversity and latitude gradient

Question 39

During the Phanerozoic ice ages, what was the relationship between biodiversity and latitude gradient?

Answer 39

Low levels of biodiversity at poles when temperatures were lower

Question 40

What led up to the Quaternary ice ages?

Answer 40

Pliocene (5.4-2.4mya) Final stages of a global cooling trend

Question 41

What was the trend of northern species during the Pleistocene (1.8m-10k ya)?

Answer 41

Lived far to the south of their present distribution during glacial periods