I. Introduction to biogeography and biomes

Question 1

What is biogeography?

Answer 1

‘…the science that attempts to document and understand spatial patterns of biodiversity’ - Brown and Lomolino (1998)

or

‘… the study of the distribution of organisms, both past and present, and of related patterns of variation over the earth in the numbers and kinds of living things.’

Question 2

What are the 4 key areas to consider in the discipline of biogeography?

Answer 2

Evolution; Tectonics; Earth History; Ecology

Question 3

History of biogeography: Darwin and Hooker (dispersalism vs extensionism)

Answer 3

Darwin - origin of species book; diversification through adaptation resulting from speciation and natural selection. BUT some species variation can’t be explained by dispersalist theory

Hooker: and “extensionist”; long-distance dispersal not strong enough reason for all plant movement. Belief in role of land bridges and ancient continental formation that allowed species to be so widely distributed across the world as we know it today.

Overall debate: extrinsic (geology, climate, tectonics, external to plant) vs intrinsic (plant attributes, traits, internal) factors in explaining plant distribution and patterns?

Question 4

History of biogeography: Sclater and Wallace

Answer 4

Sclater: a zoologist of 1870s who formed basis for the 6 biogeographic regions used today; but believed there were many separate areas of origin or creation i.e. lack of movement. (NB. high floristic turnover not an indicator of high animalistic turnover, limited ability to move)

Wallace developed biogeographic principles e.g. important role of climate, evolution, fossil record, geology, competition, speciation, both dispersal and land connections (species not long-distance dispersal-adapted)

Question 5

What is ‘biogeographic regionalisation’?

Answer 5

separating world into regions based on biogeographical traits…

Question 6

Give the three main areas of biogeography and their areas of interest.

Answer 6

1. Historical - taxonomy, evolution, phylogenies, past climates, geology, mountain uplift
2. Ecological - ecology, climate, soil, community ecol., functional traits
3. Conservation - diversity pattern overlaps, landscapes, assessment, predictions, extinction risk

Question 7

What are botanic gardens and their purpose?

Answer 7

Tourist attractions but ‘living collections’ or museums too that house plant specimens in herbariums e.g. Edinburgh has >3,000,000 specimens from 157 countries. Kew has 7 million. Some >300 yrs old.

Question 8

What is a biome?

Answer 8

Varying definitions but a working one is that ‘biomes are major vegetation formations with distinct physical forms (physionogmies) and ecological processes that can be characterised at a global scale’. (Penn., Leh., Row., 2018)

Question 9

What is the different between a biogeographic region and biome?

Answer 9

Biogeographic regions can have multiple biomes within them, broader categories/criteria.

Question 10

What is the term of dry-adapted, wet-adapted plants and those inbetween?

Answer 10

Xerophytes (dry)
Mesophytes (neither)
Hydrophytes (wet)

Question 11

What is a key assumption behind biogeography?

Answer 11

Uniformitarianism i.e. that processes today have remained unchanged throughout history

Question 12

What is highly suggestive of evolution of adaptations?

Answer 12

The fact that different areas under similar climatic/geologic constraints have different floristic groups of similarity i.e. savanna and dry forest. In other words, are environmentally similar but have distinct biota. Different taxonomic composition but serve same ecological function.

Question 13

What is meant by the terms ‘endemism’ and ‘cosmopolitanism’?

Answer 13

Endemism: organisms that occur in only one location, very small and limited distribution. (Explanations: poor dispersal, low taxonomy, isolated)

Cosmopolitanism: species with very wide distributions, but nothing is truly cosmopolitan! (Explanations: human introduction intentional and not, high dispersal, broad ecological tolerance)

Question 14

What did Holt (2013) do with Wallace’s zoogeographic regions?

Answer 14

Identified 20 distinct ‘zoogeographic regions’, grouped into 11 larger realms through the use of phylogenetic relationship similarity.

Similarities with Wallace’s original classification but some differences i.e. some islands in Oriental rather than Australian realm

Question 15

What are the 3 main tropical biomes this module focusses (will be looked at in more detail in another deck)?

Answer 15

Tropical rainforest
Savanna
Seasonally dry tropical forest

Pennington et al., 2018
Dexter et al., 2015; 2018