Macroecology

Question 1

What is Macroecology?

Answer 1

studying relationships between organisms and their environments at larger spatial scale that involves characterizing and explaining patterns of species abundance, distribution and diversity

Question 2

What kind of approach for Macroecology take?

Answer 2

• top-down
• focuses on understanding the properties of an ecosystem rather than individuals

Question 3

What is Biogeography

Answer 3

the study of variation in species composition and diversity among geographic locations

Question 4

Global scale

Answer 4

rates of speciation, extinction, long distance dispersal

Question 5

Regional Scale

Answer 5

• climate is roughly uniform, dispersal important
• regional species pool (gamma diversity)

Question 6

landscape scale

Answer 6

• physical geography of a region
• landscape connectivity shapes immigration and emigration
• beta diversity: change in species diversity and composition (turnover) from one community to another

Question 7

Local Scale (i.e., community)

Answer 7

• competition, predation, species interaction
• alpha diversity: local diversity at a site

Question 8

What is Ecological Niche Modelling?

Answer 8

attempt to predict species geographic distribution ranges, including expansion and retractions based on information of species current distribution and niche requirements, and spatial information

Question 9

How is niche modelling predictive?

Answer 9

combine species’ niche requirements with spatial distribution of environmental conditions on a landscape to identify specific locations where species could occur

Question 10

How to assess a species fundamental niche?

Answer 10

need to grow/raise the species along along an environmental gradient, in controlled experiments

Question 11

What two types of Data do you need for ENM?

Answer 11

1. info on the realized niche of the species of concern (environmental data, climate, geographic sites, etc.)
2. need to know the distribution of environmental factors in the range (climate, geological data, remote sensing data)

Question 13

Example of ENM (crabs)

Answer 13

• predicting the spread of an invasive crab species through NA
• native to east asia
• spread across the planet by hitchhiking in ballast water of trade ships
  Herborg et al. used data on distribution of crab it its native range to model areas of suitable habitat

Question 14

Limitations of ENM

Answer 14

• focuses on realized niches
• harder to model rare species bc we will have few observations from which to gather environmental data

Question 15

What are some other applications of ENM?

Answer 15

• can be used to direct researchers to areas in which rare species may be found
• can predict species movements/extinctions/immigrations under future environmental conditions

Question 16

In which areas are broader patterns of diversity across large geographic scales explored?

Answer 16

1. island biogeography
2. latitudinal gradients in species richness

Question 17

island biogeography

Answer 17

relationships between the size of a given geographic area, isolation and overall diversity

Question 18

What is considered an island?

Answer 18

any portion of isolated habitat

Question 19

What kinds of patterns are found on islands?

Answer 19

• species richness increases with island area
• species richness decreases with island isolation - distance from mainland and/or other islands

Question 20

Why is there a relationship between area and species richness?

Answer 20

larger areas likely have more resources, can support larger populations, less vulnerable to extinction, and have greater niche diversity

Question 21

What mechanisms might increase species richness on large islands while reducing richness on small, isolated islands?

Answer 21

species richness on islands can be modelled as a dynamic balance between immigration and extinction of species

Question 22

Rate of Immigration

Answer 22

rate of arrival of new species on the island
- highest on new islands because every species is new, this rate declines as speculate accumulate, until all possible species are present

Question 23

Rate of extinction

Answer 23

1. more species creates bigger pool of possible extinctions
2. as number of species increases, population size of each likely to decrease
3. as the number of species on island increases, potential for competitive interactions will increase

Question 24

What does the point of equilibrium represent

Answer 24

• predicted number of species for an island
• immigration and extinction rates are equal
• species composition can turn over but species number remains constant

Question 25

What is turnover and where is it the highest and lowest?

Answer 25

• turnover is change in species composition
• is highest on islands that are small (high extinction) but near the mainland (high immigration)
• lowest on large islands (low extinction) and far from mainland (low immigration)

Question 26

In terms of Latitude, where does species richness increase?

Answer 26

from middle and high latitudes towards the equator

Question 27

Why are the tropics more diverse? (three hypotheses)

Answer 27

1. species diversification rate is higher in the tropics
2. diversification rates are similar, but evolutionary time is greater in the tropics
3. higher productivity results in more abundant resources in the tropics that can support more species

Question 28

Species diversification rate

Answer 28

• the tropics have the most land area on Earth, and temp is very stable
• large, thermally stable areas should decrease extinction rates - population sizes and geographic ranges would be larger
• speciation by geographic isolation woudl be more likely

Question 29

Species Diversification time

Answer 29

• the tropics have been more climatically stable over time
• 65 mya entire earth was warm
• then during the Pleistocene glaciers disrupted the land that now makes up the temperate zone
• life that is currently at the temperate zone is much younger than that at the tropics

Question 30

productivity

Answer 30

• terrestrial productivity is highest in the tropics
• high productivity promotes large population sizes bc carrying capacity is larger