What is ecology?

Life on earth is wonderfully diverse and communities are complex. Why and how is biodiversity maintained or changing is the central topic in ecology.

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• Fields

・ Scale of subjects

Molecular ecology

Population ecology

Community ecology

Ecosystem ecology

・ Objects

Evolutionary ecology > Trait 

Functional ecology > Functional groups

• Big questions in community ecology 

Coexistence 

Species distribution 

They study the presence and population dynamics of species. 

• Future works (to me)

Ecologists have well-documented various phenomena and processes. They tend to discuss each phenomenon and process separately. Therefore, it is still unclear which process is important to species coexistence and distribution. Also, when there are multiple processes simultaneously, it is hard to discuss which process is relatively important. Then, we should synthesize many processes and construct a theoretical framework. To my knowledge, there are two synthesis on community dynamics. 

Example 1: Modern coexistence theory by Chesson (2000)

1. Competitive exclusion

2. Relative nonlinearlity 

3. The storage effect 

This theory enables us to discuss which is relatively important in three processes by using statistical models. 

Example 2: A theory on ecological communities by Vellend (2016)

1. Selection 

2. Stochastic processes 

3. Migration 

4. Speciation 

Reference

• Chesson (2000)

• Vellend (2016)

Big question

• What type of multi-species system is stable and robust?

  • May's paradox

• Can we predict community dynamics with abrupt changes?

  • Alternative stable states

  • Early warning signals

• Can biodiveristy boost biodiversity?

  • γdiversity

  • Speciation

Index

1. One species

a. Intraspecific competition

b. Movement

c. Demographic stochasicity / Environmental fluctuation

d. Phenology

e. Metapopulation

< Column 1: Rapid (contemporary) evolution >

a. Evolutionary rescue

• Predator-prey interactions

• Competition

b. Increasing genetic variation does not always promote coexistence 

c. Evolutionary suicide

• Tragedy of commons

d. Changing periods of a limit cycle

• Predator-prey interactions

2. Two species

a. Competition

• Resource competition

• Interference competition

• Reproductive interference

b. Predator-prey interaction

• One-predator-one-prey

c. Mutualism

• Animal-Plant

• Links to Niche theory

< Column 2: Competitive exclusion principle >

a. The mechanism of weakening competitive exclusion

< Column 3: Niche theory & Neutral theory >

a. Tilmann model

b. Unified neutral theory

3. Three species

a. Three competitors

b. One-predator-two-prey system

c. One-prey-two-predator system 

d. One-resource-two-competitor system (apparent competition)

e. Rock-scissor-paper system

< Column 4: Chaos >

a. Rarity of chaos & examples

4. Complex communities

a. May's paradigm

b. Are Specis-rich communities robust to abrupt enviromental changes?: "Catastrophic shifts"

c. Metacommunity

< Column 5: Community assembly >

< Column 6: Invasion ecology >

< Column 7: The dependency on the form of population dynamics equation >

a. Trade-offs

< Column 8: Questions & Paradox in community ecology >

References

1. Morin, 2012, "Community ecology", 

2. Mittelbach & McGill, 2019, "Community ecology", 

3. Levine, 2009, "The princeton guide to Ecology",  

keywords

• Stability and complexity of ecological communities

  • Alternative stable states

  • Early warning signals

  • Tipping points

  • Regime shift

  • Hysteresis

• Alternative transient states

[Reference]

1. May, R. M. (2019). Stability and complexity in model ecosystems. Princeton university press.