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Replacement and displacement driven by innovations, competition, and extinctions

Ripa, Jörgen LU and Johansson, Jacob LU (2016) In Evolutionary Ecology Research 17(6). p.757-770
Abstract

Background: A key innovation may allow one group of species to radiate and replace another, but the role of competition and background extinctions for the replacement process is vigorously debated and unclear. Questions: Is a minimum competitive advantage necessary to initiate replacement? Are background extinctions of the incumbent species necessary? What speciation and extinction dynamics characterize the replacement process and how do they differ from radiation into an empty niche space? Model features: We used a classic eco-evolutionary model describing asexual species competing for resources distributed along a single niche axis. Successive evolutionary branching generated an adaptively radiating community. Evolutionary innovation... (More)

Background: A key innovation may allow one group of species to radiate and replace another, but the role of competition and background extinctions for the replacement process is vigorously debated and unclear. Questions: Is a minimum competitive advantage necessary to initiate replacement? Are background extinctions of the incumbent species necessary? What speciation and extinction dynamics characterize the replacement process and how do they differ from radiation into an empty niche space? Model features: We used a classic eco-evolutionary model describing asexual species competing for resources distributed along a single niche axis. Successive evolutionary branching generated an adaptively radiating community. Evolutionary innovation was introduced as an increased carrying capacity. Externally driven extinctions were also added. Mathematical methods: The model was studied using individual-based simulations. We monitored the radiation of the new group into the niche space of the original group and recorded the time to near-complete (90%) and complete (100%) replacement, along with rates of extinction and speciation of new and old groups. Results and conclusions: We demonstrate that replacement may occur by the radiation of a competitively superior group. Increasing the competitive advantage shortened replacement times, but there was no particular threshold advantage. Origination rates in new groups were comparable to extinction rates of the original groups, keeping the total number of species approximately constant - tentatively a result of niche widths and overall available niche space in the underlying model being unaffected by these innovations. Extra background extinctions speeded up the process, consistent with observed patterns in the fossil record that replacement is sped up during mass extinctions, but an increased extinction rate also introduced uncertainty and a higher risk of global extinction of the superior group. The replacement process was mainly driven by evolutionary competitive exclusion. The old, inferior type had an elevated rate of extinction matched by an increased speciation rate of the superior type. Incumbency also played a role, but we found little support for a strict incumbent replacement scenario, where replacement is driven entirely by background extinctions of the old group and opportunistic speciations of the new group. Compared with adaptive radiation into an empty niche space, replacement was slow and relict species from the original group could linger in marginal and previously unexploited niche space that provided a niche refuge and prevented complete replacement. Similar patterns are also found in the fossil record.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Adaptive radiation, Competition, Extinction, Incumbent replacement, Key innovation, Macroevolution, Relict species
in
Evolutionary Ecology Research
volume
17
issue
6
pages
14 pages
publisher
Evolutionary Ecology Ltd
external identifiers
  • scopus:85015188060
ISSN
1522-0613
language
English
LU publication?
yes
id
aab834d6-d0d5-4d09-9d54-edb60b63083a
alternative location
http://evolutionary-ecology.com/abstracts/v17/2975.html
date added to LUP
2017-03-30 10:52:05
date last changed
2017-05-30 13:27:57
@article{aab834d6-d0d5-4d09-9d54-edb60b63083a,
  abstract     = {<p>Background: A key innovation may allow one group of species to radiate and replace another, but the role of competition and background extinctions for the replacement process is vigorously debated and unclear. Questions: Is a minimum competitive advantage necessary to initiate replacement? Are background extinctions of the incumbent species necessary? What speciation and extinction dynamics characterize the replacement process and how do they differ from radiation into an empty niche space? Model features: We used a classic eco-evolutionary model describing asexual species competing for resources distributed along a single niche axis. Successive evolutionary branching generated an adaptively radiating community. Evolutionary innovation was introduced as an increased carrying capacity. Externally driven extinctions were also added. Mathematical methods: The model was studied using individual-based simulations. We monitored the radiation of the new group into the niche space of the original group and recorded the time to near-complete (90%) and complete (100%) replacement, along with rates of extinction and speciation of new and old groups. Results and conclusions: We demonstrate that replacement may occur by the radiation of a competitively superior group. Increasing the competitive advantage shortened replacement times, but there was no particular threshold advantage. Origination rates in new groups were comparable to extinction rates of the original groups, keeping the total number of species approximately constant - tentatively a result of niche widths and overall available niche space in the underlying model being unaffected by these innovations. Extra background extinctions speeded up the process, consistent with observed patterns in the fossil record that replacement is sped up during mass extinctions, but an increased extinction rate also introduced uncertainty and a higher risk of global extinction of the superior group. The replacement process was mainly driven by evolutionary competitive exclusion. The old, inferior type had an elevated rate of extinction matched by an increased speciation rate of the superior type. Incumbency also played a role, but we found little support for a strict incumbent replacement scenario, where replacement is driven entirely by background extinctions of the old group and opportunistic speciations of the new group. Compared with adaptive radiation into an empty niche space, replacement was slow and relict species from the original group could linger in marginal and previously unexploited niche space that provided a niche refuge and prevented complete replacement. Similar patterns are also found in the fossil record.</p>},
  author       = {Ripa, Jörgen and Johansson, Jacob},
  issn         = {1522-0613},
  keyword      = {Adaptive radiation,Competition,Extinction,Incumbent replacement,Key innovation,Macroevolution,Relict species},
  language     = {eng},
  month        = {11},
  number       = {6},
  pages        = {757--770},
  publisher    = {Evolutionary Ecology Ltd},
  series       = {Evolutionary Ecology Research},
  title        = {Replacement and displacement driven by innovations, competition, and extinctions},
  volume       = {17},
  year         = {2016},
}