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A minimal model for the latitudinal diversity gradient suggests a dominant role for ecological limits

Etienne, Rampal S. ; Cabral, Juliano Sarmento ; Hagen, Oskar ; Hartig, Florian ; Hurlbert, Allen H. ; Pellissier, Loïc ; Pontarp, Mikael LU and Storch, David (2019) In American Naturalist 194(5). p.122-133
Abstract

The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Explanations for the LDG are often categorized into three broad pathways in which the diversity gradient is created by (1) differential diversification rates, (2) differential carrying capacities (ecological limits), or (3) differential time to accumulate species across latitude. Support for these pathways has, however, been mostly verbally expressed. Here, we present a minimal model to clarify the essential assumptions of the three pathways and explore the sensitivity of diversity dynamics to these pathways. We find that an LDG arises most easily from a gradient in ecological limits compared with a gradient in... (More)

The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Explanations for the LDG are often categorized into three broad pathways in which the diversity gradient is created by (1) differential diversification rates, (2) differential carrying capacities (ecological limits), or (3) differential time to accumulate species across latitude. Support for these pathways has, however, been mostly verbally expressed. Here, we present a minimal model to clarify the essential assumptions of the three pathways and explore the sensitivity of diversity dynamics to these pathways. We find that an LDG arises most easily from a gradient in ecological limits compared with a gradient in the time for species accumulation or diversification rate in most modeled scenarios. Differential diversification rates create a stronger LDG than ecological limits only when speciation and dispersal rates are low, but then the predicted LDG seems weaker than the observed LDG. Moreover, range dynamics may reduce an LDG created by a gradient in diversification rates or time for species accumulation, but they cannot reduce an LDG induced by differential ecological limits. We conclude that our simple model provides a null prediction for the effectiveness of the three LDG pathways and can thus aid discussions about the causal mechanisms underlying the LDG or motivate more complex models to confirm or falsify our findings.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Dispersal, Diversification, Ecological limits, Extinction, Latitudinal diversity gradient, Speciation
in
American Naturalist
volume
194
issue
5
pages
122 - 133
publisher
University of Chicago Press
external identifiers
  • scopus:85071939418
  • pmid:31613672
ISSN
0003-0147
DOI
10.1086/705243
language
English
LU publication?
yes
id
f88f367c-5dae-482a-88f0-15c4e2dcd543
date added to LUP
2019-09-24 14:25:24
date last changed
2020-01-13 02:25:06
@article{f88f367c-5dae-482a-88f0-15c4e2dcd543,
  abstract     = {<p>The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Explanations for the LDG are often categorized into three broad pathways in which the diversity gradient is created by (1) differential diversification rates, (2) differential carrying capacities (ecological limits), or (3) differential time to accumulate species across latitude. Support for these pathways has, however, been mostly verbally expressed. Here, we present a minimal model to clarify the essential assumptions of the three pathways and explore the sensitivity of diversity dynamics to these pathways. We find that an LDG arises most easily from a gradient in ecological limits compared with a gradient in the time for species accumulation or diversification rate in most modeled scenarios. Differential diversification rates create a stronger LDG than ecological limits only when speciation and dispersal rates are low, but then the predicted LDG seems weaker than the observed LDG. Moreover, range dynamics may reduce an LDG created by a gradient in diversification rates or time for species accumulation, but they cannot reduce an LDG induced by differential ecological limits. We conclude that our simple model provides a null prediction for the effectiveness of the three LDG pathways and can thus aid discussions about the causal mechanisms underlying the LDG or motivate more complex models to confirm or falsify our findings.</p>},
  author       = {Etienne, Rampal S. and Cabral, Juliano Sarmento and Hagen, Oskar and Hartig, Florian and Hurlbert, Allen H. and Pellissier, Loïc and Pontarp, Mikael and Storch, David},
  issn         = {0003-0147},
  language     = {eng},
  number       = {5},
  pages        = {122--133},
  publisher    = {University of Chicago Press},
  series       = {American Naturalist},
  title        = {A minimal model for the latitudinal diversity gradient suggests a dominant role for ecological limits},
  url          = {http://dx.doi.org/10.1086/705243},
  doi          = {10.1086/705243},
  volume       = {194},
  year         = {2019},
}