Population demography maintains biogeographic boundaries

Chloé Schmidt*, Gabriel Muñoz, Lesley T. Lancaster, Jean Philippe Lessard, Katharine A. Marske, Katie E. Marshall, Colin J. Garroway*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Global biodiversity is organised into biogeographic regions that comprise distinct biotas. The contemporary factors maintaining differences in species composition between regions are poorly understood. Given evidence that populations with sufficient genetic variation can adapt to fill new habitats, it is surprising that more homogenisation of species assemblages across regions has not occurred. Theory suggests that expansion across biogeographic regions could be limited by reduced adaptive capacity due to demographic variation along environmental gradients, but this possibility has not been empirically explored. Using three independently curated data sets describing continental patterns of mammalian demography and population genetics, we show that populations near biogeographic boundaries have lower effective population sizes and genetic diversity, and are more genetically differentiated. These patterns are consistent with reduced adaptive capacity in areas where one biogeographic region transitions into the next. That these patterns are replicated across mammals suggests they are stable and generalisable in their contribution to long-term limits on biodiversity homogenisation. Understanding the contemporary processes that maintain compositional differences among regional biotas is crucial for our understanding of the current and future organisation of global biodiversity.

Original languageEnglish
Pages (from-to) 1905-1913
Number of pages9
JournalEcology Letters
Issue number8
Early online date26 Jun 2022
Publication statusPublished - 25 Jul 2022

Bibliographical note

Funding Information:
This manuscript was the result of a working group funded by a Quebec Center for Biodiversity Science grant to JPL and KEM. We thank Ben Holt and the Center for Macroecology, Evolution and Climate for sharing their map of mammal biogeographic regions. We thank Laura Pollock, Isaac Eckert and Federico Riva for comments on the written document and discussion of the topic. We also thank Anna Hargreaves, Brian Leung, Jonathan Belmaker, Lilian Sales and Shahar Chaikin for additional discussions. We are also grateful to the authors whose work provided the raw data for this synthesis. KEM is supported by a NSERC Discovery Grant. GM and JPL were supported by the Concordia University Research Chair in Biodiversity and Ecosystem Functioning. GM is additionally supported by a Concordia Graduate Fellowship. CS and CJG were supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant to CJG. CS was also supported by a U. Manitoba Graduate Fellowship, and a U. Manitoba Graduate Enhancement of Tri‐council funding grant to CJG. The authors declare no conflict of interest.

Data Availability Statement

All data are already in the public domain and sources are cited in the references. Data and code to reproduce analyses are available on FigShare (DOI: 10.6084/m9.figshare.19879864).


  • biogeography
  • conservation
  • landscape genetics
  • macroecology
  • macroevolution
  • macrogenetics
  • mammals
  • management
  • north and South America
  • population genetics


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