13.4 Paleobiogeographic patterns and their ecological implications

Paleobiogeographic patterns reveal how species distributions change over time and space. These patterns, like latitudinal diversity gradients and biogeographic provinces, help us understand past ecosystems and species movements.

Studying temporal changes in species distributions, including refugia and range dynamics, gives insights into how organisms responded to environmental shifts. This knowledge is crucial for predicting future biodiversity patterns and conservation planning.

Spatial Patterns in Paleobiogeography

Latitudinal Diversity Gradient and Biogeographic Provinces

Top images from around the web for Latitudinal Diversity Gradient and Biogeographic Provinces

• 

  Frontiers | On the processes generating latitudinal richness gradients: identifying diagnostic ... View original

  Is this image relevant?

• 

  Characteristics of Terrestrial Biomes | Biology for Majors II View original

  Is this image relevant?

• 

  Frontiers | On the processes generating latitudinal richness gradients: identifying diagnostic ... View original

  Is this image relevant?

• 

  Characteristics of Terrestrial Biomes | Biology for Majors II View original

  Is this image relevant?

1 of 2

Top images from around the web for Latitudinal Diversity Gradient and Biogeographic Provinces

• 

  Frontiers | On the processes generating latitudinal richness gradients: identifying diagnostic ... View original

  Is this image relevant?

• 

  Characteristics of Terrestrial Biomes | Biology for Majors II View original

  Is this image relevant?

• 

  Frontiers | On the processes generating latitudinal richness gradients: identifying diagnostic ... View original

  Is this image relevant?

• 

  Characteristics of Terrestrial Biomes | Biology for Majors II View original

  Is this image relevant?

1 of 2

• Latitudinal diversity gradient describes the trend of decreasing species richness from the equator to the poles
  • Caused by factors such as higher energy availability, reduced seasonality, and greater habitat diversity in the tropics
  • Observed in both modern and fossil ecosystems (marine invertebrates, terrestrial plants)
• Biogeographic provinces are distinct geographic regions with unique assemblages of species
  • Provinces are shaped by physical barriers, environmental conditions, and evolutionary history
  • Examples include the Indo-Pacific, Eastern Pacific, and Western Atlantic marine provinces
  • Provinces can change over geological time due to tectonic events, climate shifts, and biotic interactions

Patterns of Species Distributions

• Cosmopolitan distributions occur when a species has a wide geographic range spanning multiple biogeographic provinces
  • Often associated with species that have high dispersal abilities or broad environmental tolerances
  • Examples include some species of foraminifera, sharks, and marine mammals
• Pantropical distributions are characterized by species occurring in tropical regions across different continents or ocean basins
  • Reflects the similarity of environmental conditions in tropical areas and the ability of some species to disperse across long distances
  • Pantropical distributions are observed in various marine and terrestrial taxa (corals, mangroves)
• Bipolar distributions involve species occurring in both the Arctic and Antarctic regions, but not in the intervening temperate or tropical zones
  • May result from dispersal events during colder climatic periods or vicariance due to the breakup of ancient landmasses
  • Examples of bipolar distributions include certain species of marine invertebrates and seaweeds

Temporal Changes in Species Distributions

Refugia and Range Dynamics

• Refugia are areas where species persist during periods of unfavorable environmental conditions, such as glaciations or droughts
  • Act as sources for recolonization when conditions improve
  • Identification of refugia is important for understanding the biogeographic history of species and their genetic diversity
• Range expansions and contractions refer to changes in the geographic extent of a species over time
  • Range expansions can occur during periods of favorable climate or following the removal of dispersal barriers
  • Range contractions may result from environmental deterioration, competition, or other biotic interactions
  • Studying range dynamics helps reconstruct the biogeographic history of species and their responses to past environmental changes

Paleoendemism

• Paleoendemism refers to the occurrence of ancient or relict species with restricted geographic ranges
  • Paleoendemic species often have limited dispersal abilities and may be confined to specific habitats or regions
  • Examples include the Wollemi pine in Australia and the ginkgo tree in China
  • Paleoendemic species provide insights into the evolutionary and biogeographic history of a region and may require conservation efforts due to their limited distributions

Analytical Approaches

Paleobiogeographic Reconstruction Methods

• Paleobiogeographic reconstruction methods aim to infer the biogeographic history of species and ecosystems based on fossil evidence
  • Parsimony analysis of endemicity (PAE) identifies areas of endemism by minimizing the number of dispersal and extinction events required to explain the observed distribution patterns
  • Brooks parsimony analysis (BPA) reconstructs the biogeographic history of species by mapping their phylogenetic relationships onto geographic areas
  • Ancestral area reconstruction methods, such as dispersal-vicariance analysis (DIVA) and the DEC model, estimate the most likely ancestral ranges of species based on their current distributions and evolutionary relationships
• Integration of fossil data, phylogenetic information, and geological history is crucial for accurate paleobiogeographic reconstructions
• Advances in computational methods and the increasing availability of large-scale datasets have enhanced our ability to study paleobiogeographic patterns and processes