GEOG20009 Lecture Notes - Lecture 17: Ecoregion, Allopatric Speciation
15 May 2018
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LECTURE 17: DIVERSIFICATION & REGIONALISATION
• Perspectives on patterns of life:
o History of place OR (changes in geography, geology, climate, environments extrinsic to organisms,
biota)
o History of lineage (series of changes in intrinsic characteristics of populations, species or higher taxa)
• General geographic patterns: endemism, provincialism, disjunction
• Barrier removal and erosion – genetic exchange
• Evolutionary trends of separation
COSMOPOLITAN
• Geographic distribution = geographic range
• Cosmopolitan: widely distributed throughout the whole world
• No species or family is truly cosmopolitan
• Key Attributes: dispersal (passive or active), tolerance, resistance
• Certain higher taxonomic levels are nearly cosmopolitan
• Higher taxonomy you go – the larger the geographic range will get
ENDEMISM
• Endemic: occurring in one geographic location and nowhere else
• Concept applied at any taxonomic or geographic scale
• More diverse taxa are endemic to larger areas
• Geographic location: not randomly distributed, coincident distribution, unique spatial assemblages
• Hotspots of endemism – WA south coast, NZ
• Organisms can be endemic to a geographic location on a variety of spatial scales and at different taxonomic levels
o Nested hierarchy
• What makes a species endemic
o Isolation (small restricted habitats): islands, mountain topography (acts as a speciation pump in
presence of climatic fluctuations - Isolated evolution (peaks or valleys) of lineages
o Hybridisation after isolation
o Elevation
Types of Endemism
Important for analysis of vicariance, 2 or more non-related autochthonous endemics = area of endemism
• Autochthonous endemic: one that differentiated where it is found today
• Allochthonous endemic: one that originated in a different location from where it currently survives (disperse and
extinct)
Often coincide, lack of dispersal, shrinking range
• Taxonomic relict: sole survivors of once diverse taxonomic groups
• Biogeographic relict: narrowly endemic survivors of once widespread taxa
Importance of timing
• Paleoendemic: old endemic species
• Neoendemic: recently formed endemic species
PROVINCIALISM
• Provincialism: geographic overlap of endemism across multiple taxa,
coincident occurrence of large numbers of well-differentiated endemic
forms in an area
• Terrestrial regions and provinces, have transition zones – also applied to
marine realm (yet too little data to be accurate)
• Differences in biota: limited distribution suggests local origin and limited
dispersal
o Button’s Law: different region with similar environments are inhabited by distinct biotas
• Reflect influences of historical events
• Subdivisions within zones
• More detail needed – important for conservation and protection – need to zoom in
Document Summary
Cosmopolitan: geographic distribution = geographic range, no species or family is truly cosmopolitan, higher taxonomy you go the larger the geographic range will get. Key attributes: dispersal (passive or active), tolerance, resistance. Endemic: occurring in one geographic location and nowhere else. Concept applied at any taxonomic or geographic scale. Isolation (small restricted habitats): islands, mountain topography (acts as a speciation pump in presence of climatic fluctuations - isolated evolution (peaks or valleys) of lineages: hybridisation after isolation, elevation. Often coincide, lack of dispersal, shrinking range: biogeographic relict: narrowly endemic survivors of once widespread taxa. Taxonomic relict: sole survivors of once diverse taxonomic groups. Importance of timing: neoendemic: recently formed endemic species. Provincialism: geographic overlap of endemism across multiple taxa, coincident occurrence of large numbers of well-differentiated endemic forms in an area.
