Biogeography Chapter 10 (B)
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- Palearctic- temperate Eurasia and Northern Africa
- Oriental- Tropical Asia
- Ethiopian- Sub-Saharan Africa
- Australian- Australia, New Guinea, and New Zealand
- Nearctic- Temperate North America
- Subtropical/tropical Central America and South America.
- Species with a very broad (roughly worldwide) ranges.
- Good dispersal characteristics
- broad ecological tolerances
- generalists food (soil) habitats
- ruderals-do well in disturbed sites
- Examples: humans, some microbes, peregrine falcon, vespertillionid bats
- Limited dispersa
- Competitive strategy
- limited tolerance
- evolutionary young
- Ex: cui-ui, bristlecone pine
- Sole survivors of a previously more diverse taxon
- Biogeographic relicts are narrowly endemic descendants of a previously more widespread taxon.
- Ex: humans (taxonomic relicts), "Living fossils" are relicts in both senses.
- Distributions in which closely related populations/species live in widely separated areas.
- E.g. Oceans for terrestrial species
- Vicariance and temporary habitat bridges
- Sister species tend to have somewhat overlapping or adjacent ranges. Diversification is often regionally local.
- Sets of distantly related taxa (e.g. plants and animals often show similar patterns of endemism. Suggest shared history of local origin and limited dispersal.
Challenge of drawing biogeographic "lines"
- Some species of mammals and fishes extend their ranges to newly available areas.
- Blurs boundaries.
- Lower taxonomic richness
- insular endemics
- species derived from ancestors that were good at over-water dispersal
- Species are closely related to continental forms or have ranges that include immigration sources.
- Biota includes poor over-water dispersers, hence are more balanced or "harmonic"
- May have recently been connected by land bridges.
Natural selection can lead to converge in phenotypes, but this typically occurs while genomes continue to diverge
Convergent Evolution: Analogy
Similarity due to convergent evolution, not common ancestor
Convergent Evolution: Homology
Similarity due to shared inheritance (common ancestor)
Maintenance of Biotas: Native Biotas
- Species may have long histories of adaptation to abiotic condtions
- Species may have coevolved ecological roles
- BUT invaders may be free of effective enemies (predators, competitors, parasites)
Many successful invasive species act ecologically like "weeds" in disturbed habitats, or have ecologically like coupled to humans. (like house mouse and some rat species)
Humans effects on invasives
- expand with roads
- landscape configuration
- land cover change
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