Unit 4 Notes
19: Patterns in Diversity 1
• Through Time
o Geologic Time
§ Patterns
• Diversity increases through time
• Periodic mass extinctions followed by faunal recovery
• Change in composition
o Not just increase in diversity
• More recent strata = more species in sample
o Diversity tends to increase over time
o Whacked back by massive extinctions (2 main ones)
§ Permian-Triassic boundary mass extinction
• Paleozoic-Mesozoic
§ Mesozoic-Cenozoic mass extinction
• Asteroid
• Fish Diversity
o Jawless fishes
o Placoderms
o Sharks and relatives
o Acanthodians
o Ray-finned fishes
o Lobe-fin fishes
o Tetrapods
• Protists and Plants
o Algae
o Protozoa
o Bryophytes
o Psilopsids
o Lycopsids
o Sphenopsids
o Ferns
o Gymnosperms
o Angiosperms
§ Mechanisms
• Speciation/extinction
• Innovation of new adaptive zone
o Colonized place or lifestyle
§ New place can be islands
o When evolved a new way of life to use new resources
§ Or old resources in new way
, § Adaptations to land
§ Adaptations for flight
§ Adapting to other organisms in environment
• Resistance to predators
• Mutualisms with other species
o Be released from competition by mass extinction of
competitors
• Radiation: explosion of species colonizing new areas
o Exploiting new environments
• Competitive contraction: winners exclude others
o Internal or external
• Response to predation
o Cnidarians are stinging predators
o Vendian period 650-543mya
§ Spriggia
•
• Soft-bodied arthropod precursor
o Cambrian period 543-490mya
§ Predation selects for anti-predator traits in prey
§ Hard parts evolve
• Burst in preserved specimens (fossils)
• More confident in placement of fossils in
Genus than species
o Speciation may not be reflected
morphologically
• Mutualisms
o Angiosperms and pollinators
o Angiosperms arise in Cretaceous
o Pollinators can be beetles, ants, bees, wasps, flies,
butterflies/moths
, • Changes in tectonics
o Plates moved apart and continents split, but they are
coming back together again
o Vicariance barrier younger or contemporaneous with
divergence event
§ Existing range is split by a barrier
§ Species A à species A’ and species A” à species B
and species C
§
§ New Zealand variation from vicariance
o Dispersal barrier older than divergence event
§ Barrier has always been present
• Migration event
§ Species A à part of species A breaks off à species
A’ becomes species B
§
§Ostriches in Africa from dispersal
• Because Africa broke off before they were
there
o Geodispersal is not clean because continents do not just
split
§ Reconnect in new patterns
§ Allow new dispersal events through continuous
habitat
§ Originally, it was western NA and eastern Europe
connected and eastern NA and western Europe
connected
• Reasons for mountains
§ Panamanian Land Bridge
19: Patterns in Diversity 1
• Through Time
o Geologic Time
§ Patterns
• Diversity increases through time
• Periodic mass extinctions followed by faunal recovery
• Change in composition
o Not just increase in diversity
• More recent strata = more species in sample
o Diversity tends to increase over time
o Whacked back by massive extinctions (2 main ones)
§ Permian-Triassic boundary mass extinction
• Paleozoic-Mesozoic
§ Mesozoic-Cenozoic mass extinction
• Asteroid
• Fish Diversity
o Jawless fishes
o Placoderms
o Sharks and relatives
o Acanthodians
o Ray-finned fishes
o Lobe-fin fishes
o Tetrapods
• Protists and Plants
o Algae
o Protozoa
o Bryophytes
o Psilopsids
o Lycopsids
o Sphenopsids
o Ferns
o Gymnosperms
o Angiosperms
§ Mechanisms
• Speciation/extinction
• Innovation of new adaptive zone
o Colonized place or lifestyle
§ New place can be islands
o When evolved a new way of life to use new resources
§ Or old resources in new way
, § Adaptations to land
§ Adaptations for flight
§ Adapting to other organisms in environment
• Resistance to predators
• Mutualisms with other species
o Be released from competition by mass extinction of
competitors
• Radiation: explosion of species colonizing new areas
o Exploiting new environments
• Competitive contraction: winners exclude others
o Internal or external
• Response to predation
o Cnidarians are stinging predators
o Vendian period 650-543mya
§ Spriggia
•
• Soft-bodied arthropod precursor
o Cambrian period 543-490mya
§ Predation selects for anti-predator traits in prey
§ Hard parts evolve
• Burst in preserved specimens (fossils)
• More confident in placement of fossils in
Genus than species
o Speciation may not be reflected
morphologically
• Mutualisms
o Angiosperms and pollinators
o Angiosperms arise in Cretaceous
o Pollinators can be beetles, ants, bees, wasps, flies,
butterflies/moths
, • Changes in tectonics
o Plates moved apart and continents split, but they are
coming back together again
o Vicariance barrier younger or contemporaneous with
divergence event
§ Existing range is split by a barrier
§ Species A à species A’ and species A” à species B
and species C
§
§ New Zealand variation from vicariance
o Dispersal barrier older than divergence event
§ Barrier has always been present
• Migration event
§ Species A à part of species A breaks off à species
A’ becomes species B
§
§Ostriches in Africa from dispersal
• Because Africa broke off before they were
there
o Geodispersal is not clean because continents do not just
split
§ Reconnect in new patterns
§ Allow new dispersal events through continuous
habitat
§ Originally, it was western NA and eastern Europe
connected and eastern NA and western Europe
connected
• Reasons for mountains
§ Panamanian Land Bridge
