Historical Biogeography

Historical BiogeographyCH 7Current DistributionResult of the interaction of:Early history and place of originFragmentation of continentsClimactic changes during CenozoicCooling and eventual ice age in PleistoceneMass extinctions and adaptive radiationsLand BridgesBeringGreenland Deep Time Perspective4 Zoic Eras Overview of Major EventsHistoric Biogeography

4Table 25.1Table 25-1b

5Table 25.1The rise and fall of dominant groups reflect continental drift, mass extinctions, and adaptive radiations6

SouthAmericaPangaeaMillions of years ago65.5135Mesozoic251PaleozoicGondwanaLaurasiaEurasiaIndiaAfricaAntarcticaAustraliaNorth AmericaMadagascarCenozoicPresentContinental DriftAt three points in time, the land masses of Earth have formed a supercontinent: 1.1 billion, 600 million, and 250 million years ago Earths continents move slowly over the underlying hot mantle through the process of continental driftOceanic and continental plates can collide, separate, or slide past each otherInteractions between plates cause the formation of mountains and islands, and earthquakes7Figure 25.13 The history of continental drift during the Phanerozoic eon

Mass ExtinctionsThe fossil record shows that most species that have ever lived are now extinctAt times, the rate of extinction has increased dramatically and caused a mass extinctionIn each of the five mass extinction events, more than 50% of Earths species became extinct

DimetrodonHallucigenia8

Fig. 25-14Total extinction rate(families per million years):Time (millions of years ago)Number of families: CenozoicMesozoicPaleozoicEOSDCPTrJ5420488444416359299251200145EraPeriod5CPN65.5002001003004005006007008001510209Figure 25.14 Mass extinction and the diversity of life describe each extinction a bit

Adaptive RadiationsAdaptive radiation is the evolution of many new species adapted from a common ancestor upon introduction to new environmental opportunities (new niches)Occurs via:Evolution of novelty (i.e., seeds)After a mass extinction (i.e., mammals) Formation of new land (i.g. islands)Piggyback on other organisms (insect radiations follow flowering plants)

BASICALLY, any time many new niches (ecological livelihoods) are available, there is opportunity for adaptive radiation.

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Table 25-1a

11Table 25.1

Table 25-1aIII. Multicellular Life - Neoproterozoic

12Table 25.1

Table 25-1a

13Table 25.1V. First Life on LandVI. Conquest of LandChallenges:structural supportdehydrationreproductionSolutions:exoskeleton, lungs in animalswhat about plants?cuticle, stomata, vascular tissue,pollen not all at once

Table 25-1a

15Table 25.1

Massive extinction 250myafollowed by adaptive radiation16Table 25.1Table 25-1b

SouthAmericaPangaeaMillions of years ago65.5135Mesozoic251PaleozoicGondwanaLaurasiaEurasiaIndiaAfricaAntarcticaAustraliaNorth AmericaMadagascarCenozoicPresentVIII. Emerging Modern LineagesTriassic/Jurassic:global warming, arid Pangaea interior, mountain formation

Reptiles loved it!

17Table 25.1

Table 25-1b

SouthAmericaPangaeaMillions of years ago65.5135Mesozoic251PaleozoicGondwanaLaurasiaEurasiaIndiaAfricaAntarcticaAustraliaNorth AmericaMadagascarCenozoicPresentExtinction20Table 25.1

Fig. 25-17Millions of years agoMonotremes(5 species)25015010020050ANCESTRALCYNODONT0Marsupials(324 species)Eutherians(placentalmammals;5,010 species)Ancestralmammal21Monotremes diverged 180mya; marsupials from eutherians 140mya,

SouthAmericaPangaeaMillions of years ago65.5135Mesozoic251PaleozoicGondwanaLaurasiaEurasiaIndiaAfricaAntarcticaAustraliaNorth AmericaMadagascarCenozoicPresent

Mountain ranges: Himalayans , Rockies (Eocene), Sierra Nevada (Miocene), Cascades, Coast ranges (late Miocene) 22Figure 25.13 The history of continental drift during the Phanerozoic eon

Great American Interchange

Panama Isthmus formed 3 myaPanama bridge26 genera S12 went NTapirs/llamas went extinct in N Am, so disjunct w/Asian