Faunal regions or Zoogeographical Regions Present-day Mammalian Faunal Diversity

Zoogeography -study of the distribution of animals -patterns and processes -can be studied at many different scales Chapter 26; Feldhammer text

Zoogeography A. Historical zoogeography Examine evolutionary history of a group of animals in the context of “earth history” Geographic patterns of diversification, extinction etc. Large geographic scales & “deep” time frames B. Ecological zoogeography What features of present-day environments restrict organisms to their current environment? Smaller spatial scales & more recent time frames (i.e., Holocene-present)

ALLOPATRIC SPECIATION A. Historical zoogeography Fundamental principle is VICARIANCE Diversification (i.e., speciation) is primarily the result of widespread populations being “split” by the formation of an environmental barrier C A species X species X B Range of species X divided species Y species Z environmental barrier forms 2 new species form via ALLOPATRIC SPECIATION

Time frame Spatial scale Ecological Zoogeography Recent Small Large Historical Zoogeography Past Combination: can tell us about the geographic history of a group AND the relationship between present environmental conditions & present mammal distributions

Faunal regions Present-day Mammal Diversity

Palearctic: Eurasia, including North Africa and all of Europe and Asia (north of India and tropical southeast Asia) Palearctic # families = 42 endemics = 0 largest faunal region in terms of area Moderate familial diversity, but no endemic families Shares ~ half of its families with the Nearctic

The Bering land bridge has been open for dispersal for periods of time during the Pleistocene

The Bering land bridge has been open for dispersal for periods of time during the Pleistocene

Nearctic: North America north of Mexico and Greenland # families = 37 endemics = 2 2nd largest faunal region Moderate familial diversity Only 2 endemic families

Nearctic: North America north of Mexico and Greenland Only 2 endemic families Aplodontidae Antilocapridae

Nearctic: North America north of Mexician lowlands and Greenland Also shares about half of its families with the Neotropics Connected relatively recently (ca. 3 MYA) with the Neotropical region through the Panamanian land bridge

Neotropical: High familial diversity (50) Greatest number of endemic Central Mexico throughout South America, including the Caribbean islands High familial diversity (50) Greatest number of endemic families (19) Long period of isolation and a warm and favorable climate has probably contributed to this

Neotropical Endemic Families Bradypodidae Myrmecophagidae Microbiotheriidae Callithrichidae

Ethiopian # families = 52 endemics = 18 D. Ethiopian: Africa south of the Saharan Desert; includes Madagascar Connected to the Palearctic via the Sahara Ethiopian # families = 52 endemics = 18 Madagascar -lemurs & tenrec radiation Much tropical land mass Much familial diversity, with many endemics (18) Many endemic primates, and especially high endemism on Madagascar

Ethiopoan Endemic Families Hyaenidae Orycteropodidae Lemuridae Macroscelididae

Oriental # families = 50 endemics = 4 E. Oriental: Tropical southeast Asia, India, and southeast Asian islands including Borneo, Sumatra, some Indonesian islands and the Philippine archipelago (does not include New Guinea and Sulawesi) Oriental # families = 50 endemics = 4 Much of it is tropical High familial diversity, but fairly low endemism

Neotropical Endemic Families Tupaiidae Tarsiidae Cynocephalidae

E. Oriental: Tropical southeast Asia, India, and southeast Asian islands including Borneo, Sumatra, some Indonesian islands and the Philippine archipelago (does not include New Guinea and Sulawesi) mountains sea central position Shares ~75% of mammalian families with the Palearctic, ~60% with the Ethiopian, and ~50% with the Nearctic no endemic families!

F. Australian: Australia, New Guinea, and associated islands # families = 28 endemics = 17 A long period of isolation with very low diversity but high endemism Only 28 families, but 17 endemics Shares <20% of its families with any other region

Australian Endemic Families Tachyglossidae Ornithorhynchidae Macropodidae Phalangeridae

G. Oceanic: The islands of the Pacific Ocean Greatly isolated; generally only various species of bats make it onto these islands (we are not considering oceanic mammals here)

Plate tectonics is the study of the movements of crustal plates, upon which the continents ride Continental drift is the movement (over geological time) of the continents

Plate tectonics is the study of the movements of crustal plates, upon which the continents ride Continental drift is the movement (over geological time) of the continents

About 225 MYA, continents were joined together into a single CONTINENTAL DRIFT About 225 MYA, continents were joined together into a single “supercontinent”: PANGAEA

Laurasia: North America, Europe, Greenland, part of Asia CONTINENTAL DRIFT ~200 MYA Pangaea began to break up into two large land masses: Laurasia: North America, Europe, Greenland, part of Asia Gondwanaland: South America, Australia, Africa, Antarctica, part of Asia

Much early evolution of mammals was going on as the continents were breaking up still further

presence of marsupials in Australia and South America due to continents being isolated for long periods Australia stayed isolated, accounting for the large number of marsupials in Australia

isolated for a long time South America was also isolated for a long time But, SA joined North America via Panamanian land bridge (3 MYA) Panamanian Land Bridge (3 MYA) extinctions of many marsupials in SA as eutherians invaded Only 1 marsupial reinvaded North America Virginia Opossum

filter route Great American Interchange Few early dispersals Entered NA & CA from SA Few early dispersals beginning ~9 MYA Reached peak ~3 MYA Isthmus of Panama emerged as dry land filter route Entered SA & from NA

Question: How did earth history, especially continental drift, influence the geographic distribution and evolutionary histories of the following? AFROTHERIA! METATHERIA! XENARTHRA!

Pleistocene Zoogeography of Mammals The last ~2 MY- characterized by repeated glacial cycles, or “ice-ages” Effects on mammals?????: Major distributional shifts Lots of extinction Speciation???

Glacial Cycles of the Pleistocene > 20 cycles during the past ca. 2 million years ~100,000 year periodicity increased in intensity last 700,000 years 2.1 million year record 700,000 year record Oxygen isotope record

Present global distribution of boreal (northern coniferous) forests