Bio 1309 Radiations & Extinctions. Patterns in Biodiversity

Size: px

Start display at page:

Download "Bio 1309 Radiations & Extinctions. Patterns in Biodiversity"

Barnaby Lindsey
6 years ago
Views:

times So far, scientists have identified and named 1.

1 Bio 1309 Radiations & Extinctions Slide 1 Patterns in Biodiversity During the 3.5 billion year history of life on Earth, the number of species has fluctuated many times So far, scientists have identified and named 1.8 million living species Recent studies estimate that there are probably 8.7 million living species on Earth Slide 2 1

7 million is just a drop in the bucket of all species that have ever existed on Earth An estimated 99%

2 Patterns in Biodiversity That means that over 79% of living species have yet to be identified However, based on the fossil record, even 8.7 million is just a drop in the bucket of all species that have ever existed on Earth An estimated 99% of all species are now extinct Slide 3 Riding the Continents - Marsupials biogeography of organisms enables a sense of where they originated For example: marsupials Slide 4 2

Riding the Continents about marsupials The oldest marsupial fossils date back 150 mya, from

3 Riding the Continents - marsupials Most modern marsupials can be found on Australia and its surrounding islands Marsupials evolved thousands of kilometers away from Australia Slide 5 Riding the Continents about marsupials The oldest marsupial fossils date back 150 mya, from China 150 mya, Asia was linked to North America By 120 mya marsupials had made it to N.A. Slide 6 3

4 Riding the Continents- marsupial travel Many new lineages of marsupials evolved in N.A. over the next 55 million years Some spread to Europe and as far as North Africa and Central Asia Slide 7 Riding the Continents northern hemisphere marsupials All northern hemisphere marsupials died out in a series of extinctions ~20-30 mya Another group of N.A. marsupials dispersed to South America ~70 mya Slide 8 4

in Australia Slide 9 Riding the Continents SA, Australia, and Antarctica drifted apart Each carried a population of

5 Riding the Continents Marsupials expanded from SA into Antarctica and Australia (Antarctica and Australia were attached to SA at this time) Marsupials arrived in Australia no later than 55 mya per oldest marsupial fossils found in Australia Slide 9 Riding the Continents SA, Australia, and Antarctica drifted apart Each carried a population of marsupials As Antarctica moved closer to the South Pole, the weather got colder and colder and Marsupials died out Slide 10 5

Riding the Continents South America In SA, marsupials diversified into many different

A., many of these marsupials died out, although still many species of marsupials living

SA and recolonized N.A. to be only living marsupial in N.A. today Australia drifted in

6 Riding the Continents South America In SA, marsupials diversified into many different forms (ex: Cat-like sabertooth marsupial - Thylacosmilus atrox When SA reconnected with N.A., many of these marsupials died out, although still many species of marsupials living in SA Thylacosmilus atrox Slide 11 Riding the Continents The Virginia opossum came from SA and recolonized N.A. to be only living marsupial in N.A. today Australia drifted in isolation for more than 40 million years 25 mya all animals in Australia were marsupials Slide 12 6

15 mya, Australia moved close enough to Asia for placental mammals (bats, rats) to begin to colonize

7 Riding the Continents Australian marsupials Australian marsupials evolved into: Kangaroos, Koalas, marsupial mouse, etc. 15 mya, Australia moved close enough to Asia for placental mammals (bats, rats) to begin to colonize Slide 13 Riding the Continents mammals in Australia Placental mammals diversified and moved into many available niches Didn t displace any of the marsupials that were already living there Slide 14 7

Readings Read about the Pace of Evolution, pages 217-218 in The Tangled Bank Slide 15 Lifetime of a Species Estimates say that about

8 Readings Read about the Pace of Evolution, pages in The Tangled Bank Slide 15 Lifetime of a Species Estimates say that about 99% of all species that have ever existed have gone extinct Most species last a few million years before they become extinct Slide 16 8

Lifetime of a Species They killed dodos for food and sport Also brought the first rats to Mauritius Rats

9 Lifetime of a Species To understand how species become extinct, biologists study extinctions that have taken place over the past few centuries Dutch explorers arrived on Mauritius in the 1600s Slide 17 Lifetime of a Species They killed dodos for food and sport Also brought the first rats to Mauritius Rats ate dodo eggs As adults and young dodos were killed, the population began to shrink Only 1 dodo left Slide 18 9

activities Slide 19 Lifetime of a Species extinction example Carolina parakeet in huge numbers in

10 Lifetime of a Species - extinction When it died, the species was gone forever Extinct Killing species isn t the only way to drive a species to extinction Habitat loss Introduction of nonnative species Human activities Slide 19 Lifetime of a Species extinction example Carolina parakeet in huge numbers in southeastern US Logging industry took out trees parakeets used as habitat in the 1900s Parakeets went extinct Slide 20 10

biodiversity questions Slide 21 Cradles of Diversity bivalve research David

11 Cradles of Diversity - Tropics Why are the tropics so diverse? Understanding longterm patterns of speciation and extinction help answer biodiversity questions Slide 21 Cradles of Diversity bivalve research David Jablonski Paleontologist University of Chicago Looked a bivalve fossil record Location Range How long they lasted Slide 22 11

Cradles of Diversity bivalve research (cont ) Analyzed 3,599 species of bivalves from the last 11 million years Found an interesting pattern Twice as many bivalve new genera evolved in tropical

12 Cradles of Diversity bivalve research (cont ) Analyzed 3,599 species of bivalves from the last 11 million years Found an interesting pattern Twice as many bivalve new genera evolved in tropical waters vs cooler waters When new bivalve genera evolved in tropical waters, they expanded towards the poles and cooler water Slide 23 Cradles of Diversity bivalve research (cont ) Over time, bivalves near the poles became extinct Bivalves in the tropics survived Tropics are both a cradle and a museum Slide 24 12

biodiversity in the tropics Slide 25 Cradles of Diversity Bird example Bradford

13 Cradles of Diversity - tropics New species evolve quickly in the tropics so greater numbers accumulate with a lower extinction rate This means high biodiversity in the tropics Slide 25 Cradles of Diversity Bird example Bradford Hawkins Biologist University of California, Irvine Saw the same trend in bird species Slide 26 13

poles Advancing and retreating glaciers in cooler regions Swings between wet and dry climates Slide 27

14 Cradles of Diversity Why? Tropics might have low extinction rates because they have more stable climates than regions closer to the poles Advancing and retreating glaciers in cooler regions Swings between wet and dry climates Slide 27 Cradles of Diversity Tropics foster a higher rate of evolution of new species May be because the extra energy the tropics receive creates extra ecological room for more new species Slide 28 14

Readings Read the following sections in the Tangled Bank: Radiations, pages 223-225 A Gift for Diversity, pages 225-226 Lighting the Cambrian Fuse, pages 226-230 Slide 29 Driven to Extinction As new

15 Readings Read the following sections in the Tangled Bank: Radiations, pages A Gift for Diversity, pages Lighting the Cambrian Fuse, pages Slide 29 Driven to Extinction As new species emerge and evolve into new forms, other species become extinct Extinctions, like everything else in nature, form patterns Extinction rates have gone up and down over the last 540 million years Millions of years Thousands of genera Slide 30 15

Driven to Extinction - pulses A few pulses of extinction

all genera 90% of all species disappeared Slide 31 Driven

mass extinctions Other 80% are called background

to survive longer than those with small geographical ranges

ranges may make a species susceptible to small-scale

16 Driven to Extinction - pulses A few pulses of extinction stand out Biggest one happened 250 mya Killed off 55% of all genera 90% of all species disappeared Slide 31 Driven to Extinction Only about 20% of all extinctions result from mass extinctions Other 80% are called background extinctions Species with large geographical ranges tended to survive longer than those with small geographical ranges Small ranges raises the odds of becoming extinct Small ranges may make a species susceptible to small-scale (local) catastrophes like volcanic eruptions or Invasion by a dangerous predator Slide 32 16

Another pattern is major lineages gradually go extinct as other lineages become more diverse

17 Driven to Extinction small ranges Small range may also be an indication that the species can survive in a very narrow range of conditions Slide 33 Driven to Extinction diverse lineages Another pattern is major lineages gradually go extinct as other lineages become more diverse Trilobites were once the dominant species in the oceans Disappeared 252 mya Replaced by new species Slide 34 17

Slide 35 Driven to Extinction Changing climate also impacts extinction rates In the middle

18 Driven to Extinction - asteroid 66 mya asteroid hit the coast of Mexico Giant tidal waves Huge forest fires Global environmental change Caused mass extinctions Dinosaurs Uh-Oh! Slide 35 Driven to Extinction Changing climate also impacts extinction rates In the middle of global climate change right now As temperatures rise, what might happen to species? Slide 36 18

19 sponsored by humans! Humans major impact on most of the world s habitats for example: Millions of acres of tropical rain forest cut down for timber and to clear land for farming Slide 37 - span Current extinction spans numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods Recorded 875 extinctions between 1500 and 2009 Vast majority of extinctions are undocumented According to the species-area theory and based on upper-bound estimating, up to 140,000 species per year may be the present rate of extinction Slide 38 19

In New Zealand, circa 1500, several species

arrived, including: Ten species of Moa, giant

Harpagornis Flightless predatory Adzebills

estimated that some 2000 bird species species

20 In New Zealand, circa 1500, several species became extinct after Polynesian settlers arrived, including: Ten species of Moa, giant flightless ratite birds Giant Haast's Eagle, Harpagornis Flightless predatory Adzebills Slide 39 In the Pacific, it is currently estimated that some 2000 bird species species have gone extinct since the arrival of humans Slide 40 20

Among the extinctions were: Moa-nalos, grazing

Goose, an extinct species of goose that once

Caledonia Mekosuchine crocodiles from New

the arrival of humans around 2000 years ago,

extinct, including: Eight species of elephant

21 Among the extinctions were: Moa-nalos, grazing ducks from Hawaii Nēnē-nui, or Woodwalking Goose, an extinct species of goose that once inhabited Maui A giant megapode from New Caledonia Mekosuchine crocodiles from New Caledonia, Fiji and Samoa Slide 41 Starting with the arrival of humans around 2000 years ago, nearly all of Madagascar s megafauna became extinct, including: Eight species of elephant birds, giant flightless ratites in the genera Aepyornis and Mullerornis Slide 42 21

22 17 species of lemur, known as giant, subfossil lemurs, including: Giant Aye-aye (Daubentonia robusta) Sloth lemurs, including chimpanzee-sized Palaeopropithecus and gorilla-sized Archaeoindris Koala lemurs (Megaladapis), a koala-like, orangutan-sized arboreal lemur Monkey lemurs, most terrestrial of lemurs, often compared to baboons or macaques Pachylemur, a genus of giant ruffed lemurs Slide 43 Giant Fossa Plesiorycteropus, a genus containing two species of digging mammal unlike anything alive today Two species of Malagasy Hippopotamus Slide 44 22

Mascarene Islands, including: Dodo Rodrigues Solitaire Réunion Solitaire Slide 45 Megafaunal extinctions

23 Starting circa 1500, a number of species became extinct upon human settlement of the Indian Ocean Islands, including: Several species of giant tortoise on Seychelles and Mascarene Islands 14 species of birds on the Mascarene Islands, including: Dodo Rodrigues Solitaire Réunion Solitaire Slide 45 Megafaunal extinctions continue into the 21st century Some examples of modern extinctions of "charismatic" mammal fauna include: Slide 46 23

24 Aurochs, Europe Slide 47 Tarpan, Europe Slide 48 24

25 Tasmanian Tiger, Tasmania Slide 49 Quagga, Southeast Africa Slide 50 25

26 Steller's Sea Cow Slide 51 Bluebuck Slide 52 26

27 Pyrenean Ibex Slide 53 Falkland Islands Wolf Slide 54 27

28 Atlas Bear Slide 55 Caribbean Monk Seal Slide 56 28

29 The closely related Bali Tiger and Javan Tiger Slide 57 Eastern Cougar Slide 58 29

extinct, we lose a bit of our history Raw material

30 Western Black Rhinoceros Slide 59 Humans driving a new pulse of extinction Every time a species goes extinct, we lose a bit of our history Raw material for: Biotechnology Chemical engineering Medicine Slide 60 30

7A Evidence of Evolution

7A Evidence of Evolution Fossil Evidence & Biogeography 7A analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical,