Biodiversity distribution How to count species? Mac Arthur and - - PDF document

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Biodiversity distribution How to count species? Mac Arthur and - - PDF document

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????? <1%? Biodiversity distribution How to count species? Mac Arthur and Wilson (1967): the theory of island biogeography Global distribution of biodiversity Global distribution of biodiversity North America Marine bivalve mollusks

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SLIDE 1

Biodiversity distribution

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How to count species?

Mac Arthur and Wilson (1967): the theory of island biogeography

Marine bivalve mollusks Ants

Latitude

Global distribution of biodiversity Global distribution of biodiversity North America

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SLIDE 2

Breeding bird richness in the state of New York Breeding bird richness in Florida USA Biodiversity “hotspots”

Global distribution of biodiversity on land Global distribution of biodiversity by sea

Damsel fish distribution

Is eveness or richness a good indicator for conservation?

Treats all species the same Favors large population sizes (not all measures) NO, but is there any better?

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SLIDE 3

Towards a phylogenetic informed biodiversity measure

instead of weighting population sizes we also could weight position on the phylogeny What is worth more, a Sphenodon (Tuatara)

  • r a 10 song bird species?

Towards a phylogenetic informed biodiversity measure

Phylogeny should play a role Abundance should play a role Ecological connection should play a role ...... [I don’t want to make such decisions]

Florida scrub jay

Endemism

Distribution of endemic bird species Distribution of endemic fish species

Global distribution of biodiversity on land

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SLIDE 4

Correlation of richness with endemism Taxon .77 Plusiinae (moths) .7 Papilionidae (butterflies) .85 Lasioglossum (bee) .81 Mammals

High endemism correlates with high diversity

Extinctions

  • Background extinction
  • Current, recent extinctions

Geological time scale

Relative lengths of geologic periods

Precambrian Earth forms First signs of life First fossil cells First multicellular animals and plants Photosynthesis starts producing O2 in the atmosphere Mesozoic era Age of Dinosaurs Paleozoic era Fish, bugs, plants

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SLIDE 5

red

Diversification of marine organisms

Extinction rate: general patterns

Extinction rates vary a lot A steady rate of extinctions, it even seems that the extinction rate was larger long time ago Speciation rate > Extinction rate Species last about 1- 25 My years On average about 1-2 species go extinct each year

Catastrophic extinction events K/T boundary Permian/Triassic Possible Sources Large meteorites hitting earth Climate change Vulcanism: Effect on climate, changing landscape Glaciation: Cooling shrinks range of species, might increase competition Formation of super-continents: better adapted species win, changes in number of habitats

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SLIDE 6

K/T boundary mass extincion was caused by meteor impact

Direct observation is difficult.

Current extinction

Table 2.1 Extinctions recorded since 1500 A.D. “Extinct in wild” indicates that individuals of the species continue to exist, but only in captivity (e.g. zoos or captive breeding programs). Data from (IUCN 2004). # Extinct # Extinct in wild Animals 697 36 Plants & algae 87 24 Total 784 60

How sure are we about these numbers? Obviously not very sure, because citing the same sources authors arrive at different numbers.

Dodo

extinct in the 17th century

Steller’s sea cow

  • Extinct 1768, 27

years after being detected

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SLIDE 7

Great Auk

hunted for fat and feathers extinct 1844

Passenger pigeon

Many millions during 19th century Last died in the Cincinnati Zoo in 1914

Passenger pigeon Carolina Parakeet

extinct around 1935? (1918?)

Panthera leo barbaricus Barbary Lion

Extinct 1922

Tasmanian Tiger

Extinct 1936

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SLIDE 8

Gastric brooding frog

  • Extinct ?
  • Not found since

1985

Table 2.2. A sample of species once thought extinct, but rediscovered. Species name Common name Date rediscovered # yrs since last sighting Dipsochelys hololissa Seychelles giant tortoise 1997 >150 Pterodroma cahow Bermuda petrel 1951 >300 Perameles bougainville Western barred bandicoot 1983 61 Trichocichla rufa Long-legged warbler 2003 109 Gastrolobium lehmannii Cranbrook pea 2001 83 Hapalopsittaca fuertesi Fuertes's parrot 2002 91 Hypsiprimnus gilbertii Gilbert’s potoroo 1994 85 Sida inflexa Virginia pine sida 1999 31 Lepidoptrix (formerly Pipra) vilaboasi Golden crowned manakin 2002 45

  • ng the

Measuring Current Extinctions

Direct observation are difficult Indirect observation: species - area relationship

Species-Area relationship

Number

  • f species S

Area A

S = c × Az

c is a taxon specific constant z is the extinction coefficient is in the range 0.1 to 0.3

Species-Area relationship

log(Number

  • f species S)

log(Area A)

S = c × Az

c is a taxon specific constant z is estimated using the slope

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SLIDE 9

Mac Arthur and Wilson (1967): the theory of island biogeography

Fig 4.5 Small mammals in forest granivores all small mammals r2 = proportion of variation explained

Estimating extinction rates

Snow Soriginal = cAz

now

cAz

  • riginal

Log(Number

  • f species S)

Log(Area A)

Estimating how many species go extinct

Log(Number

  • f species S)

Log(Area A)

Snow Soriginal = Az

now

Az

  • riginal

using z=.15 (this is arbitrary) deforestation = 1.8% per year (Anow / Aoriginal = 98.2/100) 10 million species (Soriginal) Snow = 9,973,000 Difference between Snow and Soriginal = 27,000 species per year

Snow = Soriginal Az

now

Az

  • riginal