THE REAL WORLD...

1. THE REAL WORLD...

2. Context for extinction How many species are there? How do we find out?

3. Context for extinction Extrapolate numbers based on observation that for every temperate species, there are two tropical counterparts = 3-5 million. Use information on rate of discovery of new species to project forward, group by group = 6-7 million. Species size:species richness relationship – in terrestrial animals (~ 1 cm to a few meters), approximate empirical rule for each 10-fold reduction in length there are 100 x the number of species = 10 million. Do intensive counts in small areas of each taxa, extrapolate to rest of available habitat

4. Estimates of beetle species richness (more than 1000 species recorded in one tree) in the canopies of tropical trees (about 50,000 species), and assumptions about the proportion of non-beetle arthropods that will also be present in the canopy, plus others that do not occupy the canopy – 30 million arthropods. http://www.youtube.com/watch?v=gZRgibEVXJU

5. Total # Described Phylum Order E & T species Chordates Mammals 361 5,702 Birds 316 9,956 Reptiles 124 9,347 Amphibians 35 15,000 Fishes 165 40,000 Arthropods Insects 71 1,065,000 Crustaceans 22 40,000 Plants Flowering plants 783 272,655 Conifers and cycads 5 980 Ferns and allies 30 13,025 Molluscs 126 70,000 Cnidaria Corals 2 2,175

6. Total # Described Phylum Order E & T species Chordates Mammals 361 5,702 Birds 316 9,956 Reptiles 124 9,347 Amphibians 35 15,000 Fishes 165 40,000 Arthropods Insects 71 1,065,000 Crustaceans 22 40,000 Plants Flowering plants 783 272,655 Conifers and cycads 5 980 Ferns and allies 30 13,025 Molluscs 126 70,000 Cnidaria Corals 2 2,175 Viruses 0 5,000 Bacteria 0 4,750 Protists 0 80,000 Fungi 0 80,000 Platyhelminthes 0 25,000 Rotifera 0 1,800 Bryozoa 0 5,000 Nematoda 0 25,000

7. Total # Described % Phylum Order E & T species Described Chordates Mammals 361 5,702 99 Birds 316 9,956 99 Reptiles 124 9,347 99 Amphibians 35 15,000 99 Fishes 165 40,000 75? Arthropods Insects 71 1,065,000 12 Crustaceans 22 40,000 ? Plants Flowering plants 783 272,655 55 Conifers and cycads 5 980 1 Ferns and allies 30 13,025 87 Molluscs 126 70,000 35 Cnidaria Corals 2 2,175 ? Viruses 0 5,000 1 Bacteria 0 4,750 0.5 Protists 0 80,000 5 Fungi 0 80,000 5 Platyhelminthes 0 25,000 ? Rotifera 0 1,800 ? Bryozoa 0 5,000 ? Nematoda 0 25,000 ?

8. How many species are there?? http://ocean.si.edu/oceancensus So far, the Census of Marine Life comprised 15,304 species of fish and 194,696 to 214,696 species of animals and plants, estimated to be roughly 10 percent of the world's total. The census is adding about 150 to 200 species of fish and 1,700 species of animals and plants each year.

9. Total Endangered & Threatened Species US Foreign Total Mammals 85 276 361 Birds 93 223 316 Reptiles 36 88 124 Amphibians 26 9 35 Fishes 153 12 165 Molluscs 123 3 126 Insects 67 4 71 Arachnids 12 0 12 Crustaceans 22 0 22 Corals 2 0 2 Animal totals 619 615 1,234 Flowering plants 782 1 783 Conifers and cycads 3 2 5 Ferns and allies 30 0 30 Lichens 2 0 2 Plant totals 817 3 820 Grand totals 1,436 618 2,054

10. Context for extinction How many species are there? How do we find out? How many have recently gone extinct? Are current rates of extinction higher than historic (pre-human) rates?

11. Trends in recorded animal species extinctions since 1600, for which a date is known

12. All extant species will become extinct eventually – more than 99% of species that ever existed are now extinct. • Individual species last on average 1- 10 million years. If we assume 10 million species, we would then predict 100 to 1000 extinctions each century. • Current rate: birds and mammals = 1% per century (100-1000 x background rate). Nene - Brantasandvicensis

13. Extinction: happens to all species eventually

14. Extinction stochastic results from normal, random changes; more important for smaller populations conservation solution: maintain large population sizes deterministic consequence of some progressive change in environment - addition of predator, loss of food source, degradation/loss of habitat conservation solution: identify and manage causes

15. Extinction Probability of extinction increases as population size decreases Probability increases with length of time

16. Extinction higher probability per unit time for species with: • smaller range • fewer subpopulations • low migration among subpopulations • highly stochastic environment • low genetic diversity?

17. Extinction primary species of concern tend to be large animals • no clonal propagation • long generation time • small number of progeny • low dispersal rates – inability to recolonize or escape catastrophic events • species in stable environments

18. Causes of extinction Population extinctions occur due to: • intrinsic factors • demographic stochasticity – changes in sex ratio, reproduction, survival

19. Causes of extinction Population extinctions occur due to: • intrinsic factors • demographic stochasticity – changes in sex ratio, reproduction, survival Allee effect- threshold density or N below which population goes to extinction • due to social interactions, physical alterations of environment, probability of finding a mate, etc. stanfordalumni.org

20. Causes of extinction Population extinctions occur due to: • intrinsic factors • demographic stochasticity • genetic stochasticity - founder effect, genetic drift, inbreeding – genetic load

21. Causes of extinction Population extinctions occur due to: • intrinsic factors • demographic stochasticity • genetic stochasticity • extrinsic factors • environmental stochasticity • variation in predators, pathogens, food supply (biotic) • catastrophe • fires, floods, droughts (abiotic)

22. N ~ 50 and severe winter 1927, N =13, mostly males 1932 extrinsic factors intrinsic factors

23. Most extinctions are due to multiple factors interacting simultaneously For example: causes of fish extinctions in N. America: physical habitat alteration (73%) introduced species (68%) chemical pollution (38%) hybridization (38%) overharvest (15%)

24. Extinction vortices

25. Extinction vortices A vortex F vortex

26. Extinction vortices R vortex (demographic, based on intrinsic rate of increase, r) • chance decrease in N increases variance of the population growth rate Var(r) • population becomes more vulnerable to environmental stochasticity normal demographic fluctuations decline in N – small catastrophe N increased pop’n variance Time

27. Extinctions are forever - ? ivory-billed woodpecker smoky madtom blue pike spoonhead sculpin deepwater sculpin

28. Extinctions are forever - ? ivory-billed woodpecker smoky madtom blue pike spoonhead sculpin deepwater sculpin 1942 – last seen in US waters of L. Ontario 1972 – last seen in Canadian waters 1999 – 3 caught in targeted trawls 2004 – 1 2005 – 17 in standard assessment trawls 2009 > 75 (depth > 90 m) Lazarus effect…

29. When is population size too small (hopeless)? Przewalski’s horse 13  Guam rail 10  black-footed ferret 6  European bison 6  Speke’s gazelle 4  dusky seaside sparrow 2…1..…0 note: these are all captive (regulated) populations….