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Biodiversity Crisis Two centuries of warnings from scientists of anthropogenic losses of species Since 1600s: 129 species of birds 83 species of mammals.

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Presentation on theme: "Biodiversity Crisis Two centuries of warnings from scientists of anthropogenic losses of species Since 1600s: 129 species of birds 83 species of mammals."— Presentation transcript:

1 Biodiversity Crisis Two centuries of warnings from scientists of anthropogenic losses of species Since 1600s: 129 species of birds 83 species of mammals 21 species (including 100 subspecies) reptiles 7 species amphibians

2 Biodiversity Crisis Freshwater 40 species N. American fish during latter part of 20 th century Worldwide – 20% fish in jeopardy or extinct Molluscs – 7% of 297 recognized species presumed extinct; another 65% endangered, threatened, or candidates for listing Plants last 400 yr, 600 species (176 in US)

3 Number of Plants Globally

4 Percent Fish Threatened

5 Examples from Major Faunal Groups

6 Linnaean Shortfall 1.7 million species described Estimated 5 – 30 million species Species will go extinct before are known to science

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9 Hotspots of Diversity Patterns of diversity and endemism provide clues for locating rare and endangered species. Questions: What are the locations of hotspots for particular taxonomic groups? Do hotspots of taxa overlap? Example – Endemic bird areas (EBAs) – where range of at least two restricted-range species present. Their pattern is not random

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12 Is evidence for overlap of some groups **

13 Overlap of hotspots for fish, coral, lobsters, and snails

14 Prehistoric Extinctions Permian Cretaceous Migration and radiation following linkages between continents –Formation of Pangaea –Laurasia –Great American Interchange Pleistocene (climate-driven, at least partly)

15 Prehistoric Extinctions – last 2 million years New world megafauna and human colonization Aboriginal application of fire in Australia and Americas – broad range of plants and animals Africa exception to human effects; species there evolved with humans and were able to adapt

16 Recent Historical Record of Extinctions Insular extinction rate greater than continental rate

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18 Human-related Species Introductions Similar to continental convergences? Most common species: common rabbit, cats, rats, house mice, pigs, cattle, goats, dogs Part of “naturalization”; bring along a piece of home Most common carnivores (19%) and artiodactyls (31%; deer and related ungulates) Only represent 7% of fauna

19 Human-related Species Introductions Mammal introductions to islands – 118 species, 30 families, and 8 orders Birds – 212 species, 46 families, and 16 orders Australia has received most introductions per unit area for continents

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24 Habitat Fragmentation Breaking up of large parts of ecosystems for agriculture and urbanization Puts species in peril (details later) Hardest hit are tropical rain forests 7% Earth’s surface; 50% species Madagascar – 7% left Brazil Coastal Forest – 1% left Singapore - <1%

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29 Causes of plant endangerment in US

30 Ecological Effects of Fragmentation Reduction in total area, resources, and productivity of native habitats Increased isolation of remnant fragments and their local populations Significant changes in environmental characteristics of fragments, including solar radiation, wind, and water flux

31 Stages of Biotic Collapse Stage 1: Initial exclusion – some populations not included in remnant patches Stage 2: Extirpation due to lack of essential resources Stage 3: Perils associated with small populations – genetic, demographic, stochastic problems

32 Stages of Biotic Collapse Stage 4: Deleterious effects of isolation: rescues by recruitment diminished Stage 5: Ecological imbalances: loss of interactions (mutualism, parasitism, commensals) and biotic regulation (predation, competition)

33 Biogeography of Climate Change Periods of warming from greenhouse gas accumulation before Difference is time over which it took place Human activities have greatly escalated greenhouse gas concentrations over last 50 yr Temp – Projected increase 1.5 – 6°C; mean ~2.5°C; 0.7°C since 1860 End of Wisconsin – Temp incr. 4.5°C over 5000 yr (<1°C/1,000 yr); raised sea level 100 m

34 Pattern of CO 2 last 160,000 yr

35 Changes in Greenhouse Gases

36 Change in Global Temperatures ( )

37 Departures from Average Temperature

38 Biogeography of Climate Change Biogeography helps predict changes in distributions, corridors, geographic isolation of species, and extinctions Range change IS NOT just going to be temperature Other abiotic factors must be in place Just as in other events, e.g., Pleistocene, must be able to disperse and adapt to new conditions

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43 Changes in Elevational Gradients of Habitat

44 Species-area relationship to predict change in species richness of boreal mammals in isolated mountain ranges of Great Basin (3°C increase

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46 Freshwater Biota 4°C increase in temperature Increase mean annual runoff 9 – 21% Shifts temporal runoff patterns (increase precipitation winter and spring, decrease summer and fall) Lead to changes in water quality

47 Marine Biota Latitudinal and vertical shifts in water temperature; warm waters toward poles and greater depths Alters horizontal and vertical mixing of currents Salinity near equator and higher latitudes will decrease (increased precipitation in those regions)

48 Connectivity and Corridors Redistribution and loss of habitats will create new barriers for dispersal Will also tend to increase isolation of patches in increasingly fragmented habitats (refer to human effects earlier)

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52 Tools of Biogeography Used to Create Models and Provide Answers to These and Other Conservation Questions


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