Presentation on theme: "There are about 1,700 tigers left in the wild in India"— Presentation transcript:
1 There are about 1,700 tigers left in the wild in India There are about 1,700 tigers left in the wild in India. In the past five weeks, 17 people in four states have been killed by tigers (19 Jan 2014). However, the truth is, less than 85 people are killed or injured - accidentally or otherwise - in a year by tigers here. Many times more die of snakebites or rabies.
2 Cultural dimensions of wildlife in the Anthropocene Cultural dimensions of wildlife in the Anthropocene
4 How many species? 5 - 9 million non-bacterial species estimated Some estimates have ranged up to 100 million because of potential insect diversity1.5 million cataloged, but many are only descriptions or a museum specimenNumber of species reflects a balance between extinction and speciation, the evolution of new speciesIdentification of new species and the confirmation of extinctions also shape estimates of the number of species
5 Extinctions Lose between 1-5% of species per year Calculations suggest that the current rates of extinction are 100 to 1,000 times natural background levels
6 ExtinctionsRates today in the sixth global extinction event are comparable to the mass extinctions in the geological pastPermian extinctions (225 million years ago)95% of marine species extinct because of climate change and volcanismCretaceous extinctions (65 mya)70 % of all species, including dinosaurs, due to meteorite impact in Yucatan peninsula of Mexico that resulted in global cooling
7 Extinction is not necessarily easy to conclude Extinction is not necessarily easy to conclude. Sometimes species thought to be extinct are still present in small isolated populations
9 Became endangered species because of predation by the small Asian mongoose, which was introduced in colonial times to hunt snakes and rats, as well as by feral cats and dogs. The Cuban Solenodon was thought to have been extinct until a live specimen was found in The Hispaniolan solenodon, was also once thought to be extinct, probably more because of its secretive and elusive behavior than to low population numbers. Recent studies have proven that the species is widely distributed through the island of Hispaniola, but that does not tolerate habitat degradation.
10 ExtinctionThere is evidence that contemporary extinctions, while very high, have not been as high as some had predicted, for several reasons:Effective conservation effortsSpecies surviving on their own in secondary habitats and anthropogenic land coversDistinctive patterns to extinctions in the AnthropoceneFaunal homogenizationFaunal size bias
11 Faunal homogenization Same species present at one location as anotherIncreased numbers of species locally due to human-aided dispersal of generalist speciesOverall declines in richness over larger extents because specialists and rare species extinct.A Century of Change in Kenya’s Mammal Communities: Increased Richness and Decreased Uniqueness in Six Protected AreasThe potential for large-scale biodiversity losses as a result of climate change and human impact presents major challenges for ecology and conservation science. Governments around the world have established national parks and wildlife reserves to help protect biodiversity, but there are few studies on the long-term consequences of this strategy. We use Kenya as a case study to investigate species richness and other attributes of mammal communities in 6 protected areas over the past century. Museum records from African expeditions that comprehensively sampled mammals from these same areas in the early 1900’s provide a baseline for evaluating changes in species richness and community structure over time. We compare species lists assembled from archived specimens (1896–1950) to those of corresponding modern protected areas (1950– 2013). Species richness in Kenya was stable or increased at 5 out of 6 sites from historical to modern times. Beta-diversity, in contrast, decreased across all sites. Potential biases such as variable historical vs. modern collection effort and detection ofsmall-bodied, rare, and low-visibility species do not account for the observed results. We attribute the pattern of decreased beta diversity primarily to increased site occupancy by common species across all body size classes. Despite a decrease in land area available to wildlife, our data do not show the extinctions predicted by species-area relationships. Moreover, the results indicate that species-area curves based solely on protected areas could underestimate diversity because they do not account for mammal species whose ranges extend beyond protected area boundaries. We conclude that the 6 protected areas have been effective in preserving species richness in spite of continuing conversion of wild grasslands to cropland, but the overall decrease in beta diversity indicates a decline in the uniqueness of mammal communities that historically characterized Kenya’s varied landscape
12 Comparison of species richness by site Comparison of species richness by site. Color code: yellow = 1896–1950, green = 1950–2013Species richness (the number of species) higher today due to generalist species becoming more widely distributed.
13 Diminished turnover in kinds and numbers of species from location to location for 1951-Present. In graph, size of circle indicates relative similarity in the kinds and numbers of species present. There are more differently sized circles in the earlier period ( ), indicating greater distinctiveness to species and their numbers among the different parks. Today, more of the parks have the same kinds of species.Net overall loss of species over entire region, even though local park diversity has increased over time.
14 Faunal size bias Defaunation in the Anthropocene is size-specific Large-bodied mammals and birds are more susceptible to extinction
15 Large carnivore ranges have contracted globally, leaving only a few places with more than one or two large predators.
16 Taxonomic identification of new species Relatively large, conspicuous species are still being discovered in remote or poorly studied areas. Shown are (a) an undescribed jay species from the Amazon basin, (b) a recently discovered fruit bat and (c) monitor lizard from the Philippines
17 Speciation versus taxonomic identification of new species Speciation is the evolutionary process by which new species ariseNew species may arise in the Anthropocene, particularly plants as they hybridizeNew species get counted when they are identified30,000 to 40,000 taxonomists worldwide16,000 new species identified per yearHowever, overall there are fewer species being described per taxonomist, suggesting that it may already be harder to discover new species
18 Extinctions versus identification Extinction rate estimates range from 0.01 to 1% (at most 5%) per decade.
19 Extinction versus identification At current rate of identification, if there are 5 million species, then most will have been described by the year 2220If extinction rates are as high as 5% per decade, then regardless of how many species exist on Earth, more than half will be extinct within 150 years, 2164At the rates considered more realistic (i.e., <1% per decade) the rate of species description greatly outpaces extinction rates whether there are 2 or 10 million species on Earth.
20 How many species?Actual extinction rates may become nonlinear if their causes act synergistically. Number of species is a reflection of larger ecological dynamics. Two examplesExtinction debtTrophic cascades
21 Extinction debtLock in of future extinction of species due to human impacts that occurred as some earlier point in time.Time delay between human impact and extinction
22 Trophic cascadeBecause of trophic webs, loss or reintroduction of a large predator species can have disproportionately large effects on the abundances of other organismsNational Geographic Strange Days video, start 2 minutes in
23 Trophic cascadesNational Geographic Strange Days video, start 2 minutes in