Bell Work: Intro to Biodiversity What are the kingdoms of living things? Make a list. (Hint: you should have 5.) Predict which of these has the greatest number of identified species. Predict which has the fewest number of identified species. What are the main contributions to species extinctions? Trivia: what organism do scientists believe would survive a nuclear holocaust? Suggest reasons why this or any organism could survive a nuclear event.

What is Biodiversity?   What is biological diversity ? In its narrowest sense this term refers to the number of species on the planet, and it also is used more broadly as an umbrella term. Biological diversity refers to the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, genes, and their relative abundance (Office of Technology Assessment, 1987). Or to paraphrase: number and variety of species, ecological systems, and the genetic variability they contain.

Group and Number of Described Species Bacteria/blue-green algae  4,760  Fungi 46,983 Algae 26,900 Bryophytes (mosses and liverworts) 17,000  Gymnosperms (conifers) 750 Angiosperms (flowering plants) 250,000  Protozoans  30,800  Sponges 5,000  Corals and Jellyfish 9,000  Roundworms and earthworms  24,000 Crustaceans 38,000 Insects  751,000  Other Arthropods and minor invertebrates  132,461 Mollusks 50,000  Starfish  6,100  Fishes (teleosts)  19,056  Amphibians  4,184 Reptiles 6,300  Birds 9,198  Mammals 4,170 Total 1,435,662 described species

In your notes, record these organism groups and their identified species. What is the most prevalent organism? Propose a reason why this organism is so prevalent.

What are the Threats to Biodiversity? Extinction is a natural event and, from a geological perspective, routine. We now know that most species that have ever lived have gone extinct. The average rate over the past 200 my is 1-2 species per year, and 3-4 families per my. The average duration of a species is 2-10 million years (based on last 200 million years). There have also been occasional episodes of mass extinction, when many taxa representing a wide array of life forms have gone extinct in the same blink of geological time. In the modern era, due to human actions, species and ecosystems are threatened with destruction to an extent rarely seen in earth history. Probably only during the handful of mass extinction events have so many species gone extinct.

How many of these causes are linked to man How many of these causes are linked to man? Make a list in your notes of these main causes of animal extinctions. Put an asterisk by each that man impacts.

Top Three Causes of Extinctions #1 Habitat loss/degradation/fragmentation As deforestation proceeds in tropical forests, this promises to become THE cause of mass extinctions caused by human activity. All species have specific food and habitat needs. The more specific these needs and localized the habitat, the greater the vulnerability of species to loss of habitat to agricultural land, livestock, roads and cities. In the future, the only species that survive are likely to be those whose habitats are highly protected, or whose habitat corresponds to the degraded state associated with human activity (human commensals).

Top Three Causes of Extinctions #2 Invasion of non-native species  The African Great Lakes - Victoria, Malawi and Tanganyika - are famous for their great diversity of endemic species, termed "species flocks", of cichlid fishes. In Lake Victoria, a single, exotic species, the Nile Perch, has become established and may cause the extinction of most of the native species, by simply eating them all. It was a purposeful introduction for subsistence and sports fishing, and a great disaster. 

Top Three Causes of Extinctions #2 Invasion of non-native species Of all documented extinctions since 1600, introduced species appear to have played a role in at least half. The clue is the disproportionate number of species lost from islands: some 93% of 30 documented extinctions of species and sub-species of amphibians and reptiles, 93% of 176 species and sub-species of land and freshwater birds, but only 27% of 114 species and subspecies of mammals. Why are island species so vulnerable, and why is this evidence of the role of non-indigenous species? Islands are laboratories for evolution ( occur when the removal of one species (an extinction event) or the addition of one species (an invasion event) affects the entire biological system. Domino effects are especially likely when two or more species are highly inter-dependent, or when the affected species is a "keystone" species, meaning that it has strong connections to many other species.

Top Three Causes of Extinctions #3 Climate change A changing global climate threatens species and ecosystems. The distribution of species (biogeography) is largely determined by climate, as is the distribution of ecosystems and plant vegetation zones (biomes). Climate change may simply shift these distributions but, for a number of reasons, plants and animals may not be able to adjust.  As a consequence of these three forces, many scientists fear that by end of next century, perhaps 25% of existing species will be lost. 

Summary Biodiversity refers to the number and variety of species, of ecosystems, and of the genetic variation contained within species. Roughly 1.4 million species are known to science, but because many species are undescribed, an estimated 10-30 million species likely exists at present. Biodiversity is threatened by the sum of all human activities. It is useful to group threats into the categories of over-hunting, habitat destruction, invasion of non-native species, domino effects, pollution, and climate change. Habitat loss presents the single greatest threat to world biodiversity, and the magnitude of this threat can be approximated from species-area curves and rates of habitat loss. The spread of non-native species threatens many local species with extinction, and pushes the world's biota toward a more homogeneous and widely distributed sub-set of survivors. Climate change threatens to force species and ecosystems to migrate toward higher latitudes, with no guarantee of suitable habitat or access routes. These three factors thus are of special concern.