Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Biological Dynamics of Forest Fragments Project wikipedia , lookup
Habitat conservation wikipedia , lookup
Biodiversity action plan wikipedia , lookup
Biodiversity wikipedia , lookup
Ecological fitting wikipedia , lookup
Theoretical ecology wikipedia , lookup
Natural environment wikipedia , lookup
Diversity of life; geological control on biogeography; the fossil record Jarðsaga 1 – Þróun Lífs og Lands – Ólafur Ingólfsson The Diversity of Life Biodiversity (fjölbreytileiki lífsins) is the totality of genes, species, and ecosystems The wealth of life on Earth is the product of hundreds of millions of years of evolutionary history. The Tree of Life Relationships between taxa that constitute the Archaeobacteria (forngerlar), Eubacteria (raungerlar), Protists (frumdýr), Plants and Animals is not so straight foreward as we used to think... The Six Kingdoms (ríki) of living things on Earth The six kingdoms of life on Earth When Evolved Structure Photosynthesis Bacteria 3 to 4 billion years ago Unicellular Sometimes Archaea 3 to 4 billion years ago Unicellular No Protista 1.5 billion years ago Unicellular Sometimes Fungi 1 billion years ago Unicellular or Multicellular No Animalia 700 million years ago Multicellular No Plantae 500 million years ago Multicellular Yes Kingdom Prokaryotes: (Dreifkjörnungar) Eukaryotes: (Einkjörnungar) (Frumdýr) (Sveppir) Number of species of living organisms Kingdom Named species Total species Prokaryotes ~4 000 >1 000 000 Protista ~80 000 >600 000 Fungi ~72 000 >1 500 000 Plantae ~270 000 >320 000 Animalia ~1 326 000 > 10 000 000 Bacteria and Archaea • Known total world species: ~ 1 752 000 • Estimated total world species: 10-100 million 2/3rds of all animal species are insects - It is humbling to realize that humans and other large animals are freakishly rare life forms, since 99% of all known animal species are smaller than bumble bees ... Evolutionary trends through time: • Organisms evolve from simple to complex forms over time - Bacteria ⇨ protists ⇨ multicelluar organisms ⇨ plants and animals • There is a general tendency for size to increase during the evolution of a group of animals • Evolution never goes in reverse, from complex to simple forms Classification and evolution Carolus Linnaeus (1707-1778) Charles Darwin (1809-1882), Since Darwin's time, biological classification is understood to reflect evolutionary distances and relationships between organisms. The creatures of our time have had common ancestors in the past... they are members of the same family tree... Adaptive radiation The great diversity of life is largely a result of adaptive radiation (aðlögunarkvíslun) = the diversification of a species as it adapts to different ecological niches and ultimately evolves into different species. Natural selection (náttúruval) is the principle mechanism driving adaptive radiation. Animal phylogeny (þróunarferill) This structure grows as new species arise, each forming a new branch... The Earth and all its contents have a very long history, during which they have developed and become altered: life has changed and diversified as it descended through myriad generations since its unique origins in the remote past, spreading across the globe as circumstances permitted. Taxonomy • Taxonomy is the science of classifying organisms. The Linnaean system breaks down organisms into seven major divisions, called taxa (singular: taxon; Ís: flokkunarheild). The divisions are as follows (Example: taxonomy of Man): • Kingdom (ríki) animalia (dýr) • Phylum (fylking) chordata (seilýr); subphylum: • • • • • vertibrata (hryggdýr) Class (flokkur) mammalia (spendýr); subclass: eutheria (legkökuspendýr) Order (ættbálkur) primate (prímati) Family (ætt) hominidae (mannætt) Genus (ættkvísl) homo (maður) Species (tegund) sapiens (hinn viti borni maður) Biogeography - The distribution and abundance of organisms in time and space on a broad geographical scale - Boundary conditions in biogeography area defined by temperature (solar energy and its distribution), precipitation and the existance of physical barriers Today´s biogeography reflects global distribution of energy... Simplified model for global atmospheric circulation Surface currents are generated by stable wind systems The Great Ocean Conveyor Belt The most important ecosystems of the world 1. (light green) well-tempered rain forests, 2. evergreen boreal coniferous woods, 3. (green) tropical rain forests, 4. (dark green) summer-green deciduous forests, 5. (yellowish orange) tropical dry forests, 6. (orange) dry forests of temperate areas, 7. (light violet) thorny and succulent vegetation, 8. (violet) semi-deserts, 9. (dark violet) xeromorphic vegetation 10. (light blue) dry steppe, 11. dry savannah, 12. (blue) moist savannah, 12, 13. (dark blue) pasture, steppe, 14. (brown) deserts, 15. (white) tundra, 16. (grey) ice Global biodiversity – vascular plants Vegetation and climate Iceland Latitudional temperature zones in the Oceans Surface water zonation in the N Atlantic ...and biogeography also reflects development of barriers through time Examples of types of barriers: • Oceans and straits • Mountain chains • Continental scale glaciers • Large deserts • Large river canyons Zoogeography is the study of geographical distribution of animals about the globe. The Wallace Line Alfred R.Wallace (1823 - 1913) Alfred Russel Wallace was the now-almost-forgotten co-discoverer of the theory of evolution. Darwin had pretty well formulated the theory when he learned that Wallace was about to publish a similar idea. When Wallace heard about Darwin, he politely stood aside and let Darwin publish first. The Wallace Line is a major break in faunal composition West of it, the fauna is related to mainland Asia, with its tigers, elephants and monkeys... Java tiger Java rhino Macaque Monkey Orangutang ...east of it the fauna is Australian, with kangaroos, wallabies and possums. Cassovari Possum Kangaroo Wallaby Why the Wallace Line? It marks the bondary between the Australian the Eurasian Plates The take-home messages • The wealth of life on Earth today is the product of hundreds of millions of years of evolutionary history. • The great diversity of life is largely a result of the diversification of a species as it adapts to different ecological niches and ultimately evolves into different species. The take-home messages • The development of ecological niches is over time controlled by large-scale geological events (ocean spreading, mountain-building, opening and closing of straits etc) • Today´s biogeography primarily reflects global distribution of energy (which is largely controlled by continent configuration) and the geological development of barriers to spreading of organisms. Fossils and the diversity of life • Our knowledge of past life is derived mostly from fossils • Fossil = the preserved remains or traces of a once living organism – Usually thousands or millions of years old (if it still smells, it ain’t a fossil) Earth History, Ch. 3 28 Fossils reflect evolution, and biogeography of the past The fossil record contains evidence of how life and environments have changed and evolved throughout the earth’s history. What are Fossils? • Fossils are the prehistoric remains or traces of life which have been preserved by natural causes in the Earth's crust. • Fossils include both the remains of organisms (bones or shells), the traces of organisms (tracks, trails, and burrows called trace fossils), and chemical traces of ancient organisms (molecular fossils). How to become a fossil... To be preserved as a fossil, an organism must: • • • Have preservable parts. Hard parts (bones, shells, teeth, wood) have a much better chance at being preserved than do soft parts Be buried by sediment. Burial protects the organism from decay. Escape physical, chemical, and biological destruction after burial. The remains of organisms could be destroyed by burrowing (bioturbation), dissolution, predation, metamorphism, or erosion. There are several ways in which fossils are preserved... 1. Unaltered preservation (Insects or plant parts trapped in amber) 2. Petrification (Rock-like minerals seep in slowly and replace the original organic tissues) 3. Replacement (An organism's hard parts dissolve and are replaced by other minerals) 4. Carbonization=coalification (Only the carbon remains in the specimen) 5 Recrystalization (hard parts revert to more stable minerals or small crystals turn into larger crystals) 6. Authigenic preservation (molds and casts of organisms that have been destroyed or dissolved). How likely is it that an organism is preserved as a fossil... • There are >1,7 million living species today, probably >10 million. • There are only about 250,000 known fossil species. • The fossil record covers many hundreds of millions of years, and the living flora and fauna represent only one "instant" in geologic time. Maybe >100.000.000 species have occurred through Earths history. • If fossil preservation were common, the number of fossil species should far outnumber the number of living species. •The fact that the number of fossil species is so small suggests that the preservation of organisms as fossils is extremely rare. The noted paleontologist Stephen Jay Gould estimates that 99% of all plant and animal species that have existed have already become extinct with most leaving no fossils. Why is fossil preservation so rare... 1. Habitat – most plants and animals live on dry land, where the probability of becoming buried in sediments is small 2. Lack of hard parts - For soft parts of organisms to be preserved, it is necessary to isolate them from oxygen almost immediately after death. This most likely occurs when organisms are rapidly buried in fine-grained sediment in anoxic water; this only happens in rare environments. 3. The activities of the geological engines – sea floor is constantly destroyed by subduction; weathering and erosion destroys fossiliferous sedimentary rock. Completeness of the fossil record 100% Con t Scavenging i nu ou s rem ova l of Decay of soft tissues “ po ten tia l” Abrasion And transport Burial fos sils Final Preservation Decreasing probability Death ?% The probability of preservation depends on the anatomy and habitat of the organism—marine organisms with hard parts Earth History, Ch. 3 are most likely to be preserved 35 William Smith 1769-1839 In 1819, he published a work entitled Strata identified by organized fossils. English engineer and geologist who is best known for his development of the science of stratigraphy. He determined the succession of English strata across the whole country, from the Carboniferous up to the Cretaceous. He also established their fossil specimens and laid the foundations for faunal successions in biostratigraphy. Smith's geologic map of England and Wales (1815) set the style for modern geologic maps. Distribution of fossils • The distribution of fossils within Earth´s history is not random - fossils occur in a consistent order. This is true at a regional, and even a global scale. • Fossil organisms are more unique than rock types, and much more varied, offering the potential for a much more precise subdivision of the stratigraphy and events within it. Faunal Succession - stratigraphic ordering of fossil assemblages (William Smith), which was the basis of worldwide correlation Principle of faunal and floral succession Flowering plants Dinosaurs Plesiosaurs Ferns Fishes Trilobates Everywhere in the world, trilobites are found lower in the stratigraphy than marine reptiles. Dinosaurs occur after the first occurrence of land plants. Ferns always found before the occurrence of flowering plants... Index fossils References and good web-sites Stanley, Earth System History, chapters 3, 4 and 7. Fortey, R. Life, a natural history of the first four billion years of life on Earth. New York, Vintage Books, 346 pp. http://fossils.valdosta.edu/index.html http://fossils.valdosta.edu/index.html http://www.ucmp.berkeley.edu/alllife/threedomains.html http://www.palaeos.com/Default.htm http://www.pbs.org/wgbh/evolution/library/index.html http://www.fossilmuseum.net/Time%20Machine/Geologic_Time_Machine.htm http://www.seaworld.org/just-for-teachers/guides/diversity-of-life/ http://www.palaeos.com/Kingdoms/default.htm http://www.earth.uni.edu/~groves/EHCh03lecture.ppt http://www.cartage.org.lb/en/themes/Sciences/Zoology/AboutZoology/Dive rsityLife/DiversityLife.htm http://www.ucmp.berkeley.edu/index.html