Biodiversity and Classification
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Biodiversity and Classification. Biodiversity. Biological diversity is usually the sign of a healthy ecosystem. The greater the diversity of organisms with in an ecosystem, the greater is the chance that some of those organisms will be able to survive change. Biodiversity.
Biodiversity and Classification
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Biodiversity • Biological diversity is usually the sign of a healthy ecosystem. • The greater the diversity of organisms with in an ecosystem, the greater is the chance that some of those organisms will be able to survive change.
Biodiversity • There are two levels of biological diversity: • Genetic diversity, which describes the variety of genes that code for different traits in a given species • Species diversity, which describes the number of different species.
Classification • It is often difficult to determine if subtle physical differences are variation within a species or variation between different species of closely related organisms. • Therefore, scientists need a classification system to help them study ecological diversity.
Taxonomic Systems • Taxonomy – the science of classification according to the inferred relation ships among organisms
Taxonomic Systems • Biological classification systems have two main purposes: • Identifying organisms • Providing a basis for recognizing natural groupings of living things.
Taxonomic Systems • Carl Linnaeus (1707-1778) • Developed a system of classification based on an organism’s physical and structural features, and operated on the idea that the more features organisms have in common, the closer their relationship.
Taxonomic Systems • Carl Linnaeus (1707-1778) • He was the first to use: • Binomial nomenclature a method of naming organisms by using two names – the genus name and the species name.
Taxonomic Systems • Scientific name is often based on some characteristic such as colour or habitat: • Example • Castor canadensis • Caster meaning beaver and canadensis meaning from Canada • The first part of any scientific name is called the genus. The second part is called the species.
Taxonomic Systems • The two-name system provides an added advantage by indicating similarities in anatomy, embryology, and evolutionary ancestry.
Taxonomic Systems • Present classification system there are seven main levels or taxa. • Kingdom • Phylum • Class • Order • Family • Genus • species
Today most scientists believe that organisms have changed over time. The history of the evolution of organism is called phylogeny. • Relationships are often shown in a type of diagram called a phylogenetic tree.
Assignment • Read pages 134-139 • Do questions 1-7 on page 139 • Investigation pg 162
Evidence of evolution comes from many lines of investigation. • Some from direct observation and some more indirect. • Evidence gathered from: • Direct Evidence: • Fossils • Radiometric dating
Indirect Evidence • Comparative Anatomy • Homologous structures • Analogous structures • Embryology • Vestigial Organs • Physiology • Behaviour • Plant and animal breeding • Biochemistry and genetics • The geographic distribution of species
Evidence from Fossils • Paleontology – The study of fossils • Fossilized remains, impressions, and traces of organisms from past geological ages provide scientists with direct physical evidence of past life.
Evidence from Fossils • Patterns found in fossils: • Different species lived on Earth at various time in the past. • The complexity of living organisms generally increases from the most distant past to the present. • Living species and their most closely matching fossils are typically located in the same geographic region.
Fossilization occurs in many ways • Organic components of the organism are replaced by minerals. • Impressions left by organisms are preserved by the solidification of mud. • Organisms can sometimes be caught in amber and preserved • Mammoths, bison and other extinct mammals have been found frozen in Arctic ice. • Acidic Bogs-conditions retard decomposition
Do you have a date?? • Radiometric dating • use the radioactive decay of certain elements to determine the age fossils • Example: Carbon-14
Evidence From Biogeography • Biogeography explores the variation and distribution of live over the Earth’s surface, both today and the past. • Earth’s landmasses have undergone dramatic changes by the process of continental drift.
Evidence From Biogeography • Evidence from biogeography suggest that different species evolved independently in isolated parts of the world.
Evidence of Evolution from Biology • A comparison of the physical anatomy and genetic makeup of organisms also provides evidence.
Evidence from Anatomy • Comparative Anatomy • Homologous structures • Structures having similar genetic origin but different uses in different species. • Adaptive radiation: The pentadactyl limb has evolved to suit many niches: digging, running, flying, swimming, etc. Ex: Flipper of dolphin and a forelimb of dog suggests a common ancestor
Indirect Evidence For Evolution • Analogous structures • Structures which are similar in function and appearance but came from different ancestors. • Examples: wing of an insect and a bird • Good indicators that these organisms did not evolve from a common ancestor • Illustrates convergent evolution • development of similar forms from unrelated species due to adaptation to similar environment
More Indirect Evidence for Evolution • Embryology • The study of organisms in their early stages of development. • Closely related organisms go through similar stages in their embryonic development • similarities in embryos suggests these organisms have an evolutionary relationship.
Vestigial Organs • Structure with no known function in present • Examples: coccyx and appendix in humans, vestigial leg bones in snakes
Evidence from Biochemistry • Evidence of evolution has also been found by comparing biochemical characteristics of different species.
Biochemical Evidence • Analysis of chemicals can be used to show evolution • DNA and cytochrome enzyme C (respiration) are similar in all organisms • DNA analysis-used determine how closely related organisms are • suggest a common ancestor
Assignment • Read pages 140-148 • Do questions 1 & 2 on page 143 and question 3 on pg 149
Source of Variation: • Inherited: Determined by the DNA (genetic material) inherited from the parent • i.e. hair, eye and skin color • Acquired: Developed over life time. • i.e. basketball skills, musical ability
Lamarck’ Theory • Lamarck believed that new species were continually being created by spontaneous generation • Spontaneous generation – the belief that living things arose from non-living matter.
Lamarck’ Theory • Theory of Use and Disuse: Use-remains strong. Disuse-weakens and disappears. For example snakes legs. • USE Each body part possesses a “will” which allows it to change in order to better fit its environment. • Eg. Short necked giraffe stretches its neck to reach tree tops and it develops a longer neck • DISUSE If a body part is not used it will begin to disappear • Eg. Nocturnal animals (ie. Bats) lose their vision
Lemarck’ Theory • Theory of Acquired Traits: Traits acquired in life time could be passed on to offspring. Inheritance of acquired characteristics
Problems with Lamark’s theory • “Use and Disuse” implies an organism can sense its needs and physically change to meet those needs. • Acquired characteristics are not inherited • Never confirmed by experimentation.
Darwin’s Theory of Evolution 1. Overproduction 2. Variation. 3. Competition 4. Survival of the fittest 5. Passing on of successful traits (speciation)
Overproduction • Overproduction means that the number of offspring produced by a species is greater than the number that can survive.
Variation • Differences among traits occur among members of the same species. • No two individuals are exactly alike • Caused by: • Mutation • Sexual Reproduction
Struggle for existence • Competition • Organisms of the same species, as well as those of different species, must compete for limited resources such as food, water, and a place • Natural selection: Nature selects the organisms that survive
Survival of the Fittest-Natural Selection • The most fit individuals survive • Fittest means that the individuals are best suited to the environment
Origin of new species (speciation) • Successful individuals reproduce and pass on their traits • Over numerous generations, new species arise by the accumulation of inherited variation • When a type is produced that is significantly different from the original, it becomes a new species.
