adaptations and evolution (EC).ppt

    Organisms that are native to a particular environment, have developed adaptations that enable them to survive and breed successfully. These adaptations are inherited from parent to offspring and come about as a result of genetic mutations and natural selection. All organisms including p...

    Organisms that are native to a particular environment, have developed adaptations that enable them to survive and breed successfully. These adaptations are inherited from parent to offspring and come about as a result of genetic mutations and natural selection. All organisms including plants have adaptations. There are three main types of adaptations;  Structural  Functional  Behavioural These are physical features of an organism Examples include  Camouflage – to help organisms blend into their surroundings making them less visible to predators. Can you spot me?  Insulation:  E.g. layers of fat or fur  To keep animals warm in colder climates.  Size – smaller animals are more suited to very hot climates and larger organisms are better suited to cooler environments.  Affect how the internal functions of an organism works.  Examples include:  Sweating - helps animals cool down so they don’t overheat.  Shivering when cold - helps to warm the body.  Animals can hibernate (reduction in metabolism) in winter when food is scarce.  Organisms such as the chameleon lizard can change colour to blend in with its environment.  Involve the way in which animals act to help them survive in their environment.  Examples include:  Behaviour   to avoid predators, such as Freezing when predators come near Living in larger groups / herds  Activity patterns which help them avoid unfavorable conditions:    Diurnal – active during the day Nocturnal – active at night Crepuscular – active at dawn and dusk   Describes the differences seen within species. Variation comes from:  The differences in genes and chromosomes that individuals inherit from their parents.  Mutations  Environmental factors such as diet and habitat  These variations can either help or hinder an organism within its environment.  E.g. people with light skin living in hot climates like Australia are more prone to developing skin cancer than those with dark skin     These are characteristics that help organisms survive and successfully reproduce within their environment. Through successful reproduction, these characteristics are passed on, becoming the most common. Organisms with unfavorable characteristics are unsuited to their environment are more likely to die off, becoming less common. This is known as natural selection   Evolution is the gradual development of different species from a common ancestor. Results in life on Earth changing over time.   Charles Darwin was a naturalist who traveled extensively, observing the geographical distribution of plants, animals, fossils and rocks in various parts of the world. Believed in natural selection  Variations in characteristics appear within a species  nature picked the favourable characteristics over many generations. Charles Darwin (1809-1882)  Less favourable characteristics died out.  Survival of the fittest  Evidence to support theory. Ancestral giraffes had necks of different lengths By natural selection those with longer necks survived and produced long necked offspring Eventually all giraffes had long necks  Use the information Darwin gathered on the Galapagos finches to explain his theory of evolution.    The process by which the environment ‘selects’ favourable characteristics , reducing the frequency of unfavourable characteristics. Explain the principles of natural selection using the example of the peppered moths. Explain using natural selection how antibiotic resistant strains of bacteria have developed.     Species- group of organisms that normally interbreed to produce fertile offspring. Speciation- formation of a new species Occurs as a result of natural selection, along with geographical isolation and genetic mutations Occurs over long periods of time  cannot be seen over human lifetime  Step 1- Geographic isolation  Groups will experience different circumstances such as food type and availability, climate and the presence of different predators  Step 2- Natural selection takes place  Changes take place over many generations due to the different conditions.  Mutations can also occur during this time  Leads to the development of sub-species – these are different in characteristics but still able to interbreed  Step 3- Reproductive isolation  Changes prevent interbreeding with original species  Includes:  Change in colour and mating habits so mates are no longer recognised  Seasonal differences in mating times  Changed chromosome which prevents the sperm from one group fertilising the egg from another Divergent evolution   new forms evolving from a single ancestor Results in phenomena known as adaptive radiation     In related species, characteristics have the same basic structure are called homologous characteristics. This is because related organisms share some of their genes. Studies of vertebrates show that they all have what is known as a pentadactyl limb (a limb with 5 digits) Different animals have adapted these to perform different functions.  Adaptive radiation Convergent evolution    Organisms from quite different origins evolve similar adaptations. They can have analogous structures- body parts that appear to be similar E.g. sharks (cartilagenous fish) and dolphins (mammals) are different species however they have similar adaptations that enable them to move through water quickly. Parallel evolution  Organisms that look alike and have common ancestry, but are found in different locations Evidence of Evolution  Evidence supporting the theory of evolution comes from a variety of sources>  Fossil record  Anatomical studies  Embryonic development  Distribution of organisms  Genetic evidence  Gene duplication  Biochemistry Fossil Record   Evidence for evolution comes from palaeontology, the study of fossils Fossils are:  Actual remains of organisms- preserved in ice or amber  Hard parts of organisms- shells, teeth, bones  Impressions of organisms- moulds and casts, footprints  Through the dating of fossils it can be estimated that life began on earth around 3500 million years ago.  These were single celled anaerobic bacteria   Around 1500 million years ago more complex organisms appeared Organisms recognisable as animals appeared around 600 million years ago     Only a small proportion of the species that have ever existed are preserved as fossils More fossils are found in aquatic environments than on land For major groups of fossils, transitional forms have been found These transitional forms provide the links between early and modern organisms Genetic evidence   The structure of DNA and the genetic code is universal for all living things. This supports the idea that all living things are related and evolved from common ancestors. Biochemistry  All animals and plants have similar biochemistry. Including:  Chemicals such as ATP  Similar organelles within cells  Same chemical reactions e.g. cell respiration Embryonic development  Uses similarities in the structure of embryos to support relationships between species groups Distribution of plants and animals     Biogeography studies the distribution (both past and present) of plants and animals. Can be used to help describe patterns in evolution linked with the movement of continents Task: using a specific example, describe how isolation and divergent evolution led to the development of new species.