Natural Selection and Evolution 2024 Year 10 Science PDF

NATURAL SELECTION AND EVOLUTION Year 10 Science, Semester 2, 2024 FOSSILS AND EVOLUTION Palaeontology is the study of fossils. Through studying fossils, scientists have discovered that there are many similarities in the structure of some organisms. https://www.youtube.co...

NATURAL SELECTION AND EVOLUTION Year 10 Science, Semester 2, 2024 FOSSILS AND EVOLUTION Palaeontology is the study of fossils. Through studying fossils, scientists have discovered that there are many similarities in the structure of some organisms. https://www.youtube.com/watch?v=Zo49Pyhii-k&s pfreload=10 However, over time fossils show that structures gradually change. We can see this in the diagram on the left….the length of the bones and the structure of the toes changes. https://www.youtube.com/watch?v=GhHOjC4oxh 8  EVOLUTION Complete the comparison task between early mammals using Wikipedia and other sites.  EVOLUTION Evolution: A genetic change in the characteristics of a species over many generations, resulting in the formation of a new species. Generation: The time between the birth of an individual and when that individual produces their own offspring.  EVOLUTION These diagrams show the evolution of the horse. Palaeontologists have been able to trace a path that leads to the modern horse. There are gradual changes in many parts of the skeleton over time: the body increases in size, the legs become longer and the number of toes decreases.  EVOLUTION When organisms are classified on the basis of their structure, some groups seem very similar. Other groups seem very different. Before scientists understood about the role of Genetics and DNA, they theorised that ‘organisms that were very similar in structure must be related’. Their view was based on the knowledge that organisms seemed to inherit their characteristics from their parents. Genetics has shown us that species with the same basic structure have similar genes. Genes control structure (how it’s built) and function (how it works). It is therefore theorised that two species that share genes must have had a common ancestor long ago. https://www.youtube.com/watch?v=Q5dFh00lXqs&spfreload=10  DIVERGENT EVOLUTION Divergent evolution occurs when organisms that are genetically related become dissimilar over time, due to the need to adapt to their environments. The process can result in differences in organisms that were once similar, or the creation of entirely new species. Homologous structures are the result of Divergent evolution. https://youtu.be/ZbITQ0dqxCQ https://www.youtube.com/watch?v=03YKT7ytJdE  HOMOLOGOUS STRUCTURES Homologous Structures: Characteristics that have the same basic structure, controlled by genes. The more alike two organisms are, the more genes they share. http://evolution.berkeley.edu/evolibrary/article/0_0_0/similarity_hs_01 If the structure is different but the function is similar, it is not homologous.  APES AND HUMANS SHARE OVER 99% OF THEIR GENES This means that the difference between our species is less than 1% of our genes! https://www.youtube.com/watch?v=CpLFpx-zN34 https://www.youtube.com/watch?v=RkabybLQYPw https://www.youtube.com/watch?v=BjMhSfxL1sw CONVERGENT EVOLUTION Convergent evolution occurs when organisms that aren’t closely related evolve similar features or behaviours. The process can result in matching body shapes, colour patterns or abilities. Analogous structures are the result of Convergent evolution. https://www.youtube.com/watch?v=1MBPzzXeTPg https://www.youtube.com/watch?v=Wr-OI7F4hto SAME FUNCTION, DIFFERENT GENETICS SAME FUNCTION, DIFFERENT GENETICS  ANALOGOUS STRUCTURES Analogous Structures: Structures that look similar on genetically very different organisms. https://www.youtube.com/watch?v=Edcz_MzM5qc&spfreload=10 (From 3:05 minutes)  ARTIFICIAL SELECTION For many centuries, humans have selectively bred different animals and crossed different plants to gradually change the features of the species. Artificial Selection: The process by which we choose to breed particular organisms with desirable features.  ARTIFICIAL SELECTION All wild budgerigars are green, although occasionally blue ones are born, and sometimes all yellow ones are born. Many new features were developed in pet budgerigars and they are markedly different from wild birds.  ARTIFICIAL SELECTION Artificial Selection only happens over generations. Breeders select their preferred offspring (two yellow budgies) and mate them to create more of the preferred trait. Domestic Cats and Dogs have also been bred using Artificial Selection. https://www.you tube.com/watch ?v=bi9Pa0DHG 5Y  SELECTIVE BREEDING Selective breeding is used in two main ways 1) Cross-Breeding Combining a desirable feature from one individual with a different desirable feature from another individual. Eg: Dalmachshund  SELECTIVE BREEDING Eg: Chug (Chihuahua and Pug)  SELECTIVE BREEDING Eg: Bullpug (Bulldog and Pug)  SELECTIVE BREEDING Selective breeding is used in two main ways 2) Inbreeding When related individuals are allowed to mate. This method is not often used in animal breeding as there can be health issues in the offspring. Deformities, sterility and genetic disease can be caused by inbreeding.  SELECTIVE BREEDING Animal deformities as the result of inbreeding:  SELECTIVE BREEDING Animal deformities as the result of inbreeding:  SUPER ANIMALS  Imagine you work for the super-chick egg company, and it has been decided the Kendo and Bibby have been chosen to mate  Research suggests the following: -  Supermarkets want large eggs which are brown with yellow yolks  Farmers want passive livestock which are healthy Features Kendo male bird Bibby female bird Kendo family Bibby family No. eggs per week 6 4 Colour of eggs White Brown Size of eggs Medium Large Colour of yolk Bright yellow Pale lemon Resistance to disease Highly resistant Not resistant Behaviour with other hens Aggressive Not aggressive  What features do you hope will be shown by the offspring?  SUPER ANIMALS Features Kendo male bird Bibby female bird Kendo family Bibby family No. eggs per week 6 4 Colour of eggs White Brown Size of eggs Medium Large Colour of yolk Bright yellow Pale lemon Resistance to disease Highly resistant Not resistant Behaviour with other hens Aggressive Not aggressive  You will want the following: -  6 eggs  Brown eggs  Large eggs  Bright yellow yolk  Highly resistant  Not aggressive However there are no guarantees this is the animal you will produce!  INBREEDING https://www.youtube.com/watch?v=aCv10_WvGxo NATURAL SELECTION https://www.youtube.com/watch?v=sdg6R2s-d04  IMPORTANT VOCABULARY SPECIES: A GROUP OF ORGANISMS THAT SHARE COMMON FEATURES AND CAN INTERBREED TO PRODUCE FERTILE OFFSPRING. POPULATION: GROUP OF THE SAME SPECIES IN A DEFINED GEOGRAPHIC AREA. GENE POOL: THE VARIATION OF GENES/ALLELES IN A POPULATION. EVOLUTION: THE GENETIC CHANGE IN THE FREQUENCY OF GENES/ALLELES IN A POPULATION OVER TIME.  NATURAL SELECTION Natural Selection: When natural forces act on a population and results in some organisms having more offspring than others. https://www.youtube.com/watch?v=vnktXHBvE8s  NATURAL SELECTION Natural Selection: Natural Selection can only occur when there is a genetic difference between organisms to begin with. Otherwise, all organisms will adapt (or not adapt) in the same way to the environmental changes, and there will be no difference between them.  SELECTIVE AGENTS Selective Agents: The environmental factor that causes Natural Selection to occur. The Selective Agent could be a predator, competition from other organism, temperature, water, The Selective Agent is the colour of the soil. soil or fire. SELECTIVE AGENTS  SELECTIVE AGENTS Many selective agents act by killing individuals. Such individuals are often less suited to surviving and are referred to as ‘poorly adapted’ or ‘less fit’. Survival of the Fittest: Organisms best suited to their environment are more likely to survive and reproduce. https://www.youtube.com/watch?v=oK0e3BcEkEE WHAT DOES THIS MEAN?  SURVIVAL OF THE FITTEST Selective agents do not always act by killing off the least fit. The least fit may also: - Find it harder to obtain food (slow, non- agile) - Not be able to find a mate https://www.youtube.com/watch?v=W7QZnwKqopo&spfreload=10 https://www.youtube.com/watch?v=A1FWQvaBoRg&spfreload=10 https://www.youtube.com/watch?v=8rqI8xwXVac Sexual Selection: Organisms that are ‘desired’ by the opposite sex will produce more offspring in the next generation. A type of Natural Selection.  SURVIVAL OF THE FITTEST The outcome of Natural Selection is that the ‘fittest’ organisms that are best suited to the environment have an increased chance of passing on their genes to offspring. Therefore, these ‘desired’ traits become more common.  VARIATION Natural Selection can only occur if there is variation within a population. Variation is natural differences caused by different genes.  PRIOR KNOWLEDGE Nucleotides are the building block of DNA and that genes code for alleles (genotypes). The proteins made can determine physical characteristics (phenotypes). These characteristics are inherited 20XX 38  THE PROCESS OF MITOSIS The body constantly needs new cells. New cells are created through cell division. When cells divide to create two identical ‘daughter cells’ the process is called MITOSIS. Mitosis results in two identical daughter cells. There are no variations in the original DNA unless a mutation occurs. Even if there is a mutation, it is not passed on to offspring. COMPARATIVE OVERVIEW There are two types of Cell Reproduction The reproduction of 1.Somatic (body) cells use mitosis, to create clones of the original cel. 2. Sex cells (eggs and sperm) use meiosis to create variation in the daughter cells. THE PROCESS OF MEIOSIS The product of meiosis is four DIFFERENT daughter cells. This means that all of the daughter cells contain variation compared to the parent cell.  HOW VARIATION OCCURS IN 1. Homologous Chromosomes Pair MEIOSIS… Up: During the early stage of meiosis, chromosomes that are similar in shape and size (called homologous chromosomes) pair up closely. 2. Exchange of Genetic Material: While paired, these chromosomes can exchange segments of their genetic material. This process is called crossing over. Imagine it like swapping pieces of a puzzle between two similar pictures.  HOW VARIATION OCCURS IN 3. Formation of Recombinant MEIOSIS… Chromosomes: After crossing over, the chromosomes have a mix of genetic material from both parents. This creates new combinations of genes, which is important for genetic diversity. 4. Separation and Division: The homologous chromosomes then separate and are distributed into different cells. By the end of meiosis, four unique sex cells are produced, each with a different combination of genes. Meiosis ensures that offspring have a mix o f traits from both parents, contributing to g  THE FINAL STEP… Half of the DNA goes to each daughter cell. Cell division occurs AGAIN Meiosis starts so that every the same way Crossing over daughter cell as Mitosis… has occurred only has with DNA here. HALF of the replication DNA (because it will eventually combine with another sex cell) Note that every daughter cell is DIFFERENT.  A GENETIC DEFINITION OF NATURAL SELECTION The proportion of a particular phenotype in a species changes because individuals with a particular genotype are favoured. https://www.youtube.com/watch?v=eO46vI35kdg  EVIDENCE FOR NATURAL SELECTION One of the first studies to collect evidence for Natural Selection occurred in England, last century. The peppered moth was studied. The peppered moth exists in both light and dark forms. It was found that in the cities, almost all the peppered moths were black. In rural areas, almost all were white. There was obviously a selective agent acting on the moths. In the cities, all the building and tree trunks had been blackened by soot due to the industrial revolution. Any white moths were easier to see by predators. Black moths survived and reproduced. https://www.youtube.com/watch?v=etsjB-6u-6w i) http://peppermoths.weebly.com/ In rural areas, the air was cleaner and tree trunks were lighter. This made the black moths stand out and get  ACTIVITY – CREATE YOUR OWN ‘PEPPERED MOTH’ 1. Using the outlines 2. Choose a spot in the given to you, create your room. Colour your ‘moth’ as own ‘moth’ that you will close to that spot as you camoufl age with the can. environment around you in the class. 3. We will then invite a 4. Those that camoufl age guest in the room to see if the best… you win the they can pick where your natural selection prize! moths are hidden. They will have one minute to fi nd as many as they can. 47  NATURAL SELECTION OF INSECTS In the middle of last century, agricultural scientists developed chemical insecticides. The scientists thought that they would kill all the insects, but some survived. Eventually, the insecticide had no effect at all, and none of the insects died.  NATURAL SELECTION OF INSECTS Scientists called this ability of insects to survive the poison spray resistance. https://www.youtube.com/watch?v=2J-boNjH_HA https://www.youtube.com/watch?v=r-5R41tVIDY The development of resistance to insecticides by insects is an example of natural selection.  NATURAL SELECTION OF INSECTS The resistant insects survived when the population was sprayed, but the non-resistant insects all died. The resistant insects therefore bred and reproduced which made more resistant offspring.  NATURAL SELECTION IN BACTERIA From your studies of disease in Year 9, you should remember that  Bacteria is a microorganism that causes disease.  Fleming discovered penicillin, the first antibiotic that kill bacteria. https://www.youtube.com/watch?v=tMPY-zf8X94 We also take antibiotics to cure bacterial infections. Over time, some antibiotics no longer work because some bacteria have become resistant to  NATURAL SELECTION IN BACTERIA Bacteria can become resistant to antibiotics by natural selection. In the millions of bacterial cells infecting an organism, some of these may have mutations that make them resistant to antibiotics. Bacteria divide and multiply very quickly which means that eventually there will be enough resistant bacteria to make you ill. At this stage, taking more of the antibiotic will not work. https://www.youtube.com/watch?v=znnp-Ivj2ek  GOLDEN STAPH One very dangerous type of bacteria is Golden Staph. It is resistant to many types of antibiotics and is therefore very hard to kill. It became resistant because of the widespread use of antibiotics in hospitals. This kept selecting the resistant bacteria to survive. Eventually the species became resistant. https://www.youtube.com/watch?v=fGi66W1AkJI  SOME PRACTICE Revision Questions Page 43 Questions 3 and 4 Page 45 Questions 1, 3, 4, 5 Page 47 Questions 1, 3, 4 Page 59 Questions 1, 2, 5  EVOLUTION Charles Darwin proposed that natural selection could result in the formation of new species. The Galapagos Finches - A very well known example of evolution. - Discovered by Darwin on the Galapagos Islands. - The finches had a common ancestor. - The finches had different beak shapes to suit the different food sources found on the different islands. https://www.youtube.com/watch?v=n3265bno2X0  WHAT IS A SPECIES? Species: a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. Speciation: The process by which one species splits into two or more separate species. These organisms have changed so much that they can no longer breed fertile  SPECIATION Speciation has led to the high number of biodiversity on Earth. Biodiversity refers to the number and range of different species that exist. Imagine if there was only ONE type of dog, or cat, or bird!  VARIATION The process of speciation has three steps. Step One – Variation There must be lots of different types of organisms in the population so that natural selection can occur and the ‘fittest’  ISOLATION The process of speciation has three steps. Step Two – Isolation Different groups in the population must be prevented from interbreeding for  ISOLATION The ‘barriers’ that keep organisms apart can be oceans, rivers, mountain ranges and gorges. They can also be rainfall, temperature, salinity and sunlight.  SELECTION The process of speciation has three steps. Step Three- Once separated, natural selection occurs which changes the genes of the organism. This prevents breeding should the species come back together in the future. https://www.youtube.com/watch?v=2oKlKmrbLoU  SELECTION What genetic changes can stop the birth of viable offspring?  Mating rituals may change – some organisms will no longer be attracted to the courtship behaviour of other organisms.  Breeding seasons may change – animals may breed at different times of the year.  Breeding may occur, but the offspring are sterile.  Chemical barriers may be present – sperm may be killed by the chemistry of the female.  EVIDENCE FOR EVOLUTION EVIDENCE #1 - FOSSILS Early fossils are of fairly simple organisms and later ones are increasingly complex. This suggests that organisms evolve over time. (It wouldn’t make sense for complex animals to evolve to become simpler!) The fossil record also shows that there is an increasing number of species as time passes. This is to be expected because as organisms evolve, speciation occurs. https://www.youtube.com/watch?v=cGkhRSa00Hk  EVIDENCE FOR EVOLUTION EVIDENCE #2 – COMPARATIVE ANATOMY Homologous structures provide strong evidence for evolution from a common ancestor.  EVIDENCE FOR EVOLUTION EVIDENCE #3 – SIMILARITIES IN THE DNA Organisms that have similar anatomy tend to have genes in common. This suggests they have both evolved from the same ancestor. https://www.youtube.com/watch?v=Z5ujGwNJt5E  EVIDENCE FOR EVOLUTION EVIDENCE #4 – DISTRIBUTION OF SPECIES When studying the distribution of a species (where they live), scientists have discovered that unique species occur on isolated islands. You would expect to find unusual species on particular islands because isolation is necessary before speciation can occur. https://www.youtube.com/watch?v=rR4ElV2Jz7A  EVIDENCE FOR EVOLUTION EVIDENCE #5 – EMBRYOLOGY Embryology is the study of the development, structure and function of the embryo. Similarities in embryos could be evidence for evolution. https://www.youtube.com/watch?v =uAZmLYWEPGk  EVIDENCE FOR EVOLUTION EVIDENCE #6 – VESTIGAL STRUCTURES A vestigial structure is a feature that a species inherited from an ancestor but that is now not used or is unnecessary. Usually, vestigial structures are formed when a population experiences a different set of selective circumstances than its ancestors. Examples in humans include the appendix, and wisdom teeth.  SOME PRACTICE Revision Questions Page 62 Questions 3, 7, 10, 12, 15, 17 Page 63 Questions 18, 22