L04 Adaptations & Mutations Notes PDF

Adaptations and Variations Unit 3: Evolution Learning Goals Use appropriate terminology related to evolution (ex: adaptation, mimicry, variation, mutation, natural selection, artificia...

Adaptations and Variations Unit 3: Evolution Learning Goals Use appropriate terminology related to evolution (ex: adaptation, mimicry, variation, mutation, natural selection, artificial selection, etc.) Explain the process of adaptation of individual organisms to their environment What is the basis of EVOLUTION... The two goals for all living things is to survive and pro­create >.... the function of all living things is to find the best way to do so! 7.1 Adaptation and Variation What does diversity tell us? Organisms constantly face environmental challenges that limit their ability to survive (severe weather, famine, competition for food, space, mates, etc.) Organisms that survive long enough to reproduce have the opportunity to pass along to their offspring the genetic information that helped them survive Therefore, the diversity within a species and the interactions of organisms with their environment help explain how populations can change over time and why some species survive while others become extinct 1  A) Adaptations and Survival Textbook Definition: an "adaptation" is a structure, behaviour, or physiological process that helps an organism survive and reproduce in its particular environment Examples: Camouflage allows organisms to almost be invisible to predators, therefore allowing them to survive and reproduce Migration allows organisms to move in large groups to relocate to find food, they are more protected from predators when travelling in large groups, therefore allowing them to survive and reproduce Hibernation allows organisms to reduce their metabolism to save energy, therefore allowing them to survive harsh climate conditions and reproduce text p296 Camouflage (structural adaptation if the organism is born this way, but it is a physiological adaptation if it changes colour based on mood or temperature) Stick Insect (Eurycnema goliath) Hibernation (physiological adaptation is anything that involves an internal chemistry or temperature change) Mouse (Mus musculus) Migration (behavourial adaptation is any behaviour change) Canada Goose (Branta canadensis) 2 Mimicry is a unique structural adaptation where a harmless species resembles a harmful species in colouration or structure For example: The Viceroy butterfly (Limenitis archippus) is palatable to predators, but the Monarch butterfly (Danaus plexippus)is not ­ predators will avoid both because they know that one of them tastes bad, but can not distinguish between the real and the mimic B) How do Adaptations Develop? Adaptations are the result of gradual, accumulative changes that help an organism survive and reproduce. These changes are the result of random, heritable mutations in DNA that accumulate over generations. Textbook Definition: "Variations" are structural, functional, or physiological differences between individuals within a population Not all variations become adaptations ­ environmental conditions determine whether a variation in an individual has a positive, negative, or no affect on the individual's ability to survive and reproduce ­ individuals possessing a helpful variation ("favourable") are more likely to survive and therefore have a higher chance of passing this variation on to their offspring which eventually becomes more frequent, and is then considered a characteristic or trait of the population 3  Key Question: What is the difference between an Adaptation and a Variation ? (Google Definitions & Examples :) An adaptation is an inherited trait that increases an organism's chance of surviving and reproducing in its environment. (happens over time) Eg: one tortoise is born with a short stubby neck, and another tortoise has a long neck. The short stubby­necked tortoise has a hard time reaching its' food source; tall cacti, but the long­necked tortoise can reach the food with ease. The short­necked tortoise eventually starves to death, and the long­ Pull necked tortoise survives and reproduces, passing along the long­necked allele to its offspring. A variation is a slight difference in an inherited trait of individual members of a species. (happens by mutation) Eg: variations in the color of a tigers coat, or the colors of a snail's shell. These are the result of genetic mutations. **Variations can become adaptations if they offer a survival advantage and allow a particular organism to reproduce, but they take a long period of time (generations to generations). Interaction with environments is important to variations and adaptations because environments continually change: climates over time, droughts, floods, famines, deforestation, pollution, etc. A characteristic that may not give an organism an advantage now may be come critical for survival later. Highlight: English Peppered Moth (Biston betularia) Variation to Adaptation 4  In the past in England (mid 1800's), the black coloured moth population was rare because it was more visible to predators in the trees ­ lichens that naturally grow on trees proved to be a better camouflage for the greyish coloured moth ­ due to the Industrial Revolution, air pollution killed off tree lichens and put a black soot onto the trees ­ now predators were more able to see the greyish moth, so the black moth numbers increased ­ by the 1960's, England gov't introduced clean air legislation, so the tree lichens grew back and so did the greyish moth population ­ now, it is estimated that by 2019 the black moth population will once again be more rare! (It is important to understand that the ratio of greyish­to­ black moths in the population changed over successive generations ­ individual moths did not change from grey to black!) How does genetic variation happen in a species or population? Why does genetic variation happen at all? C) Mutations and Variation The answer is in the genes ­ offspring have a combination of genetic material from both parents (sexual reproduction), so the number of possible combinations of genes that offspring can inherit from their parents results in greater genetic variation among individuals within a population Genetic variation in a population results from the variety of genetic information from all individuals of the population 5 " "Mutations" are random changes in the DNA of an organism ­ they provide new alleles in a species and are the only source of new genetic variation when inherited Mutations generate genetic variety among organisms! Mutations can occur in: Somatic Cells Gametes These mutations are These are mutations not inherited passed on through the and do not egg or sperm and they contribute to have the potential evolution ­ the to be inherited thus mutation disappears contributing to from the population changes in the when the organism gene pool dies "Fitness" is the ability of how many offspring an organism can create ­ so inheritable mutations can be: Neutral Harmful no immediate effect reduces an on an individual's fitness individual's fitness Beneficial increases an individual's fitness Mutations that were once no advantage, or perhaps were even a disadvantage, may become favourable in a changing environment ­ in this way, they can provide a selective advantage ­ a genetic advantage of one organism over its competitors ­ over time, it causes the organism to be favoured in terms of survival and reproduction ­ it helps an organism survive the changing environmental conditions and reproduce. Example: the Water Flea (Daphnia) normally survives in water at 20oC but a mutation has now enabled some populations to survive in water at 27oC or higher and therefore reproduction rates and populations are greater 6  D) Rapid Reproduction with a Selective Advantage and Selective Pressure Some organisms reproduce very quickly such as bacteria, viruses, and many insects as compared to plants and animals In these organisms, a new allele that resulted from a random mutation that was previously insignificant, may become a selective advantage when the environment changes As a result, the organisms that have the new allele may survive long enough to reproduce and pass the genetic info on to the next generation ­ in time, the gene that provided the selective advantage becomes more prevalent in the population Selective Advantage: a genetic advantage that improves an organism's chance of survival, usually in a changing environment. Selective Pressure: environmental conditions that select for certain characteristics of individuals and select against other characteristics. Example: (gram stain positive purple) Harmful Bacteria are dangerous because they.... * Reproduce quickly ­ an entire bacterial population can double in size in 30 mins or less! *When exposed to an antibiotic, certain bacteria will have already had and be born with a resistant allele that helps them survive the antibiotic *This resistant allele will be quickly passed on to their offspring ­ an entire new resistant strain can come into existence within hours * This poses a major challenge for health professionals.... (the need for new antibiotics for every new strain of bacteria)! 7