Biological Diversity BSCI 10110
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This 9 page Bundle was uploaded by Brittany Yee on Monday February 8, 2016. The Bundle belongs to BSCI 10110 at Kent State University taught by Dr. Mark W. Kershner in Spring 2016. Since its upload, it has received 43 views. For similar materials see Biological Diversity in Biological Sciences at Kent State University.
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Date Created: 02/08/16
I. Science- an organized body of knowledge explained by the natural world a. It is a systematic process of acquiring, organizing, and communicating this knowledge II. Purpose of science- to seek increasingly accurate, natural, explanations and understandings of the natural world a. Science is made up of i. Descriptions- based on observation (lowest level of science) ii. Explanations- understanding data and the description you come up with 1. Provides insight iii. Purpose/goal- something you do to get the description and explanation 1. A process method b. Assumptions of Science- science is due to natural phenomenon and has natural explanations. i. Have natural patterns ii. Are unchanging across time iii. We can understand explanations, patterns, and rules c. Science MUST be: i. Based on the best available evidence ii. It must be objective and unbiased iii. Verifiable, testable, and repeatable d. Science is self correcting- as new work is done, it solidifies the results of the first work or it can demonstrate bad science i. Needs to be acquired using the scientific method THE SCIENTIFIC METHOD I. Observation- characterizes initial data a. Must be objective and unbiased b. Single or multiple c. Restricted to the use of our senses i. Can be improved with measurement devices and instruments II. Question- formed based on data that you have initially colleted. III. Hypothesis- provides a tentative explanation for the data points that have been collected a. Not random b. An educated guess fed by what you know based on data and observations c. Should always make a clear, focused prediction d. It MUST be testable and can not be too vague or general e. Based on inductive or deductive reasoning i. Inductive reasoning- going from specific to general observations 1. EX: every dog I see has hair. Hypothesize that all dogs have hair. ii. Deductive reasoning- applying general ideas to predict specific results. 1. If A=B, then B=C, then A must = C 2. EX: Observation: every dog has hair Prediction: this organism is a dog. Therefore, this organism has hair IV. Experiment- manipulation of the variable or factor suspectd to be the cause and the measurement of effect of manipulation a. Account for most/all variables influencing the effect you’re measuring b. Repeat experiments to test consistency V. Interpret- the outcome of the experiment relative to the hypothesis to see if the explanation is supported. a. If you accept/reject a hypothesis you can either stop, run another experiment, or redesign your experiment i. Reject- definite/straightforward ii. Accept- did not prove or not find to be true -Science is not proving things. If it does not determine the truth then all results are viewed as tentative - science is based on current understanding of the best available evidence - its possible that there are multiple hypotheses fir a scientific question IMPORTANT TERMINOLOGY - Fact- a well confirmed observation o lots of independent evidence o unlikely to be overturned, but it can be o is not proof or truth - law- a general statement describing some part of the natural world o not known to vary - hypothesis- a tentative* explanation of observations o may be well or weakly supported or not supported at all as you collect more data - theory- a very well supported explanation that uses tested hypotheses, facts, and laws o supported by LOTS of observations and multiple lines of independent evidence - facts and laws require explanations - -hypotheses and theories provide those explanations - Biology- the science of life o Living things MUST exhibit the following: Made up of 1 or more cells Use energy Maintain homeostasis Ability to reproduce, grow, develop Respond to stimuli Possess a life cycle Adapt to their environment EVOLUTION - Evolution- changes over time o Within evolution, biology has a dual nature: It can be represented by observation and data over time (Facts) Theory- explanations o Example: A fact can be that living things change over time A theory can be change of living things over time leading to the diversity of organisms that are seen today - Charles Darwin- proposed a mechanism of evolution called natural selection - Alfred Russel Wallace- proposed a similar concept at the same time o Both independently collected data that demonstrated that living things change over time that led to the Darwin-Wallace theory of evolution by natural selection: A theory built around the idea that adaptation to the environment plays a large role in diversity of life and formation of species - Darwins ideas came from collecting plant and animal fossils and studying gology while on the HMS Beagle o He realized that earth is much older than we thought - Darwin’s Observations: o Realized the above was significant because it explained that natural selection occurs slowly and changes start off small and could lead to the production of a new species o Noticed fossils resemble currently living species which showed potential for a common ancestor o Similar species varied from place to place in ways that suited their environment o He concluded that even though organisms of the same species look similar, they are not identical o There are slight variations in all creatures DARWIN’S POSTULATES I. Postulate 1- individuals within a species are variable a. Variability can be advantageous or disadvantageous i. Meaning it can lead to an advantage in survival and reproduction or a disadvantage of the two II. Postulate 2- some of an individual’s variability is passed on to the offspring a. Thus, variation is hereditable III. Postulate 3- in every generation, more offspring are produced than actually survive a. Suggests that a struggle for survival exists b. Ex: two beetles mate and produce 10 offspring. If there is a struggle for survival, not all 10 will survive. Say there is only enough food for 5 of the offspring. IV. Postulate 4- those offspring that survive AND REPRODUCE may have inherited a variation that gives them an advantage over the organisms that didn’t survive. a. Say the beetles in the above example survived because their legs were longer, which allowed them to run from predators faster and get food before the other beetles could. i. These individuals have higher FITNESS ii. Fitness is not how strong or quick you are. Fitness describes reproductive success. If you don’t reproduce, your fitness is 0. b. If the struggle for survival continues, each offspring will be faster than the last. c. Conclusion: the beetles changed so much that SPECIATION occurs ( a new species is produced) In biology today, evolution by natural selection requires evidence that variation is adaptive and that variation results in selection for or against organisms and affects the probability for survival Variations may be in size, shape, behavior, etc CONDITIONS FOR EVOLUTION BY NATURAL SELECTION I. Variation must exist for a given trait a. Can be visible or not obvious (behavior, physiology) b. * Without variation, selection would not affect survival, so all organisms that lack variation would respond in the same way as those with variation to a given SELECTIVE PRESSURE i. No advantages would be passed through reproduction II. Variation results in differential survival and ultimately production and fitness a. If you survive but don’t reproduce, fitness is 0. You HAVE to reproduce to have fitness b. Ex: peppered moth- industrial melanism- prior to the industrial revolution, white moths had a higher fitness because tree bark was white. After the revolution, soot and pollution caused the tree bark to become dark, and dark moths survived. c. * change in environment=change in advantageous variant d. The variation in the moth example is the wing and body color e. The differential survival/reproductive variation changed as the ENVIRONMENT changed (tree bark color) f. The selective pressure is predation, the easier the moth is to see the less chance of survival it has III. Other factors of natural selection: a. Food availability b. EX: finches have a variation in beak depth based on the type of fruits and nuts they eat and what time of year their food is most common i. This variation is hereditable based on what type of beak is best for which type of food. Has no effect on mate choice but does influence foraging ability ii. The selective pressure in this example is the climate 1. Whichever season each type of seed is most common correlates to the advantage the bird with the appropriate beak length for the specific seed c. Jean Baptiste Lemarck- inheritance of acquired characteristics i. New trait expressions were inherited from parents use or lack of a particular trait ii. Proposed that giraffe neck length was because they had to reach for leaves, but this was proven wrong because there is no selective pressure on neck length, proving that longer necks are due to genetic differences - Variation being genetically based is NOW thought of as: o A trait variation is encoded in an organisms DNA o If base pairs of DNA differ for a particular trait among organisms, we will see different trait expressions o Chromosomes have genes along their lengths that are DNA sequences that drive trait expression Genes differ in forms based on different base pairs (ALLELES) Allele- alternate forms of the same gene that determine trait expression - Prior definition of evolution was the change in living organisms over time. Assuming variation is hereditable, we now define evolution as the change in allele frequency in populations over time o **Allele frequency relates to gene expression - Assuming trait/ allele variation and hereditability, we can assume: o Individuals are selected for/against based on their traits Means that individuals do not evolve, populations evolve with change in allele frequency Results from some mechanism of evolution like NS o NS: Is not random Has no purpose/goal * selection can only act on existing variation *does not produce new trait selections MECHANISMS OF EVOLUTION I. Natural selection (already covered) II. Mutation- new alleles can only arise from mutations in existing DNA a. Ultimate source of genetic variation b. Leads to change in allele frequency c. RARE d. Can be spontaneous- occurring during production of sperm and egg e. Can also be due to external forces- “mutagens” that cause changes in underlying DNA f. Can have neutral or negative effects or positive effects if it gives an organism an advantage g. Model organisms are used to study mutation i. Ex: adults being treated with mutagens that result in an increase in mutation rate from mutated egg and sperm h. * mutation is the ONLY place new alleles can come from i. Mutations can result from problems in the environment III. Gene flow- transfer of alleles from one population to another a. very common b. populations exchange alleles c. can occur through organismal movement (migration) or pollination d. * Breeding is required for gene flow to occur because it is the exchange of ALLELES, not individuals IV. Nonrandom mating – results in reduced genetic variability/diversity because no new alleles are introduced a. Inbreeding- self fertilization in which a single organism produces sperm and egg and its own sperm fertilizes its own egg b. Mating by closely related organisms (siblings) will likely result in the offspring having most of the same alleles V. Genetic Drift- random fluctuation of allele frequency a. completely random b. changes in allele frequency from random mating or separation of populatons c. extremely common in small populations d. can be problematic because alleles can be lost even if they are beneficial and adaptive - forms of genetic drift: o Random mating- leading to the loss of some alleles to next generation because some individuals didn’t breed Particular when alleles are uncommon in the population o Founder effect- allele frequency and diversity are determined by which individuals move to a new population and breed Founding new populations Can happen through: Simple organismal dispersal Strom events Factors that separate the population Not about who makes it to the new land, its about who makes it and breeds successfully o Bottleneck effect- a catastrophic event with only very few survivors Lose genetic diversity because of those who didn’t survive Leads to a change in allele frequency Loss of genetic variability and thus reduction to the gene pool Leads to a reduced ability to respond to selective pressures Even if a population re-establishes its previous numbers, the genetic diversity is still gone and each successive bottlenose effect results in a greatly reduced gene pool and reduced genetic diversity. The only way to increase variation again is by mutation - Microevolution- small changes from all these mechanisms that result in SPECIATION- which is the production of a new species and thus is macroevolution - All 5 mechanisms can occur at the same time in a population and lead to change in allele frequency of the population SPECIES/IDENTIFYING SPECIES - Traditionally, morphology was used to identify species. o Problems with this: sexual dimorphism- which is if males and females look completely different - Cryptic species- look almost identical but are 2 different species and can not reproduce BIOLOGICAL SPECIES CONCEPT -Generated by Ernst Mayer, who defined species as: -Species- groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups -factors leading to reproductive isolation: - climate change and differences in geography - different breeding behaviors Reproduction- union of sperm and egg: sperm=egg fertilization zygote -Prezygotic isolation- reproduction isolation occurring before fertilization -Postzygotic isolation- isolation occurring after fertilization PREZYGOTIC ISOLATION TYPES I. Mechanical isolation- it is physically impossible for mating to occur a. Due to BODY MISMATCH- no way for eachothers parts to fit together II. Lock and key mechanism- mating is impossible because even if their parts can be orientated correctly, the male reproductive organ cant fit right into the female reproductive organ a. Example: trying to use the wrong key to open a door. It fits, but its not going to open the door III. Geographic isolation- barriers to organismal movement or the movement of reproductive particles like pollen grains or plants a. ***prevents gene flow b. If reproductive particles cant move then gene flow cant move. For example if a mountain separated two populations, there will be no gene flow to the other side of the mountain -Barriers to geographic isolation: - mountains, rivers, lakes, anthropogenic structures like cities roads and dams, etc - EX: desert pupfish. Found in small pools and streams in death valley. Two distinct species exist there: the salt creek pupfish and the devils hole pupfish. Each species has its own selective pressures and live in two different habitats. However, they both came from the same place. There was a big lake that dried up and when it dried up it separated the populations and isolated them in different areas that require different adaptations for each species to survive IV. Ecological isolation- organisms living in the same location but some ecological factor isolates them reproductively a. Includes where they feed, what they eat, and where they’re most active b. Mating could potentially happen but it doesn’t c. EX: two species of lizards: one living in trees and one living on the ground. There is **no genetic drift because they don’t go in each others habitat long enough to mate. The ground lizard may go in a tree and come in contact with a tree lizard, but it does not stay there long enough to mate. There is no breeding in another habitat V. Behavioral isolation- some aspect of organismal interaction differs between groups of organisms, preventing mating a. Things such as different mating calls or dances, any change in courtship rituals b. There are species specific patterns and aspects of courtship that act as reproductive mechanisms VI. Temporal isolation- breeding of similar, closely related species occurs at different times of the year. VII. Prevention of gamete fusion- mating occurs but there is NO fertilization happening a. Can be due to the sperm not penetrating the egg of toxic uterine environments for the sperm of the incorrect species POST ZYGOTIC ISOLATION I. Hybrid inviability- accumulation of genetic differences a. Offspring dies soon after or before birth -infertility- offspring survive but are sterile and cant produce their own offspring - can be partial - EX: A horse and donkey mate to produce a mule but the mule is sterile. A horse and donkey are different but still similar enough to produce offspring
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