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Evolution
Stage 2 Biology - topic 4: Evolution
| Term | Definition |
|---|---|
| Define species | A group of similar organisms that can breed and produce fertile offspring |
| Life has existed for | 3.5+ Billion years |
| Evidence for early life | Prokaryotic fossils eg stromatolites |
| endosymbiotic theory | theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms |
| Organelles that came about by endosymbiosis | Mitochondria and Chloroplasts |
| evidence for endosymbiosis | Mitochondria and Chlorplasts have double membrane, similar size, enzymes, ribosomes, DNA, undergo binary fission which is all similar to prokaryotes |
| Formation of first membranes | Occurs spontaneously in nature, lipids naturally form spheres |
| Protocells | An abiotic precursor of a living cell that had a membrane-like structure and that maintained an internal chemistry different from that of its surroundings. |
| RNA world hypothesis | Hypothesis that describes how the Earth may have been filled with RNA-based life before it became filled with the DNA-based life we see today. |
| Ribozymes | RNA molecules that function as enzymes |
| example of a ribozyme | ribosome |
| How RNA may have replicated | Cycles of heating and cooling in the environment: When cool, free bases could bind to make a new strand, when hot the strands would separate. Could have happened near volcanic vents. |
| ring species | populations that can interbreed with neighboring populations but not with populations separated by larger geographical distances |
| Morphological similarity | Another way to classify animals into species based on appearance, most useful with fossils where DNA evidence or evidence of breeding is impossible. |
| Biochemical similarity | closely related organisms have similar chemical makeups i.e DNA and Proteins. Used to define species. |
| Sharing a common gene pool | Another way to define species. Allows for ring species to be counted as a single species even though not every population could breed with another |
| Reproductive isolation | Separation of species or populations so that they cannot interbreed and produce fertile offspring |
| Reproductive barriers | serve to isolate the gene pools of species and prevent interbreeding |
| Pre-zygotic barriers | Pre-zygotic barriers are barriers that prevent fertilization, which could be geographic or behavioral differences, such as if two species reproduce at different times of the year, which is known as temporal isolation. |
| Post-zygotic barriers | prevent the hybrid zygote from developing into a viable, fertile adult |
| Temporal isolation | form of reproductive isolation in which two populations reproduce at different times |
| Behavioural isolation | when two populations are capable of interbreeding but have different behaviours such as courtship rituals or feeding. |
| Mechanical isolation | Morphological (shape) differences prevent successful mating |
| Gametic isolation | Sperm of one species may not be able to fertilize eggs of another species |
| Hybrid inviability | A postzygotic barrier in which hybrid zygotes fail to develop or to reach sexual maturity |
| Hybrid sterility | hybrid offspring mature but are sterile as adults |
| Mutation | a random error in gene replication that leads to a permanent change in DNA, the ultimate source of variation |
| accumulation of mutations over time | over time, an individual and a population develops more mutations. The greater the number of mutations that makes species different, the further back in time they diverged |
| Sources of variation in sexual reproduction | Crossing over, independent assortment, random fertilisation |
| Comparative genomics | compares genes in different organisms to see how those organisms are related |
| Sequencing of common proteins | Allows for comparison to determine how closely related two species are |
| Cytochrome C | A protein involved in the ETC that is common to all Eukaryotes. Comparing the sequence of Amino acids between species determines relatedness. |
| DNA hybridization | The DNA of two species is mixed and heated to separate strands. When it cools, some of the DNA from different species pairs up (hybridises). It is not a perfect match because of mutations in different species. |
| DNA sequencing | Determining the exact order of the base pairs in a segment of DNA in order to compare species. A greater number of differences means more distantly related |
| phylogenetic tree | A family tree that shows the evolutionary relationships thought to exist among groups of organisms |
| phylogenetic tree node | Branching point. Point at which 2 species diverge from each other. Represents common ancestor. |
| phylogenetic tree branch | a line representing a population through time |
| Common ancestor | An ancestral species from which later species evolved |
| Phylogenetic tree - closely related | The branches of the populations of species have a common ancestor node that is close. E.g. Humans and Chimps |
| Phylogenetic tree - distantly related | The branches of the populations of species have a common ancestor that is far back. e.g Humans and Octopus |
| Gene pool | Combined genetic information of all the members of an interbreeding population |
| Natural selection | A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. |
| Overproduction | organisms produce more offspring than can survive |
| Variation | Any difference between individuals of the same species. |
| Allele | Different forms of a gene |
| compete for resources | Since natural resources are limited, all organisms must compete to gather them |
| offspring | Product of reproduction, a new organism produced by one or more parents |
| selection pressure | the environmental factors that favour certain phenotypes (traits) |
| Industrial melanism | replacement of a light variety by a dark in an industrialized area |
| peppered moth | originally, the majority of these moths were light-colored, due to natural selection and then when the trees turned black due to the Industrial Revolution in England, the black colored moths came into the majority because of natural selection |
| antibiotic resistance | Resistance evolving rapidly in many species of prokaryotes due to overuse of antibiotics, |
| large gene pool | has a large genetic diversity which makes it more likely to survive change |
| population bottleneck | A period during which only a few individuals of a normally large population survive. |
| founder effect | change in allele frequencies as a result of the migration of a small subgroup of a population |
| genetic drift | A change in the allele frequency of a population as a result of chance events rather than natural selection. |
| geographical barriers | formed by canyons, mountain ranges; bodies of water, deserts, and other features organisms can't cross |
| gene flow | exchange of genes between populations |
| reproductive isolation | Separation of species or populations so that they cannot interbreed and produce fertile offspring |
| allopatric speciation | The formation of new species in populations that are geographically isolated from one another. |
| sympatric speciation | The formation of new species in populations that live in the same geographic area |
| Polyploidy | condition in which an organism has extra sets of chromosomes, a way that sympatric speciation can occur in plants |
| hexaploid | a cell having six chromosome sets or an organism composed of such cells |
| Total non-disjunction | When a full set of chromosomes does not separate during meiosis, can lead to polyploidy |
| convergent evolution | Process by which unrelated organisms independently evolve similarities when adapting to similar environments |
| analogous structures | Body parts that share a common function, but not structure |
| examples of convergent evolution | - Sugar glider and Flying Squirrel - Bats and Birds - Shark and Dolphin |
| examples of analogous structures | - bird wing and insect wing - quills on a sea urchin, hedgehog, and cactus |
| divergent evolution | when two or more species sharing a common ancestor become more different over time (adaptive radiation) |
| adaptive radiation | evolution from a common ancestor of many species adapted to diverse environments (divergent evolution) |
| Community | All the different populations that live together in an area |
| primary succession | An ecological succession that begins in an area where no biotic community previously existed, there is no soil, eg lava fields |
| secondary succession | Succession following a disturbance that destroys a community without destroying the soil eg, fire, flood, storm, human activity |
| Examples of species with low genetic diversity | Tassie Devil and Cheetah |
| enhanced greenhouse effect | Rising global temperatures due to greenhouse gases being put into the atmosphere because of human activities |
| anthropogenic global warming | An increase in global temperature caused specifically by human activities |
| Greenhouse gasses | Carbon Dioxide, Methane, Nitrous Oxide |
| Sources of Carbon dioxide | Burning Fossil Fuels |
| Sources of Methane | Rice Paddies, Sheep and Cows |
| Source of Nitrous oxide | Fertilizers |
| migration and competition | Results from global warming causing populations to mover where it is cooler |
| coral bleaching | A phenomenon in which algae inside corals die, causing the corals to turn white. |
| pollution | Release of harmful materials into the environment |
| Microplastics | Small plastic particles posing negative consequences to marine environments and wildlife. Clog up digestive tract and carry other toxins. |
| deforestation | The removal of trees faster than forests can replace themselves. |
| habitat destruction | The loss of a natural habitat |
| Biodiversity | the variety of life in the world or in a particular habitat or ecosystem. |
| Human-centred reasons for maintaining biodiversity | Food, fibres, structural materials, medicines |
| Ethical reasons for maintaining biodiversity | - Right for all organisms to exist - Not being wasteful - Right for future generations to enjoy - Spiritual and Religious reasons |
Created by:
justineforrest
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