Evolution Latest Update with Certified Solutions

Evolution Latest Update with Certified Solutions Evolution 1. All species share a common ancestor 2. Species have changed through time. Ex. new and different environments have caused them to have change Theory A well supported testable explanation of observations that have happened in the natural world Fossil The preserved remains of ancient organisms Artificial selection Selection by humans for breeding of useful traits from the natural variation among organisms Also known as Selective Breeding struggle for existence competition among members of a species for food, living space, and the other necessities of life fitness ability of an organism to survive and reproduce in its environment to pass on its traits adaptation inherited characteristics that increases an organism's chance of survival survival of the fittest process by which individuals that are better suited to their environment survive and reproduce most successfully; the process called natural selection natural selection ->process by which individuals that are better suited to their environment survive and reproduce most successfully; ->can affect the distributions of phenotypes in any of 3 ways: directional selection, stabilizing selection, or disruptive selection descent with modification principle that each living species has descended, with changes, from its ancestors over time common descent principle that all living things were derived from common ancestors homologous structure structures that have different mature forms in different organisms but develop from the same embryonic tissues ex. pentadactyl limbs vestigial organ organ that no longer serves a useful purpose in an organism directional selection form of natural selection in which the entire curve moves; occurs when individuals at on end of the distribution curve have higher fitness than individuals in the middle or at the other end of the curve stabilizing selection form of natural selection by which the average characteristic is favored; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end. disruptive selection form of natural selection an where having an average trait results in lower fitness and a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle. genetic drift random change in allele frequencies that occurs in small populations founder effect change in allele frequencies as a result of the migration of a small subgroup of a population ex. Galapagos Finches Hardy-Weinberg principle principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change genetic equilibrium situation in which allele frequencies remain constant speciation formation of a new species reproductive isolation separation of species or populations so that they cannot interbreed and produce fertile offspring - may lead to speciation behavioural isolation form of reproductive isolation in which 2 populations have differences in courtship rituals or other types of behaviour that prevent them from interbreeding. geographic isolation form of reproductive isolation in which 2 populations are separated physically by geographic barriers such as rivers, mountains, valleys or stretches of water temporal isolation form of reproductive isolation in which 2 populations reproduce at different times because temperature change drives breeding season ex. habitat in valley bottom compared to mountain top macroevolution large-scale evolutionary changes that take place over a long period of time ->6 important topics: extinction, adaptive radiation, convergent evolution, coevolution, punctuated equilibrium, and changes in developmental genes. adaptive radiation ->process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms ->can occur on a large scale. Dinosaurs were the products of a spectacular adaptive radiation among ancient reptiles ->the disappearance of the dinosaurs cleared the way for the great adaptive radiation of mammals convergent evolution ->process by which unrelated organisms independently evolve similarities when adapting to similar environments ->two different groups of aquatic mammals, and swimming birds has resulted in sharks, dolphins, seals, and penguins whose streamlined bodies and swimming appendages look a lot alike coevolution ->process by which two species evolve in response to changes in each other ->example: many flowering plants can reproduce only if the shape, color, and odor of their flowers attract a specific type of pollinator (hummingbird, bees) punctuated equilibrium ->pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change. ->evolution has often proceeded at different rates for different organisms as different times Evidence of evolution ->the fossil record ->the geographical distribution of living species ->homologous structures of living organisms ->similarities in early development (embryology) ->comparative biochemistry (DNA) Fossil record by comparing fossils from older rock layers with fossils from younger layers, scientists could document the fact that life on Earth has changed over time Geographical distribution of living species all organisms have descended with modifications from a common ancestor similar environments sometimes have different animals that have similar anatomies and behaviours. Homologous body structures provide strong evidence that all 4-limbed vertebrates have descended, with modifications, from common ancestors Similarities in early development (embryology) the groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates. These common cells and tissues growing in similar ways, produce the homologous structures Lamarck's Hypothesis He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in the species ->tendency toward perfection: all organisms are continually changing and acquiring features that help them live more successfully in their environments ->use and disuse: organisms can alter the size or shape of particular organs by using their bodies in new ways. ->inheritance of acquired traits: acquired characteristics can be passed on to offspring Darwin's Theory of Evolution 1. individual organisms differ, and some of its variation is inherited 2. organisms produce more offspring than can survive, and many that do survive do not reproduce 3. because more offspring than can survive, they compete for limited resources 4. natural selection: organisms pass their inheritable traits to their offspring, other organisms die or leave few offspring. this process causes species to change over time. 5. species alive today are descended with modification from ancestors. this unites all organisms into a single tree of life Speciation in the Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population's gene pool, reproductive isolation, and ecological competition extinction ->more than 99% of all species that have ever lived are now extinct ->extinctions occur usually when species compete for resources, and environments change; sometimes extinction occurs through natural selection mass extinction ->it is reasonable that a large asteroid striking the earth wiped out the dinosaurs and many other organisms; scientific evidence supports it -> researchers have not yet determined the precise causes of mass extinctions molecular biology ->the relationship between the same biological molecule in different organisms tells us how closely related 2 organisms are. -> Cytochrome C and Hemoglobin are 2 common proteins used ->made up of chains of amino acids, like a necklace ->there are 20 different amino acids -> the sequence of amino acids directly reflects the DNA as each amino acid has its own 3 base DNA code -> the sequence of amino acids reflects the sequence of bases in the genes -> the more similar molecules are in 2 different species the more recently the organisms shared a common ancestor Lyell ->scientists must explain past events in terms of processes that they can be observed, since processes that shaped the Earth millions of years ago continue in the present. ->geological features could be built up or torn down over long periods of time ->helped Darwin to appreciated the significance of geological phenomena that he had observed: 1. if the earth could change over time, might life change also? 2. he realized that it would have taken many, many years for life to change in the way he suggested Malthus ->reasoned that if the human population continued to grow unchecked, soon or later there would be insufficient living space and food for everyone ->Darwin realized this applied more to plants and animals than to humans because humans produced fewer offspring than other species. 4 steps of natural selection 1. genetic variation within the species 2. more offspring produced than can survive 3. struggle for existence (competition for resources) 4. differential reproduction and survival (fitness) isolating mechanisms various factors that either prevent organisms from mating or cause the embryo, or offspring to die or not be fertile genotype genetic makeup of an organism alleles one of a number of different forms of a gene gene sequence of DNA that codes for a protein and thus determines a trait phenotype physical characteristics of an organism gene pool combined genetic information of all the members of a particular population homozygous individual an organism that has 2 identical alleles for a particular trait heterozygous individual an organism that has 2 different alleles for a particular trait bottleneck genetic drift ->an entire species goes through a "bottle neck" which is when most of the individuals in the species dies. ->a bottle neck could be a volcanic eruption in which 90% of the mountain goats die. founder effect ->a small number of individuals of a species migrate to a new location ->islands are a good example of this where most likely the founding individuals arrived on the island due to a storm migration periodic movement and return of animals from one place to another mutation change in a DNA sequence that affects genetic information