Test 3 Evolution Section 22 2 Be able to explain the difference between natural selection and evolution o 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 Overtime natural section can increase the match between organisms and their environment In an environment changes or if individuals move to a new environment natural selection may result in adaptation to these new conditions sometimes giving rise to new species Also note that natural selection occurs through interactions between individual organisms and their environment individuals do not evolve Rather it is the population that evolves over time leads to adaptive evolution o Evolution refers to the cumulated changes in a population or species through time o Natural selection is a mechanism that can drive evolutionary change o Which of the following would demonstrate natural selection on seed size a a genetic basis to seed size b an association between seed size and survival in the ocean c an association between seed size and flavor d variation in seed size in different locations e an association between seed size and thickness of shell Be able to explain the basic principles of natural selection o Members of a population often vary in their inherited traits and all species can produce more offspring than the environment can support so many of these offspring fail to survive and reproduce Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations o The traits that are favored will likely appear at a greater frequency in the next generation Thus overtime natural selection resulting from factors such as predators lack of food or adverse physical conditions can lead to an increase in proportion of favorable trait in a population Know that evolution produces allele frequency changes inherited phenotypic changes differences among populations new phenotypes and new species and phylogenetic relationships Evolution leads to o Changes the genetic nature of populations o Changes in the mean phenotype of populations o Differentiation of populations o The formation of new species o Results in branching pattern of change over time Evidence for Evolution and Modern Evolutionary Biology Readings 22 2 22 3 Concepts Be able to describe the different types of evidence for evolution and explain their significance o Life on Islands a Many of the species found on remote islands are endemic to a particular island or group of islands meaning they are found nowhere else on earth Examples of species endemic to islands include many flightless birds of New Zealand lemurs of Madagascar the Komodo dragon of Komodo the dragon s blood tree of Socotra 81 Tuatara of New Zealand and others However many such endemic species are related to species found on other nearby islands or continents the relationship of the animals found on the Gal pagos Islands to those found in South America is a well known example All of these facts the types of plants and animals found on oceanic islands the large number of endemic species found on oceanic islands and the relationship of such species to those living on the nearest continents are most easily explained if the islands were colonized by species from nearby continents that evolved into the endemic species now found there Darwin s observations of life on islands convinced him that o new species evolved from species arriving from the mainland o Fossil Record Shows nonrandom change in form over time not just different in the past but different in a consistent pattern o Observation of Natural Selection a An example of natural selection is the Soapberry Bug which feeds most effectively when their beak length closely matches the depth at which the seeds are found within the fruit Soapberry bugs normally eat from the balloon vine in southern Florida which has the seed deep in the fruit However in central Florida the balloon vine is rare so the Soapberry bugs eat on the goldenrain tree recently introduced The fruit of the goldenrain tree has seeds that are much closer to the surface than the balloon vine Thus researches predicted that the Soapberry bugs from central Florida had undergone natural selection to adapt to having a beak that is shorter due to the seeds they were feeding on This is indeed what happened It took approximately 35 years for this to occur which demonstrates that natural selection can cause rapid evolution in a wild population b Note natural selection is a process of edition not a creative mechanism Natural selection depends on time and place It favors those characteristics in a genetically variable population that provide advantage in the current local environment What is beneficial in one situation may be useless or even harmful in another environment o Artificial Selection a a a a is the intentional reproduction of individuals in a population that have desirable traits In organisms that reproduce sexually two adults that possess a desired trait such as two parent plants that are tall are bred together The many breeds of domestic dogs are a product of o Comparative Anatomy o Artificial selection o Convergent Forms is the study of similarities and differences in the anatomy of different species It is closely related to evolutionary biology and phylogeny the evolution of species Comparative anatomy has long served as evidence for evolution it indicates that various organisms share a common ancestor In evolutionary biology convergent evolution is the process whereby organisms not closely related not monophyletic independently evolve similar traits as a result of having to adapt to similar environments or ecological niches o Ontogeny is the origination and development of an organism usually from the time of fertilization of the egg to the organism s mature form Yet the term can be used to refer to the study of the entirety of an organism s lifespan b The similarities of numerous species when in the embryonic stage suggest common ancestry o Phylogeny a Based upon similarities and differences in their physical or genetic characteristics The taxa joined together in the tree are implied to have descended from a common ancestor
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