Lamarckian believed that new species were produced by an internal drive toward greater complexity modified and the change was directed to meet the needs of the organism Darwin believed that new species were produced through natural selection and that variation exists regardless of an organisms’ needs. Natural Selection: a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. In nature, the environment is the selective agent. In nature, characteristics are selected only if they give advantages to individuals in the environment as it is now.
Natural selection is based upon 4 principles: Overproduction Variation Adaptation Descent with modification Artificial Selection: the process by which humans change a species of breeding it for certain traits. Humans make use of the genetic variation in plants/animals by acting as the selective agents. Homologous structures: Features that are similar in structure but appear in different organisms and have different functions. Share a common ancestor Example: forelimbs of humans, bats, and moles Analogous structures: Features that serve related functions, but do not show moon ancestry.Example: wings of bats and insects Adaptive Radiation: Divergent and Convergent evolution Divergent Evolution: Species diverge and move away from a common ancestor into new novel habitats or niches. Ex: homologous structures Convergent Evolution: species develop similarities based on their similar environment and similar selection pressures.
Ex: analogous structures Vestigial organs: remnants of organs/structures that had a function in an early ancestor but are no longer essential Example: human appendix Species: a group of organisms so similar to one another that they can produce and have fertile offspring.Speciation: evolution Of 2+ species from 1 ancestral species 1. Founding members 2. Separation of population 3. Changes in gene pool 4.
Reproductive isolation 5. Coexistence, extinction or further evolution Reproductive isolation: final stage in speciation, in which members of isolated populations are either no longer able to mate or no longer able to produce viable offspring. New species form when 1 population becomes isolated from another and do not interbreed Due to geographic barriers, courtship, behaviors, or differences in breeding times No gene flowWithout exchange of genetic info changes in their genes can eventually form separate species.
The founding members of the new population can no longer interbreed with the original population in the wild. Geographic isolation: involves physical barriers that divide a population into two or more groups. This is the most commonly studied type of isolation. Classification: method used to order or group organisms Similar nomenclature throughout the world Compare relationships and evolutionary histories Based on shared characteristics Domain Kingdom Phylum Class Order Family Genus SpeciesTaxonomy: science of classifying and naming organisms Groups organisms into hierarchical categories Starting with the largest grouping, the organisms were placed into smaller and smaller groups (that share more and more characteristics) until the grouping includes only that single species DESKTOPS (known as tax) Only the species name has a definite biological basis, the other classifications are man-made and subject to change The classification scheme are based on physical similarities or developmental stages that were similar Newer classification schemes consider biochemical differencesScientific name: genus and species Found using binomial nomenclature (2 word naming system) Humans C homo sapiens Gene pool: collection of alleles found in all of the individuals of a population; shared genes Genetic drift: random changes in allele frequencies due to chance alone, occurring most commonly in small populations Gradualism: Evolutionary change occurs slowly and gradually; this is supported by fossil evidence Punctuated Equilibrium: Long stable periods of time interrupted by briefs periods Of rapid speciation; also supported by fossil evidence Kingdoms/Domain ins (poss. abilities)