Evolution Quiz

Evolution is the change in heritable characteristics of biological populations over successive generations, resulting from natural selection, genetic drift, and gene flow acting on genetic variation. The theory of evolution by natural selection was conceived independently by Charles Darwin and Alfred Russel Wallace in the mid-19th century and was set out in detail in Darwin's book On the Origin of Species. Heredity is the passing of traits from parents to offspring through genes, which are controlled by an organism's genotype and interact with the environment to produce its phenotype. Variation comes from mutations in the genome, reshuffling of genes through sexual reproduction, and migration between populations (gene flow). Mutations are changes in the DNA sequence of a cell's genome and are the ultimate source of genetic variation in all organisms. Sexual reproduction increases genetic variation and may increase the rate of evolution, despite the two-fold cost of sex. Gene flow is the exchange of genes between populations and between species, and can be a source of variation that is new to a population or to a species. Evolution by natural selection is the process by which traits that enhance survival and reproduction become more common in successive generations of a population. Fitness, measured by an organism's ability to survive and reproduce, determines the size of its genetic contribution to the next generation and is the central concept of natural selection. The fitness of an allele is determined by its ability to increase an organism's survival and reproduction, resulting in it becoming more common within a population, while less beneficial or deleterious alleles become rarer.Summary Title: Understanding Natural Selection

• Natural selection is the process by which advantageous traits become more common in a population over time through differential survival and reproduction.

• Three types of natural selection are directional selection, disruptive selection, and stabilizing selection.

• Natural selection occurs within ecosystems, where each population occupies a distinct niche and interacts with other parts of the system.

• Natural selection can act at different levels, such as genes, cells, individual organisms, groups of organisms, and species.

• Genetic hitchhiking occurs when one beneficial allele causes other linked alleles to become more common in a population.

• Sexual selection is a special case of natural selection that favors traits that increase mating success.

• Genetic drift is the random fluctuation of allele frequencies within a population from one generation to the next.

• Gene flow involves the exchange of genes between populations and can introduce traits that are disadvantageous in the local population, leading to the appearance of new species.

• Mutation bias refers to the difference in expected rates for two different kinds of mutations and can explain systematic differences in genomic composition between species.

• Evolutionary theory has many applications in medicine, agriculture, and computer science.

• The outcomes of evolution include specific behavioral and physical adaptations, cooperation, and the production of new species through speciation and extinction.

• Evolution does not have goals or long-term plans and does not necessarily produce greater complexity. Simple organisms have been the dominant form of life on Earth throughout its history.Evolution, Adaptation, Coevolution, Speciation, and Extinction: A Summary

• Adaptation is the process that makes organisms better suited to their habitat, and is produced by natural selection.

• Adaptations may cause either the gain of a new feature or the loss of an ancestral feature, and can increase organisms' evolvability.

• During evolution, some structures may lose their original function and become vestigial structures, such as wisdom teeth in humans.

• Exaptations are structures originally adapted for one function but which coincidentally became useful for some other function in the process.

• Coevolution is the cycle of selection and response that occurs when the interaction between pairs of species produces matched sets of adaptations.

• Cooperation within and between species has evolved through kin selection, group selection, and reciprocal relationships, such as plants and mycorrhizal fungi.

• Speciation is the process where a species diverges into two or more descendant species, and there are four primary geographic modes of speciation.

• Extinction is the disappearance of an entire species, which regularly occurs through natural processes but has been accelerated by human activities.

• The Cretaceous-Paleogene extinction event, during which the non-avian dinosaurs became extinct, is the most well-known mass extinction event.

• The evolutionary history of life on Earth is about 4.54 billion years old, and the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago.

• The causes of the continuous "low-level" extinction events may be the result of competition between species for limited resources, while the intermittent mass extinctions drastically reduce diversity in a nonspecific manner and promote bursts of rapid evolution and speciation in survivors.

• Evolutionary history has been shaped by a combination of random events and natural selection, and the study of evolutionary biology has led to a better understanding of the origins and diversity of life on Earth.Evolution: A Summary

• Microbial mat fossils have been found in 3.48 billion-year-old sandstone in Western Australia, indicating the existence of life on Earth around that time.

• Over 99% of all species that ever lived on Earth are estimated to be extinct, with current estimates of Earth's current species ranging from 10 million to 14 million.

• Highly energetic chemistry is thought to have produced a self-replicating molecule around 4 billion years ago, eventually leading to the last universal common ancestor of all life.

• All organisms on Earth are descended from a common ancestor or ancestral gene pool, with current species a stage in the process of evolution through speciation and extinction events.

• The "tree of life" may be more complicated than a simple branching tree due to horizontal gene transfer, leading some to prefer the "Coral of life" metaphor.

• Fossils, comparative anatomy, and molecular genetics provide evidence for common descent and the evolution of life.

• Prokaryotes inhabited the Earth from around 3-4 billion years ago, with eukaryotic cells emerging between 1.6 and 2.7 billion years ago.

• Multicellularity emerged in multiple independent events, leading to a remarkable amount of biological diversity in the Cambrian explosion around 610 million years ago.

• Plants and fungi colonized land around 500 million years ago, followed by arthropods and other animals, including humans around 250,000 years ago.

• Evolutionary thought has a long history, including ideas from pre-Socratic Greek philosophers, Aristotelianism, and medieval teleological understandings of nature.

• The Darwinian revolution introduced the theory of evolution through natural selection, which led to the modern synthesis connecting natural selection and population genetics.

• Further syntheses, such as evolutionary developmental biology and the extended evolutionary synthesis, have extended evolution's explanatory power.

• The idea of evolution has been a source of academic debate, with philosophical, social, and religious implications.