Genetics controls evolution. There are four major genetic systems, which are combinations of sexual/asexual and haploid/diploid. In all genetic systems, adaptive genetic change tends to start out slow, accelerate in the middle, and occur slowly at the end. Asexual haploids can change the fastest, while sexual diploids usually change the slowest. Gene frequencies in large populations only change if the population undergoes selection.
Celebrating Science & Humanity
Darwin Day is a global celebration of science and reason held on or around Feb. 12, the birthday anniversary of evolutionary biologist Charles Darwin.
On this website you can find all sorts of information about Charles Darwin and the International Darwin Day Foundation. If you are hosting a Darwin Day event, you can post information about it on our events listing. You can also locate Darwin Day programs near you by searching our events section.
We also have resources for hosting Darwin Day events, including promotional support and a list of potential Darwin Day presenters.
Click here to read more about the history of the International Darwin Day Foundation.
Darwin Day News
The Palouse Coalition of Reason and AHA teamed up to bring three speakers to the area.
News 12 Connecticut covered a Darwin Day celebration thrown by the Southern Connecticut Darwin Day Committee in Norwalk, CT.
San Diego joins a growing list of cities that have officially recognized the birthday of the father of evolutionary biology, Charles Darwin. Mayor Bob Filner issued the proclamation.
Neutral evolution occurs when genes do not experience natural selection because they have no effect on reproductive success. Neutrality arises when mutations in an organism
Mutations are the origin of genetic diversity. Mutations introduce new traits, while selection eliminates most of the reproductively unsuccessful traits. Sexual recombination of alleles can also account for much of the genetic diversity in sexual species. In some instances, population size can affect diversity and rates of evolution and fixation, but in other cases population size does not matter.
Development is responsible for the complexity of multicellular organisms. It helps to map the genotype into the phenotype expressed by the organism. Development is responsible for ancient patterns among related organisms, and many structures important to development shared by many life forms have changed little over hundreds of millions of years. Development is expressed combinatorially, allowing a relatively small amount of genetic information to be expressed in many different ways.
Reaction norms depict the range of phenotypes a single genotype can produce, depending on the environment. Reaction norms must fit within an organism.
There are several explanations for the evolution of sex evolution and its continued prevalence. One is facilitating the spread of helpful mutations while hastening the removal of harmful ones. Another is expediting resistance against pathogens. Sex does have several costs compared to asex, such as only giving half your genome to offspring, having to find mates, and the risk of predation and STDs. Overall, the benefits outweigh the costs and sex has a firm hold on the majority of the recent branches of the tree of life.
Genomic conflict arises when the interests of various genomic elements, such as chromosomes and cytoplasmic organelles, are not aligned. These conflicts arise in two situations: either when one unit is contained within another, as a mitochondrion is contained within a cell, or when inheritance is asymmetrical. Genomic conflict can thus occur within a cell, within an organism, or between two organisms, such as a mother and developing fetus. There have been several steps taken to avoid these conflicts in sexual species, including the fairness of meiosis and the uniparental inheritance of cytoplasmic genomes.
Life history covers three main classes of traits in organisms: age and size at maturity, number and size of offspring, and lifespan and reproductive investment. Organisms must make tradeoffs among these traits that typically cause them to come to evolutionary equilibrium at intermediate values. Life history traits are evolutionary solutions to the ecological problems of the risk of mortality and the acquisition of food, and they are expressed in reaction norms that determine the particular traits that an organism will exhibit when its genes encounter a specific environment during development.
This course presents the principles of evolution, ecology, and behavior for students beginning their study of biology and of the environment. It discusses major ideas and results in a manner accessible to all Yale College undergraduates. Recent advances have energized these fields with results that have implications well beyond their boundaries: ideas, mechanisms, and processes that should form part of the toolkit of all biologists and educated citizens.
Sexual Selection is a component of natural selection in which mating success is traded for survival. Natural selection is not necessarily survival of the fittest, but reproduction of the fittest. Sexual dimorphism is a product of sexual selection. In intersexual selection, a sex chooses a mate. In intrasexual selection, individuals of one sex compete among themselves for access to mates. Often honest, costly signals are used to help the sex that chooses make decisions.