7.6 Continuing Evolution

Evolution has led to new, rapidly spreading diseases, called emerging diseases.
Evolution has led to new, rapidly spreading diseases, called emerging diseases.
Biogeography provides information about the evolutionary history of organisms, specifically where they originated and how they were able to disperse.
When certain conditions are met, allele and genotype frequencies do not change, a state called the Hardy-Weinberg equilibrium. “Hardy-Weinberg equilibrium”: Refers to an idealized, non-evolving population.
Natural selection acts on individuals, but only populations evolve. Genetic variations in populations contribute to evolution.
Natural selection is the differential reproductive success of genetic variants and was independently conceived by Charles Darwin and Alfred Russel Wallace.
“Nothing in biology makes sense except in the light of evolution”—Theodosius Dobzhansky.
A virus consists only of nucleic acid, proteins, and sometimes a membranous envelope. After infecting a host cell, it uses the host cell’s molecules to make new viruses
Alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the consequent phenotype. DNA mutations can be positive, negative, or neutral based on the effect or the lack of effect they have on the resulting nucleic acid or protein and the phenotypes that are conferred by the protein.
Embryonic cells become committed to a certain fate (determination), and undergo differentiation, becoming specialized in structure and function for their determined fate. Cells differ in structure and function not because they contain different genomes but because they express different genes.
All organisms, whether prokaryotes or eukaryotes, must regulate which genes are expressed at any given time. Both unicellular organisms and the cells of multicellular organisms continually turn genes on and off in response to signals from their external and internal environments.