FORS2355 Vertebrate Natural History -- Lecture 1 (August 23, 2021)
occurring in all habitats on Earth and in wide range of sizes, shapes, etc.
Diversity -- Historical changes in environmental conditions ave caused changes in ancestral forms of organisms. More than 1 type of descendent (some better adapted to certain environments).
Evolution -- Descent with modification (Darwin's definition); change in gene frequencies in a population over time. Rate of evolution can be fast or slow.
Fast Evolution -- also known as "contemporary evolution" (within generations). Does not occur in linear fashion but rather in a branching network and sharing common ancestors. o Linear Fashion -- it is a progression from primitive to advanced.
Gene - A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.
Mechanisms of Evolution:
Mutation -- changes in DNA sequence. Meiotic Drive -- segregation distortion during meiosis. Gene Flow -- migration into new population = new material. Genetic Drif -- Random shifts in gene frequencies. Natural Selection - differential reproductive success; some traits are more adaptive which
The environmental changes: Pangea is a dynamic system. O Organisms produce far more offspring than are capable of surviving. Some offspring have traits that are better suited for the current environmental conditions than others. Offspring are better adapted to current environmental conditions will survive to reproduction (passes genes to future generations).
PANGEA
Unit of selection: Individual which has a genotype and manifests itself as a phenotype. Selection determines if it will survive or not (survives and successfully reproduces). Unit of evolution -- population. Population -- group of individuals of same species that have the potential to interbreed. Change in gene frequencies overtime.
Individuals do not evolve but a populati