BS276 Lecture Notes - Genetic Diversity, Natural Selection

• School: University of the Sciences
• Department: Biological Sciences
• Course: BS276

Document Summary

All populations have some genetic diversity, or variability in genomes of individuals; genetic diversity exists because: Random mutations while dna is being copied create new traits. Crossing over in parent chromosomes creates new combinations of genes (and therefore traits) Adaptation: a new trait that increases an organism"s fitness (ability to survive and reproduce) Natural selection: organisms that are better adapted to their environment survive and reproduce more offspring. Individuals with adaptations pass them on to offspring & individuals without adaptations die off, which leads to the entire population having the adaptation over time (evolution) Selective pressure/force: the environmental condition that kills individuals without the adaptation. The environment an organism lives in determines which traits are adaptations. As environments change, different traits may become adaptations & old traits may become disadvantages. Ex. a drought can kill off finches with smaller beaks, making larger beaks for cracking harder seeds an adaptation.