GEOG 125 Lecture Notes - Lecture 3: Biocoenosis, Genetic Variation, Ecosystem Diversity
Document Summary
Compressing earths geological history into a 24hour day would mean humans have existed on the planet for 2 seconds. Genetic change in population of organisms across generations. Mechanism by which the frequency of traits change in a population. Mutations = accidental changes in dna that may be passed on to the next generation. Phenotype = observable expressions of an organisms genotype. Lamarch 1801) had earlier propose evolution by acquired characteristics. This idea still has herit in terms of behavioural change and cultural evolution. Organisms differ in their tolerance for variation i the limiting factors in their environment. Evidence of natural selection is all around us. If the environment changes, a trait may no longer be adaptive. Allopatric speciation; due to physical separation of populations. Sympatric speciation; organisms become reproductively isolated within same general geographic range. Habitat directs diversity of species in a biotic community. Minimization of niche overlap increases diversity in biotic communities.
