GEOG 2000 Lecture Notes - Lecture 5: Heterotroph, Antibody, Speciation

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7 Aug 2016
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Chapter 5 – Evolution and Biodiversity
Chemical evolution- the chemical evolution of the organic molecules, biopolymers, and systems
of chemical reactions needed to form the first cells. This took about 1 billion years
Biological evolution- from single celled prokaryotic bacteria to single celled eukaryotic creatures
and then to multicellular organisms. This has been going on for about 3.7 billion years. This is
the major driving force of adaptation changes in environmental conditions. It is the change in a
population’s genetic makeup through successive generations
Fossil- mineralized or petrified replicas of skeletons, bones teeth, shells, leaves, and seeds, or
impressions of such items
Macroevolution- used to describe how long-term, large-scaled evolutionary changes through
which new species form from ancestral species and other species are lost through extinction
Microevolution- used to describe the small genetic changes that occur in a population
Gene pool- a population’s collection of genes or genetic resources potentially available to
members’ offspring in the next generation
Mutation- genetic variability in a population originates through mutations, which are random
changes in the structure or number of DNA molecules in a cell that can be inherited by offspring
Natural selection- occurs when some individuals of a population have genetically based traits
that increases their chances of survival and their ability to produce offspring with the same traits
Stabilizing natural selection- tends to eliminate individuals on both ends of the genetic spectrum.
This form of natural selection occurs when an environment changes little and most members of
the population are well adapted to that environment
Directional natural selection- in which changing conditions cause allele frequencies to shift so
that individuals at one end of the spectrum become more common. (ex. Insect population
develop resistance to a pesticide)
Diversifying natural selection- also called disruptive selection, occurs when conditions favor
individuals at both ends of the genetic spectrum, at the expense of individuals with intermediate
traits. Can cause a population to split into two groups, possibly providing a pressure toward the
formation of new species
Generalist species- A generalist species is able to thrive in a wide variety of environmental
conditions and can make use of a variety of different resources (for example, a heterotroph with
a varied diet)
Specialist species- A specialist species can only thrive in a narrow range of environmental
conditions or has a limited diet.
Speciation- under certain circumstances, natural selection can lead to an entirely new species. In
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