Micro-Evolution Flashcards
Species
A species is a group of living organisms that are capable of interbreeding and producing fertile offspring
Population
a group of organisms of the same species living in the same area at the same time
Discontinuous variation
Discontinuous/discrete variation is variation in phenotypic traits in which types are grouped into discrete categories with few or no intermediate phenotypes. Typically these are single allele characteristics.
A bar graph is used to represent discontinuous variation.
Continuous variation
Continuous variation is variation that has no limit on the value that can occur within a population typically multiple allele characteristics.
A line graph or histogram is used to represent continuous variation.
LAMARCKISM
Lamarckism is the idea that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime. It is also called the inheritance of acquired characteristics. Lamarck thought that organisms had an internal driving force to strive for complexity and perfection.
Law of “Use and Disuse”
Lamarck’s idea that the use or disuse of organs may cause the organs to increase or decrease in size or even disappear. In this way organisms acquire certain characteristics.
Inheritance of acquired characteristics:
Lamarck’s idea that during their lifetime, the acquired changes in characteristics are subsequently inherited by their offspring. These changes result in changes in populations and the formation of new species.
ARTIFICIAL SELECTION
Deliberate breeding of organisms to get desired characteristics that would not necessarily benefit the survival of the offspring in the wild. Humans select the desired characteristics and therefore serve as the environment e.g. sheep for wool, horses for strength and speed, and wheat for yield.
Similarities between natural selection and artificial selection
Variation exists in a particular population,
that variation is inherited from parents to offspring,
and the populations change over time with certain characteristics becoming more frequent.
Differences between natural selection and artificial selection
With natural selection, the environment acts as the selective pressure whereas artificial selection has humans determining selected traits.
With natural selection, the selected traits are advantageous in the environment whereas artificial selection selects traits that are not necessarily advantageous for survival in the wild.
Natural selection usually maintains or increases variation whereas artificial selection generally decreases variation in a population through inbreeding.
