First, let’s talk about the word THEORY… How can change in the environment initiate a change in a population? Evolution First, let’s talk about the word THEORY… scientifically acceptable general principle or body of principles offered to explain phenomena

Evidence-Based! Comparative Anatomy/Embryology DNA, Genetics Fossil Record Observable! In nature and in lab NOT a bacterium!

Comparative Anatomy the study of similarities and differences in the anatomy of different species.

Fossil Record Darwin predicted and we have found thousands of transitional forms that link ancestors and current organisms.

Catastrophism Catastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope.  Volcanoes Floods Earthquakes

Observable!!!

Darwin Charles Darwin “The Origin of the Species” Never used the word evolution in the first edition “survival of the fittest” The reproductive success of a genotype

Survival of the Fittest? Example Non Example

Descent with Modification The phrase refers to the view that all organisms are related through descent from an ancestor that lived in the remote past We've defined evolution as descent with modification from a common ancestor, but exactly what has been modified? Evolution only occurs when there is a change in gene frequency within a population over time. These genetic differences are heritable and can be passed on to the next generation — which is what really matters in evolution: long term change. Population: A population is a summation of all the organisms of the same group or species

Descent with Modification Which example illustrates descent with modification — a change in gene frequency over time? The difference in weight in example 1 came about because of environmental influences — the low food supply — not because of a change in the frequency of genes. Therefore, example 1 is not evolution. Because the small body size in this population was not genetically determined, this generation of small-bodied beetles will produce beetles that will grow to normal size if they have a normal food supply. The changing color in example 2 is definitely evolution: these two generations of the same population are genetically different. But how did it happen? https://evolution.berkeley.edu/evolibrary/article/0 _0_0/evo_16

Common Descent Common descent describes how, in evolutionary biology, a group of organisms share a most recent common ancestor.

Common Descent

Mechanisms of Change match the term to the definition Green beetles are easier for birds to spot (and hence, eat). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation. Some individuals from a population of brown beetles might have joined a population of green beetles. A change in a DNA sequence, usually occurring because of errors in replication or repair. Two brown beetles happened to have four offspring survive to reproduce. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation — but just by chance. Mutation Migration Genetic Drift Natural Selection

Natural Selection Definition: The process by which random evolutionary changes are selected for by nature in a consistent, orderly, non-random way.

Genetic Recombination the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring.

Bottleneck Effect bottleneck effect is an ecological phenomenon in which the population of a species is drastically reduced to the point where the species is still able to carry on, but the genetic diversity of the species is severely limited. Bottlenecking event - environmental disaster, the hunting of a species to the point of extinction, or habitat destruction that results in the deaths of organisms.

Gene Flow In population genetics, gene flow is the transfer of genetic variation from one population to another. If the rate of gene flow is high enough, then two populations are considered to have equivalent genetic diversity and therefore effectively a single population. 

Founder Effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

Speciation Extinction the formation of new and distinct species in the course of evolution. Extinction is the disappearance of a species. It usually involves (1) a decrease in population sizes within a species and (2) a decrease in genetic diversity within a species.

https://www.youtube.com/watch?time_continue=15&v=pQp2lFcDEbw