Patterns of Evolution Evolution Notes Part 3

What is microevolution? Evolution on a small scale within a single population

Natural selection is a mechanism for changes in populations that occurs when organisms with favorable variations survive, reproduce, and pass on traits to the next generation. Artificial selection is the breeding of certain traits over others.

Speciation What causes new species to form? Reproductive isolation – when populations are prevented in some way from reproducing with each other , their gene pools adapt and evolve separately, causing them to lose the ability to cross breed 4

Reproductive Isolation What causes reproductive isolation? Geographic isolation – mountains, rivers, canyons Temporal isolation – active or reproducing at different times of day or times of year Behavioral isolation – differences in mating rituals that prevent reproduction between groups 5

Anatomical Some adaptations involve changes in the structure of body parts: mimicry and camouflage. Mimicry enables an organism to copy the appearance of another species.

MIMICRY

Milk Snake Coral Snake

Anatomical Some adaptations involve changes in the structure of body parts: mimicry and camouflage. Camouflage is a structural adaptation that enables an organism to blend in with its surroundings.

CAMOUFLAGE

Physiological Adaptations Some adaptations are physiological or changes in an organisms metabolic processes. Keep in mind that all things are made up of cells and the organelles are structurally and functionally similar in most organisms.

Physiological Adaptations Organisms are constantly changing to adapt to their environment. Take a look at organisms that have been exposed to antibiotic and pesticides. The organisms that survive have become selected because they are physiologically more resistant.

Imagine that there are 10 bacteria growing on your hand.

You use Germ-x to clean your hand everyday.

After 4 days, there are still 3 bacteria on your hands that have survived.

Is there anything special about these bacteria. Yes Is there anything special about these bacteria? Yes..they have something about their DNA that has made them different and strong enough to survive. So now what will happen?

Those 3 that are “resistant” will undergo Mitosis.

And after a week, your hands will be covered with tons of bacteria that are ALL resistant to Germ-X. 

Macroevolution What is microevolution? What is macroevolution? Large scale evolutionary patterns and processes occurring over long periods of time Transcends the boundaries of a single species

Macroevolution What are the important topics in macroevolution? Extinction Adaptive radiation Convergent evolution Coevolution Punctuated equilibrium Changes in developmental genes

Extinction Why is extinction important? Several times in Earth’s history, mass extinctions wiped out ecosystems During these events, many species became extinct Other species took advantage of ecological opportunities as habitats opened up This produced a burst of evolution

Adaptive Radiation What is adaptive radiation? When a single species or group of species evolve through natural selection into diverse forms that live in different ways

Adaptive Radiation What are some examples? Darwin’s finches Wild mustard variations

Convergent Evolution What is convergent evolution? What are some examples? Unrelated organisms in similar environments evolve to look remarkably similar to each other Similarities between Australian marsupials and placental mammals Similarity in form between dolphins and sharks

Coevolution What is coevolution? What are some examples? Two species evolve in response to changes in each other over time Plants develop pollination methods that take advantage of insect feeding adaptations, and vice versa

Punctuated Equilibrium What is punctuated equilibrium? “Rapid” evolution after long periods of equilibrium – often occurs due to isolated populations, migrations, or mass extinctions

Developmental Genes What is meant by changes in developmental genes? Homologous control genes serve similar functions in animals that have not shared a common ancestor in millions of years

What should I believe? Although evolution is widely accepted by scientists and had broad supporting evidence, it is still a theory Remember, theories are well-supported testable explanations of phenomena that have occurred in the natural world There are differences of opinion about interpretation and every person is entitled to his or her own opinion – the experts are not always objective Our goal is to present the prevailing view and allow you to reach your own conclusions Remember that everyone is entitled to their own opinion – yours is no more right nor wrong than anyone else’s