Evolution is change over time

The scientific theory of evolution explains how living things descended from earlier organisms.

What is Evolution?

Think about the whale evolution lab, and the human skull evolution gizmo. What was used to determine how something evolved from something else?

What evidence supports evolution?

1) Fossils2) Similarities in DNA and protein structures3) Similar body structures4) Embryonic development

Fossils

Scientists use fossils to examine:

how well adapted an early human species was for walking upright how well adapted an early human species was for living in hot, tropical habitats or cold, temperate environmentsthe difference between male and female body size, which correlates to aspects of social behaviorhow quickly or slowly children of early human species grew up.  

Homologous Structures

Structures derived from a common ancestral structure (that may or may not be used for the same function in the species in which it occurs) are called homologous structures.

Evidence of Evolution

Similarities in DNA

DNA in our cells reflects each individual’s unique identity and how closely related we are to one another. The same is true for the relationships among organisms. DNA shapes how an organism grows up and the physiology of its blood, bone, and brains.DNA is especially important in the study of evolution. The amount of difference in DNA is a test of the difference between one species and another – and thus how closely or distantly related they are.

Similarities in DNA

While the genetic difference between individual humans today is minuscule – about 0.1%, a difference of 3.1% distinguishes us and the African apes from the Asian great ape, the orangutan.

Similarities in DNA

The strong similarities between humans and the African great apes led Charles Darwin in 1871 to predict that Africa was the likely place where the human lineage branched off from other animals – that is, the place where the common ancestor of chimpanzees, humans, and gorillas once lived. The DNA evidence shows an amazing confirmation of this daring prediction. The African great apes, including humans, have a closer kinship bond with one another than the African apes have with orangutans or other primates. Hardly ever has a scientific prediction so bold, so ‘out there’ for its time, been upheld as the one made in 1871 – that human evolution began in Africa.

Similarities in DNA

The DNA evidence informs this conclusion, and the fossils do, too. Even though Europe and Asia were scoured for early human fossils long before Africa was even thought of, ongoing fossil discoveries confirm that the first 4 million years or so of human evolutionary history took place exclusively on the African continent. It is there that the search continues for fossils at or near the branching point of the chimpanzee and human lineages from our last common ancestor.

Section of Cytochrome c Protein in AnimalsThe table shows the sequence of amino acids in one region of a protein, cytochrome c, for five different animals. Each letter corresponds to a different amino acid in the protein.

Evidence of Evolution

Embryonic development

https://www.youtube.com/watch?v=uAZmLYWEPGk

Scientists infer evolutionary relationships by comparing the early development of different organisms.

Evidence of Evolution

Similarities in DevelopmentThese four organisms all look similar during their early development. What are similarities and differences among them?

Darwin

Darwin hypothesized that species change over many generations and become better adapted to new conditions.

Adaptations are traits, physical or behavioral, that increase an organisms ability to survive and reproduce.

https://app.discoveryeducation.com/search?Ntt=animal+adaptations#selItemsPerPage=20&intCurrentPage=0&No=0&N=18342&Ne=18339&Ntt=animal%2Badaptations&Ns=&Nr=&browseFilter=&Ntk=All&indexVersion=&Ntx=mode%252Bmatchallpartial

Galápagos FinchesThe structure of each bird’s beak is an adaptation to the type of food the bird eats. Match each finch to the type of food you think it eats.

Darwin’s Theory

Natural Selection

The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.Three things cause natural selection:1)Variation2)Competition3)Overproduction

Darwin proposed that, over a long time, natural selection can lead to chance. Helpful variations may accumulate in a species, while unfavorable ones may disappear.

Factors That Affect Natural SelectionWhat are the factors of natural selection that affect a group of sea turtles over time?

Darwin’s Theory

Relate Cause and EffectIdentify the factors that cause natural selection.

Darwin’s Theory

Natural Selection

https://app.discoveryeducation.com/search#Ntt=natural selection&N=18342

Loggerhead Sea Turtle DataDo you think clutch size influences the survival rate of offspring?

Darwin’s Theory

Environmental ChangeWhen copper contaminated the soil surrounding the monkey flowers, the environment changed. What do you think the area will look like in ten years?

Darwin’s Theory

The map shows the ranges of Kaibab and Abert’s squirrels.

A new species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits that prevent reproduction.

Biodiversity and Extinction

What factors affect biodiversity?

1) Area – the larger the area, the more biodiversity

2) Climate – climates with warm temperatures and lots of rainfall are more diverse than cold, dry climates.

3) Genetic diversity – organisms in a healthy population have diverse traits such as color and size. Genetic diversity helps species survive changes in the environment.

4) Niche diversity – coral reefs have many niches, allowing many species to live on them.

Park SizeThe dark green area represents three different park plans. Which plan supports the most bio-diversity?

Biodiversity and Extinction

Biodiversity and Extinction

Extinction usually occurs when a species is unable to adapt within a changing environment.

Different categories:

Endangered

Threatened

Extinction and Human Activities

Extinction is usually a natural process that occurs gradually. Nowadays, scientists believe that human activities are accelerating extinction rates.

decreasing habitat

hunting

climate change

Biodiversity and Extinction

Florida PanthersThis pie chart shows the causes of death for Florida panthers between 1997 and 2007.