Transcript Evolution of Living Things
Species- a group of organisms that can mate and produce fertile offspring Population- all the members of a particular species living in a given area Adaptation- a characteristic that helps an organism survive and reproduce in its environment; it can be a behavior that helps the organism find food, protect itself, or survive, or it can be physical trait like striped fur, or long claws
Penguin Adaptations
Their wings, shaped like flippers, help them “fly” under water at speeds of 15mph Heavy, solid bones act like a divers belt, allowing them to stay under water Blubber for warmth Tightly packed feathers for waterproofing They coat their tails with oil to increase impermeability
In a single square mile of rain forest there may be dozens of species of frogs Across Earth, there are millions of different species of organisms The species that live on Earth range from single celled bacteria to multi-cellular plants, fungi and animals 99.9% of all species that have lived on Earth are extinct today!!
Prokaryotes (bacteria) are the oldest living things on Earth..they have been around about 3.5 billion years!
How old is Earth again? Raise your hand to tell me…
Scientists observe that, yes, species can change over time, but it takes lots of time for change to occur They also observe that the inherited characteristics in population change over time Scientists think that when populations change over time, new species may form So newer species descend from older species The process in which populations change over time is called evolution
Comparing DNA, scientists can determine which organisms are closely related The greater the number of similarities between the DNA of any two species, the more recently the two species shared a common ancestor
By examining the fossil record, scientists can learn about the history of life on earth The fossils in Earth’s newer layers of rock tend to be similar to present-day organisms This indicates that they were close relatives to modern organisms The fossils in older rocks are less similar to present day organisms Comparing organisms in the fossil record provides evidence for how organisms have changed over time
FOSSILS FORM WHEN A DEAD ORGANISM IS COVERED BY A LAYER OF SEDIMENT. OVER TIME, MORE SEDIMENT FORMS ON TOP OF THE ORGANISM’S REMAINS.
MINERALS IN THE SEDIMENT SEEP INTO THE ORGANISM AND GRADUALLY REPLACE IT WITH STONE. IF THE ORGANISM ROTS AWAY COMPLETELY AFTER BEING COVERED, IT MAY LEAVE AN IMPRINT
In 1835, Charles Darwin, a naturalist, set out on a ship called the Beagle, to study the animals and plants on the Galapagos Islands Darwin was interested in the laws of life.
He left medical school because of his disgust with blood, to follow his true passion- studying plants and animals
Darwin wrote a book called The Origin of Species to describe his theory of evolution. It was based largely on observations he made on his 5 year voyage around the world on the HMS Beagle .
“Science was obviously not a profession to Darwin…it was a necessity to sustain his mind, just as the food he ate and the air he breathed…” Theodosius Dobzhansky
P. 315 figure 4
The finches previously occupied the South American mainland, but somehow managed to occupy the Galapagos Islands some 600 miles away They occupied an ecological niche with little competition As the population began to flourish in these advantageous conditions, intraspecific competition became a factor, and the resources on the island became squeezed and could not sustain the population very long
As competition increased, the finches found new ecological niches that would present them with less competition and allow them, and their genome to be continued The finches adapted to the different food sources on the island and over time became very different from their original ancestors
Darwin, after years of studying animals in their natural habitat, theorized that the organisms with the more adaptable traits are likely to survive and reproduce than those with less adaptable traits, especially in a competitive environment, this over time led to evolution of species.
Natural selection acts on the phenotypes of individuals The individuals with the more desirable or adaptable traits will be more likely to survive and reproduce The less desirable traits, or phenotypes, are more likely to disappear and leave the gene pool Once the phenotype is no longer in the gene pool, it is lost
Overproduction-Typically, in nature more young are produced than will survive Inherited variations- every individual has its own combination of traits, similar but different to their parents and to other members of their species Struggle to survive-competition among resources and the threat of predators, lead to the “survival of the fittest” among organisms Successful Reproduction-the individuals that are better adapted to their environment are more likely to survive and reproduce
A species of bright colored guppies live on a coast of South America. The female guppies prefer to mate with the bright colored male guppies. You see many bright colored male guppies in the shallow waters there, but few in the deeper waters. Why do you think that might be?
What trait is natural selection acting on in this situation?
A species is a group of organisms that are closely related and can mate to produce fertile offspring A group of species living in a particular area is called a population
Sometimes drastic changes can form a new species A new species may form after a group becomes separated from the original population Over time both populations evolve different adaptations The two populations differ so greatly that they no longer mate successfully The new population may be considered a new species
A species of brown and white moths blend in to the trees in the area they populate. The brown moths blend in to the trees which are the same shade of brown as the moths, making them harder for predators to see. The white moths are easier for predators to spot, since they stick out more on the brown trees.
Which moths is this situation has an adaptation that will make them more likely to survive and reproduce?
In time, which color moths might you see less of? Why?
Why is natural selection called survival of the fittest?
Non- random mating Mutations (rare, but do occur) Environments that are rapidly changing Environments in which individuals among the species have genetic differences
Humans did not evolve from monkeys. Humans are more closely related to apes, but we didn’t evolve from them either Humans share a common ancestor with modern African apes, like gorillas and chimpanzees Scientists believe this common ancestor existed between 5-8 million years ago The species diverged into two separate lineages, one evolved to become gorilla and apes, the other to become early humans, hominids
Taxonomy is the science that involves classifying living things; developed by Carolus Linnaeus in 1750 The general idea is to give two names to for an animal, a genus and a species, a general and a specific name, plus other levels of classification
Classifying living things allows biologists to answer questions, such as: What are defining characteristics of each species?
When did characteristics of an organism evolve?
What are relationships between various species?
Branching Diagrams Branching diagrams show which characteristics organisms share and when these organisms evolved
Kingdom Phylum Class Order Family Genus Species Tip to remember the order: King Phillip Came Over For Good Supper.
Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo Species sapiens Homo sapiens (the genus name is always capital and the species name is always lower case) Homo meaning “man”, and sapiens meaning “wise”.
Kingdom Animalia Phylum Chordata (animals with a backbone) Class Mammalia (breast-feeding animals) Order Lagamorpha (rabbits, hares, pikas) Family Leporidae (rabbits and hares) Genus Orytcolagus Species Cuniculus Lago is Greek for rabbit; lepus is Latin for hare;cuniculus is Latin for rabbit
Vertebrates animals with a backbone