Evolution of Living Things

How do new species form? P. 145

What type of environment is more likely to contribute to evolution?

A stable environment where member of a species do not vary

A changing environment where members of a species vary

Warm-up Tuesday

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

Terms to know:

Skunk’s have evolved an adaptation to produce an awful scent to ward off predators

Enormous eyes and padded digits are adaptations that have evolved in the tarsisus, a nocturnal primate of the rain forests in Southeast Asia

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

Penguin Adaptations

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…

Species on Earth..

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

Do Species Change Over Time?

A theory is an explanation that is developed using scientific methods

Theory

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

Evidence which supports Evolutionary relationships (Change over time)

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

Fossil Records

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

Comparative Embryology-scientists compare embryos of different organisms; more similar at start means we may share a common ancestor

Comparative Anatomy-scientists compare the anatomy of related organisms, and thus conclude similarities among them means they may share a common ancestor

Scientists can also compare the DNA of different organisms to see determine how related to each other they are

Comparative DNA

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.

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“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

Darwin Darwin Darwin

The Galapagos Islands are located just west of Ecuador in South America.

Giant Tortoise of the Galapagos

Galapagos iguanas have evolved long claws which help them maintain their grip on slippery rocks while searching for food.

Darwin studied the varying beak shapes among the 13 different species of finches on the Galapagos Island. All these species is thought to be descendants of an ancestral finch species and are thought to have diverged in character to inhabit the different ecological niches available on the island P. 315 figure 4

Adaptive radiation is when species deriving all from a common ancestor have over time successfully adapted to their environment via natural selection.

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

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

Important Points of Natural Selection

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

Four Parts to Natural Selection- see p.310 Figure 6

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?

Warm-up…..

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

Forming a New Species

Reproductive Isolation can lead to different species over

time. Assume a population of fruit flies becomes separated from its members on the mainland.

The fruit flies now on this island begin to develop interest in a particular type of fruit, a fruit that was not abundant on the mainland.

If the flies find mates by hanging out on preferred foods, then if they return to the mainland, they will not end up mating with the mainland flies because of this different food prefernce. Gene flow would be greatly reduced; and once gene flow is reduced or stopped, larger genetic differences between the species will accumualte

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

Factors which lead to evolution of a population

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

Where did we come from?

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

Taxonomy

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?

Why Classify?

Branching Diagrams

Branching diagrams show which characteristics organisms share and when these organisms

evolved

Kingdom Phylum Class Order Family Genus SpeciesTip to remember the order: King Phillip Came

Over For Good Supper.

Levels of Organization

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”.

Classification of Humans

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

Scientific Classification of Rabbits

Vertebrates- animals with a backbone

Invertebrates-animals which lack a backbone

Kingdom Animalia

Kingdom Protista

Kingdom Bacteria