Unit 7: Evolution and Classification. Opening Assignment What is evolution? What is an adaptation?

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Unit 7: Evolution and Classification

Transcript of Unit 7: Evolution and Classification. Opening Assignment What is evolution? What is an adaptation?

Unit 7: Evolution and Classification

Opening Assignment

What is evolution?

What is an adaptation?

Charles Darwin 19th century English naturalist

developed a theory on how evolution works

studied on the Galapagos Islands because each island had different environments

wrote On the Origin of Species

Darwin’s Theory Species evolve from a common ancestor

Variation – slight difference in an inherited trait of individual members of a species occurs as a result of mutations during sexual

reproduction

Natural Selection "Survival of the Fittest” organisms with variations that help them

survive, live longer and are therefore able to reproduce to pass on those variations ex. tortoises with longer necks will survive

longer than tortoises with short necks if the food sources are up high

Adaptations an inherited trait that increases an

organism’s chance of surviving and reproducing in its environment

3 Types of Adaptations Structural – involve

physical characteristics ex. coloration, shape

Behavioral – involves the way an organism acts ex. hunting at night,

moving in herds

Functional – involve internal body systems ex. hibernation,

temperature regulation

Environmental Interactions

Camouflage

an adaptation that enables a species to blend in with its environment

Mimicry the resemblance of

one species to another species

What is our evidence of Evolution?

Comparative Anatomy the study of similarities and differences

among structures of living species

Homologous Structures – body parts of organisms that are similar in structure, but different in function

Analogous Structures - body parts that perform a similar function, but differ in structure ex. bird wings and insect wings

Vestigial Structures body parts that have lost their original

function through evolution

shows that the structures served a purpose at one point, but now are no longer needed ex. cormorant wings, whale pelvic bones

Developmental Biology Embryology – study of embryos from

fertilization to birth

Molecular Biology Scientists can use DNA to show how closely

related organisms are

Divergence – the point at which an organism breaks away from its common ancestor

The Fossil Record The Fossil Record – made up of all the fossils

ever discovered on Earth provides evidence that species have changed over

time

Fossil – the remains or evidence of once-living organisms

Fossil Formation Mineralization

minerals in water replace the organism’s original material and harden into rock

Carbonization extreme pressure drives

off the organism’s liquids and gases leaving only the carbon outline

Fossil Formation Molds and Casts

Mold – impression of an organism in hardened mud or sand

Cast – a fossil copy of an organism in a rock created by sediment filling in the mold

Fossil Formation Trace Fossils

preserved evidence of the organism’s activity, like footprints

Original Material original tissues of an

organism, like insects in amber (tree sap)

Relative-Age vs. Absolute-Age

Relative-Age – scientists determine the relative order in which rock layers were deposited( Most Accurate when the rock layers are undisturbed.) Law of Superposition – things on the top are the youngest

and things on the bottom are the oldest.

Absolute-Age (Radioactive Dating)– scientists use the ratio of unstable isotopes to stable isotopes to find the age of rocks; more precise ex. carbon-14 dating

Add these to notes

The Geologic Time Scale a chart that divides Earth’s history

into different time units

Extinctions Extinction – occurs when last

individual organism of a species dies Mass Extinction

when many species become extinct within a few million years or less

there have been 5 mass extinctions in the Phanerozoic eon

Causes of Extinction Sudden change – like meteor

impact or volcanic eruption Gradual change – like tectonic

plates or sea level changes

Biological Evolution the change over time in populations

of related organisms

The immediate ancestors of humans were members of the genus Australopithecus .  The australopithecines (or australopiths) were intermediate between apes and people.  Both australopithecines and humans are biologically similar enough to be classified as members of the same biological tribe--the Hominini .  All people, past and present, along with the australopithecines are hominins .  We share in common not only the fact that we evolved from the same ape ancestors in Africa but that both genera are habitually bipedal , or two-footed, upright walkers.  By comparison, chimpanzees, bonobos, and gorillas are primarily quadrupedal , or four-footed. 

Which of the following correctly describes the general trend in hominid evolution?

A. larger body size, broad forehead, smaller brains

B. increase in brain capacity, bipedalism, use of tools

C. thickening of the skull, protruding teeth, organized hunting

D. large canine teeth, small skulls, diet of coarse plant material

Biogeography is the study of the location of organisms around the world. Which of the following best explains how biogeography can provide evidence for evolution?

A. It shows that organisms have structures that serve no purpose but that resemble structural roles in related organisms.

B. It shows that there are similarities and differences among the DNA of different species.

C. It shows that organisms have changed gradually over millions of years.

D. It shows that some organisms that are unrelated have developed similar adaptations to similar environments.

In his trips to the Galapagos Islands, Charles Darwin observed that 4 of the 13 species of the islands' finches have beaks adapted to eating specific foods. Which best explains how these facts provide evidence for divergent evolution?

A. The finches were different species but resemble each other because of how they evolved in a similar environment.

B. The finches descended from similar ancestors and have evolved adaptations in response to each other's influences.

C. The finches descended from the same ancestor but evolved along their own lines in isolation from each other.

D. The finches descended from a common ancestor but evolved differently in response to their environment.

Opening Assignment

Why do scientists classify things?

What are the 8 levels of classification?

Classifying Organisms

Unit 7 – Evolution and Classification Part 2

Classification- putting things into groups based on shared characteristics

There have been many different ideas about how to classify living things.

Aristotle placed all organisms into 2 large groups- plants and animals

Linnaeus’ System Linnaeus founded modern

taxonomy.

Taxonomy- the science of describing , classifying , and naming living things

Based on 7 hierarchical categories

Simplified the naming of living things by giving each species a two-part specific name “Binomial nomenclature”

Binomial Nomenclature

Felis domesticus

Genus Species

In a scientific name, the first part of the name is the organism’s genus. Similar species are grouped into one genus. Ex: Felis

The second part of the name identifies the species- a group of organisms that have similar traits and are able to produce fertile offspring.

Binomial Nomenclature

Panthera tigris Panthera leo

Classification TodayTaxonomists use an eight-

level system to classify living things based on shared characteristics.

The more characteristics the organisms share, the more closely related the organisms may be.

Levels Of Classification

Domain KingdomPhylumClassOrderFamilyGenusSpecies

DOMAINS Every living thing is classified into one of

the 3 Domains:

1. Archaea2. Bacteria3. Eukarya

DOMAIN 1: ARCHAEA ARCHAEBACTERIA

Unicellular prokaryotes

Often live in harsh environments

some produce food by chemosynthesis (energy obtained from places other than the sun)

DOMAIN 3: EUKARYA EUKARYOTES

Complex cells; nuclei and organelles in cells

Some are unicellular Some are multicellular

The domain Eukarya is divided into 4 Kingdoms:1. Protista2. Fungi3. Plantae4. Animalia

Domain Eukarya: Kingdom Protista

One celled or Multicellular organisms that can either be plant-like, animal like, or both

Algae, Amoebas, Paramecium , Euglena

Domain Eukarya: Kingdom Fungi Multicellular Cell wall Does not perform

photosynthesis Absorbs nutrients Reproduce using spores.

Domain Eukarya: Kingdom Plantae Cell wall Perform photosynthesis Vascular vs. nonvascular Flowering vs.

nonflowering

Domain Eukarya: Kingdom Animalia Multi-cellular organisms that lack

cell walls

Range from simple to complex

Invertebrates- Do not have a backbone Worms Sponges Jelly Fish Mollusks Insects

Vertebrates – Have a backbone Fish Amphibians Reptiles Birds Mammals

Classification Tools

Dichotomous KeyA series of descriptions arranged

in pairs that can be used to identify an unknown organism

The chosen descriptions leads to another pair of descriptions or to the identification of the organism

Dichotomous Key

Cladogram A branched diagram that shows the relationships

among organisms

New characteristics appear before each branch