Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches Darwin & Evolution by Natural Selection

Incorrect Theories of Evolution: Lamarck Lamarck proposed an incorrect mechanism for how organisms evolve. –Believed organisms could pass on aquired traits to offspring –Simple life forms continually came into existence from dead matter –Continually become more complex –More "perfect" -- as they transformed into new species. He correctly pointed out that change in species is linked to an organism’s environment.

Charles Darwin Proposed a way how evolution works –How did creatures change over time? –by natural selection Collected a lot of evidence to support his ideas – –British naturalist –-Wrote the Origin of Species

Robert Fitzroy Voyage of the HMS Beagle Invited to travel around the world – (22 years old!) –makes many observations of nature main mission of the Beagle was to chart South American coastline

Voyage of the HMS Beagle Stopped in Galapagos Islands –500 miles off coast of Ecuador

Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. 800 km west of Ecuador

Darwin’s Observations Animals on the coast of S. America: – Resembled those on the nearby islands –Evolved differences Or –Descended w/ modification after separating from a common ancestor.

Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands? Darwin found…many unique species

present day Armadillos Darwin found: that creatures have changed over time Evidence that creatures have changed over time ancient Armadillo Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent? Darwin found…clues in the fossils

present day Sloth Darwin found… more fossils Darwin asked: Why should extinct sloths & modern sloths be found on the same continent? (extinct) Giant ground sloth Darwin found: that creatures have changed over time Evidence that creatures have changed over time

Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

Darwin was amazed to find out: All 14 species of birds were finches… Finch?Sparrow? Woodpecker? Warbler? Finch?Sparrow? Woodpecker? Warbler? But Darwin found… a lot of finches Large ground finch Small ground finch Warbler finchTree finch But there is only one species of finch on the mainland! Darwin asked: If the Galapagos finches came from the mainland, why are they so different now?

Finch?Sparrow? Woodpecker? Warbler? The finches cinched it! Large ground finch Small ground finch Warbler finchTree finch Big seed eaterSmall seed eater Insect eaterLeaf & bud eater Darwin said: Ahaaaa! A flock of South American finches were stranded on the Galapagos… Darwin found: The differences between species of finches were associated with the different food they ate. different beaks are inherited variations serve as adaptations that help birds compete for food these birds survive & reproduce pass on the genes for those more fit beaks over time nature selected for different species with different beaks

Relationship between species (beaks) & food

Darwin’s finches Darwin’s conclusions –variations in beaks differences in beaks in the original flock adaptations to foods available on islands –natural selection for most fit over many generations, the finches were selected for specific beaks & behaviors –offspring inherit successful traits accumulation of winning traits: both beaks & behaviors –separate into different species

Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous tree finch Vegetarian tree finch Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground finch Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches variation natural selection for best survival & reproduction From 1 species to 14 species…

Growth of Populations Darwin was influenced by Thomas Malthus He wrote: Populations grow as much as the environment allows.

Evolution by Natural Selection The process of: Survival of the Fittest “Survival of the Fittest” Organisms that adapt to their environment survive while those that do not adapt disappear adaptationsN.S. leads to adaptations in a population.

ADAPTATIONS LEAD TO FITNESS Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce.  An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and reproduce.  YOU CANNOT AQUIRE AN ADAPTATION, MUST BE AN INHERITED TRAIT.

Label Paper: 1.Genetic Variation a. b. 2.Overproduction of Offspring a. b. 3.Struggle for Existence a. b. 4.Differential Survival & Reproduction a. b. Natural Selection Video ution/library/11/2/e_s_4.html 6 min 39 sec

SUMMARY: Individuals best suited to their environment survive and reproduce most successfully. The characteristic that make them best suited to their environment are passed on to offspring. Individuals whose characteristics are not as well suited to their environment die or leave fewer offspring.

Species change over time. This is natural selection. Over long periods of time, natural selection causes changes in the characteristics of a species, such as in shape and form. New species arise, and other species disappear.

African wild dog These five canine species evolved from a common ancestor through natural selection Fox Thousands to millions of years of natural selection Wolf Ancestral canine Coyote Jackal Fox Species alive today have descended with modifications form species that lived in the past.

Darwin’s Ideas Updated 1) Change Within Populations N.S. causes the frequency of certain alleles in a population to change over time. 2) Species Formation Under certain conditions, change within a species due to reproductive isolation can lead to new species. 3) The Tempo of Evolution Gradualism is a process of evolution in which speciation occurs gradually Punctuated Equilibrium is a process in which speciation occurs rapidly between periods of little or no change.

Natural Selection at Work Examples of Evolution-- 1) Factors in Natural Selection Organisms w/traits helping them survive— reproduce & pass genes. 2) Evolution of Antibiotic Resistance Experiments show that evolution through N.S. has occurred within populations of antibiotic-resistant bacteria –Tuberculosis bacteria 3) Evolution in Darwin’s Finches Experiments show that evolution through N.S. has occurred in beak size in Darwin’s Finches.

Speciation 1) Speciation Speciation begins as a population adapts to its environment. 2) Forming Subspecies subspeciesPopulations of the same species that differ genetically b/c of adaptations to different living conditions are called: subspecies. Newly formed subspecies are on the road towards speciation. 3) Maintaining New Species Reproductive isolation through barriers keeps species from breeding with one another. Formation of New Species

Speciation Geographic isolationGeographic isolation of populations Can lead to Reproductive isolation of population Can lead to New Species (unable to breed when together)

Geographic Isolation Members of a population may become isolated from one another by geographic boundaries like mountains, rivers or even oceans

Reproductive Isolation

Convergent Evolution

Divergent Evolution (Adaptive Radiation)

Dichotomous Keys Tool used when new species is found Used to categorize different species based on physical characteristics Classification Classification is a way of separating a large group of closely related organisms into smaller subgroups. A Dichotomous Key is a listing of characteristics, such as structure and behavior, organized in such a way that an organism can be identified or classified.