theory of evolution
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Theory of Evolution. Chapter 15. Idea of Evolution. Charles Darwin (1809-1882) English naturalist Took a trip around the world on a ship called H.M.S. Beagle Mostly fascinated with the Galapagos Islands Best known for his theory of evolution by natural selection. Idea of Evolution. - PowerPoint PPT PresentationTRANSCRIPT
Idea of Evolution
Charles Darwin (1809-1882) English naturalist Took a trip around the world on a ship called
H.M.S. Beagle Mostly fascinated with the Galapagos Islands Best known for his theory of evolution by
natural selection
Idea of Evolution
Galapagos Islands Groups of animals vary from island to island
Ex: tortoises on each island resemble each other but differ in the shape and function of their shells
Ex: finches on each island resembled each other but differ in the shape and function of their beaks
Darwin believed these unique animals all came from a common ancestor and they changed/adapted to their environment
Idea of Evolution
Evolution Development of new types of organisms over
time Heritable change in the characteristics within
a population from one generation to the next
Ideas of Darwin’s Time
Scientists thought all species were permanent and unchanging
The Earth was believed to only be a few thousand (not billions) of years old
Charles Lyell was a English geologist that believed the Earth’s surface continues to change Influenced Darwin
Ideas of Darwin’s Time Jean-Baptiste Lamarck
French biologist that supported the idea that populations of organisms change over time
Also believed in biogenesis of simple organisms
Proposed that individuals acquire traits during lifetime from behavior and pass them onto offspring Called Theory of Acquired Traits
Darwin’s Ideas Around the same time Darwin and Wallace
formed theory to explain evolution
Published book On the Origin of Species in 1858 Book explained how evolution occurs by
means of natural selection
Descent with Modification Idea that every species must have
descended by reproduction from pre-existing species that arrange over time Ex: finch beaks at Galapagos
Natural Selection
Mechanism from descent with modification 1. Overproduction
More offspring are produced than survive to maturity
2. Genetic variation Traits vary within a
species Ex: deer fur
thickness is passed on to future offspring
Natural Selection (cont’d) 3. Struggle to survive
Organisms need to compete with each other known as “struggle for existence”
When an organism is successful in a new environment its called an adaptation
4. Differential Reproduction Organisms best
adapted for an environment will survive best and reproduce
Survival of the fittest The ability for an
organism to reproduce and pass on adaptations
The Fossil Record
Fossils Remains of an organism
that died long ago Some are remains of
extinct organisms, meaning the species is no longer alive
Superposition Idea that strata form in
layers where the layers closest to the top are the younger than below
The Fossil Record Relative Age
Age compared to other fossils in order of old to young
Absolute Age Using radiometric dating to get actual number age
The Fossil Record
Scientists use these relative and absolute ages to try and make the history of life on Earth as precise as possible
Fossil records are incomplete history because not all organisms have left fossils behind Fossils can easily be
destroyed during the process Finding fossils is rare also
Transitional Species We can infer that species have gradually
changed based on the fossil record Scientists have hypothesized ancestors and later
descendant species
Organisms with features that are between hypothesized ancestors
Biogeography Study of locations of organisms around the
world
Darwin used this method when exploring islands and observed animals variation based on environment
Anatomy and Embryology
Anatomy: study of the body
Embryology: study of development
Homologous structures Anatomical structures that
originated by heredity from a structure in most common ancestor Ex: bones in arms of humans,
penguins, alligator and bat Related structure but function
may differ
Anatomy and Embryology
Analogous Structures When structures have
similar function, but did not develop the same way Ex: wings of bat vs.
bird
Vestigial Structures Organs that no longer
serve a function in an organism
Ex: human tail bone, appendix
Phylogeny
Relationships among groups of organisms
Can make a “tree” of animals evolved Trunk of the tree would
represent species that are closely related
Branches represent a separate population or lineage
Caribbean Anole Lizard
Found in the Caribbean islands of Cuba, Hispaniola, Jamaica, and Puerto Rico Each lizard species body type differs by their habitat
Ex: stocky body and long legged lizards are best adapted for tree truck environments, slender bodies and long tails are best adapted for grassy environments
Hypothesis #1: An ancestral anole species specialized for living on twigs originally lived on one island and later migrated to other islands
OR
Hypothesis #2: Each twig-dwelling species evolved independently on each island from distant ancestor anole species
Evolution in Action
Biologists tested the hypothesis by comparing DNA from the various species DNA evidence supported hypothesis 2 that
each lizard evolved independently on each island
Convergent Evolution Process by which different species
evolve similar traits Ex: sugar glider of Australia and flying
squirrel of North America came from different ancestors but evolved similar adaptations to their environment
Divergence & Radiation Divergence evolution
Process by which the descendants of a single ancestor diversify into species that each fit different parts of the environment Ex: lizards with genes for large toe pads and
short legs ran slowly on the tree trunks and fell easily to predators, lizards with long legs and small toe pads were able to slip away and reproduce
Divergence & Radiation
Adaptive Radiation Pattern of variation when a new population in
a new environment undergoes divergent evolution
Artificial Selection Process the occurs when
human breeders choose individuals that will parent the next generation Ex: faster greyhounds, smaller
tea cup dogs, high milk yield cows, high yielding grain per stalk
Darwin hypothesized domesticated dogs diverged from wolves DNA evidence indicated
similarities with wolves in East Asia, supporting Darwin’s hypothesis and humans selected domestic dogs from wolf population 15,000 years ago
Coevolution
Evolution is on-going and many species may evolve together
Coevolution When two or more species have evolved
adaptations to each other’s influence
Predator/Prey Interactions
Introduction of new species
Creating antibiotics