Biology - Evolution

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Evolution

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Process by which modern organisms have descended from ancient organisms

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Charles Darwin

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Contributed most to understanding of evolution than anyone else, "Father of Evolution."

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Fitness

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Physical traits and behaviors enabling organisms to survive and reproduce in their environment

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Common Descent

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The principle that all species have shared or have common ancestors.

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Adaptation

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Fitness arises through this process. Inherited characteristics that increases an animal/plant's fitness for survival.

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Fossils

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Preserved remains of ancient organisms.

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Half-life

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Rate of radioactive decay

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Radioactive Dating

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Enables calculation of age of a sample through traces of radioactive isotopes.

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Eras

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Division created by scientists of the 4.5 billion years of the Earth.

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Periods

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Further division of eras.

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Epochs

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Further division of periods.

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Similarities in Early Development

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Vertebrate embryos show that similar genes are at work (body plan - head, tail, right and left, positioning of limbs are all similar)

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Similarities in Body Structure

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Limbs of each type of species based on same pattern of bones

(ex: arms, wings, legs, flippers)

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Homologous Structures

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Structures that have adapted to help organisms survive that developed from the same body parts

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Vestigial Organs

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Traces of similar organs in other species. Clue to animal's evolutionary ancestry.

(ex: Humans have a set of miniature tailbones at the base of the spine but no tail.

or

Snakes developed from four-legged ancestors. All that's left from them are the tiny bones)

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Similarities in Chemical Compounds

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i. Similar energy carriers in all living systems (ex: ATP)

ii. RNA and DNA similar in structure between different species.

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What Homologies Tell Us

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Living organisms evolved through gradual modification of an earlier form - descent from a common ancestor.

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Early Evolutionists/Helped Darwin with Theory

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1. Lamarck - first to recognize living things changed over time

2. Lyell - demonstrated the old age of the Earth and how it's changed

3. Malthus - observed that the only way to prevent endless growth of human population is famine, disease, and war.

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Lamarck's Ideas

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i. DESIRE TO CHANGE - organisms can change because of their inborn urge to better themselves and improve fitness for environment

ii. USE AND DISUSE - organs could increase in size, change in shape depending on needs of organisms or decrease size/disappear (ex: birds could transform limbs into wings if done enough, can go away if not)

iii. PASSING ON ACQUIRED TRAITS - thought that acquired body structure can be passed down (ex: a body builder's offspring can inherit genetically from parent's acquired skills/traits)

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Artificial Selection

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Only allowed individuals who suited farmer's needs to produce offspring.

Intervention of humans ensures only more desirable individuals can pass down traits.

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Natural Selection

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A process in nature that favours individuals who can survive its environment and gets to pass down traits. Those who aren't die or leave fewer offspring to pass traits down.

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Survival of the Fittest

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Principle stating that those better fit for the environment have a better chance of passing down traits

(ex: Pepper Moth's survival during the Industrial Revolution)

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Populations

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Collection of individuals of same species in a given area whose members CAN BREED with one another

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Gene Pool

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A common group of genes between organisms able to interbreed

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Relative Frequency

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The number of times alleles for the same gene occur

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How is evolutionary change related to genes and relative frequencies?

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A population's gene pool needs to have had a change in the relative frequency for their to be evolutionary change

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Niche

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A combination between an organism's "profession" and place they live.

No two species can occupy the same niche in the same location for a long period of time due to competition for food and space.

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Most common way of forming new species

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Separation of populations

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Reproductive Isolations

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A species divided into two isolated populations until gene pools become so different that they develop into two different species.

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Adaptive Radiation

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Also known as "divergent evolution" - When a species gives rise to many species

(ex: Darwin's Finches - 13 different species that shared a common ancestor)

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Convergent Evolution

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Species similar in appearance and behaviour from adaptive radiation but from different origins

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Analogous Structures

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Structures similar in appearance and behaviour but from different orgins.

(ex: butterfly wings, bird wings, bat wings allow organisms to fly, BUT...

butterfly wings - thin non-living membrane

bird wings - skin, muscles, and arm bones

bat wings - skins stretched between elongated finger bones)

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Genetic Drift

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A method of genetic change/evolution in the absence of Natural Selection.

Random change in frequency of gene.

(ex: individual with allele may produce more offspring than other members BY CHANCE not because of fitness)

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Gradualism

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Theory of evolutionary change happening gradually.

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Equilibrium

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An unchanged/balanced state

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Mass Extinction

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Phenomenon where whole species are wiped out due to changes in climate, etc.

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Punctuated Equilibria

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long stable period interrupted by brief periods of change.

(ex: mass extinction)

Theory controversial today.