“AGE OF FISH” INTERNAL FERT DEVELOP

So what is biological evolution? Successive genetic changes in a species over many generations. New species result as genetic characteristics are modified; due to: Mutation: change to DNA(random, predictable) Isolation: events that separate populations New allele combinations: results in variation w/in populations Reproduction: sexual/asexual, rates Environment: is it constant? or changing? Implies natural processes are at work

SELECTIVE BREEDING results in ARTIFICIAL SELECTION Humans have been manipulating the genetics of populations since we first began domesticating animals and plants SELECTIVE BREEDING results in ARTIFICIAL SELECTION Rather than allowing natural events to determine WHICH combinations of genes ARE SUCCESSFUL; we select THE specific traits to combine TO ACHIEVE A DESIRED RESULT This process HAS resulted in new varieties of dogs, cats, horses, pigs, chickens, tomatoes, corn, etc

Evolutionary theory suggests the same genetic mechanisms are at work in nature…but through Natural Selection

History of Evolutionary Thought Jean –Baptiste Lamarck(1744-1829) Theorized that acquired traits can be inherited. Environmental change causes changes in the needs of organisms Changing needs causes changing behavior Altered behavior leads to changes in the use of a structure Greater use- structure gets larger Less use-structure gets smaller or disappears.

Lamarck did see that organisms do change over time; that the environment drives the change… however, his “use/disuse” mechanism is completely WRONG!!!

Thomas Malthus(1766-1834) Was a political economist who studied population dynamics Observed that animals and plants produced far more offspring than can survive. Populations will grow to a size that can be supported by the environment. He related these concepts to human populations as a factor influencing poverty and famine. Darwin and Wallace related these concepts to natural selection… .

Alfred Wallace(1823-1913) 19th century's leading expert on the geographical distribution of animal species. Best known for independently proposing a theory of species evolution by natural selection that prompted Charles Darwin to publish his own theory. However, both men collaborated on the initial publication of the theory.

Noted that natural barriers like water, mountains, canyons etc, resulted in greater diversity in populations. Observed that similar environments result in similar adaptations even though populations have different geographical origins.

OSTRICH EMU RHEA AFRICA AUSTRALIA S AMERICA Wallace theorized the birds have similar structures because their environments are similar, resulting in the same demands on the species for survival

Charles Darwin(1809-1882) Developed and published a unified theory of evolution by natural selection in 1858 Based upon observations made in South America and the Galapagos Islands in 1835

Darwin’s Observations It’s a struggle to survive: species must compete for food, space, water, mates, etc

All living organisms over produce: (incorporated from Malthus)

There is natural variation within species: genetic differences exists w/in organisms of same species raw material for adaptation

Two main aspects of the Theory DESCENT WITH MODIFICATION Newer species appear to be descended from older species Species may be descended from one or a few original species

Please begin cutting… Place all the #1 pieces into a pile with the #1 heading Explanations Place all the #2 pieces into a pile with #2 heading Example Pieces are numbered on the back

EVOLUTIONARY THEORY

Environment determines which traits are successful: eventually they become adaptations

NATURAL SELECTION Mechanism for divergence Characteristics of the environment “select” traits that increase a population’s ability to survive Those organisms with favorable traits (adaptations) are best suited and are more likely to survive to reproduce and pass those traits to offspring giving them an adaptive advantage. Those that do not possess favorable traits more likely to die thus not reproduce and remove those traits from gene pool Over time organism’s variation increases from the original population, the species has diverged genetically or evolved. CALLIOPE

Necking for Repro rights More won battle To reproduce

Little Genetic Variation Very Specific Diets Limited Habitats Slow Reproductive Rates *Human influences

Greater Genetic Variation Non-Specific Diets Unlimited Habitats Faster Reproductive Rates

Take into consideration… The following genetic events randomly affect an organism’s characteristics; thus affecting evolutionary changes, if any, that may occur: Mutation(any change to DNA) Degree of variation in the population Recombination of genes through sexual reproduction Independent assortment of alleles(genes) in meiosis Isolation/Separation of populations(genetic drift) The rate of environmental change directly affects selection(stable-little change, unstable- more change, or extinction) Generally, the more complex(amt of coding DNA) the organism the slower the process: bacteria: single strand DNA-many generations very short time, greater change(resistance) elephants: lots o’ DNA- few generations in very long time(2 yrs to make 1!), less change

STEPS EXPLANATION EXAMPLE Variation is the raw material for natural selection Every species contains genetic variation: mutation, crossing over, etc Living things must struggle to survive Produce more than can survive, must evade predators, compete for living space, food Only some will survive to reproduce Some survive better than others. These are more likely to produce offspring Natural selection causes genetic change in population Each generation has more successful organisms. Species adapt to their environment Selection tends to make a population better suited to its environment.