Life Science Notes 3 PDF

fg. Imagine a plant of extremely varied heights , that is pollinated by 3 different pollinators attracted to short plants...

fg. Imagine a plant of extremely varied heights , that is pollinated by 3 different pollinators attracted to short plants preferred the plants of medium heigh dissappeared from an area, ↳ One If the pollinator that ↳ Another that preferred plants of medium height medium height plants would be selected against and the population would 4 A third that only visited the tallest plants tend to lear towards both short and tall, but not medium height plants · such a population , in which multiple distinct forms or morphs exist is said to be polymorphic selection could · Given enough time , this type of result in the formation of two new separate species Speciation Species : a group of organisms that can breed together to produce fertile offspring They reproductively isolated no genetic exchange - are ↳ with this definition : Problems ↳ Does not include organisms that reproduce by other means ↳ some separate species can produce fertile offspring ex. The "Pizzly hear" How does One species Split into Two ? · Reproductive Isolation must happen · Geography (geografical isolation) - examples : river formation /forms and separates species like insects) · Time Itemporal isolation) same habitat mate during different seasons leading to reproductive isolation species of frog - in the - examples : two · Behaviour (behavioural isolation( -examples : a species of bird uses a unique mating song that other species don't recognize · Habitat (ecological isolation) two species live in the same habitat but one lives by the water and the other prefers dry land. - example : · Reproductive Isolation means that different selective pressures exist between the two populations from generation to the next , evolve. Natural selection modifies populations · one causing them to · Sometimes evolutionary changes are so great that some organisms can no longer interbreed with the original species · When this happens it is called speciation  What type of reproductive Isolation is happening - Geographical ↳ river separates population , preventing interbreeding - Habitat - prefers different food source, prevents interbreeding Allopatric Speciation · Happens when a physical barrier separates a population into groups /Geographical isolation only) is different · Each envoirment · Different adaptations become more common o The populations charge over time so they are not the same species Sympatric Speciation temporal, behavioural, and ecological o One population separates into groups by something other than a physical barrier 2) Same Process ! · conditions for life in that envoirment are different Different adaptations become more common · T he · population changes over time so they are not the same species  lead to Speciation can Divergent Evolution Isolation (speciation event occurs/ · One species becomes two through reproductive from the same ancestor · Species come · Similarities decrease between populations over time kind of divergent evolution Adaptive Radiation special : L A ↳ One ancestral species becomes many new species · could be a result of the founder effect off and ↳ small group splinters starts a new colony Speciation Can also produce : Covergent Evolution do from the same ancestor but look similar · Species NOT evolve ↳ Analogous structures work best in that envoirment become more common ↳ Adaptations Happen ? How Quikly Does Speciation of Gradualism Theory · from small changes /slow) New species come many over time · Theory of Punctuated Equillibrium 2) Major changes in the envoirment allow many species to evolve more quickly