1. Origin of Species The term species refers to individuals in a population that are free to breed and that produce viable offspring, without outside intervention, that can carry on the lineage. – Speciation, or how species arise, can be further broken down using the concepts of micro and macroevolution. microevolution - species arise through a divergence of breeding populations that subsequently change the gene frequencies in a gene pool macroevolution - evolutionary change above the species level such as the evolution of birds from dinosaurs

2. Biological Species A biological species cannot (or does not) breed with members of a different population. The concept hinges on the concept of reproductive isolation or the existence of biological factors that inhibit or prevent reproduction.

3. Reproductive Isolation Reproductive Isolation creates a different gene pool that eventually leads to speciation – Geographic or habitat isolation - species that rarely come into contact due to occupation different habitats – temporal isolation - time of day

4. Reproductive Isolation – behavioral isolation - courtship rituals that attract mates are different – mechanical isolation - morphological differences (parts don't fit) – gametic isolation - sperm of one species cannot penetrate egg of another

5. Postzygotic Barrier postzygotic barrier - prevents a hybrid from developing or to become fertile as an adult – reduced hybrid viability - genes of the different parents impair the development and viability of the offspring – reduced hybrid fertility - adult hybrid is sterile (mule) – hybrid breakdown - fertility is decreased with each subsequent generation (more common in plants)

6. Factors that lead to speciation allopatric speciation - occurs when a population becomes geographically isolated over a long period of time. – Founders affect… few individuals that leave establish the genetic diversity of the new gene pool Causes reproductive isolation from the initial breeding population Creates Ecological competition in the new habitat – All factors drive continued evolution

7. Factors that lead to speciation sympatric speciation - occurs between members in a breeding population. Mechanisms include chromosomal changes and non- random mating that changes gene flow within a population. – polyploidy having more than 1 set of chromosomes autopolyploildy - more than 2 sets of chromosomes from a single species. More common in plants. allopolyploidy - two different species interbreed creating a hybrid with an odd # of chromosomes. The offspring then can mate with each other but not with the parental generation forming a new species – Parapatric or habitat differentiation - occurs when a portion of a populations starts to exploit a resource in the habitat which the parent generation cannot use. This can lead to differential sexual selection and speciation.

8. Factors that lead to speciation Adaptive radiation - the evolution of many diversely adapted species from a common ancestor upon introduction to a new environment (founder effect). Ex: HI islands and introductions of species. Displays the model of gradualism.

9. Changes that lead to macroevolution. shows model of punctuated equilibrium - new species is formed from parent then is stable (stasis) for many years evolutionary novelties through genes that control development - heterochromy – allometric growth changes - affected by genes that control body proportioning by affecting rate and timing – paedomorphosis - an alteration in the timing of juvenile and adult characteristics (especially in species that have distinct morphological periods) – homeotic gene changes - alter body plan (where wings or appendages form)