Descent with Modification A Darwinian View of Life

Agenda Biotechnology Quiz Natural Selection warm-up worksheet Lecture: Descent with Modification Natural Selection Activity Exit Slip Learner Outcome: I can provide examples of descent with modification by natural selection and explain how these processes account for the adaptation of organisms and the unity and diversity of life.

Descent with Modification Evolution- descent with modification; change in the genetic composition of a population from generation to generation. Carolus Linnaeus- founder of taxonomy; developed the binomial system of naming species Paleontology- study of fossils (Curvier)

Layers of deposited sediment Catastrophism- the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present.

Uniformitarianism- mechanisms of change are constant over time. Lamarck- hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics

Adaptations and Natural Selection Adaptations- characteristics of organisms that enhance their survival and reproduction in specific environments. Natural Selection- how adaptations arise; a process in which individuals with certain inherited traits leave more offspring than individuals with other traits.

Kale Kohlrabi Brussels sprouts Leaves Stem Wild mustard Flowers and stems Broccoli Cauliflower Flower clusters Cabbage Terminal bud Lateral buds Natural vs. Artificial Selection

Darwin’s Observations/Inferences Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals. This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

Data for Evolution Direct observations of evolution ◦ predator/prey relationships ◦ drug-resistant HIV Fossil record Homology ◦ Similarity resulting from common ancestry. Biogeography ◦ The geographic distribution of species.

Homologous Structures Variations on a structural theme that was present in their common ancestor. Humerus Radius Ulna Carpals Metacarpals Phalanges Human WhaleCat Bat

Evolutionary Tree A diagram that reflects evolutionary relationships among groups of organisms. Hawks and other birds Ostriches Crocodiles Lizards and snakes Amphibians Mammals Lungfishes Tetrapod limbs Amnion Feathers Homologous characteristic Branch point Tetrapods Amniotes Birds

Convergent Evolution The independent evolution of similar features in different lineages. Analogous resemblance results from convergent evolution.

Data for Evolution Direct observations of evolution ◦ predator/prey relationships ◦ drug-resistant HIV Fossil record Homology ◦ Similarity resulting from common ancestry. Biogeography ◦ The geographic distribution of species.

Exit Slip If you discovered a fossil of an extinct mammal that lived high in the Andes, would you predict that it would more closely resemble present-day mammals from South American jungles or present- day mammals that live high in African mountains? Explain.