Patterns of Evolution
Macroevolution/Microevolution Macroevolution- One genus or family evolves into another….due to large scale changes that take place over long periods of time. Microevolution- Small scale changes within a species to produce new varieties or species in a relatively short amount of time.
Macroevolution/Microevolution Both involve changes in allele frequencies in gene pools Both work through the same basic processes The difference is largely one of approach and scale Each offers different insights into the evolution process
Macroevolution/Microevolution Macroevolution 1. Large-scale changes in gene frequencies 2. Occurs over a longer (geological) time period 3. Occurs at or above the level of species in separated gene pools 4. Consists of extended microevolution Microevolution 1. Small-scale changes in gene frequencies 2. Occurs over a few generations 3. Occurs within a species or population in same gene pool 4. Refers to smaller evolutionary changes
Macroevolution/Microevolution Macroevolution 5. Has not been directly observed 6. Evidence based on remnants of the past 7. More controversial 8. Example: Birds from reptiles Microevolution 5. Observable 6. Evidence produced by experimentation 7. Less controversial 8. Example: Bacterial resistance to antibiotics
Dog Variability When bred for certain traits, dogs become different and distinctive. This is a common example of microevolution—changes in size, shape, and color—or minor genetic alterations. It is not macroevolution: an upward, beneficial increase in complexity. Macroevolution/Microevolution
Patterns of Macroevolution A. Mass Extinctions B. Adaptive Radiation C. Convergent Evolution D. Coevolution E. Gradualism F. Punctuated Equilibrium These are theories/models of evolution
Mass Extinctions Event in which many types of living things became extinct at the same time. Period in which huge numbers of species disappeared. Whole ecosystems were wiped out Left habitats/niches open Resulted in burst of evolution of new species in new habitat Disrupted energy flow throughout the biosphere and caused food webs to collapse
Mass Extinctions Possible causes Asteroids hitting earth Volcanic eruptions Continental drift Sea levels changing
Mass Extinctions Is an on-going process
Adaptive Radiation The evolution of an ancestral species, which was adapted to a particular way of life, into many diverse species, each adapted to a different habitat Many new species diversify from a common ancestor . The branching out of a population through variation. The new species live in different ways than the original species did.
Convergent Evolution Opposite of divergent evolution (adaptive radiation) Unrelated organisms independently evolve similarities when adapting to similar environments, or ecological niches Analogous structures are a result of this process
Convergent Evolution Similar body shapes and structures have evolved in the North American cacti...and in the euphorbias in Southern Africa
Coevolution The mutual evolutionary influence between two species When two species evolve in response to changes in each other They are closely connected to one another by ecological interactions (have a symbiotic relationship) including: Predator/prey Parasite/host Plant/pollinator Each party exerts selective pressures on the other, thereby affecting each others' evolution
Coevolution Bumblebees and the flowers the they pollinate have co-evolved so that both have become dependent on each other for survival.
Coevolution Praying Mantis simulates plant to protect itself from predators and eats pests that are attracted to and feed on the plant, so it protects the plant.
Coevolution Shrimp cleaningTitan triggerfish in Pacific Ocean