Show:
Adaptation
Speciation
Patterns of Evolution
Extinction
100

What are the 4 main aspects of Natural Selection?

  1. Overproduction: more offspring produced than can survive

  2. Variation: individuals have different phenotypes and genotypes. Best ones survive and reproduce.

  3. Selection: results from competition for limited resources (food, water, shelter, mates, etc)

  4. Adaptation (Inheritance): Variations (both favorable and unfavorable) get passed to offspring. Proportion of those with favorable phenotypes will be higher.

100

What is speciation?

Formation of new, distinct species.

100

Divergent evolution

When two or more species evolve from a common ancestor. 

Divergent evolution looks at longer time spans.

100

What is extinction?

  • death of entire species

  • Natural process
200

Three examples of adaptation

  • Better suited to its environment making it possible to better exploit its niche.

  • Examples: Body Structure or Function, Physiological, Behavior

200

Species

  • a group of organisms capable of interbreeding to produce fertile offspring. 

  • Reproductive isolation (biological barriers that prevent members of different species from interbreeding and producing fertile offspring) is necessary.
200

Adaptive radiation

One common ancestor gives rise to multiple species, occupying different niches.  Adaptive radiation is shorter term change.

200

Mass Extinction

  • Widespread and rapid decrease in life on Earth, not only loss of species, but entire families (made up of genera and species). 

  • 5 mass extinctions w/50% of animal species dying off

Evidence indicates we are possibly in a 6th mass extinction.

300

Examples of adaptive features that promote fitness

hummingbird's specialized beak

north american beaver adapted to aquatic and terrestrial environment

giraffe's neck

300

What is reproductive isolation?

  • When some members of a population stop breeding with other members.

  • Causes gene pool to split. Leads to speciation.

300

Phyletic Gradualism

Populations diverge slowly by accumulating adaptive features in response to different selective pressures.

300

What does each fork represent in the hominim cladogram?

Each “fork” represents an event that separated common ancestors.

400
What is convergent evolution?

  • Organisms that are not related develop similar traits.

  • Result from adapting to similar environment or niches.

400

What 3 mechanisms lead to reproductive isolation?

  • Geographical: when 2 populations are separated by geographical barriers (mountains, rivers, etc).

  • Behavioral: differences in courtship rituals or other behaviors (mating calls, dances, etc).

  • Temporal: when 2 or more species reproduce at different times (seasons, day/night, etc).

400

Punctuated Equilibrium

Populations stable but interrupted by brief periods of more rapid change.

500

What are Analogous Structures?

Structures that have the same function in unrelated taxa. Not the result of shared ancestry.

500

What type of reproductive isolation is the gray wolf in N. America and Eurasia?

Geographical 

What does this tell us about the process of species formation?