1. Vocabulary Chapter 15
Artificial selection
Natural selection
Evolution

2. Artificial selection
The process of directed breeding to produce offspring with desired traits also referred to as selective breeding
Example: when humans develop new breeds of dogs or new strains of crop plants

3. Natural selection
There is a competitive struggle for existence in the natural world if some competitors in this struggle are better equipped for survival than others, then those less equipped would die
Occurs because there is variation, heritability, overproduction, and reproductive advantages

4. Evolution
Cumulative changes in groups of organisms (species) through time
Natural selection is a mechanism of how this change occurs

5. Vocabulary Chapter 15
Derived trait
Ancestral trait
Homologous structure
Vestigial structure
Analogous structure

6. Derived Traits
Newly evolved traits, that may not appear in the fossils of common ancestors
When studying transitional fossils traits may be classified in two major categories either derived traits or ancestral traits
Example: With Archaeopteryx fossils (possible ancestor to modern birds with distinct dinosaur features) the derived traits like feathers do not appear in the fossils of common ancestors

7. Ancestral Traits
More primitive traits, that do appear in the fossils of common ancestors
Example: In Archaeopteryx fossils the ancestral traits may be the teeth and tails that do appear in ancestral forms

8. Homologous Structures
Anatomically similar structures inherited from a common ancestor
May have different function
Examples: The forelimbs of vertebrates show homologous structures. The limbs are adapted for different uses, but they all have similar bones.

9. Vestigial structures
Structures that may no longer have a function for that species and are reduced in form
May resemble functional structures in other organisms
Examples: Snake pelvis and human appendix

10. Analogous Structures
Structures that can be used for the same purpose and can be superficially similar in construction but are not inherited from a common ancestor
Example: Wings of an eagle and the wings of a beetle have the same function (flight) but the wings are constructed in different ways and from different material

11. Vocabulary Chapter 15
Embryo
Biogeography
Fitness
Camouflage
Mimicry

12. Embryo An early, pre-birth stage of an organisms development
Comparative embryology – vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms
Example: Vertebrate embryos have a tail and pharyngeal pouches (in fish develop into gills, in reptiles, birds, and mammals become part of the ears, jaws and throats

13. Biogeography
Study of the distribution of plants and animals around the world

14. Fitness
A measure of the relative contribution that an individual trait makes to the next generation
Reproductive success
Measured as the number of reproductively viable offspring that an organism produces in the next generation

15. Camouflage
Morphological adaptation that allows individuals of a species to blend in with their environment
Allows organisms to become almost invisible to predators or prey, as a result more of the camouflaged individuals survive and reproduce

16. Mimicry
Morphological adaptation where one species evolves to resemble another species
Example: Mimicry can occur in a harmless species that has evolved to resemble a harmful species, such as the California kingsnake color patterns mimicking those of the poisonous western coral snake

17. Vocabulary Chapter 15
Genetic drift
Founder effect
Bottleneck

18. Genetic Drift
Change in allelic frequencies in a population that results from chance
A random circumstance causes a certain genetic trait to become more common or rarer over time
Example: A man steps on a group of beetles, randomly killing most of the green ones but leaving most of the brown ones alive, resulting in fewer green beetles being produced in the population

19. Founder Effect
Occurs when a small sample of a population settles in a location separated from the rest of the population
Alleles that were uncommon in the original population might be common in the new population and the offspring in the new population will carry those alleles
Example: Amish seldom marry outside of their immediate community, in the Old Order Amish community there is a high frequency of six-finger dwarfism, affected individuals can trace their ancestry back to one of the founders of the Order

20. Bottleneck
Occurs when a population declines to a very low number and then rebounds
Results in decreased genetic variation
Example: Northern elephant seals where hunted by humans almost to extinction leaving only 20 individuals left in the late 1890’s, since there population has rebounded to over 30,000 but the reduced genetic variation in the population is apparent