Period+3+GR+24


 * ​AP Biology**
 * Guided Reading Chapter 24**

1.Define the following terms: beal. . . good!

a.Speciation The origin of a new species in evolution

b.Anagenesis Accumulation of heritable changes, altering the characteristics of species

c.Cladogenesis Branching evolution, in which a new species arises from a population that buds from a parent species

2.What is the biological species concept? beal. . . good!

 Definition of a species as a population of group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations.

3.What are the differences between prezygotic and postzygotic barriers to reproduction? beal. . . good!

 **Prezygotic-**Impede mating between species or hinder fertilization of a ova if members of different species attempt to mate  **Postzygotic-**Prevent zygote from developing into an adult

4.Identify each of the following as prezygotic or postzygotic barriers and write a brief definition of each: beal. . . good!

a.Habitat isolation- Prezygotic, 2 species that occupy different habitats in the same area rarely encounter each other

b. Temporal isolation- Prezygotic, species mating times of day, seasons, or years cannot mix their gametes

c.Behavioral isolation- Prezygotic, mating rituals that are unique to species create effective barriers

d. Mechanical isolation- Prezygotic, different body parts and morphological differences prevent mating

e.Gametic isolation- Prezygotic, sperm of one species may not be able to ferilize eggs of another

f.Reduced hybrid viability- Postzygotic, genes of different parent species may impair development of offspring

g.Reduced hybrid fertility- Postzygotic, offspring of 2 different parent species may be sterile

h.Hybrid breakdown- Postzygotic, offspring of 2 different parent species are fertile but next generations are not beal. . .and are weaker.

5.Detail these other definitions of species: beal. . . good!

a.Morphological species concept- characterizes species by its body shape, size, and other features

b.Paleontological species concept- species only known from fossil records

c.Ecological species concept- views a species based on its role in a biological community

d. Phylogenetic species concept- defines a species as a set of organisms with a unique genetic history

6.What is the basis for allopatric speciation? beal. . . good!

Gene flow is interupted by a geographic barrier

7.What does sympatric speciation mean? beal. . . good!

Sympatric speciation is a type of speciation that occurs from radical changes in the genome of a subpopulation, causing reproductive isolation of the subpopulation from the original population. Even though they have lived in the same areas for generations, they adapted to different parts of the environtment, causing the speciation.

8.What is the difference between autopolyploidy and allopolyploidy? beal. . . good!

=Autopolyploidy: when an individual has more that 2 chromosome sets that came from a single species. Allopolyploidy: when 2 different species interbreed and combine their chromosomes, causing a polyploid. =

9.In what types of organisms are polyploidy speciation more common and why do you think this occurs? beal. . . good!

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Polyploidy speciation commonly occurs with plants due to the fact that the reproduce in vast amounts, along with their occasional interbreeding.

10.What is adaptive radiation and why do island chains tend to be discussed often with this topic? beal. . . good!

It is the emergence of species from a common ancestor introduced to a new environment with new diversity. It is discussed with islands because many species recolonize on neighboring islands that have different environments. Also, a dispersal of food, like seeds, can cause species to immigrate. Islands are far enough to permit evolution but close enough for the diversion of species.

11.Compare and contrast the models of punctuated equilibrium to gradualism as models for the rate of evolution. Does one have to exclude the other? Punctuated quilibrium beal shows BIG changes in a species quickly a more direct evolution. The gradualism model is more spread out and shows a more gradual rate of evolution. Because the 2 models are different 1 of them usually does exclude the other one. Usually, puncuated equilibrium completely erases gradualism.

12.Define the following terms: beal. . . good! a.Heterochrony ​ evolutionary change in the timing or rate of an organism's development b.Allometric growth the variation in the relative rates of growth of various parts of the boddy, which helps shape organisms c.Paedomorphosis the retention in an adult organism of the juevenile freatures of its evolutionary ancestors d.Homeotic genes any of the genes that control the overall body plan of animals and plants by controlling the developmental route of groups of cells 13.What impact have the //Hox// genes had on vertebrates? Over the course of time, hox genes eventually aided vertabrates in developing limbs.

beal. . . more detail please!

14.How does the evolution of the horse exemplify the concept that evolution is driven by the interactions of the organism and its environment? The horses are descendants from the 40 million year old Hyracotherium (the size of a large dog, had four toes on its front feet and 3 toes on its back feet and its teeth were adapted by browsing bushes and trees.) A living horse is larger, has only one toe (hooves) on each foot, and have teeth modified to graze on grass. From the time of Hyracotherium to the horses today other living animals that also looked like horses show the changes over time. In the picture below we see that over the years these animals lost toes and their teeth changed in order to make it easier to graze grass instead of browsing bushes and trees.

beal. . . good!