Speciation PDF

SPECIES Group of populations whose members have the potential to interbreed in nature and produce viable fertile offspring, but do not produce viable offspring with members of other groups. Speciation - is how a new kind of plant or animal species is created. - occurs when a g...

SPECIES Group of populations whose members have the potential to interbreed in nature and produce viable fertile offspring, but do not produce viable offspring with members of other groups. Speciation - is how a new kind of plant or animal species is created. - occurs when a group within a species separates from other members of its species and develops its own unique characteristics. Types of Speciation Allopatric Speciation—gene flow is interrupted when a population is divided into geographically isolated subpopulations -occurs when a species separates into two separate groups which are isolated from one another. A physical barrier, such as a mountain range or a waterway, makes it impossible for them to breed with one another. Each species develops differently based on the demands of their unique habitat or the genetic characteristics of the group that are passed on to offspring. Sympatric Speciation—occurs in populations that live in the same geographic area -occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another. A new species, perhaps based on a different food source or characteristic, seems to develop spontaneously. The theory is that some individuals become dependent on certain aspects of an environment—such as shelter or food sources—while others do not. – Happens when gene flow is diminished by: Polyploidy Habitat differentiation Sexual selection  Parapatric Speciation— a species is spread out over a large geographic area. Although it is possible for any member of the species to mate with another member, individuals only mate with those in their own geographic region. Peripatric Speciation--- When small groups of individuals break off from the larger group and form a new species. *The main difference between allopatric speciation and peripatric speciation is that in peripatric speciation, one group is much smaller than the other. Unique characteristics of the smaller groups are passed on to future generations of the group, making those traits more common among that group and distinguishing it from the others.