Bio 322_take home final

Bio 322_take home final - Biology 322 Professor Hogue...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Professor Hogue 12/5/07 1. It is not accurate to believe the first two humans, animals, or insects appeared in the same area during the same time frame and chose to reproduce. Species evolve from a single common ancestor or a few due to many factors. They do not come into existence independently. Speciation is the process by which new biological species arise. Speciation begins when gene flow is disrupted and populations become genetically isolated. The most common model of speciation is the allopatric speciation model, which occurs when two populations of a given species are separated by a geographical barrier such as a mountain range, a river, or an ocean. It also may occur if individuals of a given population manage to cross bodies of water, finding themselves on other islands. Isolation by means of geographical barriers produces reproductive isolation, resulting in genetic isolation. Sympatric speciation is the divergence of many species from a parental species inhabiting the same geographic region. It may occur if new ecological niches or new food sources become available. Polyploidy is a mechanism attributed to some sympatry events. It is due to changes in number of chromosomes and is commonly observed in plants. There are many mechanisms that create the conditions for speciation to occur. In some cases, species exist for long periods of time gradually changing in response to changes in their environment. Natural selection can cause populations to diverge based on food preferences or habitat choices. The theory of Natural Selection formulated independently by Charles Darwin and Alfred Russel Wallace, is based on the premise that individuals within a population vary; they exhibit different traits or characteristics. 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/14/2008 for the course BIOL 322 taught by Professor Hoage during the Fall '07 term at CSU Northridge.

Page1 / 5

Bio 322_take home final - Biology 322 Professor Hogue...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online