GenBio Q3

• The study of the distribution of species over space and time is crucial to the study of evolution
• Biogeography


  The study of the distribution of species over space and time, crucial to the study of evolution
• The primary concern of the field of biogeography is the distribution of species over space and time
• 1. Species vary in distribution based on geographical area, latitude, climate conditions, etc.

  2. Biogeography deals with distribution patterns in terms of location and when these distributions took place

  3. Determining these factors allows scientists to put together the evolutionary historyof species

  Biogeographical Evidence of Evolution
• Biogeography tries to answer questions related to how species end up in geographic areas where they settle


  Major established concepts to help answer these questions include dispersal and vicariance
• Dispersal


  1. Population moves across a geographical barrier to settle in a new location

  2. If the population has necessary adaptations, it will thrive, impacting ecological relationships

  3. If not, the population may die out
• Dispersal refers to how plants spread seeds and how organisms occupy different geographic locations through movement
• Dispersal often leads to geographic isolation between populations


  Given enough time, speciation may occur due to inability to mix gene pools and different environmental pressures
• Vicariance


  1. A barrier appears isolating two populations of the same species that were once connected

  2. Examples include natural events like earthquakes causing isolation
• The formation of mountain ranges and other landforms can cause vicariance
• Factors and Phenomena That Shape Biogeographical Patterns

  • Continental drift
  • Migration
  • Climate
  • Sea levels
  • Geographic barriers
  • Centers of origin
• A scientist named Alfred Wegener proposed the theory of continental drift


  1912
• Continental drift


  The theory that the locations of the continents in Earth’s distant past were not the same as the locations that they are found in today, and that the landmasses on Earth are continually moving although at a very slow pace
• Evidence suggests that most of today’s continents were once connected in an ancient supercontinent known as Pangaea, made up of Laurasia and Gondwana
• Fossils, particularly of Glossopteris, can be found in different modern continents, proving that these landforms were once continuous
• The lowering of sea levels led to more land being exposed from under the sea and may have allowed species to colonize these areas
• Rising sea levels forced terrestrial species inland, affecting how species were dispersed and how they interacted with each other
• Land bridges allowed species to disperse across them in order to colonize new areas
• When land bridges were covered again with water because of high sea levels, it could have been an example of vicariance
• Migration refers to the movement of populations from one geographic location to another
• Emigration refers to the movement of a population away from an area
• Immigration refers to the movement of a population into an area
• 
  

  Movement of populations

  1. Allows for the flow of genes since they are able to reproduce with populations outside their normal range of distribution

  2. Allows variations to occur in the gene frequencies of the populations involved
• Geographical barriers


  • Landforms like mountains and valleys, bodies of water like rivers and oceans
• Sympatric speciation


  Speciation occurring even when populations are found in the same habitat
• Center of origin


  Refers to a geographic location where multiple species originate
• centers of origin

  Allows scientists to trace the evolution of certain groups of plants and animals and reconstruct their evolutionary histories
• East Indies


  • Scientists believe it is an important contributor to the evolution of marine biodiversity, diversification of many marine species occurred here and spread out to colonize other areas
• Key Points

  • Dispersal refers to when a population moves across a geographical barrier to settle in a new location
  • Vicariance refers to when a barrier appears which isolates two populations of the same species that were once connected
  • Evidence suggests that most of today’s continents were once connected to an ancient supercontinent known as Pangaea
  • The dip in sea levels meant that land bridges, which is a stretch of land that connected areas in times when sea levels were low, became exposed from underwater
  • Migration refers to the movement of populations from one geographic location to another. Migration can either be emigration or immigration
• Speciation


  Follows when a geographic barrier appears and separates populations
• Biogeography


  The science that studies the distribution of organisms relative to their histories and the history of Earth
• Vicariance leads to allopatric speciation
• Continental drift leads to changes in climate for certain areas
• The appearance of land bridges can lead to dispersal
• Taxonomy refers to the science that deals with the description, identification, nomenclature, and classification of organisms.
• Nomenclature is the system used to name taxa (groups) at different levels.
• Systematic biology is the scientific discipline concerned with classifying and naming organisms according to their evolutionary relationships.
• Taxonomy takes into account how organisms are related, but it does not totally reflect evolutionary relationships.
• Description. This basic procedure in taxonomy entails the assignment of characteristics to an organism for use in the succeeding steps.
• Identification. This step determines whether an organism already falls under a previously identified organism.