Formation of a new species Flashcards
a biological species:
: a group of organisms of
common ancestry that closely resemble each other and that
can interbreed and produce viable offspring.
the three main causes of variation in organisms
Mutations- Caused by changes in base sequences of DNA breakage and rejoining. mutation can be neutral, lethal or beneficial
Genetic recombination- occurring during meiosis and sexual reproduction
Random assortment
How do Variations in populations like Galapagos finches came about
Mutations lead to genotypic variation in populations which may or may not appear in phenotype. For example- Galapagos finches which is a type of bird on the Galapagos island, each island had a different and unique type of finch which appeared to be adapted to a particular food that was available.
The mainland finch was the ancestor of the island finches and that the island finches had each evolved differently in order to exploit the different type of food available on the different islands.
What are the two cross breeding methods we find
Inbreeding
outbreeding
What is the importance of inbreeding and outbreeding
inbreeding- increase homozygosity
outbreeding- promotes hetrozygosity
What are the problems associated with inbreeding
increased genetic disorders
lower birth rates
higher infant mortality
loss of immune system function
Give one example of inbreeding (plants)
Selection of a plant with a plant with a desired trait using self pollination to reproduce plants with desired trait ( cross between mandarin and orange produces a tangerine)
give an example of outbreeding in animals
Bonsmara cattle produced by cross breeding British beef with Afrikaner cattle
What is the founder effect
The original settlers in an were few, their genetic legacy is amplified among their descendants and have the reduced genetic diversity.
what is an example of the founder effect
Tay- Sach, disease which is recessive genetic disorder common in the south African jewfish community
What is a divergent evolution
occurs when a common ancestor gives rise to a variety of different but related organism
What is convergent evolution
organisms closely related develop similar traits( different species develop the same structure)
What is allopatric speciation give an example
geographic isolation. geographical barrier physically separates a population so they can no longer breed or interact ( earthquakes, continental drift and volcano) -. no
gene flow Genetic variation/mutations occurred in each population.
Environmental conditions on either side were slightly different. Natural selection occurred favoring certain genotypes, which were thus passed onto next generations. These differences became more pronounced until the two groups were so different that they were unable to reproduce.
Sympatric speciation
individuals in the same area can no longer interbreed- reproductive isolation
why does Reproductive isolation occur?
Temporal/seasoning- breeding at different times of the year
Behavioral isolation- species specific courtship. If courtship is unsuccessful, reproduction will not occur
adaptation of different pollinators example: insect pollinated and wind pollinated plants cannot interbreed
post- zygotic isolation, development of an abnormal zygote, after fertilizations so no viable offspring is formed
