EVOLUTION AND ORIGIN OF BIODIVERSITY

• REPRODUCTIVE ISOLATION MECHANISM - is when species are unable to breed successfully, This is due to geographical, physiological, behavioral, and genetic barriers.
• PREZYGOTIC RIMS:

  1. ECOLOGICAL ISOLATION
  2. TEMPORAL ISOLATION
  3. ETHOLOGICAL ISOLATION
  4. MECHANICAL ISOLATION
  5. GAMETIC ISOLATION
• POSTZYGOTIC RIMS:

  1. HYBRID INVIABILITY
  2. HYBRID STERILITY
  3. HYBRID BREAKDOWN
• ECOLOGICAL ISOLATION - this means that populations may not meet because they live in the same territory but in different habitat. Example is Anopheles Maculipennis includes six mosquito species
• TEMPORAL ISOLATION - isolation occurs because the is a difference in the timing of significant reproductive events from members of closely related events.
• ETHOLOGICAL (BEHAVIORAL) ISOLATION - is the weak or absence of sexual attraction between male and females. Generally, among the animal species, the first step between male and female is to look for each other then come together
• MECHANICAL ISOLATION - happens because of the incompatibility in the size and/or shape of the genitalia of the species which make it generally impossible for a sexual intercourse.
• GAMETIC ISOLATION - in marine animals, where eggs and sperms are discharged into its surrounding water, there is a failure to attract gametes of different species.
• HYBRID INVIABILITY - failure of zygotes to develop into mature individuals after hybridization. It is existent when, for an instance, in the early developmental stages, the hybrid embryos of goats and sheep die before birth.
• HYBRID STERILITY - the hybrid zygotes developed into adults but did not develop functional gametes. Hence, sterile
• EUKARYOTIC SPECIES - species whose cells has a a clearly defined nucleus
• GENETIC SEPARATION - the splitting up of one gene pool into two or more separated gene pools
• PHENOTYPIC DIFFERENTIATION - the diversification of observable physical characteristics.
• ALLOPATRIC SPECIATION - geographic isolation happens in population that are allopatric or completely separated by physical barriers including but not limited to mountain ranges, rivers or dessert.
• ALLOPATRIC SPECIATION - the populations separated develop their own environmental adaptation and become genetically different
• SYMPATRIC SPECIATION - the reproductive isolation happens in a single population. The diversity in genetic characteristics even with continuous interaction can hardly be explained
• PARAPATRIC SPECIATION - the isolation is more like of a choice
• PARAPATRIC SPECIATION - mating is not randomly made by population. The organisms prefer mating with their geographic neighbors rather than with individuals in the population's range but in a different geography.