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Diversity Of Life: 5

A deck of flashcards for Undergraduate Study of Biology. Source: Wikipedia

What are the two main species concept? Morphological species concept and the biological species concept.
Morphological species concept Simple judgement according to appearance/phenotypic traits. However, may be found invalid.
Biological species concept A population that has potential to interbreed with one another in nature but are reproductively isolated from other populations. -Ernst Mayr (1963)
Reproductive Isolating Mechanisms (RIM) Any heritable feature that prevents interbreeding between genetically different populations.
What are the 2 main categories of RIM? Prezygotic and Postzygotic RIMs.
Prezygotic RIMs It prevents zygote production through 5 isolation. Habitat/ecological isolation (reduced encounters), temporal isolation (mating periods), behavioral isolation (attraction), mechanical isolation (structural) and gametic isolation (incorrect chemicals).
Postzygotic RIMs It prevents viable, fertile offspring. Reduced hybrid viability (zygote does not complete development and embryo aborts), reduced hybrid fertility (sterile offspring/no gene flow) and hybrid breakdown (hybrid offsprings die).
What are the 2 types of speciation? Allopatric and sympatric speciation.
Allopatric speciation The initial block of geneflow being a geographical barrier which results in physical separation between two populations into different areas.
Sympatric speciation The reproductive isolation within the area of the parent population (different preference/trends).
What are the 2 ways geographical barriers may arise? It may arise through development over time or through colonization in a new area.
Adaptive radiation A process commonly found on island chains where the population occupies different islands and adapt to different conditions/lifestyles.
What are the possible mechanisms for sympatric speciation? Ecological methods and sexual selection methods, and polypoidy (in plants).
Ecological methods in sympatric speciation Tendency for individuals with a dependency on a particular lifestyle/food source to mate with similar individuals. This may cause RIMs over time.
Sexual selection methods in sympatric speciation The preference in mates with specific morphology.
Polypoidy in plants method in sympatric speciation When an organism has more than the normal number of sets of chromosomes. There are two types, autopolyploids and allopolyploids.
Autopolyploids Where a single species double its chromosome number. Two meiotic error where both gamete chromosomes don't reduce.
Allopolyploids Where it produces a sterile hybrid but produce asexually (between two species). Only one meiotic error, hybrid produce asexually reproduces to produce a viable fertile hybrid.
Anagenesis Phyletic evolution where there is a transformation of an unbranched lineage of organisms.
Cladogenesis Branching evolution where there is a budding of one or more species from a parent species that continues to exist.
What is the rate of evolution? It may occur gradually or rapidly. Unmeasurable.
What are the 2 models of the rates of evolution? Gradualism model and the punctuated equilibrium models.
Gradualism model Difficult to find evidence of as there is an incomplete fossil records.
Punctuated equilibrium model Very rapid process with the sudden appearance of a new species.Shown but incomplete fossil records.
Extinction Permanent end of a lineage.
Extant Species that are still alive today.
Turn-over species Where an extinction of a species comes a rise in a new species.
What are the 2 rates of extinction? Background extinction (continuous low level extinctions) and mass extinctions (huge number of species going extinct).
Created by: theecloud



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