BSCI 106 chapter 17 vocab
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groups of organisms that mate with one another
the divergence of biological lineages and the emergence of reproductive isolation between lineages
what is a species? many different interpretations
morphological species concept
- made by Linnaeus
- states that species are defined by groups of organisms that are similar to each other in appearance
- a state in which two groups of organisms are unable to exchange genes
- each group now part of a "new branch on the tree of life"
biological species concept
- species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups
- does not include asexual organisms
lineage species concept
one species splits into two or more daughter species that are then separate entities
- ancestor -> descendant
- over time
- allopatric - "other homeland"
- the condition of speciation caused by a physical barrier
- body of water, mountain range, or any land inhospitable to a group of organisms
- an example of allopatric speciation
- the finches crossed the sea and settled on an island to create an entirely new gene pool and lineage
species that are each others' closest relatives
- sympatric- "together with homeland"
- speciation without a physical isolation
How does sympatric speciation occur?
- disruptive selection (micro-habitats get preference for mating)
- host-plant specificity (apples vs. hawthornes)
- the duplication of sets of chromosomes within individuals
- when an individual is tetraploid, it cannot mate within the normal population and is thus reproductively isolated to only other tetraploids
polyploidy in an individual with parents from the same species
polyploidy in an individual from parents that were different species
- this is when hybrid individuals are less fit than non-hybrid individuals and selection will not select for them
- incomplete reproductive isolation
pre-zygotic isolating mechanisms
- hybridization is prevented altogether
- 1. mismatched genitalia
- 2. different mating seasons
post-zygotic isolating mechanisms
- less fitness for hybrids
- 1. sterility
- 2. developmental problems
areas where species interbreed because reproductive isolation is incomplete
chromosomes switch long arms with short arms
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