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32 Cards in this Set
- Front
- Back
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Morphological Species
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group of individuals that look similar, with only limited variation
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Biological species
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groups of actually or potentially interbreeding populations: that is reproductively isolated from other groups
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Criteria for Biological Speices
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Interbreeding individuals living together in a similar environmnet/region
recognize each other as potential mates and offspring as viable related by hared common ancestry |
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Species are made up of
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local populations
if these populations interbreed than all the same species some populations become isolated due to geography or climate change |
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sub species
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can interbreed but don't
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Speciation (steps)
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1. Establishment of a barrier to gene flow that leads to genetic isolation among populations
2. Disruption of gene flow leads to the genetic divergence between species 3. If diverfence continues long enough, populations become reproductively isolated (won't be able to interbreed even if they come into contact) |
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Reproductive Isolation
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Speciation
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Isolation
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sometimes in space and sometimes in time
physical barriers dispersal/vicariance |
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Allopatric Speciation
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divergence occurs in geographically separated groups
some physical barrier to migration of individuals and genes from one population to another initial separation (dispersal/vicariance) |
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Sympatric Speciation
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distribution of diverging populations overlap no physical barrier to gene flow
isolation due to ecological differentiation |
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Example of Sympatric Speciation
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Maggot Flies
apple race and hawthorn berry race mating takes place on fruits |
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Speciation is a by product of...
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genetic changes that accummulate between populations
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Speciation is the evolution of....
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reproductive isolation
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2 Types of Reproductive Isolation
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prezygotic
post zygotic |
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Prezygotic Isolation
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reproductive isolation before fertilization
never meet (separated in space, time or habitat) meet but don't mate (behavioral or sexual isolation) wrong key for lock mechnical isolation (mating incompatibility) |
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Post Zygotic Isolation
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lack of offspring success
death sterility hybrid breakdown |
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Hybrid Breakdown
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hybrids live and reproduce but all of the hybrid's offspring die or are sterile
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Native Species
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evolved in and for a particular ecosystem
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Alien
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migrate into/are brought from elsewhere
some go extinct because not able to adapt others out compete natives --> example: mammals brought to New Zeland |
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Keystone
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absolutely essential for particular ecosystem
--> example: plankton in arctic marine ecosystem |
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Biodiversity
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value of life forms
ecological functions they perform genetic variation they contain |
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Species Diversity
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Number of Species in a Community
More Species= Greater species diversity species abundance and evenness of distribution is also important |
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Biodiversity "Hot Spots"
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Tropic Regions
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Why are some communities more diverse than others?
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evolutionary time
climate stability productivity niche |
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evolutionary time
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FIRST EXPLANATIONS FOR WHY SOME COMMUNITIES ARE MORE DIVERSE
tropics are more ancient (not affected by ice age) so more time to develop |
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Climate stability
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SECOND REASON WHY SOME COMMUNITIES ARE MORE DIVERSE
in unstable climate species develop wider range of tolerance so can adapt to a variety of conditions so fewer species in stable climate species specialize into niches so more species can fit in |
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Productivity
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THIRD REASON WHY SOME COMMUNITIES ARE MORE DIVERSE
more resources and energy available so more species can utilize them competition is a selective factor |
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Niche
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FOURTH REASON WHY SOME COMMUNITIES ARE MORE DIVERSE
place where a species fits in the ecosystem (biological, physical and chemical conditions) |
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Fragmentation of Habitat
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As size of communities decrease so does biodiversity
certain size needed to maintain larger animals as they go extinct many other organisms that depend on them for parts of their life cycle ddo as well |
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Why Care About Biodiversity
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1. Maintains Essential Ecosystem Services and Stability
2. Provides Basis for Human Health 3. source of agricultural productivity and sustainability 4. Underlies economic, social and political stability 5. enriches the quality of our lives 6. intrinsically valuable |
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Threats to Biodiversity
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habitat loss and degredation
overexploitation of economically important species exotic or invasive species global climate change |
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Small populations face
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Interbreeding depression (mating between relatives, reduces ability to survive and reproduce)
Low genetic variation population cannot evolve or adapt |
