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Biology 104S
Exam2
24
Biology
Undergraduate 2
10/07/2013

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Term
Species-Definition
Definition
: Ernst Mayr "...groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups
Term
reproductively isolated
Definition
Individuals that cannot produce fertile offspring and members of different species
Term
Application Problems with definition of species
Definition
1. Difficult to apply to species that reproduce asexually.(example: bacteria)
2. Difficult to apply to populations that do not occur together in nature.
Term
Sympatric species
Definition
same distinct entities phenotypically different. Same location, often use different parts of the habitat. - Two species that occur together and are nearly identical
Term
Geographic Variations
Definition
Populations of a single species that occur in different areas. May be classified as a subspecies or a variety.
Term
Allopatric species
Definition
geographically separated populations. Squirrels on North + South Rims of the Grand Canyon.
Term
2 General types of Reproductive Isolation
Definition
Prezygotic and Postzygotic
Term
Prezygotic
Definition
fertilized egg starting development. Prevention of fertilization or viable zygote.
Term
Postzygotic
Definition
sterile hybrid
Term
Types of prezygotic isolating Mechanisms
Definition
Ecological Isolation, Behavioral Isolation, Mechanical Isolation, Prevention of Gamete Fusion, and Temporal Isolation.
Term
Ecological Isolation
Definition
Physical Seperation: different organisms use different parts of the environment-they don't encounter one another in nature.
Term
Behavioral Isolation
Definition
Courtship Rituals among birds, certain insects, and amphibians.
Term
Mechanical isolation
Definition
Structural differences in reproductive organs.
Term
Prevention of Gamete Fusion
Definition
Eggs Sperm
Term
Temporal Isolation
Definition
difference in the timing of breeding seasons
Term
Types of postzygotic isolating mechanisms
Definition
Hybridization, Hybrid sterility, abnormal sex organ development, chromosomal alterations.
Term
Geography of Speciation
Definition
Two identical populations must diverge, Reproductive isolation must evolve to maintain difference between the two populations.
Term
Instantaneous speciation
Definition
occurs in plants via Autopolyploidy, and allopolypoidy.
Term
Autopolyploidy
Definition
all chromosomes are from single species
Term
Allopolyploidy
Definition
2 different species hybridize
Term
Haplodiplontic
Definition
half lifecycle as a sporophyte half as gametophyte=alteration of generations
Term
Gametophytes
Definition
Photosynthetic
Term
sporophytes
Definition
attached to and nutritionally dependent on the female gametophyte
Term
non vascular plants
Definition
generally small and require water to reproduce sexually, can reproduce asexually
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