Chapter 24 & 26 Flashcards
Evolutionary Theory Evidence
Fossil record
Vestigial traits
Geographic location
Homology
Fossil record
linking features
Vestigial traits
Geographic location
similar species found in the same areas
Genetic Homology
Developmental homology
Structural homology
Natural Selection Requirements
Step one: genetic variation
Step two: the variation is heritable
Step three: there is variation in offspring production and offspring mortality
Step four: Survival is not random, the reproducers are superior to the nonproducers
Natural selection current examples
Bacteria
Fruit flies
Galapagos birds
Misconceptions
Selection is on individuals, evolution is on ecosystems
Acclimation is not adaptation
Evolution is not always good and can cause the species to die out
More evolved does not mean more complicated
Selection
on individuals
evolution
ecosystems
not always good and can cause the species to die out
More evolved does not mean more complicated
Acclimation
not adaptation
Limitations
Traits that can’t change
Genes are not infinite
Time
History
Biological species concept
The one we use
Reproductive isolation
There are two main categories for isolation
Prezygotic
postzygotic
Prezygotic isolation
Prevents a species from mating
Examples:
- Temporal isolation
- Habitat isolation
- Behavioral isolation
- Gametic barrier
- Mechanical isolation
Temporal isolation
Different breeding times
Habitat isolation
Habitats are separated somehow
Behavioral isolation
Different requirements for courtship
Gametic barrier
Eggs and sperm don’t mix
Mechanical isolation
Can not physically mate
Postzygotic isolation
Inability to pass on traits even though mating is possible
Can be from
Hybrid sterility
Hybrid viability
Hybrid viability
Embryo death or lack of development
Hybrid sterility
The offspring is sterile
Morphospecies Concept
Species are morphologically distinct from one another
Physical differences wouldn’t occur if the animals were not different
Phylogenetic species Concept
Determined by synapomorphy
Each monophyletic group is distinct from another due to different genetic features
Therefore each group is a species
Pros and Cons
Allopatric Specation
Vicariance
Physical leading to genetic separation
Colonization
Can cause some part of a population to form a new colony
Sympatric speciation
The animals can mate, but they do not have gene flow
Mechanisms
Disruptive selection
Polyploidization
Natural selection leading to genetic divergence
Genetic mutations can also lead to…
speciation, not just genetic drift
Autopolyploidy
mutation leads to a doubling of chromosome number
Allopolyploidy
different species mate and it produces an offspring with double the chromosome number
Polyploidy
is very common in plants
Self fertilization
Multiple mitosis rounds increasing chances of meiotic error
How do the species maintain distinction?
By adapting to a niche or a zone the children of any mating species will have lower fitness
Does not mean that species do not contact each other
Does not mean that hybrids cannot survive
When populations meet?
Fusion
Reinforcement
Hybrid zone
Extinction
Creation
fusion
reproductive barriers weaken until the two species become one
Groler bear
Reinforcement
Hybrid zones
