Chapter 14: The Orgin Of Species Flashcards
Do all members of a species look alike
No
Do all members of other species look different
Yes
Biological species concept
Members mate and produce fertile offspring (offspring that themselves can reproduce)
Reproductive isolation
Prevents genetic exchange (gene flow) and maintains boundary between species
Biological species concept does apply to what?
Doesn’t apply to organisms known through fossils and prokaryotes (asexually)
Hybrid
Offspring of two different species
Morphological species concept
Classifies organisms based on observable physical traits an can be applied to asexual organism and fossils
Ecological species concept
Classifies organism based on where they live and how they have adapted to a specific biological community
Phylogenetic species concept
Defines a species as the smallest group of individuals that share a common ancestor and thus form one branch on the tree of life using DNA sequences and morphological traits
Reproductive barriers
Prevent interbreeding
2 types of reproductive barriers
Prezygotic barries and postzygotic barries
Prezygotic barriers
Prevent mating or fertilization between species; exists before zygotes form
Postzygotic barriers
Occur after zygotes have formed
Prezyogotic barrier: Habitat Isolation
Two species live in the same general area but not in the same habitats
Prezyogotic barrier: temporal isolation
Two species breed at different times (seasons, times of days or years)
Prezyogotic barrier: behavior isolation
There is little or no mate recognition between females and males of different species
Prezyogotic barrier: mechanical isolation
Physical incompatibility of reproduction parts (common amount flowering plants
Pollination
Sperm carried pollen lands of female reproductive structure
Prezyogotic barrier: gametic isolation
Molecular incompatibility of eggs of sperm or pollen and stigma
Pollen is produced by what
Male reproductive structure
Stigma is a female reproductive structure,,,
Where pollen lands during pollination
Postzygotic barriers: reduced hybrid viability
Zygotes survive but hybrids development or survival impaired by interaction of parental genes
Postzygotic barriers: reduced hybrid fertility
Hybrid offspring are vigorous but sterile example mule
Mule is a hybrid of
Female horse and male donkey
Postzygotic barriers: hybrid breakdown
First generation hybrids are viable and fertile but the offspring of the hybrids are feeble and sterile
What causes a new species to arise
Allopathic speciation
Allopathic speciation
Populations of the same species of geographically separated
How can a new species arise if the environment does not change
Sympathetic speciation
Sympatric speciation
One species evolves into two or more different species while living in the same geographic area; most cases are around plants; occurs because of errors during cell cycle
Polyploid species
Have more than two sets of chromosomes,
Reinforcement
If the parent species are more fit than the hybrid offspring
Fusion
If the parent species and the hybrids are equally fit
Stability
If the parent species were less fit than the hybrids
How can several species evolve from one ancestor
Adaptive radiation
Adaptive radiation
Evolution of many diverse species from common ancestor
Punctuated pattern
One big change, species change most as they arise from an ancestral species and then experience relatively little change for the rest of their existence
Gradual pattern
Several small changes, species appear to have evolved more gradually
