unit 1-3 Flashcards
(24 cards)
What does it mean that one location can host many species?
Multiple species can coexist in the same geographic area due to different ecological niches or reproductive barriers.
Can a species exist in more than one location?
Yes, a given species can be distributed across multiple geographic regions.
What are the two requirements for speciation?
1) Reproductive isolation; 2) Divergent selection.
What is a limitation of using only fossil records to define species?
Fossils don’t show reproductive isolation, and can’t help with species that reproduce asexually or hybridize in captivity.
Why is the morphological species concept considered subjective?
It relies on physical traits, and different biologists may disagree on which traits define a species.
What is a problem with the ecological species concept?
Species with overlapping niches may be hard to distinguish ecologically.
What issue arises with genetic divergence in defining species?
It’s unclear how much genetic difference is required to define a new species.
What is ecological/habitat isolation?
Species live in the same area but in different habitats and rarely meet.
What is behavioral isolation?
Species have different courtship behaviors, preventing interbreeding.
What is temporal isolation?
Species reproduce at different times of the day or year.
What is mechanical isolation?
Structural differences prevent successful mating.
What is gametic isolation?
Sperm and egg are incompatible or can’t survive in each other’s reproductive tracts.
What is hybrid inviability?
Hybrid embryos fail to develop or die early.
What is hybrid sterility?
Hybrids survive but are sterile (e.g., mule).
What is hybrid breakdown?
First-generation hybrids are fertile, but offspring of hybrids are feeble or sterile.
Example of habitat isolation in garter snakes?
T. atratus lives in water; T. sirtalis lives on land.
Example of temporal isolation in skunks?
S. putorius breeds in winter; S. gracilis in fall.
Example of behavioral isolation in boobies?
Blue-footed and masked boobies perform different courtship dances.
Example of mechanical isolation in Heliconia plants?
Different pollinators (curved vs. straight-billed hummingbirds).
Example of gametic isolation in sea urchins?
Purple and red sea urchin sperm/eggs can’t fertilize each other.
What is allopatric speciation?
A population is divided by a barrier, evolves separately, and eventually becomes reproductively isolated.
What is sympatric speciation?
New species evolve from a single population in the same area, often through disruptive selection and prezygotic isolation.
What is reinforcement in speciation?
Natural selection strengthens prezygotic barriers when hybrid offspring are weak or infertile.
How does whole genome duplication lead to speciation?
It causes instant reproductive isolation in polyploid organisms, especially plants.
