Week 9 Flashcards
(25 cards)
What is a species?
A species is defined by differences in ploidy, slightly different habitats and ranges, morphological differences, minor differences in flowering season, and all individuals being interfertile.
Example includes solidago tree species.
How are species defined?
Species are classified systematically into discrete groups of organisms, representing evolutionary history, and applicable to a variety of organisms.
What is the species problem?
The species problem arises from the existence of many species concepts, none of which are perfect.
What are the different species concepts?
The species concepts include:
* Phenetic/morphological species concept
* Biological species concept
* Phylogenetic/lineage species concept
* Ecological species concept
* Evolutionary species concept
What is the phenetic species concept?
The phenetic species concept classifies species based on phenotypic similarity.
What are the pros and cons of the phenetic species concept?
Pros:
* Can be applied to extinct species using morphology from fossils
* Can use genetic data similarly
Cons:
* Doesn’t include evolutionary history
* Traits may arise from convergent evolution
* Fails with high within-species variation or low between-species variation.
What defines the biological species concept?
The biological species concept defines species as groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.
What are the shortcomings of the biological species concept?
Shortcomings include:
* Inapplicability to extinct species
* Asexual species
* Hybridization events.
What is the phylogenetic species concept?
The phylogenetic species concept defines species as members sharing a common evolutionary history and fate, distinguished by a shared derived character.
What are shared derived traits?
Shared derived traits are traits inherited from an ancestor and shared among organisms of the same species.
What are the three modes of speciation?
The three modes of speciation are:
* Allopatric
* Parapatric
* Sympatric.
What is allopatric speciation?
Allopatric speciation occurs when populations are geographically isolated.
What are the two models of allopatric speciation?
The two models are:
* Dispersal model
* Vicariance model.
What is genetic drift?
Genetic drift is the random change in allele frequencies in a population, with a larger effect in small populations.
What is adaptive radiation?
Adaptive radiation is when a population disperses and occupies different niches, leading to multiple speciation events.
What are the requirements for natural selection?
The three requirements for natural selection are:
* Heritable phenotypic variation
* Competition for resources
* Favorable traits lead to more offspring.
What is parapatric speciation?
Parapatric speciation occurs in the absence of geographic barriers with gene flow present, resulting in a hybrid zone.
What is sympatric speciation?
Sympatric speciation occurs with divergence in the same geographic area, often due to resource competition or ecological niche differentiation.
What are prezygotic reproductive isolating mechanisms?
Prezygotic mechanisms prevent mating or fertilization and include:
* Temporal
* Habitat
* Behavioral
* Mechanical.
What are postzygotic reproductive isolating mechanisms?
Postzygotic mechanisms prevent viable offspring from being born and include:
* Lack of hybrid viability
* Infertility or reduced fertility of offspring.
How does habitat isolation work?
Habitat isolation occurs when two populations occupy different habitats, leading to genetic isolation despite proximity.
What is polyploidy?
Polyploidy is having more than two sets of chromosomes, common in plants and rare in animals.
What is autopolyploidy?
Autopolyploidy is genome duplication within a species.
What is allopolyploidy?
Allopolyploidy involves having more than two sets of chromosomes from different species.
