Chapter 24 - Speciation Flashcards
Adaptive Radiation
rapid speciation under conditions in which there is little competition.
Paedomorphosis
Retention of Juvenile Characteristics in adults.
Population
considered separate species if they are reproductively isolated from each other:
they do not interbreed or they fail to produce viable, fertile offspring.
therefore, no gene flow occurs between these populations
Prezygotic Isolation
individuals of different species are prevented from mating.
Postzygotic Isolation
individuals from different populations do mate, but the hybrid offspring produced have low fitness and do not survive or produce offspring.
Morphological Species Concept
Biologists identify evolutionarily independent lineages by differences in morphological features.
Phylogenic Species Concept
Reconstructing the evolutionary history of populations. It relies heavily on DNA sequencing.
Monophyletic group or Clade
On phylogenetic trees, an ancestral population plus all of its descendants
Synapomorphy
a trait unique to a monophyletic group
Ecological Species Concept
defines a species as a set of organisms exploiting a single set of resources, having the same range of environmental tolerances, and facing the same predators and parasites.
Genetic Species Concept
Classifies populations as being of the same species if they have 97% of the same genome
Sub-species
populations that live in discrete geographic areas and have their own identifying traits but are not distinct enough to be considered a separate species.
Allopatric Speciation
Speciation that begins with physical isolation
Dispersal
occurs when a population moves to a new habitat, colonizes it, and forms a new population.
Vicariance
occurs when a physical barrier splits a widespread population into subgroups that are physically isolated from each other.
Sympatry
Different populations or species that live in the same geographic region live in sympatry
Allopolyploidy
Parents that belong to different species produce offspring in which chromosome number increases. In rare occasions hybridization results in fertile animal offspring.
Niche
the range of ecological resources that a species can use and the range of conditions it can tolerate
Hybrid Zone
A geographic area where interbreeding between two populations occurs and hybrid offspring are common.
How does hybridization link with extinction?
The hybrid is favoured over one of the species. Can also lead to formation of new species
Which concept(s) for identifying species cannot be applied to asexual or fossil species?
Biological Concept - cannot make deductions based on sexual reproduction
Reinforcement
type of natural selection called disruptive selection, which favours extreme phenotypes over intermediate phenotypes.
Fertilization
The process by which haploid gametes form a diploid zygote
Most polyploid plants arise as a result of _____.
Hybridization
How can an allopolyploid plant become a biologically fit new species?
If a nondisjunction event occurred that resulted in chromosome doubling, the plant’s ability to undergo meiosis would be restored and it could then produce viable gametes.
