Isolation Nation
The Movement of alleles between populations
What is Gene Flow?
The process by which individuals with advantageous heritable traits tend to survive and reproduce mroe successfully?
What is Natural Selection?
A formation of a new species
What is speciation?
The independent evolution of similar traits in different evolutionary lineages, often due to similar selection pressures.
What is convergent evolution?
An alternative form of a gene.
What is an allele?
The term for a physical barrier that separates populations like a mountain or river
What is Geographical Isolation
What is an adaptation?
This term describes populations that cannot interbreed to produce viable, fertile offspring
What is Reproductive isolation, under the biological species concept?
The evolution of different traits in related populations or species from a common ancestor.
What is divergent evolution?
A change in the DNA sequence that can introduce new genetic variation.
What is a mutation?
The name for speciation that occurs when populations are geographically separated
The term for the formation of new species from one ancestral species evolving into different forms
What is Divergent evolution?
This type of speciation occurs without geographical separation, within the same geographical area?
What is Sympatric Speciation?
The relatively rapid diversification of one ancestral lineage into multiple species adapted to different ecological niches.
What is adaptive radiation?
The term for all the alleles present in a population
What is a gene pool?
Two populations live on opposite sides of a mountain range. Explain how the mountain eventually leads to speciation
What is the mountain reduces or stops gene flow. Mutations / natural selection and genetic drift causes the populations allele frequencies to diverge. Overtime, reproductive isolation may occur separating the species?
What is different environments create different selection pressures. Individuals with advantageous heritable variations have greater reproductive success, passing their alleles on. Over generations, allele frequencies and phenotypes diverge.
Give one prezygotic and one postzygotic reproductive isolating mechanism.
Prezygotic: different mating behaviours, breeding seasons or incompatible reproductive structures. Postzygotic: hybrid inviability or hybrid sterility.
Sharks and dolphins both have streamlined bodies, but one is a fish and the other is a mammal. What evolutionary pattern does this illustrate, and why?
Convergent evolution. Similar aquatic selection pressures favoured streamlined bodies independently in distantly related lineages.
How can genetic drift change a small isolated population even if a trait provides no survival advantage?
Allele frequencies can change by chance from one generation to the next. In small populations, random events can have a large effect and alleles may be lost or become fixed.
A road divides a population of lizards. Why does this not automatically mean that two new species will form?
What is the road may reduce the gene flow, but speciation requires populations to diverge genetically and develop reproductive isolation. If they continue interbreeding, or can still reproduce successfully if they meet, separate species may not form?
A population is separated into two habitats with different food sources. Explain the chain of events that could result in two species.
What is heritable variation exists within the ancestral population. Isolation reduces gene flow. Different food sources create different selection pressures, favouring different traits. Natural selection changes allele frequencies in each population, causing divergence until reproductive isolation develops.
A plant population undergoes chromosome doubling. The resulting plants can reproduce with one another but not successfully with the original population. Explain how this could produce a new species.
Polyploidy changes chromosome number. Crosses with the original population may produce offspring with incompatible chromosome sets or reduced fertility. The polyploid plants can reproduce with one another, creating reproductive isolation and potentially a new species.
One ancestral bird species colonises several islands. Descendant populations evolve different beak shapes suited to different foods. Name and explain the evolutionary pattern.
Adaptive radiation, a form of divergent evolution. Descendants of one ancestor diversify into species occupying different ecological niches, with natural selection favouring different beak traits.
A few individuals colonise a new island and carry only some of the alleles from the original population. Name the effect and explain its significance.
The founder effect, a type of genetic drift. The new population begins with a non-representative sample of the original gene pool, so allele frequencies and genetic diversity may differ from the source population.