Chapter 7 - Evolution and adaptation Flashcards
What are some observations that can be made in a population?
- More offsprings born than ones that actually survive
- Natural variation between individuals of a population
- Offpsrings are similar to their parents because they inherit alleles
What did those observations conclude?
- Variation influences the ability to survive and reproduce viable offspring
- Survival phenotypes are passed down to the next generation
What is the survival advantage?
It increases the individuals fitness as their alleles are passed down to the next generation
What are some survival advantages
- gathering food
- avoid predators
- attracting a mate
- producing offspring
What is natural selection?
The process of increasing the likelihood of survival and reproduction of individuals with specific phenotypes
It works through selective pressures (environmental factors) and different phenotypes
What is natural selection’s effect on allele frequencies?
It increases allele frequencies for phenotypes with high survival advantage.
What is the definition of species?
A group of genetically similar organisms that can interbreed to produce viable or fertile offsprings
What are isolating mechanisms?
Factors that prevent individuals from interbreeding as they separate two or more gene pools.
What is speciation?
It occurs when one population separates to form two new populations that are different enough to no longer produce viable offsprings
often the result of isolating mechanisms that prevent gene flow between populations
What are the two main groups isolating mechanisms can be classified into?
Prezygotic barriers and postzygotic barriers
What are prezygotic barriers?
- stops fertilisation
- prevents mating from happening in the first place
What are some examples of prezygotic barriers?
- Temporal isolation
- Behavioural isolation
- Ecological isolation
- Mechanical incompatibility
- Gametic isolation
What is temporal isolation?
different specific breeding times
What is behavioural isolation?
different courtship patterns for species
What is ecological isolation?
geographical barriers like oceans and mountains
What is mechanical incompatibility?
different reproductive structures
What is gametic isolation?
conditions of the female tact being fatal for the sperm
What is postzygotic barriers?
- does not prevent fertilisation
- prevents the formation of viable offspring
What are the 3 types of postzygotic barriers?
- reduced hybrid viability
- reduce hybrid fertility
- hybrid breakdown
What is reduced hybrid viability?
hybrid offspring do not develop properly
- not born
- does not survive reproductive stage
What is reduced hybrid fertility?
if offspring survives reproductive stage, but cannot produce functional gametes
- infertile and sterile (cannot produce healthy offspring0
What is hybrid breakdown?
if first generation hybrid is fertile, then the second generation offspring does not develop properly
What are the two forms of speciation?
- Allopatric speciation
- Sympatric speciation
Which form of speciation is more common?
Allopatric
