Lecture 33: Adaptation Flashcards Preview

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Flashcards in Lecture 33: Adaptation Deck (10):

What are the principles of natural selection

- More offspring are produced than can survive to reproduce
-there is variation in the trait of interest
-a genetic basis for the trait means that it can be inherited
-individuals with the trait have more offspring than individuals without the trait
(Differential reproductive fitness)
-any entity with these properties have the potential to evolve


Give the definition of natural selection

A theory of evolution that states that organisms best suited to survive will live to reproduce, thus passing on favourable characteristic to the next generation


Give the definition if adaptive radiation
What is the definition of niche

A process of evolution in which variations of a single species fill different niches and eventually become new species.
Niche- the role of an organism in its community; what and where it eats, and what eats it


What is a species. Give a definition

Individual organisms that are very similar in appearance, anatomy, physiology, and genetics due to having relatively recent common ancestors

Groups of interbreeding natural populations that are reproductively isolated from other such groups


What is speciation?

Two modes of gradual speciation have been put forward:
1. Geographical separation of the diverging populations: allopatric speciation
2. Those without geographical separation: sympatric speciation
With genetic and phenotypic drift, both modes eventually result in reproductive isolation of two if more populations.
Genotype: the set of genes carried by an organism
-genomics-the study of the genome
Phenotype: the actual expression of the genotype (only a subset of genes are actually expressed)
Proteome: the set of proteins specified by the genome (much more complicated, as genes act in permutation and combination.)
-proteomics- the study of the proteome, and one if the most rapidly growing areas of biology


Reproductive isolation

Pre-mating mechanisms preventing crossing
-potential mates do not meet (seasonal/ habitat isolation)
-potential mates meet but do not mate (behavioural isolation)
-potential mates attempt to mate but cannot (mechanical isolation)

Post-mating mechanisms prevent crossing
-sperm are transferred but fertilisation fails
-egg is fertilised but the hybrid dies (hybrid mortality)
-hybrid is viable but partially or completely sterile eg mules


What is an adaptation? Give definition

A phenotypic feature of an individual that contributes to that individuals survival.


Adaptive niches

Generally in any environment there are a finite number of adaptive niches into which organisms can radiate
One good metaphor for adaptive niche is to think of them as peaks in a landscape
-each peak is occupied by one species
-have colonized a peak it's almost impossible to move to another unless the landscape changes drastically
-as new potential peaks appear, unspecialised forms in 'valleys' colonized them


Radiation of the Cichlids

-over 1750 species now exist in E Africa Rift Valley lakes
-rapid divergence into novel niches occurred as the environment expanded and fluctuated
(Good example of sympatric speciation)
-such rapid radiations can arise when a large number of potential niches appear at short notice


Go to yr 12 notes for this lecture...Way better