Evolution Flashcards
biological species concept (BSC)
a population or group of populations whose members have the potential to interbreed naturally to form viable, fertile offspring, but cannot do so with members of other populations.
Do Kings Play Chess On Fine Grains of Sand
Domain - bacteria, archaea, eukarya Kingdom Phylum (or Division, for plants) Class Order Family Genus Species
This is also called a Linnaean Hierarchy.
classification
the grouping/ arrangement of species, genera, families, etc. according to similarities.
taxa/ taxon
Also, taxonomy
taxonomy - the description and enumeration of species
systematics
the study of relationships between species
phylogeny
the depiction of the relationships between the species
The Linnaean system
the conventional system of binomial naming used for all organisms, devised by Carl von Linne.
Genus species, italicised and in Latin.
adaptations
traits that look designed but have evolved due to natural selection
differential replication
occurs in evolution by natural selection and means that the only variants that persist are those that are good at making copies of themselves
natural selection syllogism (3 premises and 2 conclusions)
If…
a. …there is VARIATION among individuals in some attribute/ trait, and…
b. …there is a consistent association between that trait and some measure of reproductive success, ie FITNESS CORRELATION, and…
c. …there is INHERITANCE of traits from parents to children which is at least partly independent of common environmental effects…
THEN:
1.) individuals of a given age will differ predictably from the individuals that do not survive to that age (within generation effect), and…
2.) the offspring generation will differ predictably from their parental generation (between-generation effect).
fitness
the success of an organism to contribute offspring to future generations;
the likely success of individuals of this genotype in producing offspring, which is due to the effect of the genotype on the phenotype;
the likely success of a given allele in getting into the next generation, which will depend on which genotypes it occurs in and at what freq
often measured as ‘lifetime offspring production’; but it might be even better to measure it as the number of grandchildren it produces, and it should be considered how fit those individuals are as well
relative fitness
represented by the letter “w”
the quotient of the success of the individual (or genotype or gene) divided by the average fitness for an individual (or genotype or gene) in the population.
If w=1, then the indiv is average; if w>1, then selection favours this type of indiv
group selection
a controversial concept of individuals possessing adaptations that are good for the group, ie increasing the reproductive output of the group, but not necessarily for the individual himself
more likely to occur in populations with little genetic diversity from individual to individual or, even more likely, when populations are genetically identical.
artificial selection
changes that occur in a species due to selective breeding AND when there is an end-goal in mind.
types of selection: stabilising selection; directional selection; diversifying/disruptive/divergent selection
stabilising selection: selection against extreme phenotypes;
directional selection: selection for one extreme;
disruptive selection: selection for both extremes
frequency-dependent selection: positive and negative
pos freq-dep selection: the common phenotype is favoured;
neg freq-dep selection: the rare phenotype is favoured
balancing selection
the persistence of genetic variation in a population despite a seeming directional advantage. This can be caused by a number of situations:
- neg freq-dep selection
- heterozygote advantage, e.g. sickle cell anemia
- mutations
- gene flow between populations
- temporal environmental variation
sexual selection: intrasexual and intersexual
intrasexual selection: improves competitive features between members of one sex that increases their access to mate
intersexual selection: improves attractiveness that makes some indivs mor likely to be chosen by members of the opposite sex
coevolution
more than one species evolves in step with another, perhaps in a mutually beneficial way (ants and fungus) or more likely in a competitive way (predators and prey)
stasis
the persistence of clades for long periods of time without apparent evolutionary change; giving rise to so called living fossils
anagenesis
evolutionary change without apparent speciation
prezygotic isolating mechanisms
- temporal isolation
- habitat isolation
- pollinators
- behavioural ie mate selection
also, mechanisms that prevent fertilisation:
- genetic incompatability
- gametic mortality
