Chp 21: Evolution of Population

Which of these mutations to nucletide sequences would NOT alter the reading frame?

single substitution

Define microevolution

change in allele frequencies of a population resulting in only slow MINOR changes

Define directional selection

natural selection favors ONE extreme over another

Define stabilizing selection

Natural selection favors the median/average

Define analogy

similarity between 2 species due to convergent evolution w/ no common ancestor.

When does convergent evolution occur?

When similar environment conditions + natural selection produce similar charachteristis

If two genes in organisms share the same nucleotide sequences, they are likely to be __________.

Homologous

How do researchers approx the # of years a species occured/lived in?

Molecular clock

Define molecular clock

estimating the time required for evolutionary change based on the observation that some regions of genomes evolve at constant rates.

The number of nucleotide substitutions in related genes equals _______.

Time that has elapsed since the genes branched from the common ancestor.

How can we calibrate the molecular clock?

By graphing the number of genetic differences (nucleotide, codon, amino acid) against the dates of evolutionary branch points

What causes differences in the speed at which clock like genes evolve?

• nuetral mutations

• difference in clock rate

What do nuetral mutations do?

regulate rate of evolution

What does a difference in clock rate indicate?

How important a gene is

The idea of a moleculr clock works on the notion that ________.

nuetral mutations can arise and become fixed at a constant rate.

How many kingdoms are there and list them?

There are 5 kingdoms; prokaryotes, animalia, protista, and fungi

How many domains are there and name them

3 domains; bacteria, archae. and eukarya

Define the biological species concept

defines a species based on wether they can breed and produce viable, fertile offspring

Define the morphological species concept

defines a species based on shared physical characteristics, structural anatomy, etc.

Phylogenetic specieis concept

defines a species based on the phylogenetic tree

ecological species concept

defines a species based on its ecological niche which is how the organism interacts with the living and non-living parts of its environment (what it eats, where it lives, its tolerance for heat, etc.)

The formation of new species hinges on _________.

Speciation and reproductive isolation

Define reproductive isolation

the existence of barriers that stop members of 2 species to produce viable offspring

Define prezygotic barriers

blocks fertilization from occuring; stops members from mating, mating attempts to be succesful, and hindering fertilization

What are all the prezygotic barriers?

1. Habitat isolation

2. Temporal isolation

3. Behavioral isolation

4. mehanical isolation

5. gametic isolation

Define habitat isolation

species live in relatively the same place but not the same area so they hardly encounter each other

define temporal isolation

species live in the same habitat but breed at different times/seasons

define behavioral isolation

differing mating behaviors and interaction prevent mating

Define mechanical isolation

Their mating bits dont match up so they cant mate

Gametic isolation

Mating occurs but the egg isnt fertilized/cant be fertilized.

important factor hat holds the gene pool of a species together & prevents speciation

gene flow

limitiations of the biological species concept?

• dosent include snails

• doesnt include asexdual reproduction

species in the biological species concept are designated by _____.

Gene flow

Define “Reinforcement” of a hybrid zone

natural selection strengthens prezygotic barriers to reprodction.

Define punctuated equilibria

long periods of stasis in the fossil record in which a species goes through little to no morphological (physical) change interrupted by prief change

what role does nondisjunction play in the formation of fertile alloploidy hybrids?

doubles the chromosome number in the hybrid