Test 1 study Flashcards
(27 cards)
Define natural selection and explain ‘fitness’
NS is the process in which individuals have inherited traits that allow them to survive/reproduce more because of those traits
why is natural selection not random and not goal-directed
natural selection doesn’t produce organisms perfectly suited to their environments. it allows the survival of individuals that are good enough. mutation causes genetic variation and is completely random
how is artificial selection evidence for evolution?
because it provides us with a model that helps us understand natural selection- selecting for specific traits
how are homologous structures evidence of evolution?
shows that some species derived from a common ancestor
how are vestigial structures evidence of evolution?
shows that some organisms used to have structures that are no longer of use
ex. hip bones in whales
how is convergent evolution evidence of evolution?
shows that organisms will adapt to their environments
ex. wings in many different organisms
how does biogeography show evidence of evolution?
shows that some organisms have been in environments on earth but have since diverged from the original population- they used to be together
what is the difference between homologous and analogous structures?
(H) are similar in structure but differ in function- they share a common ancestor, while (A) are structures in organisms that don’t share a common ancestor but have structures that share similar functions
what is microevolution?
microevolution is evolutionary change below the species level; change in allele frreq. in population over generations
ex. bacteria building resistance to pesticides
what is macroevolution?
evolutionary change above the species level
ex. ex. human to ape, bird to dinosaur
what are... (A) alleles (b) genes (c) genotypes (d)phenotype (e) dominant (f) recessive (g) heterozygous
(a) any version of a gene that may produce distinguishable phenotypic effects
(b) unit of hereditary info consisting of a specific nucleotide sequence in DNA
(c) genetic makeup, set of alleles in an organism
(d) observable physical traits
(e) fully expressed allele in a heterozygote
(f) allele not expressed in a heterozygote
(g) organism that has 2 different alleles for a gene
the ultimate source of variation is wha?
mutation
what conditions need to be met for a pop. to be in H-W equilibrium?
- large populatio
- random mating
- no natural selection
- no immigration/emmigration
- no chnage in allelic freq. due to mutation
What are the H-W equilibrium equations, and what do the variables represent?
Allele freq. (p+q=1) genotype freq. (p^2+2pq+q^2=1) p= all dominant alleles q= all recessive alleles p^2= homo dom. freq q^2= home rec. freq 2pq= hetero freq
Define and give examples of the two types of genetic drift
genetic drift is when chance events cause fluctuations in allele freq. from one gen to the next
founder effect- when a few indiviuals from a population become isolated and form a new population
bottleneck effect- when the size of the population is reduced, as by a natural disaster of human actions. typically the surviving pop isn’t representative of the original population
what is directional selection?
directional selection is natural selection that in which one extreme of the phenotypic range survives/reproduces more sucessfully than others
what is disruptive selection?
natural selection in which both extremes of the phenotypic range survive and reproduce more sucessfully than the intermediate
what is stabilizing selcetion?
natural selection in which the intermediate of the phenotypic range survives and reproduces most sucessfully
what is the biological species concept?
a definiton for species as a group of population whose members have the potential to interbreed in nature and produce viable offspring, but not with other such groups
what is the morphological species concept?
def. of species in terms of measurable anatomical criteria
ex.
what is the phylogenetic species concept?
species are an irreducible-(not to be reduced or simplified) group whose members are descended from a common ancestor and who all possess a combo certain defining, dervied traits
why isn’t the biological species concept perfect?
- ignores asexual organisms
- ignores isolated populations
- ignores hybridization
- fossils (no actual evidence of sex)
what is a sympatric species?
formation of new species in populations that are in the same geographic area- flies that either fed off of apples or blue berry
what are the reproductive isolation mechanisms?
habitat iso- species that occupy the same area but don’t interact
temporal iso- breed during different times
behavioral iso- diff breeding rituals
mechanical iso- mating is attempted but morphological diff prevents breeding
gametic iso- sperm cant survive/be fertilized by egg of other species
reduced hybrid viability- hybrid has impaired development that reduced its ability to survive
reduced hybrid fertility- hybrid offspring can’t reproduce
hybrid breakdown- 1st gen of hybrids are viable and fertile but every later generation increasingly becomes less fertile and viable
