BIOL 101 Unit #4 Chapter 11

what is evolution?

process through which the characteristics of species change and through new species arise

what is the inheritance of acquired characteristics?

phrase that describes the mechanism of evolution proposed by Jean-Baptiste Lamarck in which traits acquired by individuals through use or disuse could be passed on to their offspring, leading to evolutionary change in the population

- led to issues in humans, thought the poor were weak and allowed them to starve so the more wealthy "strong" survived, wasn't the case though

who conceived and described the actual mechanism for evolution?

the two naturalists: Charles Darwin & Alfred Russel Wallace

what is natural selection?

the greater relative survival and reproduction of individuals in a population that have favorable heritable traits, which leads to evolutionary change

- inspired by Galapagos island finches & their beaks

what is variation?

the variety of alleles in a population

- natural selection needs to have variation to occur, or else selection will not lead to change

how does genetic diversity in a population occur?

mutation and sexual reproduction

how does mutation play a role in genetic diversity in a population

it affects the phenotype of an organism, either benefitting it, or a negative effect, or neutral effect on fitness

how does sexual reproduction play a role in genetic diversity in a population?

it helps crossing over & unique combos of alleles

what is adaptation?

a heritable trait/behavior in an organism that aids in its survival, in its present environment

what is divergent evolution?

evolution that results in different forms in two species with a common ancestor

what is convergent evolution?

opposite to divergent evolution; evolution that results in similar forms on different species

what are analogous structures?

structure of an organism (ex. wings), similar in function (ex. flying) & appearance

what are homologous structures?

a structure that is similar because of descent from a common ancestor

what is modern synthesis?

the coherent understanding of the relationship between natural selection and genetics that took shape by the 1940's; it's generally accepted by Biologists today

what is microevolution?

the changes in a population's genetic structure (allele frequency)

what is macroevolution?

a broad scale of evolutionary changes seen over paleontological time

(ex.) - fish turns into/evolves into human overtime somehow

what is population genetics?

the study of how selective forces change the allele frequencies in a population over time

what is the gene pool?

all of the alleles carried by all of the individuals in a population

what is the genetic drift?

the effect of chance/possibility on a population's gene pool

what is migration? (in biology population)

movement of individuals & their alleles from one population to another; potentially changes allele frequencies

what is the Hardy-Weinberg equilibrium?

theory that states a population's allele and genotype frequencies are inherently stable--unless some kind of evolutionary force is acting upon the population, otherwise the population carries the same alleles generation after generation

what was Plato's view on species change back then?

species are unchanging with little to no variation

what were the views of the 18th century about evolution?

species change, go extinct, the change is slow, Earth is actually billions of years old

was Lamarck's acquired inheritance correct?

No; it also led to harm among the human population

who is Thomas Malthus?

he was the first person to argue population growth was going to end the world because there was not enough food supplies

- wrote the principles about human population

- wrote human population will increase constantly over time

what are the three principles of natural selection?

- characteristics are inherited

- more offspring produced than survived

- offspring vary amongst each other

(found in 1858)

what are the four factors that could change the Hardy-Weinberg equilibrium?

natural selection, mutation, genetic drift, and migration (gene flow)

what is the bottleneck effect?

the magnification of genetic drift as a result of natural events or catastrophes/human-caused events

- randomly kill large portion of the population, large portion of the gene pool is wiped out (ex.)

what is the founder effect?

magnification of genetic drift in a small population that migrates away from a large parent population carrying with it an unrepresentative set of alleles

what is gene flow?

the flow of alleles in and out of a population due to the migration of individuals or gametes

what are vestigial functions?

a physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor

(ex.) - human appendix

what are the different forms of evidence of evolution?

fossils, anatomy (vestigial structures), embryology, biogeography, & molecular biology

what does the term tiktaalik mean?

transition between fish and land animal

what is anatomy? (evolution evidence)

structures with same form (relates to vestigial structures)

what is embryology? (evolution evidence)

early development shared forms; all humans start with tails (ex.)

what is biogeography? (evolution evidence)

evolution in relation with the movement of tectonic plates/continents

what is molecular biology? (evolution evidence)

DNA & genetic code in universal, allowing duplication events of species

what is speciation?

the formation of two species from one original species; occurs when two new populations are formed from ONE original population

- must evolve in a way that makes it impossible for the two new populations to interbreed with e/o

what is allopatric speciation?

speciation that occurs via geographic separations

what is sympatric speciation?

speciation that occurs in the same geographic space

- species also use different resources

what is dispersal?

an allopatric speciation that occurs when a few members of a species move to a new geographical area

- nature physically divides

what is adaptive radiation?

speciation when one species radiates out to form several other species

- founder species creates several other distinct species

what is the biological species concept?

a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

- opposite of this will produce sterile (inability to breed) offspring

what is incipient speciation?

the early stages of a single species diverging into two or more distinct groups that are beginning to become reproductively isolated

- speciation seen in real time

what are the two mechanisms of reproductive isolation?

prezygotic & postzygotic

what are the categories under prezygotic?

ecological, temporal, and behavioral isolation

what is ecological isolation?

results from two species who occur in the same area but utilize different portions of the environment and are unlikely to interbreed

- live in different habitats

what is temporal isolation?

when two or more species reproduce at different times

what is behavioral isolation?

mating behavior differences prevent interbreeding of species

what are the categories under postzygotic?

prevents gametes fusion, infertile offspring

what is a theory in science?

concept that has been extensively tested and supported over time

does evolution explain the origins of life?

No! only explains how all organisms evolved from a single, common ancestor

do species evolve to be "better"?

No! they're only responding to their environments circumstances

what are the types of natural selection?

stabilizing, directional, disruptive

what is stabilizing selection?

favors intermediate variants and acts against extreme phenotypes

- likes to be in the middle, not right nor left

- baby weight (ex.) stable in the middle is good for their health and the mothers

what is disruptive selection?

favors individuals at both extremes of the phenotypic range

(bird ex.) middle sized bird beak LESS advantageous over small/large sized beak

what is directional selection?

favors individuals at one end of the phenotypic range