Evolution Flashcards
exaptations
structures that evolve and function one way in one environment, but then perform a different function when placed in a new environment
population
smallest unit that can evolve
modern synthesis
this idea ties together Darwin and Mendel; it is considered the comprehensive theory of evolution and takes into consideration the ideas of populations as a unit of evolution, natural selection as a mechanism, and the theory of gradualism
founder effect
when only a few individuals of a population newly colonize land, their respective alleles increase in frequency, but this may not be representative of the parent population
speciation
origin of new species that can follow one of two patterns: anagenesis or cladogenesis; this is also the boundary between microevolution and macroevolution
diploidy
this is the reason recessive alleles can be hidden and protected in a population; they are still there, but they aren’t expressed because we have two alleles
Hutton
came up with theory of gradualism
Charles Lyell
came up with theory of uniformitarianism
cladogenesis
building one new species from a parent, but the parent species still exists; branching evolution
natural selection
survival of the fittest - depends on who will leave the most viable (reproductively successful) offspring in the next generation; this is the mechanism for evolution
fossil record
ordered array in which fossils appear in layers; gives hints as to which species came when in time
genetic drift
changes in a population’s allele frequencies due to chance; examples are the bottleneck effect and the founder effect
cline
geographic variation where there is a graded change in a trait based on a location; ex. when the trees get shorter and the mountain increases in altitude
Thomas Malthus
he did work with populations and said that population have a tendency to over-reproduce; he also said that populations tend to exceed their resources
directional selection
a type of selection that shifts to favor one extreme of the characteristic
taxonomy
a system of classifying and naming organisms based on their common anatomy
puncuated equillibrium
the idea that species diverge in spurts, not gradually; these spurts can be 1000s of years; this theory accounts for the variation in the tempo of speciation
Darwinian fitness
measured by how many reproductively fertile offspring are left in the next generation
sampling error
if the sample size is too small, changes in the frequency of alleles will have a large effect on the population
vestigial organs
remnants of organs or structures that have no function now, but had a significant function in our ancestors
use and disuse
the idea that parts of your body you use most become stronger - hypothesized by Lamarck
allopatric speciation
type of speciation where geographic barriers lead to the origin of a new species; if the populations come back together and they can interbreed, then speciation has not occurred; if they cannot interbreed, then it has occurred
sexual dimorphism
when males and females of a species differ in size, shape, color, or markings
gene pool
the alleles and genes of all the individuals in a population
discrete characters
characters in a population that are determined by a single gene locus and are an either/or basis…. either you have it or you don’t; ex. freckles
autopolyploidy
type of polyploidy speciation in plants when the individual plant has 2 chromosome sets from the same species; caused by a mistake in meiosis
racemization
way of figuring out how old something is - not a reliable technique.
sympatric speciation
when new species arise from geographically overlapping populations (not a geographical barrier)
Alfred Russel Wallace
developed a theory very similar to Darwin’s concerning evolution; however, he did not have nearly enough evidence to support his ideas, and therefore was not taken seriously
uniformitarianism
this theory states that geological processes proceed today at the same rate as they did many years ago; the rates of change are the same
HW theorem
says that the frequency of alleles in a population’s gene pool remains constant over generations
disruptive “diversifying” selection
type of selection that favors variants of opposite extremes of a characteristic
allometric growth
this is the proportioning that gives a body its specific shape; if the rate of change is even slightly altered, it will drastically change the adult form; changing features over time
Georges Cuvier
studied fossils and was very interested in paleontology; came up with theory of catastrophism
microevolution
generation to generation change in the frequency of alleles in a population
bottleneck effect
when a disaster drastically reduces the size of a population; the organisms left may not be representative of the overall allele frequencies of the original population
principle of parsimony
idea that the simplest explanation that is consisten with the facts is probably the correct one when making phylogenic trees; “keep it simple”
biogeography
geographic distribution of species
catastrophism
theory suggests the boundary between strata of fossils must be marked by a catastrophe in time
Linnaeus
he came up with the first idea of taxonomy; classified organisms based on their common anatomy and morphology; eventually he came up with the concept of binomial nomenclature
heterozygote advantage
when the heterozygote form has an advantage over either of the homozygous forms
Darwin
proposed natural selection as a mechanism for evolution; naturalist that traveled the sea and did research in the Galapagos islands to come up with enough data to support his ideas on evolution; he then wrote a book about his theory
intersexual selection
individuals of one sex are choosy in picking a mate (no direct competition)
differential reproduction
organisms that have favorable traits for their specific environments produce more offspring than those organisms without those specific traits
anagenesis
transformation of one species into another; phyletic evolution
radiometric dating
type of absolute dating that uses radioactive isotopes with specific half-lives; the age of the fossil can be determined by examining the amount of the daughter isotopes accumulated, or by the amount of parent isotope lost
species
a group of populations whose individuals can interbreed to produce fertile offspring
gradualism
theory proposed by Hutton that explains that the features of Earth are due to slow, continuous processes, and what we see today is the culmination
Origin of Species
name of Darwin’s book that explains natural selection and evolution
homologies
similar features in two different organisms resulting from common ancestry
molecular clocks
new timing methods that are based on the idea that parts of the genome evolve at constant rates
quantitative characters
characters in a population that vary along a continuum; they have an addictive effect and they are usually polygenic
intrasexual selection
direct competition for mates
Lamarck
theorized about evolution and came up with the use/disuse theory ; also said that acquired characteristics could be inherited (incorrect)
DNA analysis
this is the best technique to use to determine the evolutionary relationship between related species of they are still alive
stablizing selection
type of selection that favors an intermediate of a character; this decreases variation and maintains status quo
polymorphic
when two or more forms of a discrete character are present in a population
evolution
this idea explains life’s unity and diversity; worked on by Darwin and Wallace
