ch 15,16, & 17 (evolution) Flashcards
evolution
change in species over time
species
a group of organisms that breed with one another and have fertile offspring
speciation
formation of new species
what are the 3 sources of genetic variation
mutations, gene shuffling, genetic drift
What is the evidence of evolution?
- Fossil Record
- Geographic distribution
- Homologous structures
- Embryology
- DNA analysis
Darwin
the scientists who contributed the most to our understanding of evolution more than anyone else. He sailed on the H.M.S Beagle and made many observations on his voyage that lead him to propose a revolutionary hypothesis
adaptation
inherited characteristics that increase an organism’s chance of survival
adaptive radiation
a process by which a single species or small group of species evolves into diverse forms that live in different ways
what is an example of Adaptive radiation
Darwins Finches, because more than a dozen species evolved from a single species
coevolution
a process by which 2 species evolve in responses to changes in each other
what is an example of coevolution
salamanders and snakes, because salamanders have poison, the snakes became resistant over time and in response, the salamanders poison became stronger
convergent evolution
a process by which unrelated organisms come to resemble one another
example of convergent evolution
a lot of aquatic animals such as sharks, dolphins, penguins, and seals, their streamlined bodies and swimming appendages look a lot alike because they need to adapt to similar surroundings so they can travel through water quickly
punctuated equilibrium
a pattern of long, stable periods interrupted by brief periods of rapid change
fitness
the ability of an individual to survive and reproduce in its specific environment
James Hutton
proposes that Earth is shaped by geological forces that took place over extremely long periods of time. He estimates Earth to be millions of years old.
Charles Lyell
explained that processes occurring now have shaped Earth’s geological features over long periods of time.
struggle for existence/survival
competition among members of a species for food, living space, and other necessities for life.
gradualism
a slow, steady change in a particular line of descent
natural selection/survival of the fittest
a process by which individuals that are better suited to their environment survive and reproduce most successfully
geological time scale
scale used by paleontologists to represent evolutionary time
geographic isolation
two populations are separated by geographic barriers
temporal isolation
when two or more species reproduce at different times
what did Darwin Observe on the Galapagos islands
he observed iguanas,tortoises, and finches that varied from the mainlands and from island to island. he observed that the characteristics of many animals and plants varied noticeably among the different islands
theory
a well-tested explanation that unifies a broad range of observations
variation
differences among individuals of a species
reproductive isolation
when he members of two populations cannot interbreed and produce fertile offspring
homologous structures
structures that have different mature forms but develop from the same embryonic tissues (come from a common ancestor)
vestigial organs
organs that serves no useful function in an organism; organs that do not serve the same purpose as they used to
gene pool
all the genes in a population
What has to happen for evolution to not occur/genetic equilibrium to occur?
random mating very large population no movement in or out of the population, no mutations, no natural selection
what are the two main sources of genetic variation
mutations and the genetic shuffling
genetic drift
a random change in allele frequency that occurs by chance
analogous structures
body parts that are used for the same purpose in different animals but do not come from a common ancestor
what were some things Darwin wondered about when he made his observations of different organisms on the islands
he wondered why different species lived and did not live in certain places, how were the living species related to the species found in fossils
common descent
all species-living and extinct-were derived from common ancestors. Therefore, a single tree of life links all living things.
descent with modification
each living species has decsended, with changes, from other species over time.
what happens as new species evolve?
populations become reproductively isolated from each other
what is evolution mean in genetic terms?
any change in the relative frequency of alleles in a population.
how did Lyell and Hutton influence Darwin’s theory
through their findings of geography, they made Darwin ask himself, If earth could change over time,might life change as well, and it made him realize that it would have taken any years for life to change in the way he has suggested
What did Lamarack propose?
that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species.
Thomas Malthus
Malthus predicts that the human population will grow faster than the food and space needed to sustain it.
summary of darwin’s theories:
-individual organisms differ, and some of this variation is heritable.
organisms produce more offspring than survive, and many that do survive do not reproduce,
-because more organisms are produced than survive, they compete for limited resources
-each unique organism has different advantages and disadvantages in the struggle for existence. Individuals best suited to their environment survive and reproduce most successfully. These organisms pass their heritable traits to their offspring. This process of natural selection causes species to change over time.
-Species alive today are descended with modification from ancestral species that lived in the distant past. This process, by which diverse specie evolved from common ancestors, unites all organisms into a single tree of life.
August Weisman
conducted an experiment where he cut of mices’ tails. he found that generation after generation the tails grew back proving Lamarcks theory wrong
lamrack
one of the first scientists who recognized things have changed over time and that all things were descended from other species. he also realized that organisms where somehow adapted to their surroundings. hypothesis was incorrect
how did thomas malthus influence Darwin
He made Darwin realize that his reasoning applied even more to plants and animals, because of their large amounts of offspring. but however the reason that plants and animals weren’t overrunning the population because many offspring did not survive. Darwin wanted to know what causes the death of so many idividuals, and what factors determine which oragnisims survive and reproduce and which don’t.
what is overproduction
when more offspring is produced than survie
What did Malthus reason?
if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.
-he noticed that the only forces that worked against this wee war, famine, and disease.
what can cause speciasation
reproductive isolation
artificial selection
nature provided the variation and humans selected those variations they found usefull
DArwins theory
stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual’s ability to compete, survive, and reproduce.
