Ch 5 exam

development of life on earth
first phase – chemical evolution of the organic molecules, bipolymers, & systems of chemical reactions needed to form the first cells ~1 bill yrs ago second phase – biological evolution from single celled prokaryotic bacteria to single-celled eukarytoic to multicellular ~3.7 bill yrs ago  anaerobic bacteria – photosynthetic bacteria (cyanobacteria) – aerobic bacteria – single-celled eukaryotes – multi-celled eukaryotes
mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds or impressions of such items  
biological evolution
major driving force of adaptation in environmental conditions
theory of evolution
all species descended from earlier, ancestral species
gene pool
collection of genes or genetic resources potentially available to members’ offspring in the next generation first step in evolution is the development of genetic variability
random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring 1. exposure of DNA to external agents such as radioactivity, X rays, and natural/human-made chemicals (mutagens) 2. random mistakes that occur in coded genetic instructions -the only source of totally new genetic raw material
natural selection
3 conditions necessary for evolution by NS: -genetic variability-trait must be heritable-must lead to differential reproduction: enable indiv. with the trait to leave more offspring that other members of the pop 
when populations of two different species interact over a long time, changes in the gene pool of one species can lead to changes in the gene pool of the other
ecological niche
species way of life or functional role in a community or ecosystem and involves everything that affects its survival and reproduction includes the adaptations/adaptive traits its members have acquired through evolution includes species range of tolerance includes the types and amounts of resources the species uses, how it interacts with other living and nonliving components of the ecosystems, and the role it plays in the energy flow and matter cycling
physical location where a species lives
fundamental niche
full potential range of physical, chemical and biological conditions and resources it could theoretically use if there were no direct competition from other species
realized niche
part of its fundamental niche in a particular community or ecosystem
generalist species
broad niches
the small genetic changes that occur in a population
long-term, large-scale evolutionary changes through which new species form from ancestral species and other species are lost through extinction
specialist species
narrow nicheshave an advantage because they have fewer competitors when evironmental conditions are fairly constant
evolutionary divergence
a single species diverging into a variety of similar species with specialized niches
Limits to adaptations in nature

change in environmental conditions can lead to adapation only for genetic traits already present in the gene pool of a population2.even if a beneficial heritable trait is present in a population, the population’s ability to adapt may be limited by its reproductive capacitymost of the pop would have to die or become sterile so that indiv. with the trait could predominate and pass the trait on

two species arise from one
allopatric speciation
two phases: -geographic isolation: different groups of the same population become physically isolated from one another for long periods-reproductive isolation: mutation and natural selection operate independently in the gene pools of two geographically isolated populations
sympatric speciation
creation of a new species when groups in a population living close together are unable to interbreed because of a mutation or subtle behavioral changes
an entire species ceases to exist99.9% of all the species that ever existed are now extinct
background extinction
as lock environmental conditions change, a certain number of species disappear at a low rate
mass extinction
significant rise in extinction rates above the background level
mass depletion
extinction rates are higher than normal but not high enough to classify as a mass extinction
adaptive radiation
periods of recovery in which numerous new species evolved to fill new or vacated ecological roles or niches in changed environments (1-10 mill yrs)
species minus extinction; planets raw material for future evolution in response to changing conditions
artificial selection
select one or more desirable trait in the population of a plant or animal and use selective breeding to end up with pop of the species containing large numbers of indiv with the desired traitresults in many domesticated breeds or hybrids of the same species, all originally developed from one wild species
genetic engineering/gene splicing
set of techniques for isolating, modifying multiplying and recombining genes from different organisms; enables scientists to transfer genes btw different species that would never interbreed in natureresults in a genetically modified organism (GMO) or transgenic organismtakes about half as much time to develop a new crop or animal varietytrial and error process; average success rate of 1%
using genetically engineered animals to act as biofactories for producing drugs, vaccines, antibodies, hormones, industrial chemicals such as plastics and detergents and human body organs
human success
two evoutionary adaptations: a complex brain and strong opposable thubgs that allow us to grop and use toools better than the few other animals that have thumbs