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45 Cards in this Set
- Front
- Back
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macroevolution
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The large scale patterens, trends, and rates of change among families and other inclusive groups of species.
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speciation
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*a macro evolutionary process
*starts when a population becomes reproductively isolated from others of the species and ends with new species. |
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Ernst Mayr
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Biological Species Concept
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Biological Species Concept
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*A species is one or more groups of individuals that can interbreed, produce fertile offspring, and are isolated from other groups
*Doesn't apply to asexual species and fossils. |
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Prezygotic isolation mechanisms
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Behavioral, temporal, mechanical, ecological, gametic mortality
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Behavioral isolation
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Birds are prewired for specific mating dances and songs
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Temporal isolation
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*Timing of reproduction is different in different species
*Cicada in eastern U.S -live inderground for 17years -"sibling" species come up every 13 years |
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Mechanical Isolation
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Animal parts and pollinator parts must match
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Ecological isolation
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*populations adapted to two different micro environment in the same habitat
*Manzanita shrubs |
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Gametic mortality isolation
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*Gametes of different species have molecular incompatibilities
*Different pollen |
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Postzygotic Isolating mechanisms
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*Unsuitable interactions of genes can lead to: Death, Stertility, Weak hybirds
*ex:mules & ligers |
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Allopatric speciation
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*speciation in geographically isolated populations
*some sort of barrier arises and prevents gene flow *Effectiveness of barrier varies with species -Isthmus of panama(seperated fish), Mississippi River(seperated insects), glaciers & mountain ranges |
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Archipelagos
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*Island chains some distance from continents
-Galapagos islands&Hawaiian islands *Colonization of islands followed by genetic divergence sets the stage for speciation |
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Hawaiian islands
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*volcanic origins, variety of habitats
*Adaptive radiatives: -Honeycreepers:in absence of othe bird species, they radiated to fill numerous niches -Fruit flies(drosophila) |
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Sympatric speciation
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*form within the home of the parents
*No physical barrier -study fish in 2 lakes -descend from single ancester *no barriers within the lake *Competition for food drove fish to diverge into 2 species *breed at the same time and place. |
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Parapatric Speciation
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Neighboring populations become distinct species while maintain contact along a common border
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Ecology
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the study of how organisms interact with one another and with physical and chemical environment
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population ecology
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Certain ecological principles govern the growth and sustainability of all population including human population
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population
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*A group of individuals of the same species occupying a given area.
*described by demographics *size, age, density,and distribution |
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population size
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number of individuals actually or potentially contribute in the gene pool
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age structure
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number of individuals in each of several age categories
(prereproductive, reproductive, postreproductive) |
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population density
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number of individuals in some specified area or volume of habitat
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population distribution
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the pattern in which the indivduals are dispersed in a specified area.
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clumped distribution
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*most common
*species are adapated to specific conditions -water holes, soil nutrients, moisture... -social groups (schoolof fish) -protection |
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Uniform distribution
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*individuals are more evenly spaced
*rare in nature *due to firece competition -nesting colonies, plants compete for water |
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Random distribution
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*only seen when habitat conditions are
-nearly uniform -resource availability is fairly steady -individuals of a population neither attract or avoid one another *Ex:wolf, spiders |
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zero growth
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*emigration or immagration equal each other
*births are balanced by deaths *stable population |
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exponential growth
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*Any quantity that is growing at a rate proportional to its size
*J shaped curve |
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logistic growth
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*population size is limited by carrying capacity
*S shaped |
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r
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*birth rate or death rate
*the net reproduction per individual per unit time |
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G=rN
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*population growth
*G=population growth *r=net reproduction per individual per unit time *N=number of individuals |
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biotic potential
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*maximun rate of increase per individual for any population that is growing under ideal conditions
*Varies between species *rarely reached in nature |
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limiting factors
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*any essential resource that is an short supply
-food -shelter -minerals *bacteria in a petri dish |
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K(capacity Carrying)
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Maximum number of individuals that can be sustained in a particular habitat
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logistic growth (con't)
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*population growth starts slow, then begins rapidly until reaches carrying capacity
*Size of population increase, rate of reproduction decrease *when reach carrying capacity, pop. growth cease *some pop. grow too fast, over shoot K and plummit below K -Ex: St. Matthews Island reindeer |
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Density dependent factors
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*Expotential & logistic growth leads to over crowding Abiotic & biotic factors reduce odds of survival
-predators -parasites -disease -toxic waste |
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Density Independent factors
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*Factors unaffected by population density
*Natural disasters or climate changes affect large & small populaton alike -Ex:Monarch butterflies (natural disasters) |
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Life history
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*Patterns of timing of reproduction & survivorship
*Vary among species *summarized in survivorship curves & life tables |
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Life Table
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*tracks age specific patterns
*population is divided into age categories *birth rates & mortality risks are calculated for each age category |
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Survivorship curve
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*graph line that emerges when eologists plot age specific survival
*3 types |
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Type I
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*typical of human populations where health care is good
*animals that have few young and extended parental care -Ex:elephants |
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Type II
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*Fairly constant death rate at all ages
-Ex:lizards, small mammals and large mammals |
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Type III
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*Death rate is highest early in life
*Species that produce many small offspring and do little parenting -Ex:Sea turtles, fish stat fish |
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Side stepping Controls
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*Expanded into new habitats
*Agriculture incresed carrying capacity; use of fossil fuels aided increase *hygiene and medicine lessened effects of density-dependent controls |
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future growth
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*Exponential growth cannot continue forever
*Breakthrough in technology may further increase carrying capacity *Eventually, density-dependent factors will slow growth |
