Which species concept defines a species as organisms that share a set of unique physical characteristics not found on other groups of organisms?
Morphological species
Species
primary classification group with most closely related members
Genus
broader group; capitalized first part of the name
Species (in a name)
second part of the name
Subspecies
additional name applied to more specific groups
The Biological species concept
a group of individuals that can interbreed and produce fertile offspring
Species are reproductively isolated
they cannot produce fertile offspring with members of other species
Gene pool
sum total of the alleles found in all individuals of a species
Gene flow
transfer of genetic material (alleles) from one population to another
prefertilization
prevents fertilization from occurring
postfertilization
fertilization occurs but hybrid cannot reproduce
Hybrid
life offspring produced by mating between two different species; often sterile
mule
hybrid of horse and donkey
Speciation
the evolution of one or more species from an ancestral from
Three steps for a new species
Isolation of gene pools of populations of the species Evolutionary changes in gene pools of populations Evolution of reproductive isolation between populations
Migration
small population becomes isolated in location far from main population
Allopatric populations
isolated from each other by distance or a geologic barrier (allo= “different”)
Sympatric populations
separate gene pools despite living near each other (sym-= “together”)
Gradualism
slow accumulation of small changes over long period of time (assumed by darwin)
Punctuated equilibrium
sudden, dramatic changes followed by long periods of little change
Biological race
populations of one species that have diverged from each other as a result of isolation of gene pools
Biologists may use genealogical species concept
organisms able to interbreed, descended from a common ancestor, and representing independent evolutionary lineage
The morphological species concept
a group of individuals with some reliable physical characteristics distinguishing them from all other species
more practical definition for paleontologists
scientists who study fossils
Homo erectus
immediate predecessor of homo sapiens
Human race
not independent evolutionary groups
Covergent evolution
unrelated organisms resemble each other due to similar environmental factors
Genetic drift
change in allele frequency that occurs due to chance (it is random)
A volcano eruption kills most of a squirrel population, the surviving squirrels have a different gene pool from the original population. What type of genetic drift did this?
Bottleneck effect
Founder Effect
genetic differences resulting when a small sample of a larger group begins a new population
Bottleneck Effect
variant of effect; a small number survives after disaster wipes out most of the population
Sexual selection
when a trait influences the likelihood of mating
Assortative mating
preference to mate with someone like self
Communicable or transmissible diseases
transmitted from one individual to another
infectious agents
invade tissues and induce damage
Epidemic
disease affecting many people within a region
Pandemic
disease that is prevalent over a whole country or the world
Pathogens
disease-causing organisms
Which statement about viruses is incorrect?
Viruses are prokaryotes
Contagious pathogen
spreads from one organism to another
Bacteria
tiny single cell prokaryotes
Toxins
bacterial secretions that also cause symptoms
Antibiotics
medications to routinely treat bacterial infections
Viruses
packers of nucleic acid (DNA or RNA) surrounded by a protein coat (capsid)
Herd immunity
indirect way to provide protection to individuals who cannot be vaccinated (pregnant women, infants, immunocompromised)
Skin and Mucous membranes are important components of the nonspecific first part of defense.
true
the immune system
protects against infection
first line of defense
nonspecific external defense
skin
physical barrier, sheds, takes pathogens with it
Mucous membranes
secrete mucus, line respiratory, digestive, urinary and reproductive tracts
First line of defense examples
ekin, mucous membranes, digestive secretions, vomiting
Second line of defense
nonspecific internal defense
Phagocytes
white blood cells that engulf and digest all invaders indiscriminately
Macrphages
one type of phagocytic white cell
Second line of defense
nonspecific internal defense
inflamation
response to tissue injury
fever
body temp above 97-99 degrees fahrenheit
Inferferons
produces by virus infected cells
complement system
enhances ability to fight off invaders
Second line of defense examples
interferons, complement system, fever, inflammation, phagocytes, macrophages
Which body structure secretes antibodies?
B cells
Third line of defense:
specific defense, used if pathogen gets through nonspecific defenses, made of white blood cells
B and T cells display specificity:
they recognize specific antigens
B and T cells produce antigen receptors
proteins that fit perfectly to antigens
B cells
lymphocytes that make antibodies
antibodies
proteins that identify and neutralize pathogens
T cells
lymphocytes that directly attack invaders, respond to body cells gone awry, fungi, cancer
Anticipating infection
ability of lymphocytes response to specific antigen, begins before birth
Immune response
ability to respond to infection
Cell mediated immunity
involves T cells rather than antibodies. t cells rapidly divide, produces memory cells
Memory cells
help body responds quickly to pathogen in future
Antibody mediated immunity
secreted antibodies attack pathogens; provided by b cells,b cell copies itself, making a clonal population of identical memory cells, these memory cells fight infection by secreting antibodies
Inactivation of the infectious agent:
occurs when antibodies encounter a pathogen matching the variable region
Vaccination
take advantage of long term protection from antibody producing memory cells
Tuberculosis(TB)consumption
disease caused by bacteria mycobacterium tuberculosis -2 billion people carry TB -new infection rate 1 per second -causes 2 million deaths per year,Symptoms: cough that produces blood, fever, fatigue, long relentless wasting, nodules in lungs,1940s, antibiotics revolutionized TB treatment, then in 1980s antibiotic resistant TB increased, now 500,000 cases every year of multidrug resistant TB
Many humans would have to die for humans to develop resistance to the bacteria that causes tuberculosis.
True
Tuberculosis fits darwin's observations
Organisms in populations vary, bacterial variants of M. tuberculosis that resist antibiotics exist The variation among organisms can be passed onto offspring. The genes for antibiotic resistance are passed to other bacteria More organisms are produced than survive. Antibiotics eliminate most of the bacteria in the infected individual An organism's survival is not random, bacteria with an antibiotic resistance are more likely to survive and reproduce
How can we stop drug resistance?
Combination drug therapy (drug cocktail), different drugs kill variants that have resistance to different compounds, prevents survival of organisms with resistance
Ecology
study of the interactions among organisms, as well as between organisms and their environment
Population
all the individuals of a species in a given area
Population structure
characteristics of a population, distribution and abundance
Distribution
the spacing of individuals
Abundance
the density of individuals
Population size
estimated by population ecologists (and others)
Direct counting
individuals are counted or surveyed, e.g. U.S. census
Mark-recapture method
Estimated the size of more mobile or inconspicuous species , mark and release all animals found, later catch another group in same area and estimate population using percent marked in second catch
Population dispersion
how organisms are distributed in space -Clumped distribution -Uniform distribution -Random distribution
On a global scale, what type of population distribution do humans show?
clumped distribution
Clumped Distribution
-high densities in resource rich areas -low densities elsewhere - ex. plants that require certain soil conditions
Uniform Distribution
-spacing between individuals tends to be equal -species with this pattern are often territorial -ex. Nesting penguins
Random Distribution
-shown by nonsocial species with ability to tolerate wide range of conditions -also occurs where resources are distributed evenly or randomly -ex. Plants with windblown seeds
Exponential growth
growth that occurs in proportion to the current total -has a j shaped curve -occurs under ideal growth conditions -density dependent
density dependent
growth is not limited by population density or resource availability
super exponential growth
faster than exponential growth) ex. human population
Growth rate
birth rate-death rate
birth rate
the number of births as a percentage of the population birth rate = 17.7/1000= 0/01700=1.77%
Current growth rate
1%
Demographic transition
the period when a society’s population shifts from high birth and death rate to low birth and death rates, usually happens during industrialization
Pre industrial revolution
high births and death rates, after death rates decrease, birth rates decrease