BIO 111 Final
life histories
- "summarize" species - vital statistics - age at first reproduction - probability of survival and reproduction at each age - litter size and frequencies - shaped by 3 variations of reproduction
RNA world hypothesis
- RNA was likely the first self-replicating molecules - able to catalyze addition of ribonucleotides
fitness
- a measure of the reproductive capacity of an individual with a particular phenotype compared to others - depends on the specific environment in which the organism lives, it's reproductive success, and is relative to other genotypes or phenotypes in the population
Darwin's Journey to an Idea
- before him, many people believed that all species had been created separately and were unchanging. - Buffon: suggested that earth was much older than previously believed - Cuvier: showed that extinction had occurred from fossil discoveries - Lamarck: suggested that living species might change over time - Lyell: argued that geological forces had gradually shaped the earth and continue to do so
reciprocal altruism
- benefits unrelated individuals, but expect goodwill in return - requires ability to recognize and punish "cheaters" - kindness towards unrelated individuals (i.e. vampire bats regurgitating blood to others when they need it) - monkeys groom each other rather than finding food, because they are more likely to receive help in the future if they are ever in danger
Physical Attributes in sex
- body size is important clue in mating behavior - competition among individuals so selection favors larger size
morphological species concept
- can be used to classify asexual species, characterizes based on physical features, does not focus on reproductive isolation
density-independent factors
- can dramatically reduce population size, is not due to density of a population - fires, floods, earthquakes
altruistic behaviors
- come at a cost to the individual, but benefit another - kin selection - reciprocal altruism
divergent evolution
- common ancestor split into multiple species - homologous structures reveal common evolutionary origins - similar bone structures are used differently: bat→ flight, human→ arm, dolphin→ swim
animal behavior that influences reproductive capacity
- conflict, aggression, and territoriality - competing for food and avoiding predators - courtship and mate choice - among many others...
Two Main Tenets of Origin of Species
- descent with modification: species are not immutable - natural selection is the driving force of adaptation
logistic growth
- describes population that is gradually reduced as the population nears carrying capacity
innate behaviors
- do not require input - do not vary among individuals - instincts - i.e. birds moving a rock thinking its an egg
prepared learned behaviors
- easy to learn - ex: fear of snakes, acquisition of language in humans, reproductive success - likely important to survival and success of ancestors
evolutionary innovations
- evolution of an innovative feature that increases fitness, a species can rapidly diversify ex: wings on an insect
paternity uncertainty
- female may mate with other males so men may be uncertain what is theirs - profound influence on mating behavior - incentive for males to provide some paternal care - at the point of mating, men will prolong mating until female is no longer receptive - use of copulatory plugs to no other male can mate with her - insures paternity - mate guarding
"survival of the fittest"
- flies that resist starvation are noticeably fatter than those in the original population - they have the greater fitness
Lines of Evidence in Evolution
- fossil record - biogeography - comparative anatomy and embryology - molecular biology - lab and field experiments
urey-miller experiment
- generated organic molecules from hydrogen, methane, and ammonia - bacteria was first life on earth - life on earth most likely originated from non-living materials
evolution
- genetic change over time - in fruit flies: over many generation of natural selection, the population evolved, only those who are most starvation-resistant live and are able to reproduce, causes next generation to live longer without food
genetic drift
- has much greater impact on smaller populations and reduces genetic variation
behaviors can evolve
- have adaptive values that respond to natural selection - feeding behavior: animals maximize the energy consumed and minimize energy used - leads to low nutritional foods (dirt) to be avoided, and high nutritional foods (fats and carbs) to be preferred
evolutionary trees
- help conceptualize and categorize biodiversity - the nodes signify a common ancestor and a speciation event when the ancestral species split into two - by tracing the branches back toward the trunk, we can follow the pathway from descendants to their ancestors - by comparing how similar DNA sequences are between two groups, we can use this data to estimate how long it has been since they shared a common ancestor
prezygotic barriers
- individuals are physically unable to mate with each other or male's reproductive cell is unable to fertilize the female's - ex: dogs and pigs
disruptive selection
- individuals with extreme phenotypes (on either end of the spectrum) experience highest fitness, and those with intermediate phenotypes have lowest - ex: salmon size
stabilizing selection
- individuals with intermediate phenotypes most fit (average) - ex: birth weight in babies
density-dependent factors
- limitations on a population's growth based on population density - reduced food supply - diminished accessibility to shelter - increased parasitism and disease - increased risk of predation
biogeography
- location and adaptions linked to different environments - evolution of similar characteristics from distantly related species that evolved in isolated environments ex: australian marsupials resemble their placental counterparts as they have adapted to similar habits
postzygotic barriers
- mating produces hybrid individuals that do not survive long after fertilization, or are infertile and cannot reproduce again - ex: horses + donkey = infertile mule
behaviors based on sex
- mating with additional males beyond the first does not increase reproductive success - mating with multiple females will increase a male's reproductive success
carrying capacity (K)
- maximum number or organisms that can be maintained in an environment (population ceiling)
natural selection may lead to evolution of complex behaviors and traits
- may arise via modification of a structure used for a completely different function - ex: insects began to evolve larger wing nubs for thermoregulatory benefit, lead to the evolution of wings when aerodynamic benefits were seen
learned behaviors
- may be altered and modified over time based on past experience
adaptions that improve fitness
- mice with white coats who live in snowy regions will survive more often, and therefor the allele for white coats will increase in the population
Which of the following is an example of a vestigial structure?
- molars in bats that consume a completely liquid diet - eye sockets in eyeless cave-dwelling fish - pelvic bones in whales
colonization events
- moving to a new location with new resources (and possibly fewer competitors)
Darwin's Finches
- observed similarities among fossils and living organisms in the same area - finch species on each of the island differed in important ways - different beaks allowed for different feeding habits
allopatric speciation
- occurs when a geographic barrier causes one group of individuals in a population to be reproductively isolated from another group - ex: river barrier forms between a population of squirrels - overtime the two groups diverge enough that they can no longer interbreed
adaptive radiation
- occurs when a small number of species diversify into a larger number of species - leads to extreme diversification - access to plentiful new resources can be triggered by: - mass extinction, colonization events, evolutionary innovations
exponential growth
- occurs when an individual produces more than a single offspring to replace themselves - populations cannot grow unchecked forever, so exponential growth never lasts long in nature - ex: human population
speciation
- one species splits into two distinct species - reproductive isolation leads to genetic divergence - requires more than just evolutionary change in a population
species
- populations or organisms that interbreed, or could interbreed under natural conditions
lab and field experiments
- provide experiments that have demonstrated evolution over short periods of time - antibiotic resistance
Big Bang Reproduction
- reaches sexual maturity at one year - mates intensely over a 3 week period - males die shortly after mating period -females usually die after weaning their first littler - certain rodents, salmon
A life history of an organism consists of the organism's:
- reproduction - death. - birth. - growth to maturity.
sexual conflict
- results from differences in reproductive investment by males and females - female produces larger gamete, male produces smaller gamete - fertilization in female, growth in development in female, lactation - woman has higher reproductive investment - the sex that invests more will be more discriminatory
sympatric speciation
- results in the reproductive isolation of populations that coexist in the same area - uncommon in animals but seen in plants - chromosome duplication within a single species or the combining of chromosomes from two different species
sexual dimorphism
- sexes differ in size/appearance - one parents invests more in caring for offspring - mating system tends towards polygamy - females are usually choosier
comparative anatomy and embryology
- similarities in development between different organisms (common ancestor) - homologous structures - similarities in bone structure of forelimbs - analogous structures - developed from different structures to perform same function - wings of a bat and firefly - vestigal structures - have little or no function, but used to have value ancestrally - ex: vampire bats have molars even though they consume completely liquid diets - common evolutionary origin
founder effect
- small number of individuals may leave a population and become the founding members of a new, isolated population - may have different allele frequencies than the original "source" population
convergent evolution
- species all become similar, analogous structures all developed from different original features - ex: hawk, bee, bat→ flight
population ecology
- study of the interactions between groups of individuals that interbreed with each other and their environment - includes patterns of growth and how they are influenced by each other
kin selection
- supports related individuals, thus promoting reproductive success of the alleles responsible for the behavior - kindness towards close relatives - ex: giving things to relatives upon death, squirrels keep watch to protect family - direct fitness is measured by an individuals total productive output, while indirect fitness includes the reproductive output brought about through seemingly altruistic behaviors - inclusive fitness is the sum of and individuals direct and indirect fitness
directional selection
- the average value for a trait increases or decreases - ex: breast size in chickens have been selected for larger breasts in recent years by farmers
maximum sustainable yield
- the point at which the maximum number of individuals are being added to the population before it starts to level off - growing at it's fastest rate (and so can be harvested or utilized) - important for effective and sustainable management of natural resources
alleles that don't have direct or indirect benefit
- these alleles will decrease over time, selfish behavior alleles will increase
fixed action pattern
- triggered under certain conditions - require no learning
molecular biology
- use of DNA and protein sequences to illustrate how long two species have been evolving independently, based on amount of differences that accumulate
fossil record
- used to identify structure and relationships of extinct species - homologous structures arose form ancestors - radiometric dating makes it possible to determine age of fossils
fixation
- when an allele's frequency becomes 100% in a population (due to genetic drift)
bottleneck effect
- when famine, disease, or rapid environmental change causes deaths of a large, random proportion of the population, the surviving individuals have different allele frequencies than the original population - they will pass down these alleles to future generations
mass extinction
- wipes out competition, allowing remaining species to rapidly diversify
why does fitness not lead to "the perfect organism"
1. environments change faster than natural selection can occur - some years a certain adaption will be more advantageous than in others 2. mutation does not produce the perfect alleles 3. multiple alleles can result in the same fitness 4. there is no single optimal adaption for an environment
key features in the evolution of life
1. formation of small molecules containing carbon and nitrogen 2. formation of self-replicating, information containing molecules (RNA) 3. development of a membrane
4 evolutionary mechanisms
1. mutation - alteration of the base-pair sequence in DNA that change's allele frequencies (must occur in gamete cell for it to passed down) ex: mutation changes a person's 2 blue-eyed alleles into a brown-eyed allele 2. genetic drift - random change in allele frequencies, unrelated to any allele's influence on reproductive success, can lead to fixation 3. migration - change in allele frequencies caused by individuals moving into or out of a population (gene flow) 4. natural selection - a change in allele frequencies that occurs when individuals with one version of a heritable trait have greater reproductive success than others
3 conditions necessary for natural selection to occur
1. variation for a trait 2. heritability 3. differential reproductive success (those with a certain trait generally leave more offspring)
Life arose from non-life around _________ years ago.
4 billion
A population of meadow voles has an annual per capita birth rate of 0.08 and an annual per capita death rate of 0.02. Estimate the number of individuals added to or lost from a population of 1000 individuals in one year.
60 individuals added
[(K-N)/K]
= 1, population growth in unchanged (exponential) = 0, then population growth is stabilized (logistic)
A storm washed five female and five male tiger beetles from the mainland to a small island that had no previous population of tiger beetles. In tiger beetles, having six spots (A) is dominant to having four spots (a). All ten beetles had six spots, but one male and one female were heterozygous for the four-spot trait. If six of the beetles died randomly without reproducing, the ratio of the genotypes could be quite different in subsequent generations. This change in allele frequencies would be an example of:
genetic drift.
Assume that you carry an allele, R, that causes you to help individuals to whom you are not related. This help increases their fitness and decreases yours. The frequency of allele R may still increase in the population:
if individuals you help are likely to return the favor and help you at some point in the future.
Disruptive selection occurs when:
individuals with extreme values of a trait have greater fitness than individuals with intermediate values of the trait.
Polyploidy as mechanism of speciation occurs most commonly in which of the following life forms?
plants - containing more than two paired (homologous) sets of chromosomes
A single breeding male red-winged blackbird (Agelaius phoeniceus) may mate with several females, but each female usually mates with only one male. This type of mating system is known as:
polygyny
Behaviors that are learned easily and by all (or nearly all) individuals in a species are called:
prepared learning.
population growth
r X N r = growth rate , N = number of individuals growth rate = birth rate - death rate - limited by the environment
Anatomical homology in vertebrate forelimbs is considered to be evidence for evolution because
similarities among vertebrate forelimbs suggest that they evolved from a common ancestor.
Human birth weight is a classic example of the results of:
stabilizing selection
Speciation without geographic isolation is called:
sympatric speciation
Genetic drift will have the greatest effects for populations:
that are very small
artificial selection
the differential reproductive success is determined by humans not nature (i.e. gmo's)
The extinction that occurred on earth 65 million years ago was immediately followed by:
the rapid divergence and radiation of modern mammals.
A gene pool consists of
the total of all alleles present in a population
In years when beech trees produced a large crop of nuts, growth rings were narrow. This is best explained by:
the tradeoff that exists between growth and reproduction.
Which of the following is an IMPORTANT difference between natural selection and genetic drift?
Natural selection involves differential reproductive success in the struggle for existence in an environment, while genetic drift does not.
Which of the following is a statement that describes the concept of convergent evolution?
Organisms that are not directly related develop similar traits.
In the lynx-snowshoe hare oscillating cycle of population growth, when the hare population size grows, more food is provided for the lynx. Which is the IMMEDIATE next step in this cycle?
The lynx reproduce at a higher rate.
A organisms with a slow development and a high investment in their young will most likely have a __________ survivorship curve.
Type I
Which of the following mammals would you expect to have the shortest gestation period?
a mouse
Horses and donkeys can breed and produce sterile offspring known as mules. Horses and donkeys remain separate species because of this hybrid sterility, which is:
a postzygotic barrier to reproduction.
Life-history patterns:
are subject to the pressures of natural selection.
classifying organisms
based on relatedness: - Domain -Kingdom - Phylum - Class -Order - Family - Genus - Species
mutations
can occur from - high-energy radiation - chemicals in the environment - or spontaneously
Gestational diabetes is thought to be the consequence of:
conflict between the mother and the fetus with respect to how much food the fetus should be given.
A population pyramid that gets wider in shape with higher age groups represents _____ while a population pyramid with nearly parallel lines represents _____.
declining growth; stationary growth
When plants of a particular species are growing too close to each other, crowding may eventually lead to mortality, known as self-thinning. This type of mortality is:
density-dependent.
A breeder of thoroughbreds selects only the fastest horses for breeding stock. This is an example of artificial ____________ selection.
directional
Which of the following is NOT an example of a density-dependent limiting factor that will influence carrying capacity?
flooding
Altruistic behavior in animals may be a result of kin selection, a theory maintaining that:
genes are more likely to persist within a population when they cause behaviors that assist other animals who share those genes.