Final Exam Flashcards
life history
life history is an individual’s pattern of allocation, throughout life, of time and energy to various fundamental activities such as growth, body repair, metabolism, and reproduction
lifetime reproductive success
the number of offspring produced by an individual in their lifetime
life history of the ideal organism
- mature at birth
- live forever
- produce large and numerous offspring
senescence
a decline with age in reproductive performance, physiological function, or probability of survival
does senescence increase or decrease an individuals fitness?
decreases
mutation accumulation hypothesis for senescence
mutations that impact fitness late in life are under weak selection
selection on late-acting mutations is ….
weak
selection of early- acting mutations is ….
strong
antagonistic pleiotropy hypothesis for senescence
mutations conferring fitness benefits early in life and fitness costs late in life will be under positive selection when the benefits outweigh the costs
in the study of Chinook salmon, do hatcheries select for large or small eggs?
the optimal egg size in the hatchery is smaller than in nature, and egg mass has evolved a smaller size in the hatchery
what is the impact of hatchery fish on natural populations?
rivers that receive lots of hatchery fry have evolved smaller eggs as a consequence of gene flow from the hatchery fish
Lack’s hypothesis for optimal number of offspring
states that natural selection will favor the clutch size that maximizes the number of surviving offspring
sexual dimorphism
a difference between the phenotypes of females vs males within a population
natural selection
- a difference between the survival or reproduction of individuals with different phenotypes
- usually refers to components of fitness other than mating success
sexual selection
a difference among members of the same sex, between the average mating success of individuals with different phenotypes, a special kind of natural selection
in what ways do females and males differ in reproductive investment?
sperm is ‘cheaper’ than eggs
how is sperm cheaper than eggs?
- eggs are 4000 times larger than sperm
- women ovulate ~300 to 400 eggs in their lifetimes
- men make tens of millions of sperm everyday
sexes differ in reproductive variance
- male reproduction is limited by access to female eggs
- females are limited by the number of eggs she can nurture and rear to maturity
Bateman’s principle
- theory when one sex invests more resources into producing offspring
- this sex will be a limiting resource over which the other sex will compete
- access to mates will usually limit male reproductive success, but the number of pregnancies will usually limit female reproductive success
Bateman’s gradient
- the slope of the best fit line relating reproductive output to mating opportunities
- strongly positive for males
- horizontal or weakly positive for females
Bateman’s gradient axis
- x axis = number of mates
- y axis = number of offspring
members of the sex subject to strong sexual selection will ________ for mates
compete
members of the sex subject to weak sexual selection will be _______
choosy
are females always the choosier sex?
no, males can invest more than females
example of males being the choosier sex
broad-nose pipefish
intersexual selection
- one sex developing or displaying traits or behavior patterns to attract the opposite sex
- male to male competition
types of male-male competition
- combat
- defenses
- indications of strength
- infanticide
male-male competition: combat
- horns
- antlers
- pincers
- body size
male-male competition: defenses
- armor
- large body size
is sperm competition intersexual or intrasexual selection?
intersexual selection
sperm competition
- large testes
- sperm plugs
sperm competition in fruit bats
- increased ejaculate
- mate guard
- sperm plugs
- inject hormones that influence female reproductive behavior
jack strategy in Salmon
occupy refuges or areas near spawning areas to sneak sperm to fertilize eggs that are being laid
How is the rock-paper-scissor game in the Side-blotched Lizard an example of negative frequency dependent selection?
- orange: large size, high testosterone, large territories
- blue: cooperates with other blues, mate guarder, small territoreis
- yellow: sneaker, mimics female behavior and coloration, not territorial
negative frequency dependent selection
selects for rare phenotypes in a population and increases a populations genetic variance
what do male damselflies do before transferring sperm to a female?
males remove rivals sperm stored by female, reducing sperm competition
why is male damselflies transferring sperm to females an example of sperm competition?
because they use their genital ligula to preform that and it involves sperm
do humans have larger or smaller testes than expected given their body size?
smaller
why do males have small testes compared to body size?
- humans tend to have one mate at a time and don’t try to mate with many females at one
- no sperm competition
do chimps have larger or smaller testes than expected given their body size?
larger than expected
why are chimps testes larger than expected?
chimps have multiple male-breeding systems, have to compete with other males to breed with females
why do male lions commonly commit infanticide?
- female lions return to breeding conditions on average 8 months sooner
- the cub is not their own
intersexual selection
when one sex chooses which members of the opposite sex to mate with
intrasexual selection
members of the same sex compete with each other for mates
Who was Darwin’s brother?
Erasmus Darwin
What did Darwin study at the University of Edenborough?
medicine
What did Darwin study at Cambridge?
he studied to be an Anglican clergyman
what boat did Darwin sail around the world? who was the captian?
- H.M.S Beagle
- Captain Robert FitzRoy
For what time period was Darwin at sea?
1831-1836
Why is Lyell considered a descendent of Hutton?
he ‘revived’ Hutton through his own work on uniformitarians and gradualism
What book of Lyell’s influenced Darwin?
“principles of geology”
true/false: Darwin came up with the idea of natural selection while sailing around the world
False, he came up with the idea in 1838
true/false: Darwin thought of evolution and natural selection at the same time
false, evolution in 1837 and natural selection in 1838
who was Emma Darwin?
Darwin’s cousin who married him
Alfred Russel Wallace
co-discoverer of natural selection
Why did Wallace send his paper to Darwin before publishing it?
Darwin was one of few who thought natural selection was a big deal at the time
Malthus wrote a book called “An essay on the principle of population.” How did this influence Darwin and Wallace?
Darwin thought of the theory of natural selection immediately after reading it
When was the Origin of Species published?
1859
What were the major proposals in “The Origin of Species” discussed in lecture?
- evolution
- natural selection
- Tree of Life
- life is old
- extinction is real
- gradual changes (species formation)
why might avocados have gone extinct at the end of the Pleistocene if it weren’t for humans?
they seem to have evolved giant pits to be passed by giant animals, but since they all went extinct, we still eat them without having to eat the pits
2 main hypotheses for the Pleistocene Megafaunal extinctions
- climate change
- hunting by humans
2 main hypotheses for the Pleistocene Megafaunal extinctions: climate change
- couldn’t survive or adapt to changing environment
- megafauna survived many glacial cycles throughout the Pleistocene
- if climate change wasn’t the reason, we’d expect all megafauna to be affected around the same time
2 main hypotheses for the Pleistocene Megafaunal extinctions: hunting by humans
- megafauna extinctions and human colonization happened around the same times
- human populations in some areas might have been to small to have such a great impact
- not enough evidence of megafaunal remains at archeological sites
Pleistocene megafauna
large-bodied mammals, reptiles, and birds
female choice
- females are choosy about what mates they want
- results in elaborate traits or displays to impress females
example of female choice
females prefer red-collared widow birds with longer tails
good genes model of female choice
- females that prefer males with good indicator traits that will have offspring with better genes
- indirect genetic benefits
how to test the good genes model
- look at tadpoles of long-calling males of frogs
- tadpoles grew faster, metamorphosed sooner, and survived better
direct benefits of female choice
females prefer males with resources or other attributes that help them now
how to test the direct benefits of female choice
watch a species that shows males that have goof foraging or nest building skills vs males that don’t and see who the females pick
sensory bias
taking advantage of female sensory system
how to test for sensory bias
see what call females prefer in a species over a different call
chase-away sexual selection
males evolve mechanisms that increase their reproductive success, so females evolve counter adaptations, then males evolve in response to females
the result of chase-away sexual selection
continual selection and evolution
parthenogenesis
skipping sex to reproduce
facultative parthenogenesis
only using sex sometimes
example of facultative parthenogenesis
aphids are all female in the summer, sexual in the fall
what is the two-fold cost of sex?
- the production of males in a population reduces its reproductive potential by a factor of 2
- the higher growth rate of asexual individuals means that they should quickly come to dominate a population all else being equal
how much of their DNA do parthenogenetic individuals pass on?
females pass on 100% of their DNA
Muller’s ratchet
cost of forgoing sex
how does sex break Muller’s ratchet?
asexual individuals pass on all of her mutations including the deleterious mutations, deleterious mutations will accumulate
How does sex bring together beneficial mutations?
- recombination from sex allows a population to purge deleterious alleles
- no-mutation group can be reconstituted by recombination
Red Queen hypothesis
species must continuously evolve to keep up with enemies who are also evolving
genetic load
accumulation of mutations in a population
why might selection in a population favor asexual individuals?
asexual individuals pass on 100% of their DNA and if passing on genes to future generations is related to fitness
why might selection in a population favor sexual species?
- sex brings together beneficial alleles, they don’t all need to evolve in one lineage
- recombination allows population to purge deleterious alleles
when is facultative parthenogenesis useful?
when reproduction is needed and a mate cannot be found
why is facultative parthenogenesis better than being completely asexual?
there is still a chance for recombination of genes to get rid of the deleterious alleles that can accumulate with just asexual reproduction because sexual reproduction still occurs
cryptic species
- a species in which a group of species contains individuals that are morphologically identical to each other but belong to different species
- lack of variance between species
why is the General Lineage Concept often referred to as “unifying” within the species concept debate?
- makes the case that most of the major species concepts are NOT concepts
- based on species as evolutionary lineages
- all have value in different situations
lineage
sequences of biological entities connected by ancestry-decent relationships
genes trees vs species trees
gene trees match species trees
gene trees
represent evolutionary history of genes included in the study and species trees recover the genealogy of taxa, individuals of a population, etc
allopatric
the evolution of distinct species when populations are geographically separated by an extrinsic barrier
two modes of allopatry
- vicariance
- dispersal
parapatric
the evolution of separate species that are continuously distributed, but non-overlapping, in space
ecotone
a transition between two adjacent but different patches of landscape
sympatric
the evolution of separate species within a shared geographic range
vicariance
occurs when a natural situation arises to physically divide organisms (changes in environment)
example of vicariance
splitting of an island into two separate islands
dispersal
occurs when few members of a species move to a new geographical area
older islands =
more ancient lineage and young island = more recent lineage
which mode of speciation is also called “divergence with gene flow”
parapatric speciation
what is the central challenge of parapatric speciation?
natural selection must overpower gene flow along the boarder where the ranges meet
which mode of speciation may be of importance for speciation in insects that are tied to particular plant species?
sympatric speciation
reproductive isolating mechanism
factors that cause individuals from different groups to fail to mate or fail to produce viable offspring
prezygotic isolation
reproductive isolation between populations due to factors that prevent mating or formation of a zygote
postzygotic isolation
mating may occur, but the zygote does not develop properly or the offspring are not viable
intrinstic postzygotic isolation
- zygotic mortality
- hybrid inviability
- hybrid sterility
zygotic mortality
the egg is fertilized, but the zygote does not develop
hybrid inviability
hybrid embryo forms, but the hybrid has developmental or physiological deficiencies
hybrid sterility
hybrid is viable, but the resulting adult is sterile
example of hybrid sterility
- donkeys and horses can mate to make a mule
- mules are very vigorous but sterile
extrinsic inviability
ecological inviability
ecological inviability
hybrids develop normally but suffer low viability because they lack an ecological niche or do not make choices that confer high fitness
genetic drift
- may play a role in allopatric speciation
- change in frequency of an existing gene variant in a population due to a random sampling of organisms
founder effects
loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population
population bottleneck
sharp reduction in the size of a population due to environmental events or human activities
in general, is there natural selection for speciation?
yes
what is the one instance in which natural selection may directly promote speciation?
speciation is a byproduct of natural selection
ecological speciation
barriers to gene flow evolve among populations as a result of ecologically-based divergent natural selection
how does parallel speciation in sticklebacks work?
- the evolution of benthic and limnetic morphs in stickleback: morphs have evolved repeatedly, benthic forms from different lakes readily mate, but don’t readily mate with limnetic forms and vice versa, the result of divergent natural selection
- an example of ecologically mediated speciation
reinforcement
the only mechanism by which speciation is the direct target of natural selection, diverge in allopatry, secondary contact with hybrid zone, if hybrids unfit, natural selection promotes the evolution of assortative mating
reproductive character displacement
occurs when sympatric and allopatric populations of a species differ in traits crucial to reproduction, and normally thought as a signal of selection acting to limit hybridization
3 principles of biogeography
- all species have a geographic distribution
- the earth has changed dramatically through time
- species distributions change through time, as so the species themselves
historical biogeography circumstances
study of historical circumstances that contribute to the distribution of taxa
questions of historical biogeographic circumstances
- where did species originate?
- where did species colonize their present distributions?
ecological biogeography
study of ecological circumstances that contribute to the distribution of taxa
questions of ecological biogeographic circumstances
- how does this location differ in climate, primary, productivity, etc?
- do species interactions differ in different locations?
endemic
restriction of taxon/taxa to a certain region or locality
Collared lemmings are found in arctic tundra, but we know they were once found as far south as West Virginia. How do we know that?
fossils of Pleistocene collared lemmings have been found
how do species respond to a changing climate?
- move
- adapt
- go extinct
Wallace’s line
a “line” in the ocean where the water is too deep for the surrounding islands to have any species interactions
altruism
actor is harmed and recipient benefits
cooperation
actor benefits and recipients benefits
selfishness
actor benefits and recipients are harmed
spite
actor and recipients are harmed
why is altruism a problem for natural selection?
contrasts with how Darwin thunks that individuals should act
inclusive fitness
direct fitness and indirect fitness
direct fitness
personal reproduction
indirect fitness
the additional reproduction by relatives that is made possible by an individuals action
kin selection
natural selection favoring the spread of alleles that increase indirect fitness
Hamiltons Rule
Br - C > 0
r = relatedness
B = the benefit to the recipient
C = the cost to the actor
adaptive radiation
- the evolution of ecological and phenotypic diversity within a rapidly evolving lineage
- involves the differentiation of a single ancestor into an array of species that inhabit a variety of environments and that differ in the morphological and physiological traits used to exploit those environments
example of adaptive radiation
- Darwin’s Finches
- Cichlid Fishes
- Anolis Lizards
what are the criteria for identifying an adaptive radiation?
- common ancestry
- trait divergence
- rapid speciation
two causes of adaptive radiation
- ecological opportunity
- key innovations
causes for the end permian extinction event
- sea level changes
- ocean chem
- volcanos
- impact by an asteroid
- synergism
End-Permian extinction event: sea level changes
- sea levels dramatically dropped
- 10% of shallow seas remained
End-Permian extinction event: ocean chem
deep water environments were anoxic
End-Permian extinction event: volcanos
released CO2 may have resulted in global warming
End-Permian extinction event: impact by an asteroid
impact may have set off volcanos
synergism
world went to hell hypothesis
what was the biggest mass extinction event ever and when did it happen?
- End-Permian Extinction
- 251.9 mya
