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Stack #4145458
| Question | Answer |
|---|---|
| Assuming the action of genetic drift alone, are polymorphisms maintained longer in small populations or large ones? | Large ones |
| Are gene flow and genetic drift the same thing? | No |
| What is gene flow? | Gene flow is the transfer of genetic material from one population to another |
| How can gene flow occur? | When individuals leave one population and join a different population |
| What is natural selection? | the process whereby organisms better adapted to their environment tend to survive and produce more offspring |
| What is an example of natural selection? | giraffes developing longer necks |
| What is fitness? | The success of an organism at surviving and reproducing, and therefore contributing offspring to future generations |
| What are the 4 postulates/conditions for evolution by natural selection to occur? | 1. Individuals within populations show variation. 2. Variations among individuals are heritable.3. Individuals vary in survival and reproduction. 4. individuals with favorable variations are selected |
| What is a polymorphism and a polymorphic species? | the occurrence of two or more clearly different morphs or forms. An example is stickleback fish. |
| How does polymorphism play a role in understanding evolution in the "snickers bar of the desert"? | a population of mice in the desert are either more easily spotted or more desirable to predators |
| How does polymorphism play a role in understanding evolution in the stickleback? | The population was separated and polymorphs within the population were better adapted to their new environments |
| Why would there be very few of the "complete" plated morph in freshwater lakes? How does natural selection act to make this happen (i.e. how does natural selection work?)? | It wasn't selected for in the freshwater environment. Those who were bony were being selected against. |
| How and why does coat color evolve in the rock pocket mouse? How do we know? | Darker coat colors are selected against with empirical data to support |
| What is an adaptation? | a mutation that aids in overall fitness of a species |
| What are some different types of adaptations (traits)? | Opposable thumbs in humans, thick skin on bananas, aerobic respiration. |
| What evolutionary process causes the evolution of adaptations? | Natural Selection |
| What were some of the strengths of Darwin's On the Origin of Species? | evidence of evolution, a mechanism for evolution, and the recognition that variation is important |
| What evidence did he use to build the case for natural selection? | several species of finch adapted to different environmental niches |
| Did domestic pigeon breeds each all arise from a single common ancestor? Why does this initially seem surprising? How/why might a professional breeder not find this surprising? | Yes, this may seem surprising because domestic pigeon breeds can vary greatly in their appearance and behavior. A professional breeder are aware of the history of domestication and the selective breeding practices. |
| Species possess adaptations that are well-fitted to the environments in which those species live. Are these then perfect species? Why not? | No, because environments are constantly changing, which means that adaptations that were once well-suited to a particular environment may become less advantageous or even harmful in a different environment |
| Does selection act on genotype? | Yes, because it is the genetic makeup of an individual that determines its phenotype, and it is the phenotype that is subject to selection pressures. |
| How big a difference does a slight increase in offspring number have on the spread of certain alleles in a population? | A larger number of offspring increases the probability that a rare allele will become more common |
| What is fitness (w)? | The reproductive success of an individual relative to other individuals in the population. |
| How is overall fitness calculated | by multiplying the survival probability and reproductive success of an individual. |
| why is overall fitness important? | it reflects the ability of an individual to pass on its genes to the next generation |
| Why are the different components of fitness important? | they represent different aspects of an individual's ability to survive and reproduce in its environment |
| 3 modes of selection | stabilizing, directional, disruptive |
| define Stabilizing selection | favors individuals with intermediate phenotypes |
| Define Directional selection | favors individuals with one extreme phenotype |
| Define Disruptive selection | favors individuals with both extreme phenotypes |
| How are adaptive landscapes used? | a means of visualizing genetics of natural selection |
| What are the sources of polymorphism? | mutation and gene flow |
| What evolutionary forces are likely to remove polymorphism from a population? | Changes in environmental conditions |
| How is polymorphism maintained in populations? | Balancing selection and gene flow |
| explain multiple niche polymorphism | when different genotypes within a population are adapted to different ecological niches or habitats |
| explain frequency-dependent selection | a type of natural selection where the fitness of a particular phenotype depends on its frequency in the population |
| explain inverse frequency dependent selection | the fitness of a phenotype decreases as its frequency in the population increases |
| What are quantitative traits? What are some examples? | traits that exhibit continuous variation and are influenced by multiple genes and environmental factors. EX: height and weight |
| What are QTLs? | specific genomic regions or loci that are associated with the variation in quantitative traits |
| What is quantitative genetics | a field of study that focuses on understanding the genetic basis of complex traits that exhibit continuous variation |
| What is population genetics | studies the dynamics of genetic variation in populations |
| What is a GWAS? | a type of study in genetics that involves scanning the entire genome of individuals to identify specific genetic variants that are associated with a particular trait or disease. |
| What does the idea of "variance" in a trait refer to? | the extent of variability or spread of that trait in a population |
| How do you calculate the total variance of a phenotypic trait in a population? | by summing up the contributions of different sources of variation |
| Is variation in phenotype usually more based on genes? | Both, some traits may be more strongly influenced by genetic factors, while others may be more influenced by environmental factors. |
| What is heritability (H)? | measure of the proportion of phenotypic variation in a population that is due to genetic variation |
| How is heritability assessed? | using statistical methods that compare the phenotypic similarity among individuals with different levels of genetic relatedness |
| What is phenotypic plasticity? | the ability of a single genotype to produce different phenotypes in response to different environmental conditions |
| How does phenotypic plasticity differ from evolution? | evolution refers to changes in the genetic composition of a population over time, resulting in heritable changes in the traits or characteristics of a population |
| 3 types of constraints? | Phylogenetic constraints, Developmental constraints, Functional constraints |
| Explain and give an example of Phylogenetic constraints | limitations imposed by an organism's evolutionary history |
| EX: mammals have a constraint on the number of limbs | |
| Explain and give an example of Developmental constraints | limitations imposed by an organism's developmental processes |
| EX: development of wings in birds is constrained by the embryonic structure of their forelimbs | |
| Explain and give an example of Functional constraints | limitations imposed by an organism's functional requirements |
| EX: the size and shape of a bird's beak | |
| What are constraints? | limitations or restrictions that influence the development or expression of adaptations in organisms |
| How does natural selection, in combination with the genes involved in the development of bird bills, act in the evolutionary radiation of Galapagos finches? | The finches evolved different beak sizes and shapes to specific diets and ecological niches |
| The adaptations of the great grey owl seem pretty perfect for how it makes a living. Explain how owl adaptations evolved through natural selection and how certain traits might not be as perfect as they seem. Why? How does this relate to Seilacher's Triang | These adaptations evolved through natural selection, as owls with advantageous traits were more successful at catching prey and therefore had higher fitness. However, Seilacher's Triangle proposes that adaptations are compromises between conflicting selec |
| Explain adaptations in light of Seilacher's Triangle. | An organism's form (morphology) results from the interplay of three factors |
| 3 factors of Seilacher's Triangle. | Historical, Structural, Functional |
| What is phylogenetic constraint? | It is the tendency of an organism to grow upon a specific body plan |
| What does the metaphor of spandrels tell us about adaptations? | adaptations allow us to see fitness working in real time |
| What are just-so stories? | Hypothetical explanations for the evolution of a trait or adaptation that are based on untested assumptions |
| Great grey owls have slightly asymmetrical skulls that assist in locating prey. Is this the only possible solution to the problem of locating prey? Why or why not? | No, because other species of owls have evolved different adaptations or strategies to locate prey |
| How do Stegosaurus plates relate to what you have learned so far about sexual selection? | there was selection for tall and wide morphs |
| What is genetic drift? | The random change in allele frequencies in a population over time due to chance events. |
| Who built the theory for genetic drift? | biologist Sewall Wright |
| What are bottlenecks and how do they work? | events that result in a severe reduction in the size of a population, often leading to a significant loss of genetic diversity |
| can occur due to natural disasters, disease outbreaks, or human activities | |
| Why do we care so much about Ne in the translocated Laysan finch populations? | it provides information about the potential strength and rate of genetic drift acting on certain allele frequencies |
| Why is popn. connectivity important in this conservation situation? | it allows for gene flow between populations |
| How might you imagine lack of connectivity might act, from the perspective of evolution more generally? | limited gene flow between them, genetic drift may become a dominant force |
| What tool do we use to identify population structure? | the calculation of Fst (fixation index) |
| What force can counteract genetic drift? | Gene flow |
| What is panmixia | a type of random mating, where individuals are equally likely to mate with any other member of the opposite sex |
| In the language of Fst, would panmixia be closer to 0 or 1? | A zero value implies complete panmixis (random matting) |
| Are species real entities? | distinct morphological characteristics, genetic differences, and ecological roles |
| What are some of the different parts of a useful species concept? | Morphological characteristics, Genetic differences, Reproductive isolation |
| How do species concepts generally differ from how we might identify a species in the field, in practice? | In the field it is often based on observable characteristics |
| Is there only one species concept? Can you name any other species concepts | No, some of the others are the morphospecies concept, the phylogenetic species concept, and the ecological species concept |
| Why is it important to figure out the different units we call species, even if you are a field ecologist? | to accurately identify and classify organisms |
| How might the practice of keying out species differ from the concept of what species actually are? | morphological characteristics may not always capture the true evolutionary relationships among populations |
| The Biological Species Concept is a commonly adopted species concept that was first advocated by Ernst Mayr, who also was a major contributor to the Modern Evolutionary Synthesis. What aspects of this concept make it so useful? | This concept is valuable for understanding the mechanisms of speciation and for studying the reproductive isolating mechanisms that evolve in populations. |
| What aspects of The Biological Species Concept make it non-ideal in some cases? | it relies on reproductive isolation, which may not always be easy to determine or observe |
| What are the advantages of morphospecies concept | easily observable physical characteristics |
| What are the disadvantages of morphospecies concept | Doesn't accurately reflect genetic or evolutionary relationships among species |
| What are the advantages of phylogenetic species | based on genetic and evolutionary relationships |
| What are the disadvantages of phylogenetic species | require more complex analyses |
| What is speciation? | the process by which one species splits into two or more distinct species |
| If speciation generally occurs in "stages" what are those stages? | geographic isolation, genetic divergence, and the development of reproductive isolating mechanisms |
| Do all the stages of speciation always occur, and are new species always the result? Why? | No and No |
| Why are reproductive isolating mechanisms important for evolution? | they prevent or reduce gene flow between populations or species |
| How big or permanent do reproductive isolating mechanisms have to be? | varies depending on the species and the ecological context |
| Do any speciation modes occur in the face of gene flow? How would this happen? | Yes, it is known as sympatric speciation. happens when reproductive isolating mechanisms evolve within a single population |
| What mode of speciation mainly resulted in the biota we see today? | Allopatric speciation |
| How might processes we discussed early in the class influence a population's evolutionary trajectory (e.g. to become more distinct or not)? | natural selection, genetic drift, and gene flow |
| Is speciation itself an adaptive process? Why or why not? | no, it can occur due to a variety of mechanisms |
| Explain Dispersal | the movement of individuals from one geographic area to another, resulting in the colonization of new habitats |
| Explain vicariance | when a population is geographically split into two or more isolated populations by the formation of a physical barrier |
| In the snapping shrimp example, would we predict that deep or shallow water populations would speciate first? Why? | shallow water populations would speciate first due to higher levels of gene flow in deep water populations |
| What factors likely promoted the evolution of the Hawaiian picture-winged Drosophila? | geographic isolation, ecological opportunities, and genetic variation |
| What is the biogeographical concept called "the progression rule" | a biogeographical concept that suggests that colonizing species on islands will follow a predictable pattern from simple to complex forms over time. |
| how is the biogeographical concept relevant to our understanding of oceanic island radiations? | it helps us understand how species evolve and diversify on isolated islands |
| What are some examples of prezygotic species isolating mechanisms? | habitat isolation, temporal isolation, behavioral isolation |
| What categories of reproductive isolating mechanisms are most likely to evolve first and second, and why? | Postzygotic reproductive isolating mechanisms evolve first because they can quickly prevent hybrid offspring from successfully reproducing. Prezygotic reproductive isolating mechanisms evolve later because they require changes in behavior or ecological tr |
| Do "lock and key" reproductive barriers evolve in all cases? Explain. Why might they be favored by natural selection sometimes? | No, because they can increase the efficiency of reproduction and reduce the chances of mating with incompatible individuals. This can lead to higher reproductive success |
| What are ring species | populations of a species that are connected in a circular or ring-like manner around a geographic barrier |
| What are a couple ways in which sympatric speciation might occur? | disruptive selection, polyploidy, and sexual selection |
| What is sexual selection? | a form of natural selection that arises from competition for mates or mate choice by individuals of one sex |
| Who is likely to be at a greater disadvantage by mating with many diseased, ugly and small members of the opposite sex—males or females? Why? | |
| Females because females typically invest | more time, energy, and resources |
| Sexual selection has a stronger effect on male peacocks than female peacocks. That doesn't seem fair. Why? | because males often compete for access to females |
| What is lekking behavior? | a mating system where males of a species gather in specific locations and compete to attract females |
| why did lekking evolve? | as a strategy for males to maximize their reproductive success |
| Which sex increases its reproductive success by increasing the number of mates it mates with? | males |
| What is the operational sex ratio | the ratio of sexually active males to females in a population at a given time |
| When does operational sex ratio impact the strength of sexual selection? | When it is skewed |
| Why is Sexual selection generally considered to be a type of natural selection | by favoring traits that enhance mating success but may not necessarily improve survival or overall fitness |
| What happens when the operational sex ratio is greatly skewed? | lead to intense competition among individuals |
| Why don't red deer roar all year round? | They roar during the rutting season to establish dominance and attract mates |
| Why are red deer more likely to roar near other males? | to establish territory and compete for mates |
| Why do male red deer and giraffes sometimes walk parallel to one another (this behavior is called, surprisingly, "parallel walk")? | to assess each other's strength and resolve dominance without engaging in physical combat |
| What are some examples of the different types of intrasexual selection? | competition for mates through direct combat, sperm competition, and mate guarding |
| How might different types of intrasexual selection behaviors or morphological traits evolve? | Natural selection |
| Does testosterone have any disadvantages? | It is energetically costly |
| Certain animals have fancy male copulatory organs. Why and under what circumstances might these morphological traits evolve? | If a male's penis stays within a female's reproductive tract longer, it ensures that more sperm will enter |
| Females can acquire both direct and indirect benefits through mating and sexual selection. What are they? | direct is better sperm and indirect is ensuring fitness of the species |
| What are the benefits of female choice specifically (examples?) | a female may improve the genetic quality of her offspring |
| If a long tail is likely to get caught up in brush, and maintaining it is costly to the male's health, why and how would this morphological feature have evolved? | female choice |
| What was the point of showing the different bird of paradise videos? | calfbirds evolved mating calls |
| How and why does the intersexual selection in calfbirds differ from New Guinea birds of paradise? | They evolved a dance, not a call |
Created by:
mcord0823