Evolution Exam 3 Hypothesis testing/Problem Solving
Which of these figures represent phylogenetic cascades and why?
Phylogenetic cascade is evolutionary history shared across more than two trophic levels. The first two represent phylogenetic cascades. Crazy lines are just the lines between the parasitoids . Black lines go to black lines, gray lines go to gray lines etc. They show that the evolution on one trophic level is mirrored by evolution on the others. The influence across trophic levels is called trophic cascade. A = species-level matching of relationships across trophic levels B = 'clade-for-clade' correspondence C = Independence across trophic levels [ A ... Phylogenetic Escape: speciation of 2 different trophic groups happens in parallel In A every single plant species has herbivore species that has evolved with it Not C because everyone is going for something different Not B because whole clade of herbivore feeds on one species of plant]
George's first cousin Marie on his mother's side marries his first cousin Bob on his father's side. Marie and Bob produce Fred. What is the relatedness coefficient between George and Fred? (squares represent males and circles represent females)
R=(0.125)(0.5)+(0.125)(0.5)= 0.125 or (0.5)^4+(0.5^4) also equals 0.125
Researcher's tested the Good Genes model of Sexual Selection on gray tree frogs. Explain the design of this study. What are the necessary variables to measure in order to test such a model?
The good genes model suggests that female will select males based on traits that may increase offspring viability. Most females will pass a loudspeaker playing short calls to approach a loudspeaker playing long calls. Females discriminate most strongly against short calls. A female's "phonotaxis score" for a particular test call is the time it took her to approach a control call with 18 pulses per second divided by the time it took her to approach the test call. Higher scores indicate a stronger preference for the test call relative to the control. Most females prefer long calls to short calls, even when the short calls are initially louder. In 1995 and 1996 the fitness of the offspring of long-calling males and short calling males were compared in high food and low food environments. Larval growth, time to metamorphosis, , larval survival, and post-metamorphic growth of the long-call offspring had higher fitness than the short-call offspring
Based upon what is known about Homo naledi, what kind of data would you collect to determine if this species diverged from Homo erectus or from Homo habilis ? Explain your answer. Remember these are fossils.
Things you can determine if Homo naledi derived from Homo erectus or Homo habilis.... 1. Brain Size - the brain size of H. naledi was 4.5 which is notably smaller than other homo. 2. Anatomy - H. naledi anatomy indicates that though they were capable of long distance travel with a humanlike stride and gait, they were more arboreal than other Homo. 3. Features - Homo naledi possessed a mixture of traits that are Australopithecus-like (particularly in the pelvis and shoulder) and Homo-like (particularly in the hands and feet, and the size of its brain).
Why do researchers hypothesize that the Denisovans, but not Neanderthals, interbred with more distant hominin species?
due to the principle of genetic equidistance that predicts that as sister groups, Denisovans and Neanderthals should be about equally distant from modern humans, they are not. instead, Denisovans are significantly greater genetic distance from humans, which shows they bred with other populations of as yet unknown hominins. [Neanderthals and Denisovans are sister species. Thus, the principle of genetic equidistance suggests that the genetic distance between humans and Neanderthals should be about the same as the genetic distance between humans and Denisovans. Yet this is not the case. Denisovans are a significantly greater genetic distance from humans. One plausible explanation is that the Denisovans interbred with a more distantly related hominin species after their divergence from the Neanderthals.]
What is Lack's hypothesis and how has it been tested?
Lack's hypothesis states that the natural selection will favor the clutch size which produced most surviving offspring. In other words, the amount of food the broods require may exceed the food their parents gather, thus reducing the survival of the offspring. Lack's hypothesis raised conflict among the scientific community as it is proved ineffective by various experiments. Meta-analysis is a method which is useful to quantitively review and examine the results from a large number of studies on subject for which there is conflict evidence. The author (Eric VanderWerf) used this method to analyze the results from 42 independent brood enlargement studies and tested Lack's hypothesis. He checked whether clutch size in birds has evolved to produce the most surviving offspring. The cumulative evidence didn't support Lak's hypothesis. It was observed that significantly more chicks were produced in enlarged broods than in normal sized ones.
Define and give examples of the four different categories of helping behavior. Discuss under what situations you would expect these behaviors to evolve?
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Grasshoppers recolonized Europe from refugia (unfavorable condition) after the last glacial period. What data were collected to determine their recolonization pattern?
Look at expansion rate within genetic data. The more they expand, the genetic diversity changes, and leads to less genetic variation. Using mitochondrial DNA. The refugium in which the crickets lived during glacial periods were in the woody-vegetation areas of Iberia, Italy, and Balkan region. When the glacial ice melted the crickets recolonized Europe. By comparing the genomes of the crickets it was apparent that Northern and Central Europe was colonized by the crickets from the Balkans while the crickets in Iberia and Italy remained in place because and did not cross the mountain ranges. You can compare genomes and view the homologous relationships between the Balkan crickets and the Northern and Central Europe crickets. [Chorthippus paralellus is the meadow grasshopper occuring all over Europe. Three subspecies were recognized and analyzed for differences in their morphology, behaviour and chromosomes. Among 40 allozyme loci tested only two gave the subspecific differences and hence, they were investigated for their mtDNA, rDNA, and ncDNA. one of the sequence showed significant variations among different geographical regions. A Fitch tree of Kst genetic distance in populations of grasshoppers from different areas of Europe was presented that incorporate both sequence divergence and haplotype frequency into measure of similarity in population. Hence, the molecular data specially from DNA sequences is used for identifying refugia and recolonized europe after last ice age. They suggest that different regions of Europe were recolonized by distinct genomes of species from Italy, Greece, Balkans, and Iberia.]
What methods are used to date fossils? What type of rock formations are important in determining fossil age and why? Would Carbon 14 or Potassium 40 be a better tool to age mammalian fossil and why?
Methods Used to Date Fossils: Relative Dating: It determines approximate age of the fossil by comparing the fossil with it's similar age known fossils. It does not give accurate age of the fossil but gives approximate age. Absolute Dating: The accurate age of the fossil is determined by this technique which uses radiometric dating that measure the decay of isotopes of the rock or the fossil Sedimentary rocks are important in determining fossil age because of their characteristic fossil content. The layers of the sedimentary rock is exposed. The deeper layer of the rock is older than compared to the initial layer of the rock Carbon 14 Mammalian fossils are dated using Carbon 14 isotope. Carbon 14 molecules are replenished in mammals until it dies and hence organic molecules are dated using Carbon 14. Potassium 40 is used to determine the age of the rocks.
Why is sexual reproduction more prevalent than asexual reproduction? How did the data from the New Zealand mud snail study inform the first question above?
Reproduction is defined as the process of producing offsprings that are biologically or genetically similar to the parent organism. Reproduction enables and ensures the continuity of species, generation after generation. The two modes of reproduction are: Asexual reproduction: refers to the type of reproduction in which only a single organism gives rise to a new individual. This does not involve the fusion of gametes, and therefore, the offsprings produced are genetically identical to the parent. The organisms produced by asexual reproduction are less diverse in nature. This type of reproduction is mainly found in unicellular organisms. Asexual reproduction is further divided into the following categories: Binary Fission Budding Sporogenesis Sexual reproduction: is the mode of reproduction in which the individuals are formed by the fusion of male and female gametes. Asexual reproduction, on the other hand, is the type of reproduction in which no fusion of gametes takes place and the offspring is genetically identical to the parent. However, the sexual mode of reproduction is better than the asexual mode. Sexual reproduction provides diversity in the genetic makeup of the offspring. This is due to the combination of genes from two different individuals. However, this is not the case with asexual reproduction since only one parent is involved. Advantages Of Sexual Reproduction Over Asexual Reproduction: - There is diversity in the genetic makeup of the individuals produced by sexual reproduction. - Since both the parents are involved, the newly formed individuals have the attributes of both. - Variations are more successful in sexual mode than in asexual one. - The species produced by sexual reproduction survive more than those produced by asexual reproduction. This is because genetic variations help them to adapt to different environments. NEW ZEALAND SNAILS Some P. antipodarum females reproduce sexually, mating with and being fertilized by males in the population. Other females reproduce asexually: these females produce unfertilized eggs that mature into the next generation of females. In these asexual lineages, each offspring is a clone of its parent. Lively tested "Red Queen hypothesis": - hypothesis hat sexual reproduction is an adaptation allowing hosts to generate sufficient genetic variation to keep up with their pathogens and parasites in the coevolutionary arms race. This hypothesis predicts that the level of parasitic infection will be related to the frequency of sexual versus asexual reproduction. Lively found that: Sexual reproduction was more common when the frequency of parasites was high, both in lakes and in streams.
