in your own words, explain why gene flow among populations reduces the potential for local adaptation within each population.
James
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get in your own words, explain why gene flow among populations reduces the potential for local adaptation within each population. from EN Bilgi.
Gene Flow
Gene Flow
Gene flow is defined as the movement of genes among populations.
From: Brenner's Encyclopedia of Genetics (Second Edition), 2013
Related terms:
PollenGenetic DivergenceGenomicsGenotypeHabitatsMutationReproductive IsolationAmphipodaAllelesHybridization
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Gene Flow
J.B. Mitton, in Brenner's Encyclopedia of Genetics (Second Edition), 2013
Dispersal
Although gene flow is not synonymous with dispersal, it is certainly true that long-distance dispersal provides the opportunity for long-distance gene flow, and hence for high levels of gene flow among populations. The larvae of some marine mollusks have been documented to be carried by equatorial currents from the coast of Africa to the Caribbean Sea, and we would expect those species to have high levels of gene flow among populations in Africa or in the Caribbean. On the other hand, some marine mollusks brood their young, or attach egg cases to the substrate, severely limiting the opportunity for dispersal, and restricting gene flow. Species that are philopatric with respect to breeding sites, such as salamanders and some species of birds that return to breed where they were born, are characterized by very low gene flow and high levels of genetic differentiation among populations.
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Fundamentals of Molecular Evolution*
Supratim Choudhuri, in Bioinformatics for Beginners, 2014
2.3.3 Gene Flow and Introduction of Genetic Diversity
Gene flow is also called gene migration. Gene flow is the transfer of genetic material from one population to another. Gene flow can take place between two populations of the same species through migration, and is mediated by reproduction and vertical gene transfer from parent to offspring. Alternatively, gene flow can take place between two different species through horizontal gene transfer (HGT, also known as lateral gene transfer), such as gene transfer from bacteria or viruses to a higher organism, or gene transfer from an endosymbiont to the host. HGT is discussed in detail later in this chapter. Gene flow within a population can increase the genetic variation of the population, whereas gene flow between genetically distant populations can reduce the genetic difference between the populations. Because gene flow can be facilitated by physical proximity of the populations, gene flow can be restricted by physical barriers separating the populations. Incompatible reproductive behaviors between the individuals of the populations also prevent gene flow.
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GENETICS OF PLANT DISEASE
GEORGE N. AGRIOS, in Plant Pathology (Fifth Edition), 2005
Gene and Genotype Flow among Plant Pathogens
Gene flow is the process by which certain alleles (genes) move from one population to another geographically separated population. In plant pathology, gene flow is very important because it deals with the movement of virulent mutant alleles among different field populations. High gene flow in a pathogen increases the size of the population and of the geographical area in which its genetic material occurs. Therefore, pathogens that show a high level of gene flow generally have greater genetic diversity than pathogens that show a low level of gene flow. In pathogens reproducing only asexually, in which no recombination occurs, entire genotypes can be transferred from one population to another. This is known as genotype flow. Pathogens that produce hardy spores or other propagules, such as rust and powdery mildew fungi, that can spread over long distances, can distribute their genomes over large areas, sometimes encompassing entire continents. However, soil-borne fungi and nematodes move slowly and are present in small areas and their level of genetic flow is limited. With all types of pathogens, however, their gene flow can be affected significantly by human agricultural practices and by intercontinental travel and commerce. In general, pathogens with a high level of gene flow or genotype flow are much more effective and pose a greater threat to agriculture than pathogens with a low level of gene flow. Also, because asexual spores and propagules contain an already well-adapted and selected set of alleles, such propagules, through their geno-type flow, pose a greater threat in enlarging the area of their adaptation than sexual propagules through their gene flow.
The frequency of alleles of importance in a population is affected by gene flow from other populations. Its magnitude depends on the number of incoming outside individuals into the population compared to the size of the population, as well as the number of different alleles brought into the population by outside individuals. Usually, allele frequencies in small populations adjacent to large ones are influenced strongly by gene flow than under any different conditions. Gene flow between distant populations is generally sporadic unless it is facilitated by intervening populations that act as stepping stones for the pathogen. The effect of gene flow is to reduce genetic differences between populations, thereby preventing or delaying the evolution of the populations in different geographical areas into separate species of the pathogen.
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Modern Morphometrics of Medically Important Insects
Source : www.sciencedirect.com
Bio Prelab 8
View Lab Report - Bio Prelab 8 from BIS 2C BIS 2C at University of California, Davis. The central idea of speciation or cladogenesis is that new species form from subsets of existing species.
Bio Prelab 8 - The central idea of speciation or...
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The central idea of speciation or cladogenesis is that new species form from subsets of existing species. Organisms live in populationswith others of “the same type.” One definition of the same type is based on the ability to interbreed or exchange genes, so a populationis a group of co-located organisms that mate with each other. All organisms presumed able to exchange genes (interbreed) belong toone species, even if they are in widely separated populations.Speciation occurs as members of some populations cease breeding with organisms in other populations. Two populations that do notexchange genes are reproductively isolated. In formal terms, two populations are reproductively isolated when fertile hybrids betweenpopulations do not form or persist. It is very easy to imagine that if some populations are separated from others by long distances orecological barriers such as mountain ranges, mating among populations across the barrier is unlikely. Once gene flow betweenpopulations ceases, isolated populations may diverge due to genetic drift or may adapt to local environmental conditions. A localresponse to natural selection can be quite rapid in a genetically isolated population because there is no influx of alleles that are favoredin other places. You may have heard about allopatric speciation in marine organisms, such as sea urchins or porkfishes, when theancestral populations were subdivided about 3.5 million years ago by the Isthmus of Panama. Once the Isthmus formed, gene flowoccurred only among populations on either side of the Isthmus.Pre-lab Questions--record your answers on the online version1.In your own words, explain why gene flow among populations reduces the potential for local adaptation within each population.
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Imagine that you could watch several populations over time. What aspects of behavior and morphology might differ amongpopulations? The answer to this question will depend on the particular kind of organism under study. In this lab, you will be looking atinsects, soapberry bugs, so it is worth thinking more about speciation in insects. The process of lineage-splitting has been studied insome detail in a fly species called the apple maggot (Rhagoletis pomonella). Have you ever seen tiny brown spots on apples? Somemight be bruises, but others occur when you have shared the fruit with a tiny larval fly (long-gone by the time you get to the apple).The life cycle of apple maggots may be new to you. There are male and female flies living in orchards. The flies are drawn to the sightand scent of apples and meet on fruits to mate. The female lays her eggs (oviposits) on an apple. The eggs hatch to release tiny larvae,maggots, which feed on the fruit. When the apple falls to the ground, fly larvae move into the soil and pupate. You have probably seen
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What is meant by diversity
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The different species and number of indivduals of wach species that inhabit a specific area
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What are the 2 components of diversity
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Species richness: how many species are there
Species evenness: how many individuals of each species there is
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Terms in this set (82)
What is meant by diversity
The different species and number of indivduals of wach species that inhabit a specific area
What are the 2 components of diversity
Species richness: how many species are there
Species evenness: how many individuals of each species there is
What is p(i) in the diversity ondex
The proportion of how many individuals of each species; number of individuals of a species divided by the total number of individuals of all species
How can one measure diversity?
Diversity index
What does the calculated D tell you
How diverse the habitat is
If D of habitat 1 is greater than D of habitat 2, what can you conclude about these two habitats?
Habitat 1 is more diverse than habitat 2.
If you calculated D=1 what does this tell you about the habitat? What must be true in order to calculate D=1?
There is only one species present
What is the value of using OTUs initials rather than formal scientific names
It allowed us to determine the different type of organisms present in our habitat bc were not scientists
What would be the value of ultimately assigning formal scientific names to your OTUs?
So someone else can do the same study and have results that can be
compared or confirmed (science should be repeatable).
When choosing areas to sample why was it important to randomize? How did you randomize your sampling?
Randomizing eliminates our own biases as we might choose a sample with the most or fewest individuals (depending how motivated we are). You can randomize in a number of ways using random number tables, rolling dice etc.
Describe the difference between a transect and a quadratic?
Transects: line through the habitat where you sample at random intervals
Quadrant: a known area like a square that you sample; not linear
What is a photoautotroph?
Creates energy from sunlight for itself. (Photosynthesis)ex: plants
What is a heterotroph?
An organism that cannot make its own food. Derives it's energy from other organisms; ex: tiger
What are some chemical elements almost organism require
oxygen, carbon, hydrogen, nitrogen
What are the products of photosynthesis? How do heterotrophs benefit from these products?
glucose and oxygen; if consuming they get the necessary nutrients from the sugar while obtaining oxygen through respiration
What is one reason water is so important to organisms?
Water is the solvent that transports many essential molecules and other particles around the body
What are the products of respiration?How might autotrophs benefit from these products?
carbon dioxide and water; plants need carbon dioxide in order to photosynthesize
What is the geenral function of a root, stem, and leaf?
root: uptake nutrients for plant
stem: transport water and nutrients to the rest of the plant
leaf: broad to capture sunlight for photosynthesis
How do plants increase their ability to take in nutrients from the soil?
the roots and root hairs allow plant to cover a lot of surface area to receive alot of nutrients from the soil
Would you expect a plant living in a very dry environment (desert) to have leaves with a high surface area to volume ratio or a low surface area to volume ratio?
low surface area to volume ratio
To retain heat would an organisms more likely have a high surface area to volume ratio or a low surface area to volume ratio? How about for respiration?
low surface area to volume to retain heat; high surface area to volume for respiration
Why are Rhizobium bacteria critical for the survival of plants (and even us)?
nitrogen fixation; converts nitrogen to a form the plant can use found in roots
What is a primary producer and why are they called primary producers?
A primary producer is an autotroph. They are called primary producers because they produce biomass from inorganic compounds.
What do omnivores eat? Carnivores? What is an example of a carnivore?
omnivores: both plants and animals
carnivores: other organisms ex is a tiger
What is an adaptation?How does this differ from an acclimation? Can an acclimation be an adaptation?
evolutionary change in genotype that maximizes performance and is passed down;
acclimation+reversible change in an organisms phenotype that allows it to perform better in the environment in which it occurs- usually reversible;
no acc is only phenotype
What is gravitropism? Is it found in an animal or a plant? How does it allow a plant to acclimate to the environment?
a plant's response to gravityI;t allows the plant to know which way to grow.
Describe the difference between a blind gut and a 2-way gut. Which one has specialized structures to aid in digestion?
A blind gut has one opening and anything that cannot be digest is released via the mouth.A 1-way gut is has two openings a mouth and an anus. Food moves in one direction from entrance to exit. 1-way gut has processing guts that contain regions of the digestive tract specialized for particular functions.
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