BIO Exam 2

look over problem set

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allopatric speciation by vicariance

1. Geographic isolation: chance by event physically separates population into subgroups 2. genetic isolation: the two populations are genetically isolated from one another due to the absence of gene flow 3. genetic divergence: the populations diverge due to mutation, genetic drift, and selection

Please examine Figure 23.13 (reprinted below) from your textbook. In the space provided, please illustrate what these simulation results would look like for a population size of 4,000 (chapter 23 reading questions)

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law of segregation

A sperm or egg cell contains only one allele for each gene because allele pairs separate from each other during meiosis I

Albinism Effects of albinism may include:

Albinism is characterized by an absence of melanin from the hair, skin, eyes, scales, feathers, and/or cuticle of an organism, Loss of coloration Abnormal development of the eye Impaired hearing Reduced protection from sunlight Reduced viability

Albino organisms

Albino organisms lack an enzyme involved in the synthesis of melanin

Are dominant traits always "better"? Do they always occur at higher frequencies than Recessive traits?

Dominant traits are not inherently "better" than recessive traits, and they do not always occur at higher frequencies in populations. The concepts of dominance and recessiveness relate to how alleles for a particular trait are expressed, not to the intrinsic value or superiority of the trait. Dominance and Recessiveness: Dominant traits are expressed when an organism carries at least one dominant allele for a particular trait, and recessive traits are only expressed when an organism carries two recessive alleles for that trait. This means that dominant traits are more likely to be visible in heterozygous individuals (those carrying one dominant and one recessive allele), while recessive traits are typically only seen in homozygous recessive individuals (those carrying two recessive alleles).

law of independent assortment

Each pair of alleles segregates independently of other pairs of alleles during gamete formation, at least when different genes are located on different chromosomes

What features of the garden pea (Pisum sativum) made it a good model organism for Gregor Mendel's experiments? (make sure this is right)

Easily observable traits: Garden peas exhibit a variety of easily distinguishable and quantifiable traits, such as flower color (purple or white), seed color (yellow or green), seed shape (round or wrinkled), and stem length (long or short). These traits were controlled by a small number of genes with clear dominant and recessive alleles, making it easy for Mendel to track and analyze their inheritance patterns, Controlled pollination: Pea plants have both male and female reproductive organs, but they can be easily manipulated for controlled cross-pollination. Mendel could choose which plants to cross, ensuring that he controlled the genetic makeup of the parent plants and could accurately predict the outcome of the crosses.

gene flow does what?

Gene flow homogenizes populations, Over time, high levels of gene flow tend to reduce differences in allele frequencies between populations Gene flow can work in the opposite direction of selection

genetic drift leads to what?

Genetic drift refers to random changes in allele frequencies from one generation to the next These random changes can be a result of some gametes participating in fertilization at the expense of others or unpredictable events that remove some alleles from the population at greater frequencies than others Often, effects of genetic drift will be most pronounced in small populations

In most cases, new species arise in a splitting event that happens in two steps:

Genetic isolation (absence of gene flow) Genetic divergence (mutation, selection, and drift happening independently in isolated populations)

evolution and how we can quantify it

In biology, we define evolution as a change in allele frequencies in a population over time

epistasis

In epistasis, the expression of one gene controls the phenotypic expression of another gene, For example, in many mammals, coat color is under the control of two genes - one gene that determines color and a second gene that determines whether pigment is deposited in the hair

fitness

Lifetime reproductive success (fitness) is a combination of survival, reproductive success, and mating success

What does mutation do?

Mutation introduces new alleles, Mutation is the source of all new genetic variation within populations Importantly, mutation is random! Populations do not mutate toward traits that are helpful Without mutation, evolution by natural selection could not occur

natural selection produces what?

Natural selection produces adaptations, Many processes can lead to evolution, but natural selection is the ONLY process that can produce adaptation.

In order for a population to remain in HWE, five conditions must be met:

No mutation No selection No genetic drift No gene flow Random mating

Please fill in the blank spaces in the table below to summarize how average phenotype and genetic variation in a population change (or not) when subjected to each mode of natural selection listed below.

Online

On page 483 in your textbook, the authors outline three important points about how genetic drift functions in populations. What are they? (make sure this is correct)

Random Changes in Allele Frequencies: Genetic drift is a random process that can cause changes in the frequency of alleles within a population over time. It is driven by chance events, such as the random sampling of alleles in small populations, and can lead to fluctuations in allele frequencies. More Pronounced in Small Populations: Genetic drift tends to have a more significant impact on small populations. In small populations, the chance sampling of alleles during reproduction can lead to more dramatic fluctuations in allele frequencies, potentially resulting in the loss of alleles (fixation) or the fixation of one allele at a locus. Loss of Genetic Variation: Over time, genetic drift tends to reduce genetic diversity within a population, as it can lead to the fixation of one allele and the loss of others. This is in contrast to natural selection, which often acts to preserve or increase genetic diversity by favoring certain alleles. In small populations, genetic drift may have a more pronounced effect on genetic diversity.

secondary contact

Secondary contact refers to the removal of a barrier to gene flow

Mutation alone is rarely sufficient to change allele frequencies in a population in any significant way. In what sense is mutation important in directing the evolution of populations?

Source of Genetic Variation: Mutation is the ultimate source of new genetic variation in populations. It introduces new alleles into the gene pool, which are then subject to other evolutionary processes like natural selection, genetic drift, gene flow, and recombination. While the rate of mutation may be low, over long periods of time, it contributes to the overall genetic diversity within a population. Diversification and Adaptation: Mutation is instrumental in the long-term diversification and adaptation of species. Accumulated mutations over evolutionary time can lead to the development of entirely new features, functions, or adaptations, enabling organisms to exploit new ecological niches or respond to changing environmental conditions.

what else can affect gene expression?

The environment can also affect gene expression!, In Himalayan rabbits, a gene that produces dark pigmentation is active only when temperatures are between 15 and 25 degrees Celsius!

Please explain how a cross between Emmer wheat (a tetraploid (4n) species) and a wild, diploid (2n) wheat gave rise to bread wheat (a hexaploid (6n) species) that is grown throughout the world today.

The evolution of bread wheat (Triticum aestivum) from its ancestral species, including emmer wheat (Triticum dicoccum), involves a complex history of hybridization and polyploidization. It's important to understand some key concepts: Polyploidy: Polyploidy is a condition where an organism has more than two complete sets of chromosomes. In wheat, there are three major types: diploid (2n, with two sets of chromosomes), tetraploid (4n, with four sets), and hexaploid (6n, with six sets). Hybridization: Hybridization occurs when individuals from different species or populations mate and produce offspring. This can lead to the combination of genetic material from the parent species. Here's how the evolution of bread wheat occurred: Wild Diploid Ancestors: The wild ancestors of bread wheat were diploid, meaning they had two sets of chromosomes (2n). Hybridization: Around 10,000 years ago, a spontaneous hybridization event took place in nature. It's believed that a wild diploid grass closely related to the wild einkorn wheat (Triticum boeoticum) cross-pollinated with a tetraploid emmer wheat (Triticum dicoccum) plant, leading to a fertile offspring. Polyploidization: This fertile offspring, called Triticum turgidum, was a tetraploid, having inherited two sets of chromosomes from the wild diploid and two sets from the emmer wheat. This hybridization event is also known as a natural allopolyploidization event, combining different species' genetic material and resulting in a tetraploid plant. Cultivation: The new tetraploid wheat (T. turgidum) had beneficial characteristics like larger seeds, which made it suitable for cultivation. Early farmers selected and cultivated these plants. Further Hybridization and Polyploidization: Over time, further hybridization events occurred, leading to hexaploid wheat. These hybridization events involved tetraploid wheat (T. turgidum) and a wild diploid grass related to Aegilops tauschii. This gave rise to hexaploid bread wheat (T. aestivum), which has three sets of chromosomes from T. turgidum and three sets from Aegilops tauschii. Cultivation of Bread Wheat: Hexaploid bread wheat was prized for its adaptability and high yields, making it a staple food crop. It eventually became the do

polygenic

Traits that appear to exhibit continuous variation are often under the control of a large number of genes (polygenic)

Why is understanding speciation important?

Understanding speciation helps us to understand how much genetic diversity we have on Earth and how much genetic diversity is at risk of being lost at any given time

pleiotropy

When a single gene influences multiple aspects of an organism's phenotype

gene located on the X chromosome

a woman will have two alleles, while a man will have only one, Most often, sex-linked traits occur on the X chromosome because there are substantially more genes present on it, Because females carry two copies of each X-linked gene, any recessive disease alleles are less likely to be expressed in females than in males

For a gene located on the Y chromosome

a women will have zero alleles, while a man will have one

how do you get allele frequencies?

add up total of big A for example with total of alleles overall

If a population is in HWE... Two mathematical certainties:

allele frequencies will not change from one generation to the next alleles will always be distributed within individuals in the proportions of p^2, 2pq, and q^2 p + q = 1 p^2 + 2pq + q^2 = 1

Codominance

arises whenever heterozygotes express both of their alleles (red + yellow = red and yellow stripes)

If the blue allele is incompletely dominant over the yellow allele, what genotypic and phenotypic ratios would you expect among the offspring of two individuals that are heterozygous at this gene? (HINT: What will heterozygotes look like?)

do problem

A gene with two alleles for height is present in corn (T and t.). T is completely dominant to t and produces a normal sized plant; homozygous recessives are very stunted in height. If the frequency of t = 0.3 What are the expected phenotypic frequencies?

do the problem

multiple independent colonization

each founded/created population is independent of previous populations and lacks direct connection/relation to them, happens in non-sequential ways -> genetic drift -> creates more variation of allelic richness in populations -> Atlantic ocean

Pre-zygotic Isolation within outcome 1

ecological isolation behavioral isolation temporal isolation mechanical isolation prevention of gamete fusion

stepwise dispersal

encompasses a relationship where every new founding of a population is dependent on the previous one, a process by which a species expands from one area to another in a pattern of stages, the species initially colonizes an new habitat that is good/suitable for them and then expands further from there. Species might adapt to new environment and grow -> dispersing to areas surrounding their home which are uninhabited -> genetic drift -> similar pattern of allelic richness (decline in allelic richness with increasing distance from the USA -> pacific ocean)

allopatric speciation by dispersal

geographic isolation: some individuals disperse from their population and colonize a new habitat, genetic isolation: the two populations are genetically isolated from one another due to the absence of gene flow genetic divergence: the populations diverge due to mutation, genetic drift, and selection

An organism that has two copies of the same allele for a gene An organism that has two different alleles for a gene

homozygous for that gene said to be heterozygous for that gene

In Labrador Retrievers, a single gene controls whether an individual dog will be black or brown. Black labs have at least one copy of the dominant allele (B), while chocolate labs have two copies of the recessive allele (b). Imagine that a black lab and a chocolate lab mate and produce a litter of five puppies. Three of the puppies are black and two are chocolate. What are the genotypes of the parents at this gene?

in notebook

what genotypic and phenotypic ratios are expected for a cross between an Hh man and an hh woman?

in notes

If the blue allele is codominant with the yellow allele, what genotypic and phenotypic ratios would you expect among the offspring of two individuals that are heterozygous at this gene? (HINT: What will heterozygotes look like?)

notebook

Imagine that a single gene determines the coloration of individuals in a population of beetles. Two different alleles exist in this gene. One allele codes for yellow coloration and a second allele codes for blue coloration. If the blue allele is completely dominant over the yellow allele, what genotypic and phenotypic ratios would you expect among the offspring of two individuals that are heterozygous at this gene?

notebook

In one species of flowering plant, dark red flower color (RR) and white flower color (WW) show incomplete dominance, with the intermediate plants (heterozygotes - RW) having flowers with a pink color. Without making any assumptions about Hardy-Weinberg equilibrium, you walk into a population of this species and count all the individual plants that contain flowers. You return to your home and tally your counts, which reveal 380 plants with red flowers, 10 with pink flowers, and 210 with white flowers. What are the allele counts and frequencies in this population? According to Hardy-Weinberg, what are the expected numbers of plants with red, pink and white flowers? Can you conclude that this population is at Hardy-Weinberg Equilibrium for this gene locus?

online

ratites

ostriches, emus, rheas, cassowaries, and kiwis, all are flightless but they are widespread throughout the southern hemisphere

Allopatric speciation

populations are genetically isolated by a geographical barrier

Sympatric speciation

populations are genetically isolated by non-random mating no geographic isolation: sympatric individuals live in the same geographic area genetic isolation: begins to occur when mating becomes increasingly nonrandom genetic divergence: occurs as mutation, genetic drift, and selection increase the differences between populations over time Example: in notes

Outcome 4 + example

populations interbreed successfully to produce viable and fertile offspring - a hybrid zone will form Hybrid sunflowers grow in more arid habitats than either parental species

genetic drift

random changes in allele frequencies

how did kiwis and tinamous remain small when most paleognaths got really big as they evolved?

small body size could have been advantageous for foraging and moving around in their habitat, the absence of predators on the ground in new zealand might have been reduced selective pressure for them to have a greater body size -> ancestors could have been small as well

What hypothesis did Mendel propose to explain the results he obtained?

the hypothesis of "particulate inheritance" or the concept of "heritable factors" (which we now refer to as genes). Mendel's hypothesis stated: Law of Segregation: Mendel proposed that there were discrete units of hereditary information (which he called "factors") responsible for the inheritance of traits. He hypothesized that each individual inherited one factor (allele) from each parent for a given trait, and these factors segregated or separated during gamete (sperm and egg) formation. This segregation explained how traits were inherited from one generation to the next. Dominance and Recessiveness: Mendel also proposed the concept of dominance and recessiveness. He suggested that some alleles (dominant alleles) could mask the expression of others (recessive alleles) in heterozygous individuals. In his experiments, this was evident when traits with dominant alleles were expressed in the F1 generation, while traits with recessive alleles were not. Mendel's hypotheses were revolutionary at the time because they provided a coherent and quantitative framework for understanding how traits are inherited. His work laid the foundation for the field of genetics and helped to explain the patterns of inheritance that he observed in his experiments with pea plants.

Punnett squares visually highlight what?

the possible gametes involved in a genetic cross and the resulting combinations of potential offspring

In order for evolution by natural selection to occur, a trait must be...

(1) Variable (2) Heritable (3) Associated with variation in lifetime reproductive success

Please explain how each of the following processes can result in evolution due to genetic drift: (a) random fertilization, (b) loss of unlucky individuals due to accidents, (c) founder effect, and (d) population bottleneck. For each of these processes, please illustrate your explanation with a specific (real or made-up) example.

(a) Random Fertilization: Explanation: In random fertilization, gametes (sperm and eggs) combine randomly to form offspring. The genetic makeup of each offspring depends on the random assortment of alleles from the parents. Over generations, random fertilization can lead to fluctuations in allele frequencies in a population. Example: Imagine a population of flowers with two alleles for flower color: A (red) and a (white). In each generation, flowers produce gametes containing either A or a alleles. The specific combinations that result from fertilization are random. Over time, the frequency of each allele in the population can change due to these random combinations, leading to shifts in flower color proportions. (b) Loss of Unlucky Individuals due to Accidents: Explanation: Genetic drift can occur when individuals are lost from a population due to random events like accidents or natural disasters. The individuals that are lost may carry specific alleles, and the loss can lead to changes in allele frequencies. Example: Consider a small population of birds living in a forest. A lightning strike causes a tree to fall, killing several birds that happened to be nesting there. These birds carried a specific allele for beak size. The loss of these individuals affects the allele frequencies in the population, potentially leading to changes in beak size over time. (c) Founder Effect: Explanation: The founder effect occurs when a small group of individuals from a larger population establishes a new, isolated population. The genetic diversity of the founding group is limited, and their offspring inherit this reduced diversity. Over generations, genetic drift can result in changes in allele frequencies. Example: Suppose a small group of individuals from a larger population of butterflies migrate to a remote island. These founding butterflies represent only a subset of the alleles found in the original population. As the isolated island population reproduces and expands, genetic drift can cause changes in allele frequencies, leading to different wing patterns in the island population compared to the mainland population. (d) Population Bottleneck: A population bottleneck occurs when a large population is drastically reduc

At the time that Mendel carried out his experiments on garden peas, there were two major hypotheses for how traits are passed from parents to offspring? What were they?

Blending Inheritance: The prevailing hypothesis before Mendel's work was the theory of blending inheritance. According to this theory, traits from the parents blend together in the offspring. For example, if one parent had a trait for tallness and the other parent had a trait for shortness, their offspring would inherit an intermediate height, resulting in a blend of the parental traits. Over successive generations, this theory suggested that traits would continue to blend, ultimately leading to a uniform population with no clear distinction between traits. Inheritance of Acquired Characteristics: Another prominent theory at the time was the idea of the inheritance of acquired characteristics, proposed by the French biologist Jean-Baptiste Lamarck. Lamarck's theory proposed that traits acquired by an organism during its lifetime (through use or disuse) could be passed on to its offspring. For example, if a giraffe acquired a longer neck by stretching to reach higher leaves, it was believed that this acquired characteristic could be inherited by its offspring, leading to progressively longer-necked giraffes in subsequent generations.

Please provide one example of how gene flow may increase fitness in a population and Another example of how gene flow may decrease fitness in a population.

Example 1: Gene Flow Increasing Fitness Scenario: Consider a population of salamanders living in a mountainous region. Within this population, some individuals are adapted to high-altitude environments, with physiological traits that help them thrive in the thin air, such as efficient oxygen transport systems. However, in a lower-altitude neighboring valley, there's a separate population of salamanders with different adaptations better suited to the lower altitude, such as energy-efficient metabolic processes. Effect of Gene Flow: Occasional migration or gene flow between the high-altitude population and the low-altitude population can introduce new genetic diversity into each population. This gene flow can have a beneficial effect, especially if it introduces alleles from the other population that improve the fitness of individuals. For instance, a salamander from the high-altitude population that migrates to the low-altitude population may carry alleles for efficient energy metabolism. These alleles could increase the fitness of the low-altitude population, as they provide an advantage in utilizing available energy resources more effectively. Similarly, a low-altitude salamander migrating to the high-altitude population may carry alleles related to improved oxygen transport, enhancing the fitness of the high-altitude population. In this case, gene flow increases genetic diversity within both populations, potentially leading to individuals with improved fitness characteristics. Example 2: Gene Flow Decreasing Fitness Scenario: Imagine a population of wildflowers inhabiting a specific ecological niche with unique soil conditions, nutrient requirements, and interactions with pollinators. In an adjacent area, there's another population of the same species of wildflowers, but they are adapted to different soil conditions and have specific mutualistic relationships with different pollinators. Effect of Gene Flow: If gene flow occurs between these two populations, alleles from one population may be introduced into the other. However, if the introduced alleles are not well-suited to the recipient population's ecological niche, this can decrease fitness. For example, if alleles from the population adapted to one typ

HH: widow's peak (label which is the genotype and the phenotype

HH: genotype widow's peak: phenotype

What does it mean if a population is not in HWE?

If a population is not in HWE (i.e., if its alleles are not distributed randomly within individuals or allele frequencies are changing over time, then it means that at least one agent of evolutionary change is acting on the population (or that mating is non-random with respect to the trait of interest)

What phenotypic ratio is expected from a cross between two individuals with genotypes AaBb and AaBb if genes A and B are located on different chromosomes? do a regular punnett square

If genes A and B are located on different chromosomes, they assort independently during meiosis, leading to the phenomenon of independent assortment. When two individuals with the genotypes AaBb (heterozygous for both genes) are crossed under independent assortment, the expected phenotypic ratio among their offspring is typically 9:3:3:1. Here's how this phenotypic ratio is derived: AB: Individuals with dominant alleles for both traits (A and B). Ab: Individuals with a dominant allele for trait A and a recessive allele for trait B. aB: Individuals with a recessive allele for trait A and a dominant allele for trait B. ab: Individuals with recessive alleles for both traits (a and b). Each of these phenotypic categories can be further broken down into genotypes as follows: AB: AaBb (homozygous dominant for both genes). Ab: AaBb (heterozygous for gene A, homozygous dominant for gene B). aB: AaBb (homozygous dominant for gene A, heterozygous for gene B). ab: AaBb (heterozygous for both genes). Now, let's calculate the phenotypic ratio: AB (AaBb): 9/16 of the offspring (3/4 x 3/4) Ab (AaBb): 3/16 of the offspring (3/4 x 1/4) aB (AaBb): 3/16 of the offspring (1/4 x 3/4) ab (AaBb): 1/16 of the offspring (1/4 x 1/4) So, the expected phenotypic ratio from this cross is 9:3:3:1, indicating that 9/16 of the offspring will exhibit the dominant phenotype for both traits, 3/16 will exhibit the dominant phenotype for one trait and the recessive phenotype for the other, 3/16 will exhibit the recessive phenotype for one trait and the dominant phenotype for the other, and 1/16 will exhibit the recessive phenotype for both traits.

What are the allele frequencies in offspring? (might want to refer back to notes)

Imagine that 100 offspring are produced that conform to each of the genotype frequencies represented below 49 AA individuals contain a total of 98 A alleles and 0 a alleles 42 Aa individuals contain a total of 42 A alleles and 42 a alleles 9 aa individuals contain a total of 0 A alleles and 18 a alleles Frequency of A = (98 + 42)/200 = 140/200 = 0.70 Frequency of a = (42 + 18)/200 = 60/200 = 0.30 Allele frequencies have not changed from parents to offspring!

Godfrey H. Hardy and Wilhelm Weinberg did what

In 1908, Godfrey H. Hardy and Wilhelm Weinberg independently solved the puzzle of how allele frequencies change in populations over time - unless some agent of evolutionary change is acting, allele frequencies will remain the same from one generation to the next

What did the reciprocal cross for the above scenario look like and what result did it obtain? What did this result tell Mendel about how inheritance works at the round/wrinkled seed gene?

In Mendel's experiments with pea plants, he not only performed the cross where he applied pollen from a true-breeding round-seed pea plant to the female reproductive organs of a true-breeding wrinkled-seed pea plant (which resulted in all round-seed offspring), but he also conducted a reciprocal cross. In the reciprocal cross, he applied pollen from a true-breeding wrinkled-seed pea plant to the female reproductive organs of a true-breeding round-seed pea plant. The result of the reciprocal cross was the same as the initial cross: all the offspring had round seeds. This result provided further support for Mendel's understanding of how inheritance works at the round/wrinkled seed gene. Mendel's conclusion from these reciprocal crosses was that there must be discrete units of hereditary information (now known as genes) that come in pairs (alleles). In this case, there were two alleles for seed shape, one for round seeds (R) and one for wrinkled seeds (r). The round seed allele (R) was dominant to the wrinkled seed allele (r), and individuals with one dominant allele (R) and one recessive allele (r) would exhibit the dominant trait (round seeds). Mendel's work laid the foundation for our modern understanding of genetics and the principles of dominant and recessive alleles in inheritance.

Polyploid individuals might be favored by natural selection?

In general, polyploidy is considered an important factor in species invasion success via, e.g. pre-adaptation to novel conditions or higher adaptive potential due to increased genetic diversity, Polyploidy is the heritable condition of possessing more than two complete sets of chromosomes.

population genetics provides us with what

In order to study changes in allele frequencies within populations, we need a framework for understanding the behavior of alleles within groups of organisms - population genetics provides us with this framework

In closely related species of fruit flies (genus Drosophila), individuals of different sympatric species seldom mate when brought together in a laboratory setting. In contrast, individuals of different allopatric species often mate with one another in a laboratory setting. Why does this difference in behavior likely exist?

In summary, sympatric species often evolve mechanisms to avoid mating with closely related species due to competition for resources and the need to maintain their own ecological niches. These mechanisms, including differences in mating behaviors, are part of the process of reproductive isolation that prevents hybridization. In contrast, allopatric species do not face the same selection pressure for reproductive isolation, and in a laboratory setting, they may still possess the ability to interbreed because they haven't evolved strong barriers to hybridization.

incomplete dominance

Incomplete dominance is a genetic phenomenon in which neither of two alleles in a heterozygous individual is fully dominant or recessive over the other. Instead, the heterozygous individual displays an intermediate phenotype that blends characteristics of both alleles. In other words, in incomplete dominance, the heterozygote's phenotype is a mix or "blend" of the phenotypes associated with the two different alleles. (Red + yellow = orange)

Why does inbreeding often increase the rate of evolutionary change?

Increased Homozygosity: Inbreeding leads to an increase in homozygosity. Homozygous individuals have two identical alleles for a particular gene. This means that if there are harmful recessive alleles in the population, they are more likely to be expressed when individuals are homozygous for those alleles. Genetic Drift: In small populations, inbreeding is more likely to occur due to the limited number of available mating partners. When populations are small, genetic drift plays a significant role in changing allele frequencies. Genetic drift can lead to the fixation of alleles (the loss of all other alleles) or their complete loss. This can lead to rapid changes in the genetic makeup of a population Mutation Accumulation: Inbreeding can lead to the accumulation of mutations. Mutations continuously arise in populations, but in outbred populations, these new mutations are often masked by the presence of functional alleles. Inbreeding, by increasing the expression of recessive and deleterious mutations, makes it more likely that these mutations will be exposed and either eliminated or, in rare cases, provide new adaptive variation.

Imagine two populations that are separated by a geographic barrier. In Population 1, allele frequencies at gene A are A = 0.2 and a = 0.8. In Population 2, allele frequencies at gene A are A = 0.8 and a = 0.2. Imagine that the geographic barrier that separates these two populations is removed and that individuals can now move freely between the two populations. What will likely happen to allele frequencies in each population over time?

Initial Allele Frequencies: Population 1 has allele frequencies of A = 0.2 and a = 0.8, while Population 2 has A = 0.8 and a = 0.2. Rate of Gene Flow: The rate at which individuals migrate between the populations influences the degree of gene flow. If migration is high, gene flow can rapidly equalize allele frequencies between the populations. Population Size: The size of the populations also plays a role. In smaller populations, the impact of gene flow may be more pronounced. Selection: Whether there are selective pressures favoring one allele over the other can affect the outcome. If one allele has a fitness advantage in one population, it may eventually dominate. Given the initial allele frequencies, if gene flow between the two populations is substantial and ongoing, over time, the allele frequencies in both populations are likely to become more similar. This is because gene flow tends to homogenize populations in terms of allele frequencies. In your scenario, as individuals move freely between the populations, the following might occur: Population 1 may experience an increase in the frequency of allele A (from 0.2) due to individuals from Population 2 carrying a high frequency of allele A (0.8) migrating into Population 1. Population 2 may experience a decrease in the frequency of allele A (from 0.8) due to individuals from Population 1 carrying a low frequency of allele A (0.2) migrating into Population 2. However, the extent and rate of change in allele frequencies will depend on the factors mentioned above, including the strength of selection, population sizes, and the number of migrants. If gene flow is very high, allele frequencies in both populations may eventually converge or become nearly identical.

What is the difference between intrasexual selection and intersexual selection?

Intrasexual selection and intersexual selection are two distinct mechanisms of sexual selection, which is a subset of natural selection that involves the evolution of traits related to an organism's ability to secure and reproduce with mates. These mechanisms operate through different dynamics and processes and can lead to the evolution of different types of traits. Here's how they differ: 1. Intrasexual Selection: Definition: Intrasexual selection, often referred to as male-male competition or female-female competition, occurs when members of one sex (usually males but not exclusively) compete with one another for access to mates. This competition can take various forms, such as combat, displays, vocalizations, or other behaviors aimed at outcompeting same-sex rivals. Mechanism: In this form of selection, individuals of the same sex typically compete directly with each other for the opportunity to mate with individuals of the opposite sex. The competition can be intense and can lead to the evolution of traits and behaviors that enhance an individual's ability to outcompete same-sex rivals. These traits are often referred to as "weapons" or "competitive traits." Outcome: Intrasexual selection often leads to the evolution of traits that improve an individual's competitive abilities, such as larger body size, weaponry (e.g., antlers in deer, tusks in elephants), or physical strength. These traits help individuals to outcompete rivals and gain access to mates. 2. Intersexual Selection: Definition: Intersexual selection, often referred to as female choice or mate choice, occurs when members of one sex (usually females but not exclusively) are choosy about their selection of mates, and the other sex (usually males) evolves traits and behaviors to attract and satisfy the preferences of the opposite sex. Mechanism: In this form of selection, the focus is on the preferences and choices of the opposite sex. One sex (typically females) assesses the quality of potential mates based on various traits or behaviors displayed by the other sex (typically males). The selection process involves mate preferences, courtship displays, and behaviors aimed at impressing potential mates. Outcome: Intersexual selection often leads to

What is the "fundamental asymmetry of sex"? How does this hypothesis help to explain why peacocks have large, extravagant trains but peahens do not?

It suggests that the potential reproductive success of males and females is often fundamentally different due to differences in the amount of parental investment and the limiting factor for reproduction. This concept helps explain various aspects of sexual dimorphism and mating behaviors in many species, including the extravagant plumage of peacocks and the more subdued appearance of peahens. Differing Reproductive Investment: In many species, including humans, females invest significantly more in reproduction than males. Female reproductive investment includes carrying and nourishing offspring during gestation (in species with internal fertilization) and nursing and caring for young after birth. Males typically invest less directly in offspring production. Variability in Reproductive Success: Because females typically have a limited number of reproductive opportunities (e.g., limited by the number of eggs they can produce), their reproductive success is more influenced by the quality of mates and the resources provided by those mates. In contrast, males can potentially achieve greater reproductive success by mating with multiple partners, as they can produce numerous sperm and have more opportunities to mate. This hypothesis helps explain the extravagant train of peacocks (Indian Peafowls) in the context of sexual selection. In the case of peacocks and peahens: Peacocks (Males): Peacocks have evolved large, colorful, and extravagant trains as a result of sexual selection. The peacock's train is a classic example of an extravagant secondary sexual trait that is costly to produce and maintain. These ornate displays, including the iridescent feathers and the extended train, are used by peacocks during courtship displays to attract peahens. The size, color, and quality of the train serve as indicators of the male's genetic quality, health, and ability to obtain resources. Because of the fundamental asymmetry of sex, males benefit from attracting multiple females and have evolved these ornate displays to enhance their mating success. Peahens (Females): Peahens do not possess such extravagant traits because they do not need to compete for the attention of males in the same way. They are more focused on selecting t

Are most mutations beneficial, neutral, or deleterious? Why?

Most mutations are neutral or deleterious, and only a relatively small fraction of mutations are beneficial. 1. Neutral Mutations: Frequency: Neutral mutations are the most common type of mutations. The majority of mutations have no noticeable effect on an organism's phenotype or fitness. Reason: Neutral mutations often occur in non-coding regions of the genome or in regions where changes in the DNA sequence do not result in significant changes to the protein structure or function. These mutations are "silent" in terms of their impact on the organism. 2. Deleterious Mutations: Frequency: Deleterious mutations are more common than beneficial mutations. Reason: Biological systems are finely tuned by natural selection. Most mutations that occur in functional genes or regulatory elements are likely to disrupt the structure or function of a protein or other biomolecule, leading to reduced fitness or even lethality. Natural selection acts to remove or minimize the impact of deleterious mutations, which is why they are less common in the population. 3. Beneficial Mutations: Frequency: Beneficial mutations are relatively rare compared to neutral and deleterious mutations. Reason: Beneficial mutations occur when a change in the DNA sequence results in an adaptation that enhances an organism's fitness in a specific environment. Such mutations are less likely to occur because they require specific changes that improve an organism's ability to survive and reproduce in a particular ecological context. It's important to note that the prevalence of these different mutation types is linked to the evolutionary concept of natural selection. Natural selection favors those mutations that enhance an organism's survival and reproduction, while it reduces the impact of deleterious mutations. Beneficial mutations are retained and accumulate over long periods, contributing to evolutionary changes.

Crossing over and independent assortment generate novel genetic variation. How does the process of mutation differ in the kind of genetic variation that it creates?

Mutation is a different process that introduces entirely new genetic variants. It is the primary source of new alleles in a population. Mutations can occur due to various factors, such as spontaneous errors during DNA replication, exposure to environmental mutagens, or other genetic changes. Mutations can result in base pair substitutions, deletions, insertions, or rearrangements of DNA sequences. These changes can create entirely new alleles, and if they occur in germ cells (sperm or egg cells), they can be passed on to the next generation. So, while crossing over and independent assortment lead to the recombination and reshuffling of existing genetic variants, mutation introduces entirely novel genetic variations by altering the DNA sequence. Mutations are the raw material for evolution, as they provide the genetic diversity on which natural selection can act, leading to the adaptation and evolution of species over time.

Non-random mating does what?

Non-random mating alters genotypes, By itself, non-random mating does not change allele frequencies over time However, it DOES result in alleles being distributed non-randomly within individuals Assortative mating occurs when individuals choose mates that are phenotypically similar to themselves 🡪 produces an excess of homozygotes Disassortative mating occurs when individuals choose mates that are phenotypically different from themselves 🡪 produces an excess of heterozygotes

Imagine a population of 20 self-fertilizing plants. We will examine genetic diversity in this population at a single gene (gene A), which contains two alleles (A and a). Five plants have genotype AA, 10 plants have genotype Aa, and five plants have genotype aa. Imagine that each plant simultaneously produces 10 offspring and then dies immediately following reproduction. If self-fertilization is the only reproductive mode available to members of this population, what will allele and genotype frequencies be in the grand offspring of the 20 individuals in the starting population? How do these allele and genotype frequencies compare to those in the original population? Has evolution occurred? ask

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what happens when previously isolated populations come back together?

Outcome 1: populations have diverged sufficiently that they cannot or do not interbreed successfully - reproductive isolation is complete!

Many diploid plant species have close relatives that are polyploid, suggesting that polyploidy is favored by natural selection when it appears. Why might polyploidy be advantageous over diploidy?

Polyploidy, the condition in which an organism has more than two complete sets of chromosomes, can offer several advantages over diploidy (having two sets of chromosomes), which is why it appears to be favored by natural selection in certain situations. Here are some reasons why polyploidy can be advantageous: Increased Genetic Diversity: Polyploidy instantly increases genetic diversity within a population because it combines the genetic material from multiple sets of chromosomes. This genetic diversity can provide the raw material for adaptation to changing environments and increase the evolutionary potential of the population. Masking of Deleterious Mutations: In diploid species, harmful recessive mutations can be hidden when they are in the heterozygous state. In a polyploid individual, these recessive mutations may become less detrimental because they are less likely to be present in a homozygous state. This can reduce the immediate negative effects of deleterious alleles. Enhanced Adaptability: Polyploids often have increased tolerance to environmental stressors, such as drought, extreme temperatures, and salinity. The multiple copies of genes in a polyploid genome can provide redundancy, allowing the organism to better withstand challenging conditions. Hybrid Vigor (Heterosis): Allopolyploids, which result from the hybridization of two different species, can exhibit hybrid vigor or heterosis. This means that they may outperform their diploid ancestors in terms of growth, yield, and fitness. Allopolyploids can combine the advantageous traits of both parental species. Reproductive Isolation: Polyploidy can lead to reproductive isolation from diploid progenitors. Polyploids may have different chromosome numbers and may not be able to successfully interbreed with diploid individuals, creating a reproductive barrier. This can lead to the formation of a new species. Resilience to Pathogens and Herbivores: Polyploids can exhibit increased resistance to pathogens and herbivores due to differences in the composition of secondary compounds or surface structures. This makes them less attractive or less vulnerable to pests. Enhanced Fertility and Seed Production: Some polyploids have improved fertility and seed pro

What are the steps for figuring out if alleles are in HWE?

Step 1: Calculate allele frequencies from observed genotype frequencies Step 2: Calculate expected genotype frequencies from allele frequencies Step 3: Compare expected and observed genotype frequencies If similar, conclude that population is in HWE if different, conclude that population is NOT in HWE 🡪 examine deviation from HWE expectations to determine why -> look in notebook

What happened when Thomas Hunt Morgan mated a red-eyed female Drosophila fly to a white-eyed male fly? Did he obtain the same result when he performed the reciprocal cross? What explains this pattern of results?

The F1 (first generation) offspring all had red eyes. This was expected because red eye color is the dominant trait. In the F2 (second generation) offspring, Morgan observed a surprising result. He found that all the females had red eyes, but approximately half of the males had red eyes, and the other half had white eyes. When Morgan performed the reciprocal cross by mating a white-eyed female fly to a red-eyed male fly, he obtained the same result. This pattern of results was consistent, whether he used red-eyed females or males as parents. The explanation for this pattern of results lies in the fact that the gene responsible for eye color in Drosophila (fruit flies) is located on the X chromosome. In this case, the gene for red eye color (wild-type allele) is dominant, and the gene for white eye color (mutant allele) is recessive. Here's how it works: Red-eyed females have two X chromosomes with the dominant red allele (X^R X^R) because they inherit one from each parent. Red-eyed males have only one X chromosome with the dominant red allele (X^R Y). White-eyed males have one X chromosome with the recessive white allele (X^w Y) because they inherit the X chromosome with the white allele from their mother and the Y chromosome from their father. When red-eyed females (X^R X^R) mate with white-eyed males (X^w Y), all the F1 offspring inherit one X chromosome from the mother (X^R or X^w) and one Y chromosome from the father. Since the Y chromosome does not carry the eye color gene, the male offspring will have either red eyes (X^R Y) if they inherit the X^R chromosome or white eyes (X^w Y) if they inherit the X^w chromosome. This pattern of sex-linked inheritance, where a trait is located on the sex chromosomes (in this case, the X chromosome) and is expressed differently in males and females, is known as sex-linked inheritance. It was one of the key discoveries made by Thomas Hunt Morgan and his colleagues in their studies of

How many species contribute to the genome of a species generated through autopolyploidy?How many species contribute to the genome of a species generated through allopolyploidy?

The number of species that contribute to the genome of a species generated through polyploidy can vary depending on the specific type of polyploidy: Autopolyploidy: In autopolyploidy, the extra sets of chromosomes come from within the same species or population. It involves the duplication of the entire genome of a single species. As a result, only one species contributes to the genome of the autopolyploid species. However, this species has multiple sets of chromosomes, often indicated as 2n, 3n, 4n, etc., reflecting the number of genome duplications that have occurred. Allopolyploidy: In allopolyploidy, the extra sets of chromosomes come from different, but often closely related, species. Allopolyploids are the result of hybridization between two or more distinct species, followed by chromosome doubling (polyploidization). Therefore, in allopolyploidy, two or more different species contribute to the genome of the allopolyploid species. The resulting genome is a combination of the genetic material from the parent species. So, to summarize: In autopolyploidy, one species contributes to the genome, but with multiple sets of chromosomes. In allopolyploidy, two or more species contribute to the genome of the allopolyploid species, leading to a combined genome with genetic material from multiple parent species.

Imagine that you have an individual with the genotype AaBbCc, where genes A, B, and C are all located on different chromosomes. In the diagrams below, please draw out the different ways that each type of gamete produced by this individual could be generated by drawing cells in various permutations of metaphase I, at the end of meiosis I, and at the end of meiosis II. Ignore crossing over for the time being. What genotypic ratio of gametes results?

To illustrate how the different types of gametes could be generated by an individual with the genotype AaBbCc, where genes A, B, and C are all located on different chromosomes, we can consider the segregation of alleles during meiosis. I'll provide a simplified representation of possible gamete combinations without considering crossing over. Remember that each gamete will carry one allele from each of the three genes (A, B, and C). Let's use "a," "b," and "c" to represent the different alleles: Metaphase I: At this stage, homologous chromosomes segregate, and allele combinations start to differ. Parental chromosome pairs: Aa, Bb, Cc (Homologous pairs) Metaphase I End of Meiosis I: After meiosis I, two daughter cells are formed, each with a unique combination of alleles. Daughter cell 1: ABc Daughter cell 2: AbC End of Meiosis I End of Meiosis II: Each of the two daughter cells from meiosis I undergoes meiosis II, resulting in four gametes. Gamete 1: ABc Gamete 2: AbC Gamete 3: aBc Gamete 4: abC End of Meiosis II The genotypic ratio of gametes produced by this individual is 1:1:1:1, meaning that each of the four possible combinations of alleles (ABc, AbC, aBc, and abC) is equally likely to be produced in the gametes. This assumes that there is no crossing over or genetic linkage between these genes, as indicated in your question. In reality, crossing over can lead to different combinations of alleles on the same chromosome, but it has been excluded from this illustration as per your request.

When Mendel applied pollen from a true-breeding round-seed pea plant to the female reproductive organs of a true-breeding wrinkled-seed pea plant, what did the offspring of this cross look like? Which of the hypotheses that you listed above did this result support?

When Gregor Mendel applied pollen from a true-breeding round-seed pea plant to the female reproductive organs of a true-breeding wrinkled-seed pea plant, the offspring of this cross all had round seeds. This result supported Mendel's hypothesis of dominance and recessiveness in the inheritance of traits. Mendel's experiments with pea plants led to the formulation of several hypotheses, and one of these hypotheses was that there are dominant and recessive traits. In this case, the round-seed trait was dominant over the wrinkled-seed trait. When he crossed a true-breeding round-seed plant (homozygous dominant) with a true-breeding wrinkled-seed plant (homozygous recessive), he observed that all the offspring had round seeds. This indicated that the dominant trait (round seeds) masked the expression of the recessive trait (wrinkled seeds) in the F1 generation, which supported his hypothesis of dominance.

vicariance biogeography hypothesis

ancestral ratite populations speciated into the current suite of species that we see today as different sectors of contiguous populations split apart on their respective landmasses and then diverged from one another in isolation -> phylogenetic tree is composed of the animals that live in the same areas

Assume that allele C (coding for copper eyes) is completely dominant to allele c (coding for silver eyes) and that allele D (coding for a short tail) is completely dominant to allele d (coding for a long tail). Consider a cross between two individuals with genotypes CcDD and ccDd. What proportion of their offspring are expected to have copper eyes and a short tail?

answer in note book

In many species of birds, males are colorful during the breeding season but molt into drab colors during the non-breeding season that more closely resemble the coloration worn by females all year long. Please explain this pattern in light of the Bateman-Trivers hypothesis and the idea of life-history trade-offs.

bateman t - It suggests that in many species, there are fundamental differences in the reproductive investment and potential reproductive success of males and females. This fundamental asymmetry of sex results from differences in gamete size and parental investment. Females typically invest more in reproduction due to their larger, energetically costly gametes (e.g., eggs) and their role in gestation, birthing, or incubation. Males generally invest less in offspring production because they produce small, energetically inexpensive gametes (e.g., sperm). As a result, the hypothesis predicts that males, which have greater potential to mate with multiple partners, will often exhibit extravagant or costly traits to attract females. In contrast, females, which are more selective in mate choice, tend to exhibit less extravagant traits. 2. Life-History Trade-offs: Life-history trade-offs refer to the allocation of limited resources (such as energy, time, and nutrients) to different aspects of an organism's life history, including growth, maintenance, reproduction, and survival. Organisms must make decisions about how to allocate these resources based on the trade-offs between these different aspects. Now, let's apply these concepts to the pattern of male birds being colorful during the breeding season and adopting drab colors during the non-breeding season: Breeding Season (Reproduction): During the breeding season, male birds need to attract and compete for mates to maximize their reproductive success. To achieve this, they often display colorful, extravagant plumage, vocalizations, and courtship behaviors. These traits are signals of their genetic fitness, health, and ability to provide resources for potential offspring. This investment in ornate traits aligns with the Bateman-T Drab Non-Breeding Plumage: After the breeding season, males molt into drab or inconspicuous plumage. This shift is related to life-history trade-offs. During the non-breeding season, there may be different selective pressures. Maintaining and displaying colorful plumage can be energetically costly and might make males more visible to predators. In contrast, during this time, males may need to allocate resources to other aspects of life, suc

What is ecological selection and how does it differ from sexual selection? (please note that both of these are forms of natural selection)

both ecological selection and sexual selection are forms of natural selection, but they differ in terms of the specific factors that drive them and the traits they target. Ecological selection is primarily concerned with survival and adaptation to the environment, while sexual selection is focused on traits and behaviors related to mate attraction and reproduction. Sexual selection is a specific type of natural selection that operates based on an individual's ability to obtain mates and successfully reproduce. It often involves traits that are not directly related to survival but play a role in attracting mates and competing with rivals of the same sex. Ecological selection, often referred to as natural selection, is the process by which environmental factors, including abiotic (non-living) and biotic (living) factors, influence the survival and reproductive success of individuals in a population. It favors traits that enhance an organism's ability to survive, find food, avoid predators, and successfully reproduce in a given ecological context.

Imagine that you are studying two traits in a species of lizard. The first trait, color, comes in two varieties: purple (P) and yellow (p), where purple is dominant to yellow. The second trait, dorsal pattern, also comes in two varieties: spots (S) and no spots (s), where having spots is dominant to not having spots. Imagine that you cross two individuals, both of the genotype, PpSs, that were themselves generated by crossing a true-breeding purple individual with spots and a true-breeding yellow individual without spots. This dihybrid cross generates offspring that exhibit the following phenotypes: Purple, spots: 460 individuals Purple, no spots: 100 individuals Yellow, no spots: 380 individuals Yellow, spots: 84 individuals Based on these results, are these two genes located on different chromosomes or on the same chromosome? How can you tell? ask

if the two genes are located on different chromosomes (unlinked), we would expect to see a 9:3:3:1 phenotypic ratio in the offspring. This ratio is the typical outcome of a dihybrid cross involving two unlinked genes. It means that for each trait (color and dorsal pattern), the genes segregate independently of each other, resulting in a 3:1 phenotypic ratio for each trait. However, the provided results do not match the 9:3:3:1 phenotypic ratio expected for unlinked genes: Purple, spots: 460 individuals (this matches one of the expected phenotypes). Purple, no spots: 100 individuals (this also matches one of the expected phenotypes). Yellow, no spots: 380 individuals (this does not match the expected 3:1 ratio for yellow individuals without spots). Yellow, spots: 84 individuals (this does not match the expected 3:1 ratio for yellow individuals with spots). The fact that the phenotypic ratios for both traits do not match the 3:1 ratio suggests that these two genes are not assorting independently on different chromosomes. Instead, it suggests that these two genes are linked, meaning they are located on the same chromosome. The non-Mendelian ratios are indicative of genetic linkage, which occurs when genes located close to each other on the same chromosome tend to be inherited together and do not segregate independently. In this case, the deviation from the expected 3:1 ratios for each trait indicates that the genes for color and dorsal pattern are linked, and their inheritance is not independent of each other. Linked genes are usually located on the same chromosome, and their patterns of inheritance deviate from the typical Mendelian ratios seen in unlinked genes.

how did ratite speciation happen?

initial common ancestor most likely flight capable bird, breaking up of gondwanaland resulted in isolation of various groups, flightlessness may have developed adaptation to large landmasses and absence of major predators that required them to be airborne for survival

law of independent assortment

means that we can examine multiple genes in the same way that we would examine a single gene - our Punnett square just gets bigger!

Please examine the pedigree below. What pattern of inheritance (autosomal dominant, autosomal recessive, X-linked dominant, or X-linked recessive) best describes this trait? How can you tell? (chapter 14 reading questions)

notebook

Red-green color blindness in humans is X-linked, where Xc (color blindness) is recessive to Xc+ (normal vision). Imagine that a female who is a heterozygous carrier of the color-blindness allele and a male with normal vision have a child. What is the likelihood that their child will be a son with normal vision?

notebook

Suppose both parents are carriers (heterozygous) for the mutant allele for PKU, phenylketonuria, a somatic metabolic disorder that can result in mental retardation. What is the chance that their first child will suffer from PKU (be homozygous recessive)? If their first child suffers from PKU, what is the chance that their next child will have PKU? If one in 4,000 individuals nationally suffer from PKU, what proportion of the population is expected to not carry any copies of the PKU allele under HWE?

notebook

Imagine that a couple whose respective blood types are AB and O have a child. What is the likelihood that their child will have Type AB blood?

notebook-> do we need to memorize what O blood type is? (ii) AB (I^AI^B)

The Morphospecies Concept defines species, pros and cons

on the basis of differences in size, shape, or other morphological features Pros: Easy to apply to wide range of organisms Cons: Subjective, may miss cryptic species, may split polymorphic species

The Phylogenetic Species Concept defines species pros and cons,

on the basis of monophyly Pros: Easy to apply to wide range of organisms Cons: Requires good phylogeny, may overestimate number of species

The Biological Species Concept defines species, pros and cons

on the basis of reproductive isolation, Pros: Clear criteria for defining species Cons: Difficult to apply to some populations

A gene with two alleles for ear size is present in cats (E and e.). E is completely dominant to e and produces large ears; homozygous recessives have small ears. If the frequency of ee = 0.25, what are the expected allele frequencies under Hardy-Weinberg assumptions? What are the expected frequencies of the homozygous dominant and heterozygous genotypes? What are the expected phenotypic frequencies?

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A gene with two alleles for height is present in corn (T and t.). T is completely dominant to t and produces a normal sized plant; homozygous recessives are very stunted in height. If the frequency of t = 0.3, what are the expected frequencies of the three genotypes under Hardy-Weinberg assumptions?

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Outcome 3 + example

populations interbreed successfully, but resulting offspring are inviable or infertile - reinforcement will occur, Mules are the product of a mating between a donkey and a horse - typically sterile

Outcome 2 + example

populations interbreed successfully; gene flow resumes and differences between populations are eliminated (fusion), In Norway, invasive vendace are outcompeting pelagic whitefish, forcing them into spaces occupied by littoral whitefish 🡪 interbreeding will likely lead to fusion of populations and extinction of pelagic ecomorph

In phalaropes, females are territorial and mate serially with a number of different males, who they then provide with a clutch of eggs. Each male incubates and cares for the clutch of eggs provided to him without any help from the female (females leave for migration shortly after laying all clutches). Please examine the photograph below. Which individual is the male and which is the female? Please explain your answer.

right -> fundamental asymmetry of sex (life history trade off)