biology exam 1 natural selection

Do individuals evolve?

(No, populations evolve! Evolution is the change in allele frequencies within a population)

Intersexual selection

(typically female choice)-typically the males will display a certain trait or behavior with the goal of attracting and mating with the opposite sex

what are the steps to natural selection?

1 Overproduction. An organism produces more offspring than can survive to maturity Ex. ... 2 Genetic Variation. the offspring will have some variation (differences) in appearance or behaviors. ... 3 Struggle to Survive. ... 4 Successful Reproduction.

Gene pool

A gene pool is the total genetic diversity found within a population or a species

Gene

A segment of DNA on a chromosome that codes for a specific trait

How does artificial selection relate to natural selection?

Artificial selection is distinct from natural selection in that it describes selection applied by humans in order to produce genetic change. When artificial selection is imposed, the trait or traits being selected are known, whereas with natural selection they have to be inferred.

Populations contain heritable variation and great potential to increase in size

But, because resources are limited, populations don't tend to increase

Is natural selection random?

Evolution is not a random process. The genetic variation on which natural selectionacts may occur randomly, but natural selection itself is not random at all. The survival and reproductive success of an individual is directly related to the ways its inherited traits function in the context of its local environment.

Locus

Location of a gene on a chromosome

Why aren't new antibiotics being rapidly developed?

New antibiotics are seen as 'drugs of last resort' against dangerous bacteria. So, to limit the development of antibiotic resistance, they need to be used sparingly - and not sold in large volumes. Plus, compared to more expensive treatments, antibioticstend to be quite low in price.

if an insect is sprayed with a pesticide, does natural selection cause it to become resistant? (NO!) How does it work, then?

Subsequent uses of the pesticide increase the proportion of less-susceptible individuals in the population. Through this process of selection, the population gradually develops resistance to the pesticide.

What is gene flow and how does it affect variation among populations?

The introduction of new alleles through gene flow increases variability within the population and makes possible new combinations of traits.

How does gene flow impact speciation?

When gene flow is blocked by physical barriers, this results in Allopatric speciation or a geographical isolation that does not allow populations of the same species to exchange genetic material.

What would life be like without antibiotics?

Without new antibiotics, common infections and minor injuries could become life-threatening and major surgeries and chemotherapy impossible because the treatments we have been using for years are no longer effective

Evolution

a change in allele frequencies in a population from generation to generation

Bottleneck effect

a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts or human activities such as specicide and human population planning.

How quickly does Antibiotic resistance evolve? Is it inevitable?

about 4 years and yes its is inevitable

If a characteristic is "adaptive" (good for survival and reproduction) in one environment, is it adaptive in other environments or when the environment changes?

adaptive evolution

Heterozygote advantage

describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype. The specific case of heterozygote advantage due to a single locus is known as overdominance.

directional selection

directional selection, or positive selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype

Why do medical doctors need to understand evolution?

doctors need to understand the evolution of antibiotic resistance, methods for tracing pathogen phylogenies, how selection shaped mechanisms that regulate protective responses such as pain and fever, and the intimate connections between evolution, environment, and diseases of aging.

Frequency-dependent selection

evolutionary process by which the fitness of a phenotype or genotype depends on the phenotype or genotype composition of a given population. In positive frequency-dependent selection, the fitness of a phenotype or genotype increases as it becomes more common.

How does natural selection work?

genetic mutations that are beneficial to an individual's survival are passed on through reproduction. This results in a new generation of organisms that are more likely to survive to reproduce. ... The process carries on generation after generation.

Sickle cell anemia and malaria

individuals who are carriers for the sickle cell disease (with one sickle gene and one normal hemoglobin gene, also known as sickle cell trait) have some protective advantage against malaria. As a result, the frequencies of sickle cellcarriers are high in malaria-endemic areas.

stabllizing selection

is a descriptive term for what happens to an individual trait when the extremes of the trait are selected against. This increases the frequency of the trait in the population, and the alleles and genes which help form it.

Sexual dimorphism

is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and some plants.

Natural Selection

main mechanism for how adaptive characteristics evolve

Gene Flow

migrants carrying alleles into and out of a population-Increasing gene flow decreases differences among populations

Does Natural selection lead to perfection? Why not?

natural selection is not all-powerful; it does not produce perfection. ... The population or individual does not "want" or "try" to evolve, and natural selectioncannot try to supply what an organism "needs." Natural selection just selects among whatever variations exist in the population. The result is evolution.

Five mechanisms of evolution

natural selection, mutation, genetic drift, and migration (gene flow).

Sexual selection

non-random mating- is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection).

allele

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Natural Selection

organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.

Adaptive evolution

pertains to evolutionary changes in an organism that make it suitable to its habitat. The changes result in an increased chance of survival and reproduction. The changes enable the particular organism to fit to an environment.

What are some of the causes of antibiotic resistance?

routine use, mutations and antibiotic foods

diruptive selection

selects against the average individual in a population. The makeup of this type of population would show phenotypes (individuals with groups of traits) of both extremes but have very few individuals in the middle.

Non-random Mating - sexual selection

sexual selection

Genetic drift

small population size; random changes in allele frequencies.

What can farmers do?

stop giving the animals antibiotics

What can patients do?

stop pretening to be sick!

What can doctors do to slow the process?

stop proscribing antibiotics as often

allele Frequencies

the number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene

Founder effect

the reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors.

What does it mean to be in HW equilibrium? What are the conditions for HW equilibrium?

to identify evolution and understad how it changes from generations, if itdoesnt add up to 100 then evolution has occurred

Intrasexual selection

typically male-male competetion- intrasexual selection refers to competition with members of the same sex.

Intersexual selection

typically means "female choice" of a mate

Intrasexual selection

typically means "male-male competition" for access to females

Mutation

ultimate source of new alleles (characteristics)

When does evolution happen?

when these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift.