5.2 & 10.3, Natural selection & Speciation

Recombination

(genetics) a combining of genes or characters different from what they were in the parents

Charles Darwin

-Evolution by "natural selection" (the weaker die out) wrote On the Origin of Species the "father" or popularizer of the theory of evolution and the theory of natural selection

genetic drift

A change in the gene pool of a population due to chance A change in the allele frequency of a population as a result of chance events rather than natural selection.

Polyploidy

A chromosomal alteration in which the organism possesses more than two complete chromosome sets. In plants, the result of an extra set of chromosomes during cell division.

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Gradualism

A proposed explanation in evolutionary biology stating that new species arise from the result of slight modifications (mutations and resulting phenotypic changes) over many generations. Big changes occur by the accumulation of many small ones. Continuous change over a long period of time Slow Gradual accumulation of mutations / variations LIMITATION:

prezygotic barriers

A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted Barriers that impede mating or hinder fertilization.

Adaptations are characteristics that make an individual suited to its environment and way of life

Adaptations are characteristics that make an individual suited to its environment and way of life. ... Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring. Individuals that reproduce pass on characteristics to their offspring.

Allele

An alternative form of a gene.

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species evolution from a common ancestor of many species adapted to diverse environments

Contrast acquired characteristics with inheritable characteristics

An inherited characteristic is controlled by genes and can be passed on to offspring, while an acquired trait is developed or acquired during an organism's lifetime and cannot be passed on to offspring.

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits. the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Explain how natural selection leads to changes in antibiotic resistance

Antibiotic resistance is a consequence of evolution via natural selection. The antibiotic action is an environmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspring, which will be a fully resistant generation.

Compare the reproductive success of better and less well-adapted individuals in a population

Better adapted individuals survive and are able to reproduce to pass on the adapted characteristic to their offspring. ... Better adapted individuals survive and reproduce, increasing the frequency of the adapted trait over time.

List examples of adaptations

Camouflage, mimicry, and animals' body parts and coverings are physical adaptations. The way in which an animal behaves is an adaptation, too—a behavioral adaptation . Behaviors that animals are born knowing how to do are instincts . A lion preying upon a zebra and a bird building a nest are examples of instincts.

gene pool

Combined genetic information of all the members of a particular population

Selection pressures that lead to natural selection

Competition for space, food, mates, increased predation, disease, parasitism

Contrast discrete with continuous variation

Discrete variation is either/or and is often caused by the presence or absence of a small number if genes. ... Height is a good example of continuous variation. There are a wide range of different heights and if you look around your class it is unlikely that any two individuals are exactly the same height.

Explain the effect of the selective pressure on the more and less adapted individuals in a population

Due to the variation in the population, some individuals are better adapted and able to survive and reproduce in the presence of the selective pressure while the less adapted do not survive and reproduce as successfully. This leads to a shift in population — more individuals with the adaptation.

Define stabilizing, disruptive and directional selection

Each type of selection contains the same principles, but is slightly different. Disruptive selection favors both extreme phenotypes, different from one extreme in directional selection. Stabilizing selection favors the middle phenotype, causing the decline in variation in a population over time.

List examples of selective pressures

Examples of selective pressures include competition, predation, land clearance, pollutants, diseases and illnesses, climate change and parasitism. A famous example of selective pressure is the long neck and legs of giraffes.

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population. A change in allele frequency following a dramatic reduction in the size of a population

founder effect

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population. change in allele frequencies as a result of the migration of a small subgroup of a population

List the sources of genetic variation in sexually reproducing organisms.

Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

Species definition

Group of Organisms with a unique set of characteristics that distinguish them from all other organisms

State an example of a continuous variation

Height is an example of continuous variation - individuals can have a complete range of heights, for example, 1.6, 1.61, 1.62, 1.625 etc metres high. Continuous variation is the combined effect of many genes (known as polygenic inheritance) and is often significantly affected by environmental influences.

Individuals surviving

Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.

Individuals that reproduce pass on characteristics to their offspring

Individuals that reproduce pass on characteristics to their offspring. Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.

Process of natural selection

Inherited variation Competition due to overproduction Selection Adaptation or differential reproductive success Microevolution Macroevolution

gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population

Mutation, meiosis and sexual reproduction cause variation between individuals in a species

Mutation, meiosis and sexual reproduction cause variation between individuals in a species. ... Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring. Individuals that reproduce pass on characteristics to their offspring.

When can natural selection occur?

Natural selection can only occur if there is variation among members of the same species

Natural selection

Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species

Explain why natural selection can only function if there is variation in a species

Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.

Overproduction of offspring

Organisms produce more offspring than needed to sustain the population.

Use an example to illustrate the potential for overproduction of offspring in a population

Over the course of their lifetime, species have the ability to produce far more offspring than the environmental resources (food/water/shelter) can support. Eg: An example of overproduction is sea turtles, which can lay up tp 100 eggs in a clutch with only about 1 hatching and surviving to reproduce.

Evolution of antibiotic resistance in bacteria

Over time bacteria has become more resistant to antibiotics. There is variation in the bacteria so some will be resistant to antibiotics but some will not be, and some will be resistant to some antibiotics but others won't be. So because some bacteria will have the gene and become resistant to the specific antibiotic while others will lack the gene and so will die if exposed to the antibiotic. Over time, the non-resistant ones will all die off as doctors vaccinate patients, but the resistant ones will survive. Eventually, the resistant ones will be the only ones left as a result of natural selection and so a new antibiotic must be created. Antibiotic resistance can be increased if you don't complete the antibiotics then there is other bacteria that can uptake the antibiotic resistance plasmids or if you take antibiotics when you don't need them

Outline the role of Charles Darwin and Peter and Rosemary Grant in the study of Galapagos finches

Peter and Rosemary Grant have seen evolution happen over the course of just two years. The Grants study the evolution of Darwin's finches on the Galapagos Islands. The birds have been named for Darwin, in part, because he later theorized that the 13 distinct species were all descendants of a common ancestor.

Species are formed through a two-step process:

Populations become genetically isolated from each other.

punctuated equilibrium

Punctuated Equilibrium Species diverge in spurts of relatively rapid change Long periods of stability followed by sudden changes ("sudden change" may be thousands of years on the vast scale of geological time). Fossil record supports this Rapid evolution due to major environmental changes / volcanic eruptions / meteor impact Natural selection in the new environment can be intense and can cause rapid change, as only advantageous alleles ultimately survive the hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change.

Progressive natural selection and adaptation can lead to speciation

Speciation

pace of evolution

Speciation sometimes requires millions of years, but some species can form more rapidly. There are two main ideas about the pace of evolution: Evolution is a slow process. Many ideas about evolution are supported by FOSSIL RECORDS, however these are often INCOMPLETE.

biological species concept

Species is a group of populations whose members have the potential to produce fertile offspring.

Species

Species tend to produce more offspring than the environment can support Species have the ability to produce more offspring than the environment can support

List reasons why evolution of antibiotic resistance has been rapid

The antibiotic resistance crisis has been attributed to the overuse and misuse of these medications (in humans and agricultural applications) as well as a lack of new drug development by the pharmaceutical industry.

Define variation

The difference in the physical traits of an individual from those of other individuals in the group to which it belongs

sympatric speciation

The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present.

allopatric speciation

The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier. The formation of new species in populations that are geographically isolated from one another.

Example formation of a polyploid

The genus Allium includes onion, garlic, chives, scallion, shallot and leek. In many of these species of plants, polyploidy has created a large number of phenotypes and chromosome numbers. This results in a number of reproductively isolated but similar species.

Explain the cause of the change in frequency of traits in a population through natural selection

The more offspring an organism can produce, the higher its fitness. As novel traits and behaviors arise from mutation, natural selection perpetuates the traits that confer a benefit. Mutation and natural selection: As mutations create variation, natural selection affects the frequency of that trait in a population.

State an example of a discrete variation

Variation between individuals of a species can be grouped into two large categories: discrete and continuous. Discrete variation is either/or and is often caused by the presence or absence of a small number if genes. For example, our ability to "roll" our tongues is determined by just one gene.

Variations can be discrete or continuous

Variation between individuals of a species can be grouped into two large categories: discrete and continuous. Discrete variation is either/or and is often caused by the presence or absence of a small number if genes. For example, our ability to "roll" our tongues is determined by just one gene.

State that only inherited characteristics can be acted upon by natural selection

While acquired characteristics are often important and aid in survival, they are not acted on by natural selection. Only inherited characteristics can be acted upon by natural selection. Outline how a "selective pressure" acts on the variation in a population. List examples of "selective pressures."

What is a species?

a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.

Mutation

a random error in gene replication that leads to a change

adaptation or adaptive trait

any heritable trait that enables an individual organism to survive through natural selection and to reproduce more than other individuals under prevailing environmental conditions

Define adaptation

any inherited characteristic that increases an organism's chance of survival

limitations of biological species concept

cannot be applied to fossils or asexual organisms, emphasizes absence of gene flow Extinct species Asexual reproducing species Hybrids

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

Temporal Isolation

form of reproductive isolation in which two populations reproduce at different times

Fitness of organism

organism is a better competitor, able to contribute to the next generation's gene pool

postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown Barriers that prevent the hybrid zygote from becoming a fertile adult.

Speciation definition

the formation of new and distinct species in the course of evolution.

Use theories to explain natural phenomena

the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria