Natural Selection, Evolution, Organism Relationships, Species Interactions, and More

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Biological evolution

Change in a population's gene pool over time, leads to changes in frequency of appearance/behavior from generation to generation.

Gene pool

All of the genes present in a population.

Genes

Control pattern and color (of eg. fish scales).

Mutation

Changes in DNA that give rise to genetic variation, such as a mutation in sperm/egg cell that may be passed to the next generation.

Migration

Population change due to immigration or emigration that causes a change in the proportion of traits in the gene pool.

Genetic drift

An unusual event (natural disaster or fishing net) that kills/separates all but a few individuals, resulting in a different gene pool for the next generation.

Natural selection

The process where certain traits become more or less common in a population due to the survival and reproduction of individuals with those traits.

Conditions of natural selection

Factors that explain patterns seen in nature, including the relationship between organisms and their environment.

Condition 1 of natural selection

Organisms produce more offspring than can survive, leading to a struggle for existence due to limiting factors.

Condition 2 of natural selection

Individuals of a species vary in their characteristics, with variations being heritable if passed from parent to offspring.

Condition 3 of natural selection

Individuals vary in fitness, where variations can be harmful or helpful, affecting survival and reproduction.

Survival of the fittest

High fitness individuals produce more offspring and pass genes more frequently than low fitness individuals.

Fitness

Defined in context of environment, can change based on conditions, and traits that are adaptive may vary by location or season.

Artificial selection

Results of natural selection visible in adaptations, where humans breed organisms for desirable traits.

Artificial selection with dogs

Diverse dog breeds are variations on a single species, with any two dogs able to interbreed and produce offspring.

Artificial selection with agriculture

Most crop plants for food are based on artificial selection, resulting in diversified single plant species into many different crops.

Example of biological evolution

40% brown mice and 60% tan mice → 28% brown mice and 72% tan mice.

FOUR PRIMARY MECHANISMS/PROCESSES

Mutation, migration, genetic drift, natural selection.

Darwin's publication

In 1859, Charles Darwin published 'On the Origin of Species', providing decades of scientific evidence for natural selection.

Limiting factors

Restrictions that prevent all individuals in a population from reproducing to their full biotic potential.

Heritable variations

Variations among organisms that are due to differences in genes/environments and can be passed from parent to offspring.

High fitness individual

An individual that produces more offspring and passes genes more frequently than low fitness individuals.

Adaptive traits

Traits that maximize success in a given environment, which may change based on location and conditions.

Selective breeding

The process where humans choose and breed animals or plants with desirable traits.

Broccoli, cabbage, brussel sprouts, cauliflower

From Brassica oleracea

SPECIATION/EXTINCTION

Reason why Earth has many species, estimated all species today are a tiny fraction of those that have ever lived

SPECIATION

Occurs in many ways, speciation caused by geographic separation of populations = most important (allopatric speciation)

Allopatric speciation

Speciation caused by geographic separation of populations

Genetic divergence

Occurs when mutations in DNA of an organism in one isolated population cannot spread to other populations

Long-term geographic isolation

Can lead to allopatric speciation and can happen in many ways (e.g., glacial ice sheets moving across continents, rivers changing, dry climate partially evaporating lakes)

Isolation process

Must be long (generally thousands of generations) for speciation to happen

Speciation process

One species is separated into groups and those mutations in each individual group cannot mix with the others

EXTINCTION

About 99% of all species that ever lived are gone, average time a species spends on Earth is 1-10 million years

Background extinction rate

Rate at which extinction occurs gradually, one species at a time

MASS EXTINCTIONS

5 events of large proportions that killed off a huge number of species at once

Best-known mass extinction

Happened 65 million years ago (ended dinosaurs and others)

Evolution

As a general term, means 'change over time'

Gene

A sequence of DNA that codes for a particular trait

Mutation

Changes in DNA

Genetic drift

Biological evolution that occurs by chance

Natural selection

The process by which traits that improve an organism's chances for survival and reproduction

Fitness

Reproductively successful an organism is in its environment

Adaptation

A heritable trait that increases an individual's fitness

Artificial selection

The process of selection conducted under human direction

Extinction

The disappearance of a species from Earth

Natural selection and environment

The connection between natural selection and the environment, as the environment allows organisms with the best adaptations to live, reproduce, and grow the most

Ecologist's consideration

Must consider both speciation and extinction because each contributes to analyzing the diversity of life on Earth

Speciation's effect

New species slowly form over time and increase the total number of species

Organism's habitat

describes the general place it lives

Niche

habitat where organism lives, food it eats, how/when it reproduces, other organisms it interacts with, summary of everything an organism does and when/where it does it

Specialist

extremely good at certain things but struggle to adapt in changing conditions

Generalist

able to live in many places but not as successful in a given situation

Intraspecific competition

multiple organisms of the same species seek the same limited resources

Interspecific competition

multiple organisms of different species seek the same limited resources

Competitive exclusion

very effective competitive species may exclude another species from same resource use entirely

Fundamental niche

full niche of a species

Realized niche

a niche restricted by competition

Resource partitioning

competing species may evolve to occupy only realized niche, adapt to competition by using slightly different resources or shared resources in different ways

Character displacement

resource partitioning leads to evolution of physical traits that reflect their specialized role

Predation

predator hunts/captures/kills/consumes another organism (different species) or the prey

Predator/prey interaction

influences community structure, determines relative numbers of predators/prey

Population cycles

Increase in prey population leads to more food, survival, reproduction for predator; predator population rise leads to lower prey population

Natural selection

process where predators better at getting prey are more successful, leading to evolution of adaptations

Co-evolution

a change in one species leads to changes in the other species in a predator-prey relationship

Herbivory

interaction where herbivores consume plants, affecting plant populations

Parasitism

relationship where one organism benefits at the expense of another

Competition relationship

(-/-) relationship, harmful and beneficial for one and the other (+/-)

Parasitism

A relationship in which one organism, the parasite, depends on another, the host, for nourishment or some other benefit.

Symbiosis

A long-lasting and physically close relationship in which at least one organism benefits.

Herbivory

The interaction in which an animal feeds on a plant.

Mutualism

A relationship in which two or more species benefit.

Commensalism

A relationship in which one species benefits and the other is unaffected.

Niche

Describes its use of resources and its functional role in a community.

Tolerance

The ability to survive and reproduce under changing environmental conditions.

Resource partitioning

The species partition, or divide the resource they use in coming by specializing in different ways.

Predation

The process by which an individual of one species, a predator, hunts, captures, kills, and consumes an individual of another species, the prey.

Coevolution

The process by which two species evolve in response to changes in each other.

Competition

When multiple species compete with each other for the exact same resources, they may adapt to competition by using different resources or using them in different ways.

Realized niche

A portion of the resources that a species can use, limited by competition.

Arms race

A kind of coevolution where each species develops stronger and stronger 'weapons' in response to each other.

Natural selection

The process that does not produce adaptation for a purpose but enables organisms to better survive/reproduce in their environments.

Pollination

An important mutual relationship where bees, birds, bats, and butterflies transfer pollen from flower to flower, fertilizing eggs and providing food.

Mycorrhizae

Symbiotic associations formed between plant roots and fungi, where the plant provides energy and protection while the fungus assists in nutrient absorption.

Ticks

An example of a parasite that attaches to a host's skin, benefiting while harming the host.

Plant defenses

Natural selection leads to the development of defenses against herbivores, such as toxic chemicals, thorns, spines, and irritating hairs.

African moths

An example of a coevolving species with orchid flowers, where the moth's proboscis is adapted to reach the nectar.

Bacteria and human digestive tract

An example of a mutual species interaction where bacteria help digest food, benefiting humans, while also receiving nutrients.

Effect on Species A

The impact of an interaction on the first species involved.

Effect on Species B

The impact of an interaction on the second species involved.

Interaction

The type of relationship between two species, such as commensalism, competition, herbivory, mutualism, parasitism, or predation.

Predator

An individual of one species that hunts, captures, kills, and consumes an individual of another species.

Prey

An individual of another species that is hunted, captured, killed, and consumed by a predator.