Molecular Clock and Natural Selection

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Questions and Answers

What does the Red Queen Hypothesis explain about species in an environment?

The environment does not affect the evolution of species.

Species become extinct if they do not evolve quickly enough.

Species must adapt continuously due to the evolving nature of other species. (correct)

Species evolve independently without influence from one another.

What is a consequence of negative assortative mating?

It can enhance genetic diversity through increased heterozygosity. (correct)

It reduces the overall genetic diversity in a population.

It increases the likelihood of inheriting harmful recessive genes.

It can lead to increased homozygosity in a population.

What are the main risks associated with inbreeding?

Higher likelihood of genetic disorders and reduced fertility. (correct)

Decreased likelihood of inheriting dominant traits.

Increase in genetic diversity and reproductive success.

Enhanced fitness of the population.

What is the role of female spotted sandpipers during the breeding season?

They compete for males and lay multiple clutches. Signup and view all the answers

Which of the following diseases is caused by pathogenic spirochete bacteria?

Syphilis Signup and view all the answers

What is a distinguishing feature of the fungi kingdom compared to animals?

They digest food extracellularly. Signup and view all the answers

Which of the following diseases is primarily caused by a unicellular fungus?

Candidiasis. Signup and view all the answers

In the lifecycle of Plasmodium falciparum, which stage occurs after the sporozoites enter the vertebrate bloodstream?

They invade the liver. Signup and view all the answers

What type of reproduction is predominant in the life cycle of Plasmodium falciparum within the vertebrate host?

Asexual reproduction. Signup and view all the answers

How do fungi primarily obtain their nutrients?

By digesting food extracellularly. Signup and view all the answers

Which statement reflects a characteristic of the domain of Archaea?

They contain histones, similar to eukaryotes. Signup and view all the answers

What trait distinguishes fungi from plants?

Cell walls made of chitin. Signup and view all the answers

Which is true regarding the evolutionary relationship of fungi?

Molecular evidence places fungi in a clade closer to animals than plants. Signup and view all the answers

What is directional selection in natural selection?

It favors one extreme phenotype within a population. Signup and view all the answers

How does kin selection influence evolutionary processes?

By sacrificing individual fitness for the benefit of relatives. Signup and view all the answers

What is altruism in the context of kin selection?

Behaviors that benefit others at a cost to oneself. Signup and view all the answers

What threat do selfish mutants pose in altruistic groups?

They can exploit altruists for their own benefit. Signup and view all the answers

Which of the following describes Batesian mimicry?

Non-venomous species mimic the appearance of venomous species. Signup and view all the answers

What potential issue arises from altruism within a group?

It is undermined by selfish individuals who do not contribute. Signup and view all the answers

What is a consequence of having both altruists and selfish mutants in a population?

Selfish behavior can ultimately replace altruism. Signup and view all the answers

Which behavior is an example of altruism in social insects?

Guarding the queen while not reproducing. Signup and view all the answers

Study Notes

Molecular Clock

A figurative clock used to measure evolutionary time
Measures random neutral mutations in DNA at a constant, predictable rate
Neutral mutations are not selected for or against in natural selection
Organisms that diverged recently have fewer nucleotide differences
Organisms that diverged long ago have many nucleotide differences

What is a Molecular Clock?

A method to estimate when lineages diverged from a common ancestor
Based on the assumption that mutations accumulate at a constant rate in DNA
Used to date evolutionary events (e.g., the divergence of species)
Can be used to measure evolutionary time

Natural Selection

The process by which organisms better adapted to their environment are more likely to survive and reproduce, passing advantageous traits to future generations.
Natural selection is not perfection, but rather favors traits that improve reproductive success
Natural selection in nature involves competition for resources, and this can lead to conflict and cooperation, depending on ecological context. It does not create harmony or justify human actions.

Types of Natural Selection

Stabilizing Selection: Favors average traits; individuals with average or moderate traits are more likely to survive and reproduce.
Examples: Human babies of intermediate birth weight have higher survival rates compared to very small or very large babies; nesting birds.
Diversifying Selection: Favors multiple extreme phenotypes and leads to increased genetic diversity in a population.
Examples: Gray and Himalayan rabbits; color in peppered moths
Directional Selection: Favors one extreme phenotype, causing the population to shift in that direction.
Examples: Light-colored peppered moths are more common when the environment is pristine, but dark-colored peppered moths are better camouflaged against a sooty environment; Industrial melanism
Kin Selection: A natural selection process that favors traits that help an organism's relatives reproduce, even if it means the organism sacrifices its own survival and reproduction.
Traits include helping relatives, sharing food, and defending relatives.
This can lead to altruism, in which individuals act in ways that benefit others at a cost to themselves to benefit relatives; social insects like ants, bees, wasps, and termites

Founder Effect

A phenomenon that occurs when a small group of individuals from a larger population establishes a new population
The new population's gene pool is a smaller and potentially different representation of the initial pool.
This can lead to higher or lower concentrations of genetic mutations that cause otherwise rare diseases
Examples: Eastern Pennsylvania Amish/ Old Order Amish; Sephardic Jews in Ecuador

Asexual vs. Sexual Reproduction

Asexual reproduction is more advantageous in stable environments without competitors or predators.
It allows for quick population growth without the need to find a mate and produces offspring with the same genetic makeup as the parent
Reproduction is efficient in stable environments where finding mates is difficult.

Positive vs. Negative Assortative Mating

Positive Assortative Mating: Individuals choose to mate with similar individuals based on physical characteristics or genotype. This can increase homozygosity.
Negative (Disassortative) Assortative Mating: Individuals choose to mate with dissimilar individuals. This can increase heterozygosity.

Inbreeding

Inbreeding occurs when two closely related individuals mate and have offspring.
It significantly increases the likelihood of the offspring inheriting harmful recessive genes which are more common in a small population..
Higher risks of genetic disorders, reduced fertility, and reduced genetic diversity.
Inbreeding depression describes the overall reduced fitness in a population.

Spirochetes Bacteria

Pathogenic species cause human diseases such as syphilis, Lyme disease, and periodontal disease.

Polyandry in the Spotted Sandpiper

Sandpipers can be found in the Arctic and subarctic regions.
The spotted sandpiper has invaded temperate climates, allowing for a longer breeding season; early breeding season.
Females arrive at breeding grounds before males and compete for them.
A female lays multiple clutches with different males, and each male incubates the eggs and care for the young.

The Red Queen Hypothesis

Species are locked in a coevolutionary arms race.
Adaptations in one species drive the evolution of counter-adaptations in another.
Continuous cycle of adaptation to stay alive, keep up with competitors and predators.
Sexual reproduction is advantageous—leads to greater genetic diversity that makes it harder for parasites or predators to adapt to a single host genotype

Who are the Fungi?

A major branch of Eukarya;
They have cell walls containing chitin.
Heterotrophs- digest food extracellularly; absorb it
Most are multicellular, but some have reverted to unicellular forms (yeasts)
Many ecological associations, including decomposers, parasites, mutualists, and commensals.

Land Plants

They use chlorophyll a and b
These include Bryophytes (liverworts, mosses, hornworts), Seedless vascular plants (ferns, horsetails), Gymnosperms (conifers). Angiosperms (flowering plants)..
They typically reproduce through spores or seeds, and have various adaptations for survival in different environments, including damp or arid environments.

Protostome vs. Deuterostome

Protostomes: First opening is the mouth in embryo development
Deuterostomes: First opening is the anus in embryo development; a later opening will lead to the formation of the mouth
This is a crucial distinction in animal phylogeny

Higher Level Taxonomic Branches

Higher level taxonomic diversity within species reflects an important concept
Represents a loss of diversity among species within a larger group like an order, or class and this is important due to the loss of species in a genus, order, class and so on.
For example, if the tuatara disappears, then a whole class of reptiles will disappear too; an entire branch on the tree of life will be lost.

What are the largest groups of animals on Earth?

The Ecdysozoa are a remarkably large group among all animals.
This group includes arthropods (insects, crustaceans, and spiders) and nematodes.
It contains a large portion of all known species on Earth.

Whale Watching

Whale watching generates significant revenue
Whales act as ecosystem engineers, playing an important role in nutrient cycling and fertilizing the water.
Tourism brings more revenue than whaling; which is environmentally detrimental.

Ecosystem Services

Ecosystem services are the direct and indirect benefits humans receive from ecosystems. Supporting: Nutrient cycling (water and soil), photosynthesis. Provisioning: Food, fresh water, fiber, biomass fuel, and medicine. Regulating: Air quality, water runoff, , climate, natural hazards. Cultural: Existence, ethical and recreation values, ecotourism

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Description

Explore the concepts of molecular clocks and natural selection in this quiz. Understand how molecular clocks estimate evolutionary time and the role of natural selection in shaping species. Test your knowledge on mutations, lineage divergence, and the implications of evolutionary mechanisms.