Mastering Evolution: Male Redback Spiders' Behavior

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Questions and Answers

What is a vestigial structure?

A feature that is adaptive for the organism's ancestor and still functional

A feature that was adaptive for the organism's ancestor but evolved to be non-functional (correct)

A feature that has no connection to the organism's ancestor

A new feature that enhances the organism's survival

What does echolocation in bats help them do?

Evade predators

Catch insects (correct)

Survive in extreme temperatures

Mimic leaves

Which of the following is NOT mentioned as an adaptation in the text?

Presence of eyes in fish living in dark caves (correct)

Production of toxins by creosote bush

Mimicry of leaves by insects

Echolocation in bats

Which of the following is described as reducing competition for nutrients and water?

Production of toxins by creosote bush Signup and view all the answers

What is a behavior that might be considered an adaptation?

Mimicking leaves to evade predators Signup and view all the answers

Why did fish living in dark caves end up with nonfunctional eyes?

There was no longer natural selection to maintain eye function in dark environments Signup and view all the answers

Why is sexual selection considered powerful?

Individuals who don't produce offspring don't pass on their genes. Signup and view all the answers

In sexual selection, what happens to an individual who lives long but doesn't produce offspring?

Their fitness is zero as their genes are not passed on. Signup and view all the answers

How does male competition play a role in sexual selection?

Males compete for access to females and fertilization of eggs. Signup and view all the answers

What is a common behavior in male damselflies during mating?

They scrub rival sperm out of the female reproductive tract. Signup and view all the answers

Why is it important for individuals to leave behind offspring in terms of gene transmission?

Not having offspring is detrimental as it results in no gene transmission. Signup and view all the answers

What factor did Maydianne focus on in relation to the male redback spiders' mating behavior?

Paternity Signup and view all the answers

What is the median mating duration for second males that are not cannibalized?

11 minutes Signup and view all the answers

What is indicated by the upward slope of the regression line on the plotted data?

A positive correlation Signup and view all the answers

What percentage of eggs would self-sacrificing males be expected to father based on the data?

92% Signup and view all the answers

What aspect of male redback spiders' behavior seems to be shaped by sexual selection according to the text?

Mating duration Signup and view all the answers

What could potentially increase confidence in the interpretation of the data according to the text?

Increasing the sample size Signup and view all the answers

What type of mutations are important for the evolution of life’s diversity?

Germline mutations Signup and view all the answers

What is the impact of a mutation that occurs in a stretch of DNA with no function?

It often has no effect on the organism Signup and view all the answers

Which type of mutation does Marfan syndrome result from?

Detrimental mutation Signup and view all the answers

What is the outcome of detrimental mutations known as lethals?

They disrupt critical DNA and cause death Signup and view all the answers

What is one possible effect of a mutation occurring in a protein-coding region but not affecting the amino acid sequence of the protein?

No noticeable effect on the organism Signup and view all the answers

Why are mutations in reproductive cells like eggs and sperm considered important for evolution?

Because they can be passed on to offspring Signup and view all the answers

What do squirrels have a difficult time with in relation to pinecones?

Large, heavy pinecones with fewer seeds Signup and view all the answers

Why do Crossbill birds not get as many pine seeds as squirrels?

Squirrels are faster at reaching the seeds first Signup and view all the answers

In places without red squirrels, who becomes the most important seed predator for lodgepoles?

Crossbill birds Signup and view all the answers

How do Crossbill birds counteract the challenge of extracting seeds from tough pine cones?

Adapting deeper, shorter, less curved bills Signup and view all the answers

What ecological relationships set the stage for coevolution to potentially occur?

Predator/prey relationships Signup and view all the answers

What evidence is needed to suggest coevolution has occurred between the prey and predator in this scenario?

Evidence of both prey and predators evolving in response to each other Signup and view all the answers

Study Notes

Mutations and Evolution

Mutations that affect the individual carrying them but are not passed directly on to offspring do not contribute to the evolution of life's diversity.
Only germline mutations, which occur in reproductive cells like eggs and sperm, can be passed on to offspring and affect evolution.

Effects of Mutations

A single germline mutation can have a range of effects, including:
- No effect or neutral effect: the mutation does not have a noticeable effect on the organism.
- Detrimental effect: the mutation harms an organism's ability to survive and reproduce.
- Lethal effect: the mutation disrupts DNA critical to survival and causes the death of the organism.

Sexual Selection

Sexual selection can shape male behavior, such as self-sacrificial mating behavior in male redback spiders.
In this case, males that allow themselves to be eaten by the female mate for longer and father more eggs, increasing their fitness.
Sexual selection is powerful because individuals who do not produce offspring do not pass on their genes to the next generation.

Adaptations

Adaptations are features that have evolved to improve an organism's ability to survive and reproduce.
Examples of adaptations include:
- Mimicry of leaves by insects to evade predators.
- Echolocation in bats to catch insects.
- The creosote bush's production of toxins to prevent other plants from growing nearby.
Vestigial structures, such as non-functional eyes in fish that live in completely dark caves, are not adaptations.

Coevolution

Coevolution occurs when two species, such as predator and prey, evolve in response to each other.
An example of coevolution is the relationship between crossbill birds and lodgepole pine trees, where the birds have evolved deeper, shorter, less curved bills to extract seeds from tough cones.

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Description

Delve into the intriguing behavior of male redback spiders and their contribution to mates and offspring. Explore the mechanisms of evolution through this fascinating study in invertebrates. Join the journey from studying natural environments to experiencing sunny Australia!