Evolutionary Biology Quiz

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Questions and Answers

Which species is characterized by features indicating both walking and climbing adaptations?

Paranthropus

Kenyanthropus

Ardipithecus ramidus (correct)

Australopithecus afarensis

What evidence do paleontologists often rely on when analyzing ancient hominins?

Complete skeletal remains

DNA analysis from fossil samples

Measurements of skulls, teeth, or jaws (correct)

Cultural artifacts found with fossils

What is a key concept regarding the evolutionary process of hominins?

Hominin evolution is a linear progression towards modern humans.

Modern humans evolved directly from Australopithecus afarensis.

Hominin evolution reflects a process of diversification with several lineages. (correct)

All hominins that once existed have left living descendants today.

What historical evidence shows the presence of Australopithecus afarensis around 3.6 million years ago?

Footprints preserved in volcanic ash Signup and view all the answers

What distinguishes robust Australopithecines, such as Paranthropus, from other hominin lineages?

They possess unique morphological characteristics that have no living descendants. Signup and view all the answers

What is the primary benefit of forming a supergene from well-adapted traits?

It prevents recombination and maintains trait integrity. Signup and view all the answers

What is a significant cost associated with mate searching in sexually reproducing individuals?

Higher probability of predation. Signup and view all the answers

How does mating with larger males affect female beetles in terms of predation risk?

It reduces the chances of being attacked. Signup and view all the answers

What is a potential consequence of organisms mating concerning diseases?

It increases the probability of disease transmission. Signup and view all the answers

Which of the following statements best explains Muller's Ratchet?

It illustrates the accumulation of deleterious mutations in asexual populations. Signup and view all the answers

What overall effect does recombination have on offspring fitness when traits are well adapted?

It generally reduces offspring fitness. Signup and view all the answers

What is one major energetic cost associated with sexual reproduction?

The need for mate selection. Signup and view all the answers

What describes the mutational mode in evolving populations?

New mutations arise in every generation. Signup and view all the answers

What is one primary adaptation of early hominins that is highlighted in the content?

Massive jaw and teeth Signup and view all the answers

What is the overall effect of deleterious mutations on the genome referred to as?

Mutation load Signup and view all the answers

Which species is described as being discovered by an all-women team of paleoanthropologists?

Homo naledi Signup and view all the answers

What concept explains the small size of Homo floresiensis due to limited resources on islands?

Island dwarfism Signup and view all the answers

What happens to the minimum number of mutations across a population as new deleterious mutations accumulate?

It increases Signup and view all the answers

Why can the ratchet mechanism only turn in one direction?

Mutational load can only increase Signup and view all the answers

How long ago did Homo floresiensis live, according to the content?

40 thousand years ago Signup and view all the answers

What is stated about early hominins and their relationship to modern humans?

They shared common features with other apes. Signup and view all the answers

How many new deleterious mutations do humans typically carry that are absent in their parents?

2-3 Signup and view all the answers

What is the primary advantage of recombination in sexually reproducing lineages?

Increases genomic diversity Signup and view all the answers

What distinguishes Homo naledi from other early hominins?

The number of fossils recovered Signup and view all the answers

What is the main implication of Muller's ratchet on populations reproducing asexually?

They cannot effectively manage deleterious mutations Signup and view all the answers

Which statement about the genus Homo is correct based on the content?

All modern humans belong to the genus Homo. Signup and view all the answers

What is indicated about the existence of different hominin lineages?

Many existed simultaneously for millions of years. Signup and view all the answers

What hypothesis describes how recombination facilitates faster adaptation by combining beneficial mutations?

Fisher-Muller Hypothesis Signup and view all the answers

What effect does increasing frequencies of specific adaptive alleles have on asexually reproducing populations?

It maximizes the risk of genetic homogeneity. Signup and view all the answers

What significant evolutionary feature is primarily associated with early hominins?

Adaptations for bipedal walking Signup and view all the answers

Which species is identified as the first wave out of Africa?

Homo erectus Signup and view all the answers

What is a major change that was observed in hominin evolution?

Increased cranial capacity Signup and view all the answers

What adaptation did Homo erectus possess to facilitate its long-distance travel?

Characteristic bipedal movement Signup and view all the answers

During which time period did Neanderthals predominantly inhabit Eurasia?

400-40 kya Signup and view all the answers

Which climatic change is suggested to have influenced the evolution of bipedalism?

Transition from tropical rainforests to savannah-like forests Signup and view all the answers

When did modern humans begin to disperse out of Africa?

Approximately 100 thousand years ago Signup and view all the answers

What characteristic differentiates Neanderthals from modern humans?

Wider rib cage and stockier build Signup and view all the answers

What is Clonal Interference?

Competition among beneficial mutations that cannot coexist in a single genome. Signup and view all the answers

Which advantage does sexual reproduction have over asexual reproduction?

Increased genetic variation through recombination. Signup and view all the answers

What role does bet hedging play in sexual reproduction?

It produces a range of offspring types to adapt to unpredictable environments. Signup and view all the answers

How does asexual reproduction impact the mutation load in a population?

It leads to an accumulation of harmful mutations as beneficial ones fix. Signup and view all the answers

What is the significance of host-parasite interactions in sexual reproduction?

They create pressure for hosts to evolve and resist parasites. Signup and view all the answers

How does sexual reproduction facilitate the formation of a super genome?

Through the encounter and recombination of beneficial mutations. Signup and view all the answers

Why might an asexual population initially outperform a sexual population?

Asexual clones can produce more offspring quickly. Signup and view all the answers

What happens to asexual lineages under strong selection pressure?

They may be selected out as global conditions change. Signup and view all the answers

Study Notes

Why do organisms reproduce sexually?

Reproduction is paradoxical, costly in many ways
Asexual reproduction is better for organisms evolutionarily
Sexual reproduction ultimately is better
Most species in the tree of life reproduce sexually
Sharing genetic material and recombination are key to sexual reproduction

"Twiggy" Phylogenetic Distribution of Asexuality

Asexual lineages spontaneously appear on the tree of life, but are usually short-lived
Lizards provide an example
Sometimes asexuality offers an advantage over sexual reproduction

Types of Asexual Reproduction - Apomictic Parthenogenesis

A form of asexual reproduction, common in whiptail lizards and some New Zealand mud snails
Diploid cells undergo mitosis, not meiosis, creating eggs without genetic contribution from a male

Gynogenesis

Similar to apomictic parthenogenesis on a cellular level
Requires a male to stimulate egg production; sperm only necessary for initiating mitosis, not contributing genetically
Supports the idea of recent evolution of asexuality

Independent Evolutions

Independent evolutions of asexual reproduction in related but not identical species
Female diploid having genetic contributions from both parents
Kick out of the male maternal genome for reproduction to continue

Sexual Reproduction

In meiosis, a reduction in copy number occurs, diploid adults make haploid gametes with genetic material from both parents
Genetic shuffling is key to sexual difference
Horizontal gene transfer is extreme example of asexuality
Sexual reproduction involves recombination and genetic material exchange

The Cost of Sex

Anisogamy: different investment in male vs female gametes; female investment for egg production is high
Two-fold reproductive cost of sexual reproduction due to anisogamy

Costs of Sex

Sexually transmitted diseases and parasites: transmission probability increases
Finding mates takes energy
Breaking up favorable gene combinations

Benefits of Sex

Muller's Ratchet and Mutational Load: reduces accumulation of deleterious mutations in asexually reproducing organisms due to limited recombination
Recombination facilitates faster adaptation to changing circumstances; beneficial mutations get combined.

Testing the Benefits of Sex: Experiments

Did a study showing reduced fitness for asexually reproducing yeast
Genetically variable offspring in sexual reproduction may be an advantage in a fluctuating environment

Adapting to Changing Circumstances

Sexual reproduction aids adaptability to environmental changes and competition, offering offspring diversity.
Variability in offspring is an advantage in changing circumstances

Red Queen: Outrunning Parasites

Sex aids in keeping up with evolving parasites and pathogens in a coevolutionary arms race.

Tests with New Zealand Snails

Snails may be entirely asexual with only females
Asexual reproduction is dominant in snails with higher parasite prevalence

What is Sexual Selection?

Competition for mates; determines who gets to reproduce
Variances in mating success
Sexual Selection - individuals of one sex are more competitive for the opportunity to mate

Types of Sexual Selection

Intersexual Selection: mate choice
Intrasexual Selection: male-male competition

Sexual Conflict

Different mating interests from males and females

Humans as Primates

Nearly all apes are found in Africa
Hominins are the lineage closest to modern humans

Interbreeding and Introgression

Constant mixing of gene pools between and within species

Our Closest Extinct Relatives

Hominins lineages that have gone extinct, but were relatively close to modern humans

Incomplete Lineage Sorting

Gene trees may not match the species tree if speciation events are close in time

Testing Evolutionary Hypotheses of Common Ancestry

Using evidence to show links and relationships among species

Humans and other hominins

Early lineages that were possibly early hominin

Evolution and Behavior

Evolution of sexual reproduction varies
Adaption to climate and environment affect evolutionary selection outcomes
Human diversity in terms of genetic background

Evolvability of Infectious Diseases

Evolutionary pressures result in pathogen resistance to treatments
Understanding genetic and environmental influences on pathogens aids treatment strategies.

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Description

Test your knowledge on key concepts in evolutionary biology, particularly related to hominins and their adaptive traits. This quiz covers the evidence used by paleontologists as well as evolutionary processes impacting species adaptation and reproduction. Understand the balance between mating strategies and energetic costs in sexual reproduction.