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The ancient Greek concept of scala naturae posited a hierarchical arrangement of life. Which of the following best describes the core idea of this concept?
The ancient Greek concept of scala naturae posited a hierarchical arrangement of life. Which of the following best describes the core idea of this concept?
- Life forms are ordered in a continuous chain from least to most complex, with humans at the apex. (correct)
- Organisms develop by recapitulating the adult stages of their evolutionary ancestors.
- Developmental stages of an organism strictly mirror its evolutionary history, reflecting a simple-to-complex progression.
- Species evolve linearly over time, progressing from simple to complex forms.
Meckel and Serres' concept of 'parallelism' built upon the idea of scala naturae. How did parallelism extend the ancient Greek perspective on biological organization?
Meckel and Serres' concept of 'parallelism' built upon the idea of scala naturae. How did parallelism extend the ancient Greek perspective on biological organization?
- By focusing on genetic mechanisms driving developmental changes rather than philosophical observations of complexity.
- By suggesting that developmental stages of an individual organism mirror the sequence of species on the _scala naturae_, moving from simple to complex traits. (correct)
- By proposing that embryos of complex species pass through the adult stages of simpler species on the _scala naturae_.
- By refuting the _scala naturae_ and introducing the concept of branching evolutionary lineages instead of a linear chain.
Ernst Haeckel's 'biogenic law,' often summarized as 'ontogeny recapitulates phylogeny,' is an extension of earlier ideas. What is the central claim of the biogenic law?
Ernst Haeckel's 'biogenic law,' often summarized as 'ontogeny recapitulates phylogeny,' is an extension of earlier ideas. What is the central claim of the biogenic law?
- General characteristics in development appear later, while specialized traits that distinguish species appear earlier.
- Embryos of different species are most similar in their adult forms, diverging only in early developmental stages.
- Developmental processes are largely independent of evolutionary history, shaped primarily by environmental pressures.
- The evolutionary history of an organism is mirrored in its developmental process, with each stage representing an ancestral adult form. (correct)
Karl Ernst von Baer challenged the 'biogenic law' with his own observations. What is the core principle of Von Baer's law of development?
Karl Ernst von Baer challenged the 'biogenic law' with his own observations. What is the core principle of Von Baer's law of development?
Von Baer's law suggests that early developmental stages are conserved across species. What is the primary evolutionary reason proposed for this conservation?
Von Baer's law suggests that early developmental stages are conserved across species. What is the primary evolutionary reason proposed for this conservation?
The 'modern synthesis' in evolutionary biology significantly shifted the focus of evo-devo research. What was a key outcome of this shift?
The 'modern synthesis' in evolutionary biology significantly shifted the focus of evo-devo research. What was a key outcome of this shift?
Heterochrony is defined as changes in the timing or rate of developmental processes. Which of the following is NOT a type of heterochrony?
Heterochrony is defined as changes in the timing or rate of developmental processes. Which of the following is NOT a type of heterochrony?
Consider 'acceleration' as a type of heterochrony. How would you best describe the developmental outcome of acceleration?
Consider 'acceleration' as a type of heterochrony. How would you best describe the developmental outcome of acceleration?
'Paedomorphosis' is a category of heterochrony where adult forms retain juvenile traits. Which of the following mechanisms can lead to paedomorphosis?
'Paedomorphosis' is a category of heterochrony where adult forms retain juvenile traits. Which of the following mechanisms can lead to paedomorphosis?
'Neoteny' is a specific type of paedomorphosis. What developmental change characterizes neoteny?
'Neoteny' is a specific type of paedomorphosis. What developmental change characterizes neoteny?
In contrast to paedomorphosis, 'recapitulation' is another major category of heterochrony. How does 'recapitulation via acceleration' manifest in development?
In contrast to paedomorphosis, 'recapitulation' is another major category of heterochrony. How does 'recapitulation via acceleration' manifest in development?
'Hypermorphosis' is another type of recapitulation. What is the developmental characteristic of 'recapitulation via hypermorphosis'?
'Hypermorphosis' is another type of recapitulation. What is the developmental characteristic of 'recapitulation via hypermorphosis'?
Research on primates has revealed neotenic changes in human brain development compared to chimpanzees. What does this neoteny in human brain development primarily involve?
Research on primates has revealed neotenic changes in human brain development compared to chimpanzees. What does this neoteny in human brain development primarily involve?
Farnsworth and colleagues studied heterochrony in insect brain development, comparing Drosophila melanogaster and Tribolium castaneum. What type of heterochrony did they find in the development of certain nerve clusters in Tribolium compared to Drosophila?
Farnsworth and colleagues studied heterochrony in insect brain development, comparing Drosophila melanogaster and Tribolium castaneum. What type of heterochrony did they find in the development of certain nerve clusters in Tribolium compared to Drosophila?
In the insect brain study, researchers also discovered 'sequence heterochrony'. What does 'sequence heterochrony' refer to in the context of development?
In the insect brain study, researchers also discovered 'sequence heterochrony'. What does 'sequence heterochrony' refer to in the context of development?
The central complex (CX) in insect brains is associated with specific functions. Which of the following sets of functions is primarily linked to the central complex?
The central complex (CX) in insect brains is associated with specific functions. Which of the following sets of functions is primarily linked to the central complex?
What ecological rationale is proposed for the accelerated development of the central complex in Tribolium castaneum larvae compared to Drosophila melanogaster maggots?
What ecological rationale is proposed for the accelerated development of the central complex in Tribolium castaneum larvae compared to Drosophila melanogaster maggots?
Which of the following statements best distinguishes between Haeckel's 'biogenic law' and Von Baer's law of development?
Which of the following statements best distinguishes between Haeckel's 'biogenic law' and Von Baer's law of development?
In the context of heterochrony, consider a species where adults are significantly larger than their close relatives due to a prolonged growth period. Which type of heterochrony is most likely responsible for this size difference?
In the context of heterochrony, consider a species where adults are significantly larger than their close relatives due to a prolonged growth period. Which type of heterochrony is most likely responsible for this size difference?
If 'ontogeny' refers to the development of an individual organism and 'phylogeny' refers to the evolutionary history of a species, how does Haeckel's phrase 'ontogeny recapitulates phylogeny' misrepresent the actual relationship between development and evolution, according to Von Baer's perspective?
If 'ontogeny' refers to the development of an individual organism and 'phylogeny' refers to the evolutionary history of a species, how does Haeckel's phrase 'ontogeny recapitulates phylogeny' misrepresent the actual relationship between development and evolution, according to Von Baer's perspective?
Flashcards
Scala Naturae
Scala Naturae
Species are classified from simplest to most complex, with humans at the summit.
Parallelism
Parallelism
Developmental stages mirror the scala naturae, moving from simple to complex traits during an organism's lifetime.
Von Baer's Law
Von Baer's Law
General traits develop before specialized traits, making embryos of different species more similar than adults.
Heterochrony
Heterochrony
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Neotenic Changes
Neotenic Changes
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Central Complex (CX)
Central Complex (CX)
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Acceleration
Acceleration
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Sequence Heterochrony
Sequence Heterochrony
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Study Notes
- Evo-devo's origins trace back to ancient Greek philosophers like Aristotle and Plato, who conceived the scala naturae, or "great chain of being."
- The scala naturae classifies species from simple to complex, with humans at the top
- Ancient Greeks saw parallels between the scala naturae and organismal development (ontogeny), suggesting development progresses from simple to complex.
- Parallelism, championed by Meckel and Serres, proposed that developmental stages mirror the scala naturae's progression from simple to complex.
- Haeckel's biogenic law stated that "ontogeny recapitulates phylogeny," meaning organismal development replays its evolutionary history.
- Von Baer rejected the biogenic law, arguing general traits develop before specialized ones during development.
- Von Baer's law proposes embryos of different species are more similar than their adult forms.
- Structures appearing early in development are resistant to evolutionary change, explaining similarities across taxa.
- Changes early in development have significant, potentially fatal consequences, limiting evolutionary flexibility.
- Evolutionarily novel traits tend to emerge later in development, distinguishing closely related species.
Timing of Development
- Research shifted in the 1930s and 1940s to focus on the role of genes in shaping development.
- Some genes control the rate of development, influencing the timing of developmental stages.
- Heterochrony studies how relative timing of developmental processes varies between species and how those differences lead to differences in phenotype
- Somel, Pääbo, Khaitovich et al. found neotenic changes in human brain development, with postnatal development delayed compared to other primates.
- Human neuron development is delayed relative to chimpanzees and bonobos.
- Farnworth et al. tracked homologous nerve clusters in the brains of Drosophila melanogaster and Tribolium castaneum.
- The central complex (CX) relates to locomotor activities, vision, and spatial orientation in insects.
- Some neuron clusters develop earlier in red flour beetles than in fruit flies, an example of heterochrony called acceleration.
- Acceleration is when juveniles show somatic traits typically not seen until later stages in related species.
- Sequence heterochrony involves changes in the order in which developmental stages appear
- Beetle larvae's earlier development of nerve clusters may be linked to their reliance on visual cues for food, unlike fruit fly maggots.
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