Embryology and Developmental Biology Overview

What term describes the phenomenon where adults resemble the juveniles of their ancestors?

Which law posits that embryonic development progresses from general forms to more specific forms?

In the context of evolution, what does the term 'ontogeny' specifically refer to?

What is 'heterochrony' primarily concerned with in terms of organismal development?

What does 'peramorphosis' involve in terms of development?

Which of the following statements accurately describes the relationship between ontogeny and phylogeny according to Ernst Haeckel's argument?

How does von Baer's law differentiate between embryonic development patterns?

Which process is characterized by adults resembling the juvenile stages of their ancestors?

In modern evolutionary developmental biology, which statement reflects the current understanding of embryonic development patterns?

What does the term 'heterochrony' encompass in the context of evolutionary biology?

Embryonic Development Variations

Vertebrate embryonic development varies across species.
Some develop into larvae, others into fetuses.
All major features develop during the fetal stage.

Metamorphosis

Metamorphosis is a significant post-embryonic transformation to adulthood.
This process is common in animals, including vertebrates.
It involves distinct larval and adult stages.
Thyroid hormones control metamorphosis.
Metamorphosis may even predate vertebrates.
Some non-vertebrate chordates, like lancelets, undergo metamorphosis, triggered by thyroid hormones.
Non-jawed vertebrates exhibit metamorphosis.

Ontogeny

Ontogeny is the development from organism to adulthood.
This process occurs throughout an individual's lifespan.

Haeckel's Biogenetic Law

Ernst Haeckel proposed that embryonic development mirrors evolutionary history.
Ontogeny recapitulates phylogeny.

Von Baer's Law

Karl Ernst von Baer stated development proceeds from general to specific.
This is a fundamental principle of development.

Phylotypic Stage and Hourglass Model

The vertebrate body plan is observed during the phylotypic stage.
Embryonic development converges toward this conserved body plan, then diverges again (hourglass model).
Modern evolutionary developmental biology supports von Baer's Law.

Heterochrony

Heterochrony refers to changes in the timing of adult features in descendant species during development.

Paedomorphosis

Paedomorphosis is when adult features resemble juvenile ancestors.
It includes:
- Progenesis: Early cessation of somatic development (early sexual maturity)
- Neoteny: Features grow slower, sexual maturity surpasses somatic maturation.

Peramorphosis

Peramorphosis involves extending the ancestral ontogenetic sequence, producing new adult forms.

Explore the fascinating processes of embryonic development, metamorphosis, and ontogeny. Learn about key laws proposed by Haeckel and Von Baer, and how these concepts relate to evolutionary history. This quiz covers variations in vertebrate development and transformations into adulthood.