Animal Development, Phylogeny, and Human Evolution: Key Concepts and Traits

What is the cleavage pattern and blastopore fate for a protostome?

Spiral, determinate cleavage; blastopore becomes the mouth.

What is the cleavage pattern and blastopore fate for a deuterostome?

Radial, indeterminate cleavage; blastopore becomes the anus.

What structural protein provides support in animal cells?

Collagen.

What are the two tissue types unique to animals?

Muscle and nervous tissue.

How does a larval stage benefit a species ecologically?

It partitions resources and habitat to avoid competition with adults.

What is the difference between radial and bilateral symmetry?

Radial symmetry has multiple planes of symmetry; bilateral symmetry has one plane of symmetry.

What is the closest phylogenetic relative to chordates?

Echinodermata.

What are the four main characteristics of chordates?

Notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail.

What is the function of pharyngeal slits in aquatic vertebrates?

Suspension feeding and gills for gas exchange.

What is the function of pharyngeal slits in terrestrial tetrapods?

They become modified into structures like auditory tubes and glands.

What key trait defines vertebrates on a phylogeny?

Vertebrae.

What key trait defines gnathostomes on a phylogeny?

Jaws and a mineralized skeleton.

What key trait defines tetrapods on a phylogeny?

Limbs with digits.

What key trait defines amniotes on a phylogeny?

The amniotic egg.

From which fish group did tetrapods evolve?

Lobe-finned fish.

What are three anatomical changes that allowed tetrapods to move onto land?

Development of a neck, fins into legs with digits, and air-breathing organs.

What is the leading hypothesis for the origin of bone and teeth?

A transition in feeding from suspension feeding to predation.

How did jaws evolve in vertebrates?

From the modification and fusion of skeletal rods that supported the pharyngeal slits.

What was the first vertebrate group to have true jaws?

Gnathostomes.

Why were jaws a key innovation for vertebrates?

They enabled new feeding strategies, leading to massive adaptive radiation.

What are the key features of an amniotic egg?

Four specialized extraembryonic membranes.

Why was the amniotic egg a key evolutionary innovation?

It allowed embryo development on land.

What are the three major reptile groupings based on skull features?

Anapsids, Diapsids, Synapsids.

What is the main difference between endothermic birds and ectothermic reptiles?

Birds generate internal body heat; reptiles rely on external environmental heat.

What are three features unique to mammals?

Hair, milk production, and differentiated teeth.

What are the three mammal subclasses?

Monotremata, Metatheria, Eutheria.

What is the key reproductive feature of monotremes?

They lay hard-shelled eggs.

What is the key reproductive feature of marsupials?

Young are born very early and complete development in a pouch.

What is the key reproductive feature of eutherians?

Complete development occurs within a uterus with a placenta.

What are four primate adaptations for an arboreal lifestyle?

Grasping hands/feet, flattened face with binocular vision, nails instead of claws, large brain-to-body ratio.

How do New World monkeys differ geographically from Old World monkeys?

New World monkeys evolved in Central/South America; Old World monkeys evolved in Africa/Asia.

How do New World monkeys differ anatomically from Old World monkeys?

New World monkeys have wide nostrils and prehensile tails; Old World monkeys have narrow nostrils and no prehensile tails.

What are three major anatomical changes that allowed for bipedalism in hominins?

Backbone changed to S-shaped, foramen magnum moved, femur bones lengthened.

What are two advantages of bipedalism?

Frees hands for tool use and improves energy efficiency.

What are the two models of modern human evolution?

The African Emergence Model and the Multi-regional Model.

What does the African Emergence Model propose?

Homo sapiens evolved in Africa and migrated out.

What does the Multi-regional Model propose?

Homo erectus evolved into H. sapiens simultaneously on different continents.

Which model of human evolution is most plausible and why?

The African Emergence Model, supported by molecular data and fossil evidence.