Which synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates? a. multicellularity b. coloniality c. heterotrophy d. movement

Verified step by step guidance

1. Understand the term 'synapomorphy', which refers to a characteristic that is shared by a group of organisms and is derived from their most recent common ancestor.
2. Identify the traits listed in the options and determine which are common to all animals but not present in their closest relatives, the choanoflagellates.
3. Consider the trait of multicellularity. Recall that choanoflagellates can be either single-celled or colonial, but they do not form true multicellular organisms with differentiated tissues.
4. Analyze the other options: coloniality (choanoflagellates can also form colonies), heterotrophy (both animals and choanoflagellates are heterotrophic), and movement (choanoflagellates also exhibit movement using flagella).
5. Conclude that the trait which is unique to animals and represents a significant evolutionary step from choanoflagellates is the development of true multicellularity with specialized, differentiated cells and tissues.

Key Concepts

Synapomorphy

A synapomorphy is a shared, derived trait that is used to define a clade in evolutionary biology. It is a characteristic that is present in an ancestor and its descendants but not found in more distant relatives. Identifying synapomorphies helps in understanding evolutionary relationships and classifying organisms based on common ancestry.

Monophyletic Group

A monophyletic group, or clade, consists of an ancestor and all its descendants, representing a complete branch on the tree of life. This concept is crucial for understanding evolutionary biology, as it distinguishes groups that share a common evolutionary history from those that do not. Monophyletic groups are essential for constructing accurate phylogenetic trees.

Choanoflagellates

Choanoflagellates are a group of unicellular organisms that are considered the closest living relatives of animals. They possess a unique collar of microvilli surrounding a flagellum, which aids in feeding. Understanding choanoflagellates is important for studying the evolutionary transition from single-celled to multicellular organisms, highlighting the traits that differentiate animals from their closest relatives.