Which statement is true about endothermy in mammals and birds?
a. They both inherited this trait from a common ancestor.
b. Birds are more closely related to mammals than to reptiles.
c. Endothermy arose independently in these two lineages.
d. Birds are reptiles and all reptiles are ectothermic.

Verified step by step guidance

1. Understand the concept of endothermy: Endothermy refers to the ability of an organism to maintain a stable internal body temperature through metabolic activity, regardless of external environmental conditions.
2. Recognize the evolutionary context: Birds and mammals are both endothermic, but they belong to different evolutionary lineages. Birds are part of the class Aves, which is closely related to reptiles, while mammals belong to the class Mammalia.
3. Consider the evolutionary history: Endothermy is a trait that evolved independently in birds and mammals. This means that the ability to regulate body temperature through metabolic processes did not come from a common ancestor shared by both groups.
4. Evaluate the relationship between birds and reptiles: Birds are considered part of the reptile clade, specifically within the group Archosauria, which includes dinosaurs and modern reptiles like crocodiles. Not all reptiles are ectothermic; birds are an exception as they are endothermic.
5. Analyze the statements: Based on the understanding of endothermy and evolutionary relationships, the statement that endothermy arose independently in these two lineages (option c) is true. This reflects the separate evolutionary paths that led to endothermy in birds and mammals.

Key Concepts

Endothermy

Endothermy is the physiological ability of an organism to maintain a stable internal body temperature through metabolic activity, regardless of external environmental conditions. This trait is characteristic of mammals and birds, allowing them to thrive in diverse climates by generating heat internally.

Evolutionary Lineages

Evolutionary lineages refer to the ancestral lines of descent that lead to the current diversity of life forms. In the context of endothermy, understanding the evolutionary pathways of mammals and birds helps clarify whether they inherited this trait from a common ancestor or developed it independently.

Phylogenetic Relationships

Phylogenetic relationships describe the evolutionary connections between different species, often depicted in a tree-like diagram. Birds are considered part of the reptile clade, which includes dinosaurs, while mammals are a separate lineage. This concept helps determine the closeness of relationships and the independent evolution of traits like endothermy.