15.2

When trying to determine the evolutionary relationships between two species would a biologist concentrate on homologous features or analogous features explain why

A biologist would concentrate on homologous features since they originated from a shared ancestor.

fossil, principle of superposition

A fossil is the remains or traces of an organism that died. Principle of superposition states that if a rock strata has not been disturbed the lowest stratum was formed before the strata above it.

Explain the evidence that indicates that species evolve over time

Fossil show that a group of marine animals have change over time to adapt to different environments

The wing of athat and the foreleg of an alligator are

Homologous features

homologous structure, analogous structure

Homologous structure are anatomical structures that occur in different species and that originated by hereditary from a structure in the most recent common ancestor of the species. Analogous structures have closely related function but you not derived from the same ancestral structure.

How does biogeography contribute to an understanding of evolution

In biogeography studies similar animals seem to be closely related are adapted to different environment in nearby areas. Also in areas that are widely separated animals that seem to be unrelated are observed to have similar adaptations to similar environments in the separate areas.

According to the principle of superposition, lowest layer in a cross section of a rock sequence

Is the oldest

Embryological comparisons reveal that

Many vertebrate embryos look similar at early stages of development

relative age, absolute age

Relative age is determined by comparison to other fossils by referring to geologic timescale. Absolute age uses processes such as radiometric dating.

Fossils are

Remains or traces of pre-existing organisms

If an animal has a vestigial feature what might a biologist infer about the animal's evolutionary history

The animal Evald from an ancestor I which that structure was functional

Why do you vestigial structures persist in modern organisms

The environment will not select for or against organisms that have a particular structure unless it affects and organism's fitness

Features that were useful to ancestral organisms but are not useful to a modern organism that inherited them are said to be

Vestigial