Introduction to Comparative Anatomy

Comparative Anatomy

The study of and comparison of body parts of different species

Comparative Anatomy

Is the study of anatomical structures and evolutionary relationships.

Comparative Anatomy

Indicates that various organisms share a common ancestor.

Homologous Structures

Structures with similar structure, but different functions

Analogous structures

Have different anatomies but similar function

Analogous structures

These are seen on organisms that are not necessarily closely related, but live in similar environments and have similar adaptations

Vestigial structures

Anatomical remnants that were important in the organism’s ancestors, but are not longer used in the same way

Adaptation

Genetic and physiological changes that occur due to pressures or changes in an animals environment

Adaptation

The process or the state of adjusting or changing to become more suited to an environment

Adaptation

the trait as a result of the process.

• Forelimb

• Webbed foot

• Front feet

Adaptation Changes

Phylogeny

inheritance

Evolution

modification and inheritance

convergence

found in distantly related groups; evolved independently.

parallelism

found in closely related groups; evolved independently

independent evolution/convergence

unrelated groups

Carolus Linnaeus (1707-1778):

species unchanged; used characters to group organisms

Jean Baptiste de Lamarck (1744-1829):

progressive change of characters (and species) dictated by use or disuse

Alfred Russel Wallace (1823-1913):

survival of the fittest

Charles Darwin (1809-1882

survival of the fittest, tree of life

Georges Cuvier (1769-1832)

form and function/comparative methods/species immutable

Richard Owen (1804-1892

archetypes/homology

Preadaptation

structures evolve not with a purpose, but with a 'potential'

Remodeling

evolution is not about inventing new things, it is mainly about switching/alteration

ontogeny

from fertilisation, to death of individuals

embryology

from fertilization to birth, hatching

fertilisation

the union of sperm and egg

cleavage

cell division

biogenetic law

ancestor's form reappears in the ontogeny of descedents

von Baer's law

the resemblance between embryos of ancestors and descendents.