Chapter 1(part2) by kardong

Evolutionary Morphology

Part 2 of Chapter 1By Geonyzl Alviola

Function and Biological Role

Function = is restricted to mean the action or property of a part as it works in an organism.

Biological Role = (or just role) refers to how the part is used in the environment during the course of the organism’s life history.

For example

1. Cheek muscle

Function: to close the jaw

Biological Role: for food processing (chewing)

Biological Role: (biting) for protection against threat

For example (one part with several function)

2. quarate bone (in reptiles

Function: to attach the lower jaw to the skull. It also functions to transmit sound waves to the ear.

Biological role: feeding (food procurement) and hearing (detection of enemies or prey)

Example

Function?

Biological Role?

Functions of a part are determined largely in laboratory studies; biological roles are observed in field studies.Inferring biological roles only from laboratory studies can be misleading

Preadaptation

Preadaptation means that a structure or behavior possesses the necessary form and function before (hence pre-) the biological role arises that it eventually serves.

In other words, a preadapted part can do

the job before the job arrives

For example: Bird Feather Story

feathers likely evolved initially in birds (or in theirimmediate ancestors) as insulation to conservebody heat. Like hair in mammals, feathersformed a surface barrier to retard the loss ofbody heat. For warm-blooded birds, featherswere an indispensable energy-conservingfeature. Today, feathers still play a role inthermoregulation; however, for modern birds,flight is the most conspicuous role of feathers.Flight came later in avian evolution.

Phylogeny

can be summarized in graphic schemes, or dendrograms, that depict treelike, branched connections between groups.

Dendrograms summarize evolution’s course

Of Beanstalks and Bushes

1896, Ernst Haeckel wrote The Evolution of Man

Evolution does not proceed up a single ladder, but bushes outward along several simultaneous courses.

Humans share the current evolutionary moment with millions of other species, all with long histories of their own.

All adapted in their own ways to their own environments.

The apparent discreteness of species or groups at the current moment is partly due to their previous divergence.

When followed back into their past, the connectedness of species can be determined. A dendrogram showing lineages in three dimensions (figure 1.22) emphasizes this continuity.

DenrogramsIt is a summarized graphic representation

of the course of evolution or phylogeny

- it is also used to express relative abundance and diversity.

- presented like a branching tree or any form.

Gradual presentation / Abrupt dendogram

A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor.

Monophyletic clade - it includes an ancestor and all its descendants

Paraphyletic clade- one that includes a common ancestor and some but not all, of its descendants.

Polyphyletic cladeIs one that does not share an immediate common ancestors

Parallelism and Convergence

Parallelism is evolutionary change in two or more lineages such that corresponding features undergo equivalent alterations without becoming more or less similar

a b

The ancestor is common in both a and b

Kangaroo ratNorth America

JerboasAfrica and Asia

Convergence

Is evolutionary change in two or more lineages such that corresponding features that were formerly dissimilar become similar

ABSimilarity

between A and B evolved from different lineages

For example

Studying phylogeny

Studying the history of an animal

Tracing its relatives

Associating its resemblance

=======> Paleontology

Paleontology

= study the fossils

= recovery and restoration

= dating the fossils

= stratigraphy

= indexing

= radiometric dating