Unit ____: Adaptations to Niches over Time          Name: _____________________________

THEMES:

Commonality with Diversity

Form and Function

Interaction and Interdependence

Feedback for Regulation

Nature of Science

LEVELS OF ORGANIZATION:

Molecules

Cells

Organisms

Ecosystems

Every organism has a niche; the organism’s habitat, its tolerance limits and its function within that habit (C.1).

Species have adapted through natural selection to fill available niches (5.2.U3).

Evolution of homologous structures by divergent evolution explains similarities in structure when there are differences in function (5.1.U4).

Examples of homologous structures include the pentadactyl limb and the modification of leaves and flowers (5.1.A1, 5.1.NOS).

The fossil record provides evidence of divergent evolution (5.1.U2).

When a change in the environment opens new environmental niches, organisms diversify rapidly from an ancestral species into a multitude of new forms (5.1.U4)

Gradualism and punctuated equilibrium are two ways in which the evolution of a species can occur.  (10.3.U4 and 10.3.U5)

Analogous structures evolve by convergent evolution to fulfill the same function (5.4.U4).

Ecological Niche

        temperature, precipitation, solar radiation, terrain

competition, predation, mutualism

nocturnal, diurnal, phenology

Range of Tolerance

For any environmental factor there will be a range which a particular species can tolerate.

Niches are restricted by the competition between species for resources.

Species have adapted through natural selection to fill available niches

Adaptations

Structural Adaptations

Physiological Adaptations

Behavioral Adaptations

Homologous Structures

Define:

Homologous structures are the result of divergent evolution.   

Pentadactyl Limb as Homologous Structure

In tetrapods, the basic pentadactyl limb has been adapted to serve specialized locomotory functions.

https://classconnection.s3.amazonaws.com/239/flashcards/782239/jpg/homology-limbs1360130251235.jpg

Such homologies indicate divergent evolution, as the basic limb plan has been adapted to meet the needs of different niches.

Leaf as Homologous Structure

In some plants the leaves show different functions and shapes from the 'normal' leaves we think about.

However, these structures share common ancestry with typical leaves, and as such are homologous!

Flower as Homologous Structure

The general flower structure pattern is homologous, meaning it is a similarity due to shared ancestry of all angiospermatophyta.   A typical flower has four major structures:

As flowering plants diversified, different lineages evolved to use these basic parts in different ways.

Fossils

The fossil record is a substantial, but incomplete, record of evolutionary history:

Adaptive Radiation

Define:

 

EXAMPLES:

Example

What caused the niches to be available for new species?

What was the ancestral species?

How many species were formed from the ancestral species?

How many years did it take for the adaptive radiation to occur?

Mammals after dinosaur extinction

Finches on Galapagos Islands

Ant Nest Beetles on Madagascar

Silversword on the Hawaiian Islands

Anoles on Caribbean Islands

Pace of Evolution                                                 

Gradualism  

Punctuated Equilibrium

  • Continuous, gradual change over a long period of time

  • Slight variations with a selective advantage differentially survive and reproduce

  • When species evolve by gradualism there are transitional forms seen in the fossil record

  • EXAMPLE:  

  • Long periods of stability followed by spurts of sudden change (“sudden change” may be thousands of years on the vast scale of geological time).  

  • Rapid evolution may be due to:

  • When species evolve by punctuated equilibrium, there are few transitional forms seen in the fossil record.


Analogous Structures

Define:

Analogous structures are the result of convergent evolution.   

EXAMPLES:

illustrate two examples