7. Changes in biodiversity over time Part 2

Question 1

What does biogeography refer to?

Answer 1

The study of the distribution of organisms and ecosystems across the world and through geological time.
-The far-flung distribution of similar groups of organisms provides evidence that Gondwana once existed.

Question 2

What is structural morphology and describe what its 2 types include:

Answer 2

Used to establish an evolutionary relationship of the basis of structural similarities and differences.

• External morphology includes shape, structure, colour, pattern, and size of features.
• Internal morphology includes bones and organs.

Question 3

What is embryology?

Answer 3

The study of the developing embryo in animals or plants.

-Closely related organisms go through similar stages during their embryonic development

Question 4

What is developmental biology?

Answer 4

Compares the development processes of different organisms to uncover the ancestral relationships between them, and also investigates how developmental processes have evolved.

Question 5

Give an example of developmental biology:

Answer 5

Species do not appear to differ much in their structural genes, such as those coding for enzymes, but what does differ is the way that gene expression is regulated and controlled during development in different organisms.

Question 6

What are homologous structures? Give an example:

Answer 6

Structures that have a common evolutionary origin and similar underlying anatomy, but have evolved in different ways in different groups due to different selection pressures.
Eg. The pentadactyl limb: A hand or foot with 5 fingers or toes. In different species the limb has been modified to suit a variety of different ways of life. (evidence of common ancestry).

Question 7

What are vestigial homologous structures? Give an example:

Answer 7

Structures that are reduced in size and role due to lack of selection pressure for their maintenance. The structure remains part of the organism’s anatomy despite having no useful purpose because there is no selection pressure for its complete removal.
Eg. Coccyx (tailbone) in humans. (evidence of shared ancestry)

Question 8

What are analogous structures and what are they a result of? Give an example:

Answer 8

Structures that have similar functions but have evolved independently. The same selection pressures have caused the same feature to be selected for in diverse species.
-Result of convergent evolution
Eg. The body shapes of sharks (fish) and dolphins (mammals).

Question 9

What is divergent evolution and how does it result in specialisation? Give an example:

Answer 9

An evolutionary process resulting in a variety of different forms which have been derived from a common ancestor.
-Differences between groups of organisms accumulate to a critical point that leads to speciation.
-This is usually the result of a dispersal of a single species to different environments, such as populations that become isolated from one another and evolve different adaptions in response to environmental pressures.
Eg. Koalas (tree-dwelling herbivores), Tasmanian devils (ground-dwelling carnivores) and marsupial moles (dune-burrowing insectivores) have a common marsupial ancestor, however, have quite different feeding structures.

Question 10

What is adaptive radiation in relation to divergent evolution? Give an example:

Answer 10

Form of divergent evolution where one ancestral species gives rise to many new species that occupy different niches.
Eg. Darwin’s finches

Question 11

What is convergent evolution? Give an example:

Answer 11

An evolutionary process resulting in unrelated species developing similar features due to similar selection pressures.
Eg. Anteaters – many animals eat ants and termites and have developed similar structures even though they are not closely related. (structures are analogous structures)

Question 12

What are extinctions and mass extinctions?

Answer 12

Are patterns of evolution have been important in determining the species that are present today.
-Mass extinctions open up many niches, which allows adaptive radiation to occur

Question 13

Describe a mass extinctions which has been documented in the fossil record within the last 500 million years:

Answer 13

The Cretaceous mass extinction 65 mya which saw the demise of the dinosaurs

Question 14

List the 3 major causes of mass extinctions:

Answer 14

• Climate change
• Volcanic events
• Cosmic factors

Question 15

Explain how climate change is a major cause of mass extinctions:

Answer 15

Climate change can be gradual or rapid, and affect the available niches for species.
-A cooling climate will produce more ice at the poles, which in turn causes more reflection of light and heat, which makes the Earth cool more.

Question 16

Explain how volcanic events are a major cause of mass extinctions:

Answer 16

Lava flows can have local effects on species, but ash explosions can influence climate, causing more widespread effects on species. Acid rain from volcanic gases can cause changes in the acidity of the oceans.

Question 17

Explain how cosmic factors are a major cause of mass extinctions:

Answer 17

Large impacts can cause changes in volcanic activity and climate - clouds of smoke causing cooling, and fires releasing greenhouse gases into the atmosphere, causing rapid warming.

Question 18

List the significant changes in life forms in Earth’s geological history (oldest to youngest):

Answer 18

• Earth formed
• First prokaryote cells
• First eukaryotic cells
• First simple multicellular organism
• First multicellular animals appear
• First land animals
• First mammals
• First flowering plants