Intro and Darwin

Question 1

What is biological diversity and what does it include?

Answer 1

• variety of life on earth
  includes all the different plants, animals, and microorganisms; the genes they contain; and the ecosystems they form on land and in water. (constantly changing)

Question 2

How many species are estimated to live on earth vs species are known on earth?

Answer 2

2 billion (2017 estimate, which, unusually, projected for bacteria too) vs described only 1.5 million (less than 1% of them)

Question 3

Give an example of number of certain species known

Answer 3

7% of fungi are known
10% of spiders are known
10,000 vertebrates still undetected

Question 4

Why is it difficult to estimate the number of species in earth?

Answer 4

• hard to count life
• true diversity of microorganisms may have been underestimated
• life living in life may not be accounted for
• definition of species

Question 5

Why is it hard to count life and how do scientists actually attempt to do it?

Answer 5

• Many live in inaccessible habitats (such as the deep sea), are too small to see, are hard to find, or live inside other living things.
  Instead of counting, scientists try to estimate the total number of species by looking for patterns in biodiversity (look at rate of discovery of new ones), for example Terry Erwin

Question 6

How did we come up with the estimate for no of species on earth?

Answer 6

• early 1980s, American entomologist Terry Erwin estimated the number of species on Earth by spraying pesticides into the canopy of tropical rainforest trees in Panama.
• least 1,200 species of beetle fell to the ground, of which 163 lived only on a single tree species.
  -assume each tree species had a similar number of beetles, and given that beetles make up about 40% of insects (the largest animal group), Erwin arrived at a controversial estimate of 30 million species on Earth.
  (Many scientists believe the 30 million number is far too high. Later estimates arrived at figures under 10 million.)

Question 7

How can the true diversity of micro organisms be underestimated?

Answer 7

estimates of global biodiversity overlook microorganisms such as bacteria because many of these organisms can only be identified to species level by sequencing their DNA
compiling and analysing a database of DNA sequences from 5 million microbe species from 35,000 sites around the world - 1 trillion species on Earth.
like previous estimates, this one relies on patterns in biodiversity, and not everyone agrees these should be applied to microorganisms.

Question 8

How are life forms living inside other life forms disregarded when referring to biodiversity and abundancy on earth?

Answer 8

Most – and possibly all – insect species are the victim of at least one or morespecies of parasitic wasp. These lay their eggs in or on a host species (think of the movie Aliens, if the aliens had wings). Researcherssuggestthat the insect group containing wasps may be the largest group of animals on the planet.

Question 9

Approximately, how many species are turning up each year?

Answer 9

New species are turning up all the time, at a rate of roughly 18,000 species each year. For example, researchers in Los Angeles found 30 new species of scuttle fly living in urban parks, while researchers also in the US discovered more than 1,400 new species of bacteria living in the belly buttons of university students.

Question 10

What is the source of diversity

Answer 10

The source of this diversity is evolution, the process of gradual change during which new species arise from older species.

Question 11

Biological diversity is constantly changing. How is it increased or decreased?

Answer 11

It is increased by new genetic variation and reduced by extinction and habitat degradation.

Question 12

Life is designed for a purpose, give an example

Answer 12

“what is a mountain for?” (UNIQUE)
Frog has 
Fingers for grasping,
Eyes placed so it can see out of the water, 
Colour to blend in with leaves

Question 13

Give an example of poor design for life?

Answer 13

Wiring - collects information from light to help draw picture. In humans, doesn’t come from side of receptors - eyes aren’t as good as it could be, unlike insects (wiring doesn’t get in the way)

Question 14

What was vertical speciciation?

Answer 14

First coherent theory of evolution

Question 15

What are the two forces that drive vertical speciation?

Answer 15

Complexifying force

Environmental force

Question 16

What is the complexifying force that drives vertical speciation?

Answer 16

complexifying force driving organisms up a ladder of complexity from single cell “infusorian” towards more complex species, get more complex with time

Question 17

What did the complexifying force suggest in terms of the evolutionary process?

Answer 17

suggested species change into other species, so a real evolutionary process.

Question 18

What is the environmental force that drives vertical speciation?

Answer 18

) environmental force adapted them to local environments throughuse and disuseof characteristics. Regularly used organs got stronger, disused ones disappeared.
These adapted characteristics were passed on to the offspring of that animal = inheritance of acquired characteristics

Question 19

What did the environmental force suggest in terms of the evolutionary process?

Answer 19

we don’t now think modifications to traits acquired during life usually get passed on (but see epigenetics for a case where they are).

Question 20

What were the two major breakthroughs that would lead to what is now the theory of evolution

Answer 20

1) Lamark and vertical speciation

2) Matlhus and Principle of Population

Question 21

What was the principle of population?

Answer 21

Human population inc exponentially, food supply isnt. (depends on area available) Will not keep up with population

Question 22

What will restore the balance in the principle of population?

Answer 22

Famine, war, disease

Question 23

What was the short step to natural selection

Answer 23

Principle of population

Question 24

What were the insights of darwin and wallace?

Answer 24

• horizontal speciation
• gradualism
• common descent
• man as an animal
• mechanism of evolution = natural selection

Question 25

What is horizontal speciation?

Answer 25

Darwin observed 2 species of rhea, and realised they could BOTH have evolved from the same ancestor by a split in the evolutionary line.

Question 26

How did Darwin and Wallace conclude that evolution was gradual (gradualism)

Answer 26

Darwin observed three species of mockingbird on three islands, and their slight differences.
speciation happened gradually, not a sudden change to a new type

Question 27

How did darwin and wallace conclude the idea of common descent?

Answer 27

Gradualism + Horizontal Speciation led to idea - that branching of the tree could be at any level,
if 2 species of mockingbird bird could have a common ancestor, so could 2 phyla (e.g. birds and reptiles).
All life must have one ancestor!

Question 28

How did darwin and wallace conclude the idea that man is an animal?

Answer 28

Man is part of this tree of life, among the apes.

Follows logically from common descent idea.

Question 29

What did darwin and wallace conclude as the mechanism of evolution?

Answer 29

Natural Selection - First and still only good mechanism for evolution proposed.
Not a theory - Inevitable outcome of excess production, survival of the best adapted, and heredity of those traits.