A4.1 Evolution and Speciation (year 6)

Question 1

Define evolution

Answer 1

The process of cumulative change in the heritable characteristics of a population

Question 2

Evidence for evolution

Answer 2

Biomolecules such as DNA, RNA, proteins can be processed to show differences and similarities between species, to show how specieis are realted to one another.

Question 3

practice drawing and analysing Phylogenetic trees

Answer 3

good luck

Question 4

Descibe the evidence for evolution from selective breeding of domesticated animals and crop plants (?)

Answer 4

After practicing selective breeding for hundreds of generations, farmers realized that certain varieties of animals now had unique combinations of characteristics that did not exsist before.
e.g. the transformation from teosinte to maize (??)

Question 5

Describe the evidence for evolution frfom homologous structures

Answer 5

Homologous structures - same format
PENTADACTYL LIMBS:
penta = 5
dactyl = fingers

The general format of the five-fingered limb found in animals is the same, although the specific functions of the limbs may differ

Question 6

Explain convergent evolution as the origin of analogous structures + 1 example

Answer 6

analogous structures - different format, same function

e.g. WINGS - wings in mosquitoes, eagles, bats, structurally all different but for the same function

These analgous structures indicate that this evolution (e.g. wings) is clearly advantageous. It is possible to have different organisms with different PHYLOGENIES (when a species split from another species) to share similar physical aspects.

Example: Marsupials are mammals that have a pouch instead of a placenta for nourishing their young during early development. The isolated continent of Australia is rich with examples of marusupials who have developed in similar ways as their distant placental cousins on other continents. FOR EXAMPLE: Tasmanian tiger was a marsupial that looked and behaved similarly to wolves and tigers from other continents

Question 7

What is the process of new species forming called?

Answer 7

SPECIATION- speciation is the ONLY WAY in which new species have appeared.
Gradual evolutionary change in a species IS NOT SPECIATION.

e,g, if a subgroup of a reproducing popoulation gets separated from the main population, it might evolve differently from the main population.

Question 8

How does speciation take place? + 1 example

Answer 8

Geographical isolation leads to reproductive isolation, where due to the geographical isolation the 2 populations will face different selection pressures, and evolve in different ways.

eventually the 2 populations will change so much that they will.be unable to reproduce with the other species = reproductive isolation = become 2 separate species

Example: BONOBOS and COMMON CHIMPANZEES: the congo river is a physical barrier preventing the 2 populations from interacting or interbreeding. The differences in habitat, availability of food and the presence of enemies led to differences in traits, more notably behavourial triats.

Chimpanzees are considered to be more aggressive and territorial, and have a male dominated social structure.
Bonobos are more peaceful and nomadic, and have a matriarchal social structure.

Question 9

Define + similarities/differences btwn allopatric and sympatric speciation

Answer 9

Allopatric speciation: a new species forms from an exsisting species because the population is separated by a physical barrier (e.g. geographical isolation)

Sympatric speciation: a new species forms from an exsisitng species living in the same geographical area.
Temporal isolation: incompatible time frames e.g. female and male parts of flowers reach maturity at difeerent times
Behavioral isolation: part of the population develpos a different hehaviour that isolates it from the rest of the population. e.g. songbirds develop different songs, over time part of the population will recognise diferent songs.

Question 10

Define + explain + 1 example adaptive radiation

Answer 10

Adaptive radiation occurs when many similar but distinct species evolve relatively rapidly from a single species/from a small number of species. More importantly, it allows closely related species to coexsist without competing, thereby increasing biodiverstiy in ecosystems where there are vacant niches

This happens because variation within a polulation allows certain members of that population to occupy different niches. e.g. having different beak shapes leads to eating different types of nuts

Question 11

Describe the barriers of hybridization of different animal species

Answer 11

Courtship behaviour - behavioral isolation = one populations lifestyle and habits are not compatible with those of another population

Sterile hybrids - e.g. mules - mules have an odd no. of chromosomes, 63, whereas gorses and donkeys have 64 and 62 respectively. So this mismatch makes the production of egg and sper cells difficult, if not impossible for mules and other species. = when hybrids form they will be sterile

Question 12

Describe abrupt speciation in plants by polyploidy+ 1 example

Answer 12

Polyploidy refers to the situtation in which a cell contrains 3 or more set sof chromosomes. It happens during the production of sex cells, and is much more common in plants than in animals.
In animals, polypkoidy is usually fatal, although in plannts it can lead to bigger fruits, more diseases resistant etc as there is extra geneti material to give the plant an advantage.

example: SMARTWEED has about 120 species, having members that are diploid, tetraploid, and even hexaploid. suggesting doublings of the chromsome numbers and hybridizations at some point.
It is an example of abrupt speciation as this speciation happens very quick, also known as instant speciation.