migration notes

Question 1

what is Migration

Answer 1

Migration is the seasonal mass movement of animals from their breeding area to another location

Question 2

The triggers for migration depend on the species but could be

Answer 2

-Changes in temperature
- Change in the length of day (photoperiod)
- In-built genetic drive
Reproductive need/reaching reproductive maturity.

Question 3

witch is the most reliable trigger of migration

Answer 3

The photoperiod is a more reliable cue than temperature as its length is the same each year on a particular day however temperature can vary year to year.

Question 4

what would have had to happen for animals to evolve for migration

Answer 4

The benefits for an animal to migrate must have outweighed the risks otherwise it would not have evolved as a behavioural response in so many species.

Question 5

benifits of migration includes:

Answer 5

• Migration avoids climatic conditions and move to an area of more favourable conditions e.g. cold temperatures, snow that may have killed the individual, meaning less individuals reproducing come breeding season – population numbers drop
• Migrating species often meet in an area to breed. Therefore migration increases the chance of meeting a breeding partner. This also increases the genetic variation of a species allowing it to better cope with a changing environment.
• Living in cold conditions requires a great deal of energy expenditure keeping warm. Migrating to warmer climates reduces this energy expenditure allowing organisms to be in better physiological condition for reproduction – population numbers rise
• Migrating to an area where there is a great food source or less competition for food. Organisms gain greater energy from food and are in better physiological state for reproduction – population numbers rise
• Migrating away during a time when predator numbers may be high will increase an individual’s chance of survival, more therefore reach reproductive age – population numbers rise

Question 6

disadvantages of migration includes

Answer 6

• Migrating long distances requires a huge energy input/expenditure. The journey may end up costing too much energy and the organism dies causing a drop in population numbers. The organism could also put so much energy into migrating that they are in poor reproductive state that offspring numbers are down and the population remains static in size or drops
• There is a huge potential risk of getting lost despite having effective navigating tools. If individuals are lost they die or become unable to be part of a breeding colony. Less individuals reproducing causes a drop in population numbers
• There is also a risk in getting caught by predators or killed due to environmental extremes. This would mean less individuals reaching reproductive age and population declines