Costs, benefits and consequences of interactions 5.2 Interactions with the environment

What can an organism do if their external environment changes? 1.Resist or tolerate the change (eg. feels cold but doesn’t die!) 2.Regulate the internal equilibrium as a response to the change (eg. Homeostasis) 3. They can move away to an area that is more suitable 4. Adapt - an ORGANISM can’t adapt but the species can over a very long time

Resistance or toleration of change % survivability Environmental condition or resource LowHigh Zone of tolerance Key point - there are limits to the ability to tolerate change. Zone of resistance

Tips for Note-taking 1.Have the internet to hand to check words and read about ideas. 2. Include definitions. 3.Include examples. 4.Group information – use bullets or numbers to make lists 5.Mind Map it 6.Digest the information then explain first using complex terminology then in simple terms. 7.Try to link ideas together 8.Summarise what you have just learned.

Example - Life in deserts Adaptations to cope with dry conditions:- see box p27 and make notes Points to consider: 1.What are the 2 main problems facing organisms in this environment? 2.Why is this so difficult to overcome? 3.List any totally new terms at the end of your note.

Costs, benefits and consequences of interactions 5.3 Variation in life history

Life history is organised to suit specific needs Stable predictable environment, climax community long lifespan Changing environmental conditions, pioneer species early reproduction slow growing slow reproduction rate high rate of population increase rapid development K - strategists (large mammals, some birds) r - strategists (bacteria, insects, weeds)

Reproduction styles Multiple breeding opportunities e.g. humans or trees Single breeding opportunities e.g. salmon, squid, eels Broadcast fertilisation huge numbers of gametes produced survival rate is low little or no parental care Narrowcast fertilisation small numbers of gametes produced survival rate is high lots of parental care K - strategists r - strategists

Life History Adaptations to Cope with environmental Change Seasonal change requires a period of rest dormancy (period of ‘rest’) diapause (period of cessation of growth)

‘Rest’ of either type can be Predictive (usually K - strategists) occurs in advance of adverse conditions where seasons are predictable genetically determined Consequential (usually R - strategists) occurs when conditions become suddenly adverse

Types of Dormancy Facultative (consequential) optional, occurs when conditions become adverse Obligate (predictive) associated with a stage in development - bacteria and fungi - stage in insect life cycle where growth stops completely (pupa) -inactive state where metabolism slows down to conserve energy - inactive period during hot dry Resting spores (F) Diapause (O) Hibernation (O or F) Aestivation (F)

Today (and Homework) 1.Complete Scholar online activity “Life history of Chlamydomonas” 2.Complete Scholar online activity “Life history of Taenia spp” 3.Using the examples of fish and elephants, compare the life histories of an r-selected species and a K-selected species. (15) Hand in next week. 4.Explain the function of dormancy and describe the different types. In your jotter - don’t hand in. 5.For next week (Monday) reading on “Homeostasis” - Monograph Pg 30-32