BioKnowledgy presentation on A.6 Ethology

Essential idea: Natural selection favours specific types of behaviour.

A.6 Ethology

Bird courtship displays are very visual examples of behaviours that have arisen and been exaggerated by natural selection. For example male Greater Frigate birds (Fregata minor) use sight as well as sound to attract a mate.

By Chris Paine

http://www.bioknowledgy.info/ http://www.bbc.co.uk/programmes/p00m3rn5

https://commons.wikimedia.org/wiki/File:Male_greater_frigate_bird_displaying.jpg

http://www.bioknowledgy.info/




http://www.bbc.co.uk/programmes/p00m3rn5

http://www.bbc.co.uk/programmes/p00m3rn5



Understandings, Applications and SkillsStatement Guidance

A.6.U1 Ethology is the study of animal behaviour in natural conditions.

A.6.U2 Natural selection can change the frequency of observed animal behaviour.

A.6.U3 Behaviour that increases the chances of survival and reproduction will become more prevalent in a population.

A.6.U4 Learned behaviour can spread through a population or be lost from it more rapidly than innate behaviour.

A.6.A1 Migratory behaviour in blackcaps as an example of the genetic basis of behaviour and its change by natural selection.

Other examples, including local examples can be also be studied.

A.6.A2 Blood sharing in vampire bats as an example of the development of altruistic behaviour by natural selection.

A.6.A3 Foraging behaviour in shore crabs as an example of increasing chances of survival by optimal prey choice.

A.6.A4 Breeding strategies in coho salmon populations as an example of behaviour affecting chances of survival and reproduction.

A.6.A5 Courtship in birds of paradise as an example of mate selection.

A.6.A6 Synchronized oestrus in female lions in a pride as an example of innate behaviour that increases the chances of survival and reproduction of offspring.

A.6.A7 Feeding on cream from milk bottles in blue tits as an example of the development and loss of learned behaviour.

A.6.U1 Ethology is the study of animal behaviour in natural conditions. AND A.6.U2 Natural selection can change the frequency of observed animal behaviour. AND A.6.U3 Behaviour that increases the chances of survival and reproduction will become more prevalent in a population.

Ethology is the study of animal behaviour especially under natural conditions

Most of the examples of behaviour included are innate. They are automatic responses to stimuli, which are controlled by genes and therefore subject to natural selection.

The environment alters the stimuli and hence the behaviours observed. Therefore to fully understand behaviours the conditions under which they are studied are as natural as possible.

1. Populations tend to produce more offspring that the environment can support. This leads to competition for resources and a struggle for survival.

2. Populations show variation in behaviours due to mutation of genes.

3. Behaviours that improve an organism’s survival or reproductive fitness will be selected for.

4. Therefore over time (generations) the frequency of genes for the optimised behaviours in a population will increase.

https://commons.wikimedia.org/wiki/File:Birdwatching.jpg



A.6.A1 Migratory behaviour in blackcaps as an example of the genetic basis of behaviour and its change by natural selection.

Migratory behaviour : Natural selection in Blackcaps (Sylvia atricapilla)

http://scienceblogs.com/notrocketscience/2009/12/03/british-birdfeeders-split-blackcaps-into-two-genetically-dis/

http://www.nature.com/nature/journal/v360/n6405/abs/360668a0.html

http://evolution.berkeley.edu/evolibrary/images/news/blackcapmap.gif

Normal behaviour: in autumn most blackcaps migrated south to Spain to avoid the cold winter

Variation in behaviour: small number of blackcaps migrated north-west to the UK

*The reproductive advantage could come from several sources: exploiting food resources with initially less competition, occupying choice territories, hatchlings have longer to develop before the autumn migration.

Selective advantage: shorter flight to the UK and agood supply of food (from bird enthusiasts) plus.Bird wintering in the UK return to breeding sites before those migrating south and hence are reproductively more successful*.

Natural selection: the genes for north-west migration increased in frequency amongst the blackcap population.












Nature of science: Testing a hypothesis - experiments to test hypotheses on the migratory behaviour of blackcaps have been carried out. (1.9)

Migratory behaviour : Natural selection in Blackcaps (Sylvia atricapilla)




Normal behaviour: in autumn most blackcaps migrated south to Spain to avoid the cold winter

Variation in behaviour: small number of blackcaps migrated north-west to the UK

*The reproductive advantage could come from several sources: exploiting food resources with initially less competition, occupying choice territories, hatchlings have longer to develop before the autumn migration.

Selective advantage: shorter flight to the UK and agood supply of food (from bird enthusiasts) plus.Bird wintering in the UK return to breeding sites before those migrating south and hence are reproductively more successful*.

Natural selection: the genes for north-west migration increased in frequency amongst the blackcap population.

Experimental evidence: eggs were taken from both populations and the

hatchlings raised in captivity, independent of parents. The hatchlings

persisting in following the migration patterns of their genetic parents.












A.6.A2 Blood sharing in vampire bats as an example of the development of altruistic behaviour by natural selection.

Altruism is behaviour which benefits another individual at the cost of the performer

Groups of breeding females will reguritate blood for females that have failed to feed. This is called reciprocal altruism because bats that donate food in the future might receive blood when hungry. This ensures low mortality rates and a high rate of breeding success within the group. It has been shown that blood sharing happens between related and unrelated bats.

Edited from: http://www.slideshare.net/gurustip/e6-further-studies-of-behaviour-hl

Altruistic behaviour : blood sharing in Vampire bats

https://youtu.be/9Va9ull44yw

Due to the the increasing rate of breeding success the Altruistic behaviour is selected for opposed to more selfish behaviours.

http://www.slideshare.net/gurustip/e6-further-studies-of-behaviour-hl







http://i-biology.net/


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For a given sized crab there is an optimal mussel size at which profitability (energy content/handling time) is at a maximum. The optimal mussel size increases with crab size.

With unlimited prey availability, crabs choose mussel sizes close to the predicted optimum.

As the optimal mussels become depleted, crabs choose progressively less valuable mussels both above and below the optimal size.

Suboptimal mussels may initially be rejected, but are consumed at a a second or third inspection as the optimal sized mussels become scarce.

Foraging behaviour : Shore crabs (Carcinus maenas) feeding on mussels (Mytilus edulis)

http://biology-forums.com/gallery/33_02_08_11_12_19_05_13601522.jpeghttp://www.jstor.org/stable/3925?origin=crossref&seq=1#page_scan_tab_contents

http://biology-forums.com/gallery/33_02_08_11_12_19_05_13601522.jpeg


http://www.jstor.org/stable/3925?origin=crossref&seq=1%23page_scan_tab_contents



asdasdasdForaging behaviour : Shore crabs (Carcinus maenas) feeding on mussels (Mytilus edulis)


Repeated studies have observed (see the graph) that the size of mussel most frequently consumed is below that which provides maximum profitability. Can you suggest a reason for this?






asdasdasdForaging behaviour : Shore crabs (Carcinus maenas) feeding on mussels (Mytilus edulis)


Repeated studies have observed (see the graph) that the size of mussel most frequently consumed is below that which provides maximum profitability. Can you suggest a reason for this?

It takes greater force to feed on larger mussels, this causes ‘wear and tear’ damage which shortens the crab’s life expectancy.

Extension: studies have also observed that crabs use different feeding mechanisms with different sized prey and that the shape of a mussel shell is as important to foraging behaviour as size. What is described in the example is one aspect of shore crab’s complex foraging behaviour.





A.6.A4 Breeding strategies in coho salmon populations as an example of behaviour affecting chances of survival and reproduction.

Breeding strategy : sneaker jacks in Coho salmon (Oncorhynchus kisutch)

Close encounters of the sneaky kind - Smithsonian.comhttp://www.smithsonianmag.com/science-nature/close-encounters-of-the-sneaky-kind-85147028/?no-ist

http://www.centralcoastbiodiversity.org/uploads/1/4/9/9/14993002/6123046_orig.jpg?366

Commonly larger males out-compete smaller males for access to mates and so are more likely to breed successfully. In some animals, e.g. Coho salmon, sneaker males, who fertilise by stealth, are as successful as the larger males.

Hooknose (sneaker) JacksTime maturing at sea 3 years 2 years

Size, shape Large, pronounced hooknose Smaller, less pronounced nose

Survival rate(to spawning age)

Low - suffer from predation and fishing

High - less time exposed to predators

Breeding strategy Fight for access to females Being quicker and more agile can sneak up on a mating pair and deposits sperm on the eggs

http://www.smithsonianmag.com/science-nature/close-encounters-of-the-sneaky-kind-85147028/?no-ist







A.6.A6 Synchronized oestrus in female lions in a pride as an example of innate behaviour that increases the chances of survival and reproduction of offspring.

Innate behaviour : synchronized oestrus in female lions (Felix leo)

A second benefit synchronised oestrus may be that young male lions can more easily form coalitions with others that leave the pride at the same time. Coalitions are more successful than single males in taking over a pride and breeding.

https://commons.wikimedia.org/wiki/File:Lion_cub_with_mother.jpg

*A coalition can typically maintain control of a pride for up to 4 years before being supplanted by a new coalition.

Lion prides consist of females, cubs and a small coalition of dominant males*. Most adult males live singularly or in a small coalition independent of a pride. Only dominant males can breed.

Female lions raise their cubs together in a creche. All the mothers work together to feed (mother will suckle unrelated cubs) and protect the cubs increasing the chances of survival for all.

To facilitate the creche behaviour female lions have a variable cycle and will come into oestrus (become fertile) at the same time; hence the birthing of cubs from different mothers is close together. Stimuli provoking oestrus is typically a female in the same pride enters oestrus or infanticide of all cubs by a coalition of males taking over a pride.



A.6.U4 Learned behaviour can spread through a population or be lost from it more rapidly than innate behaviour. ANDA.6.A7 Feeding on cream from milk bottles in blue tits as an example of the development and loss of learned behaviour.

Development and loss of learned behaviour :

Observation identified Blue Tits as the culprits. The cream was easily accessible and a rich source of nutrients for the birds. The behaviour spread rapidly to Blue Tit and Great Tit (Parus major) populations throughout Europe. The introduction of aluminium foil bottle caps did nothing to change the behaviour.

In 1921, people who had milk delivered to their door in Swaythling, England started to notice that the cream was being consumed from the top of the milk bottle.

The behaviour rapidly disappeared in the 1990s. This was thought to be due to a combination of factors:• A decline in doorstep deliveries

as more people bought milk from supermarkets

• People started to favour low fat (low cream) milk

• More secure caps for bottles

The rapid spread and loss of the behaviour indicate that this is a learned behaviour. The spread of Innate behaviour is limited to the production and survival of offspring.

Blue tits (Cyanistes caeruleus) and milk bottles

read more: More than just milk thieveshttp://www.dailymail.co.uk/sciencetech/article-2868613/Great-tits-pass-traditions-adapt-fit-locals.html

http://www.dailymail.co.uk/sciencetech/article-2868613/Great-tits-pass-traditions-adapt-fit-locals.html





Mate selection: courtship in birds of paradise

http://kstreetmagazine.com/wp-content/uploads/2012/10/06_birds_of_paradise_p.112-BOP-100916-076.jpeg

The male Greater bird of paradise (Paradisaea apoda) is larger and has much more showy plumage than the plain female.

Male birds gather at courtship sites called ‘leks’ to compete for a female reproductive partner. The females then select a male based on both spectacular plumage and a vigorous performance of the courtship dance.

There is a trade-off for males between having showy plumage and avoiding predation. Those that survive and successfully mate with a female will pass on their genes for plumage and courtship dance behaviour. Therefore genes for exaggerated plumage and courtship dances are selected for, if combined with genes that favour surviving to a reproductive age.






Discuss the innate and learned behaviours humans use

for mate selection.


Bibliography / Acknowledgments

http://ib.bioninja.com.au/


Education

BioKnowledgy presentation on A.6 Ethology