Testing Hypotheses In Behavioural Ecology (Sexual Segregation) Flashcards
List the stages in which one can approach the study of behaviour? (4) [IN ORDER]
• Observations.
• Hypotheses.
• Predictions.
• Tests.
Main ways in which one’s idea can be tested? (3)
• Comparison between individuals within a species.
• Experiments.
• Comparison among species.
Comparison between individuals within a species attributes? (2)
• Observational.
• Difficult to deal with confounding variables.
How do we tackle confounding variables when Comparing between individuals within a species?
Choose two populations that are similar with similar environments.
Pros of Comparison between individuals within a species? (2)
• No manipulation.
• Less costly.
Con of Comparison between individuals within a species?
• Can’t control all potential confounding variables
Experiments/Experimentation attributes? (2)
• Allows isolation of factors for comparison.
• Not just lab work.
Pro of Experiments?
• Control confounding variables.
Cons of Experiments? (2)
• Risk manipulation of results.
• More costly.
Comparison among species attribute?
Looking at the results of a long-term experiment done by NS.
Pro of Comparison among species?
Less costly.
Con of Comparison among species?
Time-consuming.
Sexual segregation?
= when females & males within species tend to segregate outside of the breeding/mating season.
Types of sexual segregation? (2)
• Habitat segregation.
• Social segregation.
Hypotheses/explanations under Habitat segregation? (2)
• Predation-risk hypothesis.
• Foraging preference hypothesis.
Hypotheses/explanations under Social segregation? (3)
• Social preference hypothesis.
• Activity budget hypothesis.
• Aggression hypothesis.
Predation risk hypothesis?
= based on the risk of being predated on.
Predation risk hypothesis attributes? (2)
• Males seek high risk, high energy areas.
• Females seek safety first.
Why do males seek high risk, high energy areas in Predation risk hypothesis?
It’s because they have high energy requirements (B>C).
Why do females seek safety first in Predation risk hypothesis?
It’s because they are often with young & would even compromise quality food (B>C).
Predation risk hypothesis papers? (2)
• Kohlman et al, 1996.
• Mooring et al 2003.
Egs of Predation risk hypothesis? (2)
• Nubian ibex.
• Desert bighorn sheep.
Foraging preference hypothesis attributes? (3)
• Males need quantity.
• Females seek higher quality food.
• Quality vs Quantity.
Why do females seek higher quality food? (2)
• Smaller body size.
• Lower digestive efficiency.
Why do males seek high quantity food? (2)
• Large body size.
• Higher digestive efficiency.
Foraging preference hypothesis paper?
Smith et al, 2007.
Smith et al, 2007 summary? (2)
● Bulls are more widely scattered across Kruger looking for quantity vegetation.
● Females & young have higher nutritional requirements per unit body mass.
Eg of Forgaing preference hypothesis?
Elephants.
Kohlman et al, 1996 summary? (3)
● Speaks on the Predation risk hypothesis in Nubian ibexes.
● Females with young foraged in safer areas even though they comprised the quality of food they foraged.
● Females without young (young in nurseries) foraged small groups in high risk areas that enabled them to get high quality food.
Mooring et al, 2003 summary? (3)
● Speaks on Predation risk hypothesis in Desert bighorn sheep.
● Rams went to forage in places with more food (high energy, high risk areas).
● Ewes went to rugged terrain regardless of whether those areas had good quality food or not, safety was prioritized.
Activity budget hypothesis attributes? (3)
• Mixed sex groups could be costly.
• Sexually size-dimorphic ungulates.
• Unisex groups in which activity budgets can be optimised & not compromised.
Activity budget hypothesis?
= based on males & females having different energy requirements.
Why could mixed sex groups be costly in Activity budget hypothesis?
It’s because it implies that some individuals would have to compromise on preferred areas.
Activity budget hypothesis paper?
Calhim et al 2006.
Eg of Activity budget hypothesis?
Feral goats.
Explain Activity budget hypothesis graph 1 (%Herd vs Time of day)? (2)
● Time spent in a particular (i.e., different individuals within the herd).
● F=foraging; L=lying; W=walking; S=standing.
Social preference hypothesis attributes? (2)
• Same-sex preferences alone lead to social segregation.
• Males prefer to stay with males & females with females.
Why do males prefer to stay with males & females with females in Social preference hypothesis?
It’s because of similar needs.
Social preference hypothesis paper?
Michelena et al, 2004.
Michelena et al, 2004 summary? (3)
● Speaks on social preference among Merino sheep.
● Found that sexual segregation was solely due to social preferences & not foraging activity budgets.
● Social preference due to male Merino sheep walking faster than females as they forage for shorter times than females.
Eg of social preference hypothesis?
Merino sheep.
Aggression hypothesis attributes? (2)
• Based on the fact that males tend to harass females.
• Females have to choose between predation-risk & male harrassment.
Why would women choose predation-risk over male harrassment in Wild guppies experiment for Aggression hypothesis?
It’s because the benefits were higher than the costs.
Aggression hypothesis paper?
Croft at al, 2006.
Croft et al, 2006 summary? (3)
● Speaks on Aggression hypothesis in Wild guppies.
● Female guppies had to choose between predation & male harrassment, and chose predation.
● Why predation? Females are inconspicuous in the deep, dark depths of the sea due to their small body size and dull colours in comparison to males, making them less detectable & prone to predators.
Eg of Aggression hypothesis?
Wild guppies.
Hypotheses explaining sexual segregation? (5)
• Predation-risk hypothesis.
• Foraging preference hypothesis.
• Social preference hypothesis.
• Activity budget hypothesis.
• Aggression hypothesis.
Comparison between individuals within a species paper?
• Calhim et al, 2006.
Experiments paper?
• Michelena et al, 2004.
Comparison among species paper?
• Mysterud, 2000.
Mysterud et al, 2000 summary? (1)
● Speaks on Activity budget hypothesis in sexual-dimorphic large herbivores.
3 methods of hypothesis testing?
• Comparison of individuals within a species.
• Experiments.
• Comparison among species.
Confounding variable?
= an external variable that systematically affects one or more levels of the independent variable.
Why compare among species?
To help us understand how differences in feeding or predation pressure (eg) influence the tendency to live in groups or to be solitary.
Investigating adaptation using Comparison among species?
= involves linking the different behaviours of species with differences in their ecology.
Egs of investigating adaptation using Comparative studies? (2)
• Comparison of breeding behaviour between Black-headed gulls & Kittiwake.
• Comparison between social organization in weaver birds.
Limitations using comparative studies to investigate adaptation? (3)
• Alternative hypotheses.
• Cause & effect (consequence & not a cause).
• Differences between species may reflect different solutions to the same problem.
Eg which has tried to overcome limitations of Comparative studies?
Primate ecology & behaviour.
Black headed gulls vs Kittiwake in terms of Nest site?
● Black headed gull = on ground.
● Kittiwake = on ledge on steep cliffs.
Black headed gulls vs Kittiwake in terms of Predation risk to nest?
● Black headed gull = high.
● Kittiwake = low.
Black headed gulls vs Kittiwake in terms of Chick behaviour?
● Black headed gull = cryptic colouration & hides in vegetation.
● Kittiwake = not cryptic & ignores predators.
Black headed gulls vs Kittiwake in terms of Adult response to predators?
● Black headed gull = alarm calls & attacks predator.
● Kittiwake = rarely alarm & weak attack.
Black headed gulls vs Kittiwake in terms of Chick feeding?
● Black headed gull = food calls to attract hidden young.
● Kittiwake = no food calls.
List differences between Black headed gulls & Kittiwake? (5)
• Nest site.
• Chick behaviour.
• Adult response to predators.
• Predation risk to nest.
• Chick feeding.
Improvements to Comparative studies? (3)
• Measure data on a continuous scale (continuous variables).
• Consider alternative hypotheses.
• Use different genera instead of species.
Investigating adaptation using Experimental studies?
= focuses on behaviour of individuals of the same species & analyzes it in terms of costs & benefits.
Eg of using Experimental studies to investigate adaptation?
Egg shell removal in Black headed gulls.
Limitation of Experimental studies to investigate adaptation?
Lack of quantitative predictions.
Way to improve on limitation of Experimental studies?
Include both qualitative & quantitative predictions of costs and benefits (optimalilty model).
Eg which has tried to overcome limitation of Experimental studies?
Crows & whelks.
Explain Crows & whelks example?
Crows reduce their ascending flight to break whelks.
Optimality model?
= model that is used to predict which trade-offs between costs & benefits give the maximum benefit.
Once you have a research idea, what are the steps to take to investigate it?
Once you formulate a research question, and you need to test a hypothesis, which 3 ways could you do it?
• Comparison between individuals within a species.
• Experiments.
• Comparison among species.
What does sexual segregation measure?
The degree of separation between males & females outside o the breeding season.
What hypotheses have been proposed to explain sexual segregation? Explain the mechanisms behind them.
