BIOL1003 Study Guide - Final Guide: Behavioral Ecology, Quantitative Trait Locus, Pupa
Behavioural Ecology
• "Behavioural ecology" - concerned with how behaviour evolves through the process of natural
selection, and focuses on the adaptiveness of behaviour.
Tinbergen's Four Questions
1. Development – how does behaviour develop during an aial’s lifetie?
2. Mechanism – what are the physiological and other direct causes of behaviour?
3. Adaptive function – how does a behaviour help an animal survive or reproduce, and therefore
why has it evolved?
4. Evolutionary history – how has current behaviour changed from ancestors?
Testing for Heritability of Behaviour
• An evolutionary approach assumes that behaviour is heritable, so that it can evolve by the
process of natural selection.
• We consider four ways to test if behaviour can be inherited.
1. Correlation
between parents
and offspring
• Similarity between parents and offspring that is not due to learning or
the environment shows that behaviour is heritable.
• Eg: Blackcaps raised in captivity show the same pattern of migratory
behaviour as their parents.
• Nocturnal restlessness in cages is noted, and direction, magnitude and
duration are recorded.
• Migration is in the blackcaps genes - the direction they travel, the
distance and the urge to migrate.
2. Cross-breeding
experiments to
look at genetic
mechanisms
• Genetic crosses between populations with different behaviours can
reveal the mechanisms of inheritance.
• Eg: Cross-breeding in the blackcap leads to an intermediate behaviour
that is probably due to polygenic inheritance.
• The German flies SW, the Austrian flies SE and the hybrid flies in the
intermediate direction (S).
• Eg: Cross-breeding reveals simple inheritance of hygienic behaviour in
honeybees.
• Two components of behaviour:
1. Uncap cell of dead pupa
2. Remove dead pupa from hive
• Crossbreeding showed 2 alleles at 2 loci:
1. U doesn't uncap; u uncaps
2. R doesn't remove; r removes
3. Artificial
selection
experiments
• If some of the variation in behaviour among individuals in a population
is heritable, it should be possible to artificially select for different
behavioural traits.
• Eg: Field crickets can be selected to sing more or less than the parental
population.
• Eg: Behavioural variation among different breeds of dogs.
4. Molecular
genetics - to look
at specific genes
that influence
behaviour
• In some cases it is possible to track down the particular gene
responsible for differences in behaviour, and even use molecular
genetic methods to transfer genes from one species into another.
• Eg: Paternal behaviour in voles:
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• Prairie vole - lasting pair bonds, paternal care, active vasopressin
receptor gene ("social" gene).
• Meadow vole - solitary, no paternal care, less active vasopressin gene.
• Inserting the Prairie vole "social gene" into solitary Meadow voles
made them social.
Evolutionary History of Behaviour
• The heritability of behaviour means that it is valid to ask questions about both the adaptive
value and evolution of behaviour.
• Behaviour doesn't fossilise so it is usually not possible to follow its evolutionary history directly
in the fossil record, but comparison among species can suggest possible sequences of
behavioural evolution.
• Eg; The bizarre courtship behaviour of the balloon fly could have evolved in small seeps, like
the differences among species within the living empidid fly family.
• Courtship in the balloon fly - males carry silk balloons and females select the males carrying
the silk balloons.
• Courtship of empidid flies - males gather in swarms, males catch mosquitos, females select the
males with largest prey, during mating she will eat the prey item.
• Evolution of Balloon Fly Courtship
• Male searches for female alone → gives food to female → wrap food in silk - longer
distraction → suck prey dry before wrapping → nectar feeder - wraps insect fragment → silk
balloon without any content.
Making Decisions
• Makig deisios like what tie to get up i the orig a affet a aial’s haes of
survival or reproduction.
• We therefore assess whether animals do make adaptive decisions.
• To do this we also illustrate three methods to study adaptive questions about behaviour:
observation, experiment and optimality modelling.
• We do not have to assume that animals are able to make conscious decisions, merely that
natural selection has resulted in behaviours that help an animal to survive and reproduce.
• The mechanisms that affect behaviours are often unknown.
Provisioning of Young by Siberian Jays
• Siberian jays have well-hidden nests, but parents visiting a nest with food can give away its
location to predators.
• Parents therefore should visit less when there are more predators around.
• Observation - in support of this idea, Eggers found that jays fed at the greatest rate very early
in the morning before most predators became active.
• Experiment - this feeding pattern was absent in areas without
predators ad ould e propted y the playaks of predators’
calls, suggesting that jays indeed time feeds to avoid being spotted by
predators.
• Regardless of when they feed, jays face the dilemma that reducing
the risk of predation increases the risk of starvation and vice versa.
• An intermediate rate of feeding would therefore be the best.
Optimal Decisions
• The optiality approah to studyig adaptatio is ased o akig preditios aout the
optimal behaviour and testing these predictions with observations and experiments.
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