BIOL1997 Flashcards
Module 5
What are coping mechanisms to deal with the environment?
o Morphology
o Physiology
o Behaviour
What is behaviour?
part of how organisms respond to the biotic and abiotic environment
What does behaviour affect?
Fitness
What is fitness?
An individual’s relative contribution to the next generation’s gene pool
What is the experiment involving the small heath butterfly?
Experiment
• Provide food of different quality for butterfly larvae to feed on
o Fertiliser levels either low or high- unenhanced and enhanced nutrition grass
• Larvae can feed on either grass
• When they become adults, given different foods
o Low in amino acids or high with amino acids
• Larvae that were fed with highest quality food had the highest fitness
o Variables looked at for this conclusion were egg quantity and hatching mass
o However, not much difference between butterfly that were fed high quality and low quality food
Why is behaviour ecologically significant?
Is a link between individuals and their environment
Affect demographics (population levels outcomes)
Affects interactions among species (community-level outcomes)
Why is behaviour evolutionarily significant?
Has some genetic basis
Affects fitness
Can be selected
How do lizards behave to cool themselves down in the desert? What is their interaction with the abiotic environment.
o E.g. lizard cooling feet on hot Namib desert sand to avoid overheating
Rhythmically lift up and put down its feet to maintain cool
Feet never stays on same for more than a few seconds
How do ant lions interact with biotic environments (ambush)?
o Ant lions ambush
Buried with pincers below the sand surface
If ants walk by, will unbury itself and catch the ant
Cook prey before they eat it by putting it on sand surface
What are the properties of active predators such as dingos?
• Active predators- Agile, fast
o Probability of prey encounter is increased by chasing it
What are foraging strategies defined by?
- What they eat: frugivore, herbivore, nectivore, granivore, gramnivore, insectivore, carnivore, omnivore
- How they get it: ambush vs active
- Diet breadth: specialist (one kind of food) vs generalist (variety of foods)
What are common features of all foraging strategies?
- Non-random, that is, individuals make foraging choices
- Make choices about what to eat
- Optimal foraging theory- Macarthur, Piancka , Krebs
- Marginal value theorem- Charnov
What is the optimal foraging theory?
o Modelled which food items to eat in a non-depleting environment
o Predicts foragers should maximize net rate of food intake
What is the marginal value theorem?
o Modelled when to leave a food patch in a depleting environment
o Predicts that foragers should leave food patches when capture/harvest rate at patch is smaller than average capture/harvest rate
What are criticisms of the commonly known foraging strategies?
o Foraging will occur at cost of energy if a particular nutrient is needed
o Animals that are hungry vs animals that are not hungry would forage differently
What is the net rate model?
foraging maximizes net rate of energy delivered (energy gain per unit time)
What is the efficiency model?
maximize energy gain per unit energy spent
To discriminate against the net rate and efficiency model what experiment was done with bees and what was concluded?
• Tested with individually marked worker bees and artificial flowers
• Hence, found that efficiency model was upheld
• Conclusion:
o Forage non-randomly
o Maximize a foraging variable
What are predictions of the optimal foraging theory?
Try to draw the graph
• Focuses on efficiency of energy gain
• But most foragers are also prey
• Should expect
o Foraging strategies to be linked to predator avoidance strategies
o Trade-off between nutrient value of food and predator hunting grounds
o All prefer the lowest cost patch
How can organisms avoid being food?
• Run-away • Group together – more chance of bluffing it out or repelling predator • Hide (stick insect crypsis) Act costly • Act dangerous, mimic toxic organisms Be costly • Be toxic, have spines Feed in safe places or times • Vegetation cover
How do red-bellied pademelons avoid being eaten?
- Red-bellied pademelons more likely close to shelter
* Probability of pademelons being spotted are less likely the further away from cover they are
What are costs of anti-predator strategies?
- Feeding near vegetation cover may miss opportunities to forage elsewhere
- Grouping would result in competition for food and social aggression
What do you need for anti-predator strategies to evolve?
Benefits>costs
Using the barnacle geese as an example, what are the benefits/costs of being in a large group?
Competition for food –> less grass to eat
More birds present –> more eyes to look for predators
Less chance of being eaten in group due to dilution factor
What do courtships and mating behaviours involve?
o Male-male competition o Female choice o Results in non-random mating and non-random offspring o Sexual selection Put forward by Darwin
What are the costs and benefits of the Peacock mating behaviour?
o Peacock tail heavy and impractical but needed for courting
o High costs of a tail
Energy in production and maintenance
Risk of predation
o Benefits:
Access to mates and females
o Peacock tail arises from natural selection, via selective pressure associated with sexual reproduction
o Tail can be affected by predators and parasites- marker for male fitness so an intact tail is important
What is intrasexual selection?
Competition between males
Sexual dimorphism between males and females
• Females are smaller than male
What is intersexual selection?
Mate choice (females often choose the males)
Sexual dimorphism
• Females are plain but males are flashy
What is sperm competition?
Females mates with a lot of males
When fertilization takes place, female will use fittest sperm to fertilize
What are the benefits and costs of parental care? Provide an example for benefits.
• Benefits: survival and growth of offspring
• Costs: missed opportunities to reproduce again
• In some species, offspring stay and help parents rear more offspring
• Example: superb fairy wren- 19 year study
o Offspring help parents rear more offspring
Collect more food for the next generation
o Increase of independent young with more helpers
Can beings without a central brain behave?
- Slime molds behave and aggregate together even though they don’t have a central brain
- While foraging they have to be aware of the risks such as being in the light or being in dry conditions
How do plants behave?
• Leaves and stems o Grow towards light o Respond to their environment by moving • Roots o Grow along chemical gradients towards nutrients o Respond to their environment by moving • Plants behave but o In a different time frame o A different way of moving
What is a group and what are properties of a group?
o Multiple organisms occupying a common space
o Can be ephemeral or consistent
Ephemeral- last for a very short time
o Can be social (positive or negative), indirect (sharing common resource) or accidental (random chance)
-Not structured
What is a population and what are properties of populations?
o A number of organisms of the same species in a define geographical area
o Properties of populations include:
Number of individuals or population size
Area they occupy
Age structure
Sex ratio
What is the composition and structure of a population influenced by?
life history, mobility and habitat
What are populations essential in the study of?
Ecology • Distribution and abundance of individuals • Density Evolution • Populations of organisms evolve, not individuals • Gene flow Conservation and management • Invasive species • Defining threat status of taxa • Translocations and restoration
A population must be:
Cohesive
Aggregate
Structure
What is a unitary individual?
o Develop from zygote: genetically distinct
o Form is determinate
o Development and growth predictable
What is a modular individual?
o Grow by addition of modules (runners) and are genetically identical
o Individuals are highly variable in the number of modules
o Modular individuals often hard to count and define
What do populations have in terms of dynamic and distribution?
o Temporal dynamics
Lynx populations always peak after that of snowshoe hare
o Spatial distribution
-Affected by natural selection
How do you calculate population growth rate?
o Populations change in numbers over time
o Change can be positive or negative
o Rate(r) = change/unit time
o Geometric increase in growth represented by exponential growth
Do populations grow at the same rate?
No- at a different rate
What are the variables that drive changes in population size?
Birth Death Emigration (number leaving population) Immigration (number entering population) Growth (individual) Age at maturity Sex ratio
What is the population growth rate?
The change in numbers of individuals over time
What determines growth rates?
Addition and loss balance
When is a population closed?
When there is no emigration or immigration
Geometrically, how do you predict the number of individuals in the population at time t+1 when it is a closed population?
o Nt+1= Nt + Births-Deaths
What is discrete reproduction? Draw the graph and describe
o Discrete- reproduction occurs periodically (seasonally)
Results in pulses- pulse of individuals that have entered population, population decreases, another pulse occurs
What is continuous reproduction? Draw the graph and describe
o Continuous- reproduction occurs year-round
Smooth curve with no seasonality effect
How are birth rates estimated?
o Histology of reproductive organs o Capture/counting of fertilized gametes o Counting of newly born individuals Eggs, fruits… Marsupials- number of young developing in pouch
When does growth stop?
At carrying capacity
Is population growth limited? How?
Yes, it is limited by resources
How do you estimate death rates?
o Tagging
Following individuals (for sessile organisms)
Probability based ( for more motile organisms)
o Changes in size structure
Look at frequency vs age curve to look at mortality age
Estimate death rate from that
o Very challenging
Geometrically, how do you predict the number of individuals in the population at time t+1 when it is an open population?
• Nt+1= Nt + Births-Deaths + immigrants- emigrants
When is a population open?
If individuals immigrate and emmigrate
How do you estimate demographic rates in open populations?
o Tagging and recapture
Physical
GPS
Radio telemetry
Acoustic
o Genetics
Genetic similarity occurs with only very low levels of interbreeding between populations
Genetic differences- no movement between populations
Genetic analysis of microsatellites
Genetics measures the spatial and temporal aspect of different species
What are metapopulations and how are they formed? What do they depend on? Describe an example.
o Local populations, but individuals move
o Local populations in a big population
o Demographic rates vary spatially
o Large-scales dynamics dependent on local demographics and connectivity
• Mayfly o Larval stages mature in local pools o Adults disperse between pools o Mortality variable from pool to pool o Some pools are sources (low mortality) while others are sinks (high mortality)
How do you estimate population size?
- Counts
- Mark-release-recapture
What are different types of counts?
o Visual
o Auditory
o Acoustic
Why is the mark-release recapture method done?
o The MRR method estimates the total population size from a sample proportion of a mobile species
What is the mark-release-recapture method?
Take a sample of organisms
Mark them
Release them into population
Sometime later, recapture samples
What are the assumptions of the mark-release-recapture method?
Close population (that is, no immigration, not emigrations)
All individuals are equally likely to be marked
Marked individuals do not lose their mark
Marked individuals move back into the population randomly
What is the mark-release-recapture formula?
o Formula- M/N= R/n N= population size M= marked 1st time R=recaps (marked) n= sampled second time
How do you estimate growth and age in
- Trees
- Perennial plants
- Mammals
- Fish
o Trees-tree rings
o Perennial plants- rings in tap root
o Mammals- cementum rings in teeth
o Fish-otoliths
What do age and size structured population dynamics affect?
Fecundity
Survival
Population growth
What do life tables show?
o Life tables: show survivorship probability at each age
Long term studies- key to understanding population dynamics
Can all members of a population be treated as identicals?
o Cannot treat all members of a population as identical as unrepresentative of natural population structure
Why is there growth rates in western countries?
o Changes in human population size-mostly due to behavioural changes
o Current trend in developed countries- ageing population
o Growth rate of many western countries
Below replacement rate-falling death rates
So population numbers will level out then fall
What can contribute to extinction events?
o Genetic stochasticity (small populations) o Demographic stochasticity ( random nature of births and deaths) o Environmental stochasticity (variability) o Catastrophes (cyclones, epidemics, fire) o Human impacts (habitat loss, fragmentation, over-exploitation, hunting, pollution, introduction of new pest species, other environmental changes)
What is population viability analysis and why is it useful?
Tool to model population dynamics over time
• Uses basic population data
• Includes environmental variation in these values
• Can change values to reflect human impact
-Finds minimum viable population size
What information is needed for population viability analysis (PVA)?
- Carrying capacity
- Annual variation
- Maximum age
- Adult and juvenile mortality
- Mean litter size
- Chance of predator arrival
How can robustness of conclusions be tested?
• Test the robustness of conclusions using sensitivity analysis of the parameters based on known or hypothesized variance in the data used to estimate the parameters
What is a species?
• A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring
What is the biological species concept?
o Mayr’s definition of a species
Groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups
Can breed one variety with another
What are limitations of the biological species concept?
o This concept may not be relevant to organisms that are capable of asexual reproduction
o If the definition of a species requires that two individuals are capable of interbreeding, then an organism that does not interbreed is outside of that definition
o Does not apply to: as interbreeding cannot be observed
Fossils
Clonal species
Asexual species
o Organisms may also breed beyond the notional definition of species
Interspecific hybrids
• Fertility depends on which way the cross is going (what species the male and female are)
o Such as lomatia hybrids that have a lot of intermediate forms in overall size of the plants, partial amounts of divided leaf, stem…
Ring species
What is a ring species?
• A ring species arises when a parental population expands around an area of unsuitable habitat in such a way that when the two fronts meet they behave as distinct species while still being connected through a series of intergrading populations
• Geography can change when the species can breed and when they can’t
-ensatina high vs low elevations can’t breed
What are other species concepts?
o Ecological species How do they live, where do they live Classified by geography o Biological/Isolation species o Genetic species Cryptic species defined by their genotype o Cohesion species o Evolutionarily significant unit (ESU) o Phenetic species Classified through phenotype o Microspecies o Recognition species o Mate-recognition species
How does hybridization occur?
• Breakdown of reproductive isolating barriers which usually prevent gene flow between closely related species
• Potential causes include
o Habitat disturbance (species in closer proximity)
o Secondary contact (increased migration distances- pollinator change or dispersal)
o Altered phenology (leading to overlap in flowering times and pollen transfer)
o Altered genetics (not proven for Lomatia species)
What are the potential evolutionary outcomes of hybridization?
o Sterile first generation
o Speciation
o Enhanced variation
Why do we have a species problem?
• Because:
o Differing measures are often used, such as similarity of DNA, morphology and ecological niche
o Presence of specific locally adapted traits may further subdivide species into “infraspecific taxa” such as subspecies
o Many organisms do not conform to the reproductively isolated criteria
o Not possible to test this for fossil taxa
What is the species problem?
The difficulty of defining species
In different domains of study, what under-species classifications are used?
• Groups within a species can be defined as being of a taxon hierarchically lower than a species
• In zoology only the subspecies is used
• In botany, the variety, subvariety and form are used
• In conservation biology, the concept of evolutionary significant units is used, which may be define either species or smaller distinct population segments
• In horticulture there are cultivares
o Same species but slightly different genetics
• There are also breeds of domesticated animals such as dogs
• Variation between males and females
What are estimates of the number of species on Earth?
1.8 to 160 million
What is the range of the current species count?
1.5-1.8 million
How many named and unnamed species are there in Australia?
19200 named species
420000 unnamed species
Is the number of possible/named species accurate?
No- sources say different things