Exam prep Flashcards
What is animal behavior?
The internally coordinated responses (actions or inactions) of whole living organisms (individuals or groups) to internal and/or external stimuli, excluding responses more easily understood as developmental changes.
History of ethology?
Aristotle to Darwin to George Romanes to C L Morgan to Donald Griffin
Tinbergens 4 question?
Function (adaptation) - Why is the animal performing the behaviour? In which way does the behaviour increase the animal’s survival or reproduction?
Eg: nurturing of young, migration to warmer (and more food rich) habitats
Evolution (phylogeny) - How did the behaviour evolve? How has natural selection changed the behaviour over evolutionary time?
Eg: include reconstruction of phylogenies of closely related (or extinct) species and determining how the behaviour differs between these species. Comparison between species are needed to answer this question. For instance how flight in birds may have evolved from gliding in dinosaurs.
Causation (mechanism) - What causes the behaviour to be performed? What stimuli elicit the response?
Eg: include pheromones and hormones, such as increasing testosterone (caused by increasing day length) levels causing male display behaviour in many species of birds or moving shadows causing ragworms to withdraw into their burrows or contrast on beaks causing herring gull chick to peck.
Development (ontogeny) - How has the behaviour developed during the life time of the individual? In what ways has it been influenced by experience and learning?
Eg: include how courtship behaviour improves with age in many birds and how predators learn to avoid toxic or dangerous prey with experience.
E.g - Escape behaviour in cockroaches!
Function: Orientating away and escaping clearly enhances survival (reduce risk of getting eaten)
Evolution: Arms race between cricket reaction time and frog tongue strike
Causation: The air moved by the tongue hits the crickets sensitive abdominal hairs and triggers a rapid response of nerves and muscles.
Development: Even young 1st instar crickets show the escape response, i.e. it must be genetically determined, but plasticity in system from damage or loss of hairs.
E.g 2 - Courtship behaviour in the sage grouse!
Function: Attracts females (potentially result in mating, increase of fitness)
Evolution: Exaggeration of and amplification of feather erection (occurs when some birds are excited), sexual selection
Causation: Difficult to give details. Sight and calling of other males. Increase in sex hormones caused by increasing day length.
Development: Occurs in adult males. But young males have a poor outer territory so do not successfully mate (may take years to get to better territory)
How do animals use their environment?
The ways in which animals exploit their spatial environment is driven by the distribution of resources and the presence of predators
Predator presence indirectly influences animal distribution as they adjust their distribution in response to their perception of predation risk
Parameters of landscape of fear?
Animal knows where to find food, and shelter from predation.
What do predators and prey need to know?
save areas with environmental advantages and dangerous areas.
Assumption about animal in environment?
Implicit in the concept is that animals already have the ability, or they can learn, to differentiate dangerous versus safe habitats before they are killed
Use for quantifying landscape of fear?
Knowing how predator-prey relationships operate at the landscape scale should allow us to better assess the suitability of a landscape for future species re-introductions/translocations.
9 ways animal behavior studies could be used to solve conservation problems?
Response to human activities Response to land-use change Use of corridors Avoidance of roads Reserve design Response to exploitation Captive breeding Reintroduction and restoration Monitoring
Categories for Links between animal behavior and anthropogenically driven environmental change?
descriptions of changes in behavior in response to human activities,
animal behavior research that may have use in captive breeding and reintroduction programs,
and behavioral solutions to the major concerns of conservation practitioners. (Only this ne leads to significant change).
Can behavioral ecology contribute to conservation of areas?
Yes.
Habitat Loss and Fragmentation -
Functional landscape connectivity (degree to which landscape impedes or facilitates animal movement) explicitly concerns animal behaviour.
Habitat Degradation - Habitats can be degraded by introduction of noise, light and chemical pollution, disrupting critical behaviours, including those associated with signal transmission and the accurate assessment of predation risk and habitat quality.
Human–Wildlife Conflict and Overexploitation - They are often inter-related and invoke lethal effects. Human–wildlife conflict can be worsened by conservation efforts that alter the abundance, movement, or distribution of wildlife populations.
Disease and Invasive Species - Challenges in controlling disease and invasive species can be linked to the behavioural parameters affecting movement and reproduction. Behavioural traits can also be used to identify individuals most susceptible to disease, more likely to colonise new areas, or otherwise disproportionately important to the dynamics of disease and invasion.
Conservation Breeding and Translocation - By considering behavioural factors, such as social context, breeding success might be greatly improved. Understanding mate choice can have major effects on the productivity of breeding programs.
Three factors where animal behavior could aid conservation efforts?
Anthropogenic impacts on animal behavior
Behavior based management
Behavioral indicators
In what ways in behavior a conservation issue?
In wild: Behavioural modification due to: Rareness Habitat fragmentation Community depauperation Human and invasive species disturbance
In captivity: Inability to carry out natural behaviours due to lack of knowledge/inappropriate facilities. Stereotypic behaviours Imprinting issues Enclosure planning and enrichment Demographic imbalance
What behavioral characteristics have consequences for Ne (Population size)?
Deviations from monogamy (i.e. polyandry and polygyny) reduce Ne.
Promiscuity can enhance Ne.
Demographically unbalanced mortality (e.g. related to age or gender) can seriously reduce Ne.
What can be determined from effective population size?
Effective population size (Ne), which approximates the number of breeding individuals, can be used to determine the rate of loss of genetic heterozygosity from a population.
How do we modify animal behavior in the wild?
Inhibition of communication systems by noise or artificial light
Inhibition of movement by barriers - avoidance of roads; species-specific preferences for overpasses versus underpasses
Veterinary cordon fences e.g in Botswana
Attraction to crops and livestock e.g PAC (Problem Animal Control)
Direct interaction
Disruption by hunting or culling
Cautionary tales
Reintroductions
Captive breeding
True or false? Behavior is assumed o have evolved to be adaptive?
True.
What is needed to stimulate expression of behavior?
Environment still necessary to
stimulate development and/or
expression of behaviour
True or false - Genes do not encode behaviors directly?
True.
How do you identify a mutant? What do these methods work well with?
Determine phenotype.
Recessive or dominant
Plasticity (i.e. investigate the mutant under a range of environmental conditions
Pleiotropy (i.e. are other traits affected?)
Developmental integration
Does the mutation bestow a new function upon the gene, or eliminate its function?
Are there mutations with similar effects (think Gene Regulatory Networks)?
Mutagenic screens
Mutant hunt
Mutant selection
But also Genome-wide association studies
Works very well with morphological, and relatively non-plastic and discreet, traits
What follows mutant identification?
Mutations assigned to genes using complementation tests
Then, Functional analysis (e.g.) Where is the mutation located in the genome and what effect does it have at the molecular level?
The, expand to non-model organisms - reverse genetics and use genomic approaches
Then, Aim to identify the integration of the behaviors and the relevant morphological and physiological traits.
Complementation test?
If two separate recessive mutations that result in the same uncoordinated behavior
If they are 1) both present n a trans configuration and 2) the uncoordinated behavior is observed, then they are not complimentary and are alleles of the same gene.
But if the trans configuration results in wild type behavior then they are complimentary and are alleles of different genes.
Behavior of CRISPR protein?
1) Cuts genomic DNA resulting in random mutations or targeted mutations.
2) For random mutations there’s attempted DNA repair by cell which results in nonfunctional gene with random mutations.
3) For targeted mutations repair is guided by DNA template and results in gene with targeted mutation.
Use of CRISPR protein and its benefits?
Disrupts or introduces targeted mutations in human disease linked genes in mice.
Mice studied to see how each gene and mutation affects disease. - leading to drug cultivation.
Benefits:
Accelerates mouse models of multiple diseases
Enables studies sooner
Allows generation of models that at first were not feasible.
Features of phenotyping?
Phenotyping morphological traits is easier than identifying the phenotypes of behavioral mutants (plastic and quantitative traits).
However, when the mutant effect is manifested under a range of conditions it can result in the absence of a behaviour altogether.
Features of behavior?
Assumed to have evolved, and be adaptive
Can be plastic or stereotypical
Genes involved in its regulation
Can animals delay gratification?
Yes, it is a survival strategy.
Features of fear behavior?
Used in situations where mistake can be extremely costly or lethal
Fear behavior learned from observing behavior displayed in other animals.
Also through epigenetics
Phobias are genetically determined
Features (not all) of behavioral development from childhood
Behavior developmental abnormalities can be detected through mutations, brain damage or lesions
Multiple genes to explain variability in maternal care
Mothers capable of neglecting offspring but d not benefit from it - causes drop in offspring dopamine levels.
Oxytocin dictates social behavior and is mainly produced in pituitary gland
Cycle of oxytocin in maternal bonding?
- Hormonal changes
- Pup attachment
- Raise in Oxytocin
- Parental behavior
- Raise in oxytocin
- Increased parental behavior
- Increased social stimuli from mother
- Higher oxytocin levels in both mice.
What can parents lacking in the fosB gene mean?
They are not naturally urged to nurture their young
Role of serotonin during juvenile animal development?
Serotonin isolated in 1948 by Page and recognized as vasoconstrictor.
Chemical name: 5-hydroxytryptamine or 5-HT
Produced in pineal gland
Its a neurotransmitter
Occurs in other species
Excess serotonin molecules are taken back up by the presynaptic cell and reprocessed.
Raise serotonin through: exercise and healthy eating
Antidepressants block re-uptake of serotonin at presynaptic cells (Selective Seratonin Reuptake Inhibitor’s). E.g prozac.
-Found that: effect of prozac during mouse development leads to anxiety and depression in adult life - therefore use of SSRI medications in pregnant mothers and young children may pose unsuspected risks of emotional disorders later in life.
-In early life serotonin acts as a growth factor in the brain, modulating nerve cell growth, differentiation and migration. Interfering with this function can therefore have all sorts of consequences, including effects on behavior in later life.
Neurotransmitter?
Chemical messengers within the brain that allow the communication between nerve cells.
What does serotonin control in the body?
Appetite sleep memory and learning temperature regulation behavior cardiovascular function muscle contraction endocrine regulation mood
Three terms of social behavior?
Cooperation: a behaviour that provides a benefit to another individual (recipient), and the evolution of which has been dependent on its beneficial effect for the recipient.
Kin selection: process by which traits are favoured because of their beneficial effects on the fitness of relatives.
Altruism: a behaviour that is costly to the actor and beneficial to the recipient. Cost and benefit are defined on the basis of the lifetime direct fitness consequences of a behaviour.
When should social behavior evolve?
- Costs must outweigh the benefits depending on natural history and environment of species
- When cohesive behavior (grouping) provides greater net reproductive success than spacing behavior (dispersal). i.e. sociality must be adaptive, raising the inclusive fitness of its participants.
- Only where group size/structure is regulated to maximize net reproductive success relative to larger and smaller groups.
- When groups start to function as integrated units (teams)
What is greenbeard?
a hypothetical gene that causes in carriers both a phenotype that can be recognised by conspecifics (a ‘green beard’) and a cooperative behaviour towards conspecifics who show a green beard.
Evolutionary consequences of social behaviour?
Proportion of taxa in social groups is positively correlated with encephalization slope (relative brain size measure that is defined as the ratio between observed to predicted brain mass) in mammals.
Physiology of Social behavior?
Internal drivers of sociability - e.g. The non-steroid peptide hormones vasopressin and oxytocin play a role in the association of odour cues with social reward
External communication and manipulation - e.g. The organization of eusocial insect societies involves regulation of complex behaviours by hydrocarbon pheromones present on the cuticle.
Costs of Social behavior?
Increased individual competition for resources/mates
Increased disease risk
Interference with reproduction
Expensive neurological apparatus for monitoring group dynamics, particularly in mammals (i.e. the sensory demands of sociality).
Consensus costs (following group decisions)
Skew (only a few dominant individuals mate)
Benefits of social behavior?
Protection from physical environment Protection from predators Foraging/obtaining food Group defense of resources Finding mates Cooperative breeding Social learning and local culture Division of labour Greater learning opportunities for progeny
What is social learning?
Learning by observing others performing a task.
Groups can be manipulated into following particular foraging behaviors by “seeding “ with trained demonstrator individuals.
e.g. meerkats
What are local traditions?
The inheritance of an array of behavioral traditions through social learning from others.
e.g. blue-headed wrasse use the same mating sites on coral reefs over many generations but, if removed, new fish will use different sites.
Models for learning?
Imprinting Habituation Sensitisation Conditioning (associate learning) Social learning (observational learning)
Example of social learning?
Food avoidance in rats, they only eat a bit of their food so they don’t die if its poisoned.
Define public information?
Any feature that other animals can perceive such as signals, health status, mating condition and size.
Example of local tradition?
Humpback whale innovation of slapping the sea surface to refine predation spread over two decades to create a new tradition in others.
Co-operative breeding in social groups have 2 forms.
Helper-at-den: Only alpha individuals breed, helpers are usually related, helping raises inclusive fitness
Communal Breeding: Subordinates can breed, but reproductive success correlates to position in hierarchy, which is often heritable
These alternatives seem to be obligate in some species but vary in others and appear to be correlated to group size.
Levels of co-operation in breeding?
Low cost:
Indirect provisioning (sharing food)
Increased vigilance
High cost: Direct provisioning (lactation and regurgitation) Physical defense
Kin selection?
Process by which traits are favoured because of their beneficial effects on the fitness of relatives.
Altruism?
A behavior that is costly to the actor and beneficial to the recipient. Cost and benefit are defined on the basis of the lifetime direct fitness consequences of a behavior.
Altruism threatened idea of natural selection.
Inclusive fitness?
The total fitness of an animals consists of its direct fitness (own reproduction) as well as the additional reproduction of is its relatives arising from its help.
Hamilton’s rule?
An altruistic act will spread due to kin selection if:
rB > C
Where:
r = coefficient of relatedness of the actor to the recipient
B = benefits to the recipient
C = costs to the actor
Types of altruism?
Kin selection: Helping a relative increases the individuals inclusive fitness.
Mutualism (instant reciprocity): Helping or working together may have immediate benefits. Mopping behaviour in birds or defense behaviour in bisons, true mutualisms.
Manipulation: Appears like altruism, but the helper is in fact being manipulated. For instance, in brood parasitism.
Reciprocal altruism: An individual help now with the expectation of being helped in return later.
Reciprocal altruism?
Mostly occurs between unrelated individuals when there will be repayment of the altruistic act in the future.
Game theory?
Method of analyzing the evolution of phenotypes (including types of behaviors) when the fitness of a particular phenotype depends on its frequency in the population.
Can reveal ESS’s (evolutionary stable strategies), i.e., behaviours (phenotypes) associated with optimal fitness that cannot be invaded by another strategy.
Tit for Tat?
The best strategy when two individuals interact sequentially, i.e., first cooperate and then do what the partner did last.
Eusocial species? Features?
Some animals within groups pay the very high cost of lifetime sterility; these animals spend their lives working for others and gain reproductive benefits only if their relatives reproduce. e.g naked mole rat.
Many eusocial species are coordinated by pheromones
1. Distinct castes or reproductive division of labour (with or without sterile castes)
2. Living in colonies with overlapping generations
3. Cooperative care of young
Eusocial castes of leafcutter ants?
Minims: Tiny ants that take cares of fungus garden and brood
Minors: Scouts and solders, patrol terrains
Mediae: Generalised foragers, cut and bring back leaves
Majors: The large soldier caste
Social recognition and is levels?
Social recognition is the ability to classify or individually recognize members of a social group. - Cooperation often requires that an animal can identify the targets of its behavior. Levels: Species recognition Gender recognition Social group recognition Individual recognition Kin recognition
Phenotype matching?
When an animal learns its own phenotype, or the phenotype of animals around it, and then used that information to classify previously unmet individuals.
Levels of sociality?
Simplest social groups are often families
Expanded by additional generations
Kinship groups
Larger aggregations, troops, colonies, clans, etc.
Potential perspectives of social structures?
Traditional demographics: age and gender (e.g. group composition)
Social hierarchies: matriarchal (including eusociality), patriarchal, etc. (e.g. reproductive partitioning)
Levels of connectedness: social networks (e.g. information exchange)
SNA?
SNA is a mathematical technique for analysing social relationships and the patterns and implications of these relationships.
Methods of social climbing?
Aggression e.g. female hyenas, male gorillas Coalition e.g. lions Look/sound good e.g. many primates Manipulation e.g. us Sex e.g. bonobos Patience (e.g. inherit territory)
Features of dominance hierarchies?
Dominance rank relationships are transitive within families and highly asymmetrical within dyads, such that older, larger females consistently dominated smaller, younger females.
Determinants of group size?
Basic group size model. Fitness costs associated with group size and the asterisk indicates the optimal group size
If food scarcity increases intragroup competition large groups suffer disproportionately.
If food scarcity primarily increases intergroup competition, small groups suffer disproportionately
Relationship of socially transmitted behavior in primates?
The enhanced reliance on socially transmitted behavior observed in some primates has coevolved with enlarged
brains, complex sociality, and extended lifespans.
This coevolution is consistent with the hypothesis that the evolution of large brains, sociality, and long lifespans has promoted reliance on culture, with reliance on culture in turn driving further increases in brain volume, cognitive abilities, and lifespans in some primate lineages.
What determines cohesion in social systems?
Ecological circumstances and group interactions determine the dispersal/non-dispersal threshold.
Types of parental care? Process oriented types?
Biparental care
Uniparental care by the female OR male
Cooperative (helpers in addition to parents)
No care
Depreciative care (decreasing with brood size) Non-depreciative care (independent of brood size)
Decisions for raising offspring?
When? (sperm storage, gestation period, hatching dynamics, etc.)
Where? (nesting, carrying, leading, ignoring, etc.)
Alone or with company? (mother only, father only, both parents, social group, territory, etc.)
How many and how often? (e.g. semelparity vs. iteroparity, r-selected vs k-selected)
Parental care? (oviparity vs viviparity )
Level of dependence? (altricial vs precocial? Both are one day old)
Staying or going? (Progeny disperse or remain -
cooperative breeding)?
Options of animals for when to give birth?
Pre-zygotic - e.g - Sperm storage: Yellow dungflies store sperm from about three males in three separate spermathecae.
Post zygotic - e.g - Gestation/incubation period/Hatching dynamics (e.g. bet-hedging)/Post-hatching/parturition/emergence
Hatching asynchrony
What is bet hedging?
Organisms suffers decreased fitness in their typical conditions in exchange for increased fitness in stressful conditions.
Features of nesting?
Nests chose based on.
Pros - Protection, liberation of parents and control of natal microclimate (e.g. temperature-dependent sex determination in reptiles
Cons- Nest sites may not be ideal locations for maximal foraging success
Repeated occupancy increased risk of ectoparasites on young
- Nests may need active defense, maintenance, supporting territories, etc. Risk of brood parasites.
- Siblicide and infanticide.
- Limited resources resulting in intraspecific and interspecific competition.
Monogamy?
Each individual mates exclusively with one partner.
Life-long (but often not exclusive)
Equal post-embryonic investment in progeny
Polygamy.
Individuals mate with more than one partner
Polygyny?
One male mates with many females.
Polyandry?
One female mates with many males..
Polygynandry?
Species varies strategy e.g. dunnock.
Promiscuity?
multiple mating by both sexes.
Components of parental care?
Feeding: Delivering food to progeny
guiding progeny to food
Protecting: Shelter and defence against biotic and physico-chemical components of environment
Teaching: Threats, foods, shelter, geography, social/communication skills, etc.
Intra and inter-specific adoptions?
Giving parental care to a genetically unrelated animal Results in, Misdirected parental care Kin selection Milk evacuation Doesn't result in, Reciprocity and parenting hypothesis
Biparental care?
Both parents help to raise offspring.
Common in birds.
Uniparental care?
Only one parent raises the offspring.
Often found in mammals (female), fish (sometimes males) and some invertebrates (females).
Cooperative care?
Helpers (related or non-related) help parents raise the offspring.
Found in birds, mammals (female) and insects.
No parental care?
Offspring are left to their own devices
Most often in egg-laying animals – Amphibians, reptiles and invertebrates.
Depreciative care?
Care that declines in value as the number in the brood increases. E.g. food is often shared unevenly in brood, for example in great tits.
Non-depreciative care?
independent of brood size. E.g. protection from predators, for example in ducks.
What care are birds, mammals and fish associated with?
Birds: Bi-parental care (monogamy)
Mammals: Uni-parantal care – females (polygyny)
Fish: varied (polygamy)
Three theories of parental care?
Paternity certainty
Order of gamete release
Association
Paternity certainty theory?
Trivers (1972) suggested that certainty is increased with external fertilisation. Male has increased drive to care for young.
Less certain with internal fertilisation & male more likely to desert. Sperm competition
Desertion can only be favoured if reproductive success is not compromised.
External fertilisation though does not guarantee paternity e.g. stickleback - sneaking male strategy
Order of gamete release theory?
Dawkins and Carlisle (1976) suggested with external fertilisation, the female has first opportunity to desert.
36 out of 46 species that have simultaneous gamete release and mono-parental care have care given by male.
Also in some families males build foam nests and releases sperm prior to egg deposition.
Association theory?
Williams (1975) hypothesises simple association with parental care.
With internal fertilisation, the female is closest associated with the young (she often carries the young or has to lay the egg).
With external fertilisation, eggs are generally in male territory therefore parental care may be an incidental by-product of territoriality.
Indeed male parental care is most common in territorial fish.
Constraint of parental care?
Proposed by Lack - Limit to how much parent can look after offspring. Also parents can clash. Parents can expend too much energy on care and die to a predator.
Opposing factors to successful parenting?
Male x Female: Battle of the Sexes New males: Infanticide and the Bruce Effect Parent-Offspring Provisioning vs rationing Sibling Rivalry Siblicide
Determining when parental care stops?
Parent and offspring are expected to disagree over how long the period of parental investment should last and over the amount of parental investment that should be given.
In general, parent-offspring conflict is expected to increase during the period of parental care, and offspring are expected to employ psychological weapons in order to compete with their parents.
Conflict in some species, including the human species, is expected to extend to the adult reproductive role of the offspring
Life history traits? And its features?
Concept to describe a species or population’s reproductive strategies. And have implications in terms of fitness and energetics.
-Age at first reproduction
Number of offspring in a clutch
Number of clutches in a lifetime
etc.
-The life history traits affect species’ decision on how much time, energy and other resources are given to progeny
Life history and parental investment in K and R adapted species?
K-adapted species: e.g. Wolves, elephants, whales and primates Long life Slower growth Late maturity Fewer large offspring High parental care and protection High investment in individual offspring Adapted to stable environment Later stages of succession Niche specialists Predators Regulated mainly by intrinsic factors High trophic level/climax species
R-adapted species: Insects, rodents, parasites and annual plants Short life Rapid growth Early maturity Many small offspring Little parental care or protection Little investment in individual offspring Adapted to unstable environment Pioneers, colonizers Niche generalists Prey Regulated mainly by extrinsic factors Low trophic level/pioneer species
Territoriality and features?
Territories are spatial regions, defended against conspecifics, for the purpose of using resources and providing mating opportunities
Benefit: Exclusive access to resources (food, mates, nesting sites, etc.)
Cost: Defence
Why have a territory?
Breeding, feeding, security, familiarity, etc.
e.g. Clutch size correlated to territory quality in magpies
Who defends a territory?
Males
Females
Pairs
Kinship groups
Larger social groups
Home range?
That area traversed by an individual in its normal activities of food gathering, mating and caring for young.
Territorial animal?
When occupying space involves marking and defending a given area, the animal is said to be territorial.
- By scent marking the locations that an animal visits, it conveys to a potential intruder that the area is claimed by another animal.
- Once an intruder encounters a foreign scent, it typically retreats from it to avoid an aggressive response by the resident animal. This is the so-called mechanism of conspecific avoidance.
Parameters controlling territory?
The average territory size, i.e. the inverse of the population density
The time span during which animal scent marks remain active.
How do we map territory?
Direct observation
Mapping traces e.g. scats
Camera traps
Radiotelemetry & satellite tracking
What territorial information can we map?
Size and shape
Spacing
Patch quality
Resource availability
Signs of territory on a map?
Dots: locations collected for this individual during the sampling period.
Outermost line: territory boundary.
Shaded areas: core areas for this particular individual.
What is required to fully understand spatial behavior in animals?
Measure of altitude of territory, so can map animals territory’s longitude, latitude and altitude.
Costs of sexual reproduction?
Fitness and survival
Sexually transmitted diseases
Sexual antagonistic conflict/Intersexual conflict
Sperm and eggs are both costly to produce
Loss of mating (EPC) - EPC = Extra-Pair Copulations
Death
Reduced life span - Drosophila
Coercion in ducks
Predation - Most antelope species have very quick copulation
Disease related costs of sexual reproduction?
Feline Immunodeficiency Virus (FIV, related to HIV)
Canine transmissible venereal tumour (always found on the genitalia)
Sexually transmitted mites in ladybirds
Bacteria Chlamydia as a factor to the decline and long-term viability of affected koala
Sexual antagonistic conflict/Intersexual conflict?
- Intralocus sexual conflict –when there are sex-specific optima for a trait that is expressed in both sexes and when the constraint of a shared gene pool prevents males and females from reaching their optima independently
- Thus, alleles that reduce fecundity when expressed in females spread in the population because of their benefits in selfish males
- Males in their semen give out anti- aphrodisiacs preventing the female from wanting to mate again.
- Males will try to increase the amount of energy the female puts into the offspring.
Passing of alleles in sexual and asexual reproduction?
Asexual – all alleles are passed to offspring.
Sexual – half alleles passed on.
Effect of habitat stability on sex?
Stable habitats favor asexual reproduction
Unstable (unpredictable) habitats favor asexual reproduction
Genetic recombination theory?
Beneficial mutations from separate ancestries can be combined.
- Beneficial mutations can be separated from harmful mutations.
- Unsuccessful genetic traits can easily disappear from an existing population.
- Less than one in four offspring will receive the best genetic traits from BOTH parents.
- However Natural Selection is very good at eliminating the least successful variations
- Remember only a few offspring will survive anyway.
True or false? Sexual reproduction provides an evolutionary advantage in parasite rich environments?
True.
Muller Ratchet theory?
In small asexual populations without recombination, deleterious mutations will accumulate leading to loss of fitness and extinction.
Depends on mutation rate, ability to repair and gene conversion mechanisms
Parthenogenesis?
asexual reproduction without any required participation from males, as the development of offspring from unfertilised egg.
Increased Rate of Evolution theory?
- Evolution generally favours organisms that evolve quickly (i.e. those that mutate quicker)
- However, mutations are more often harmful than not.
- But with sexual reproduction, beneficial mutations can be separated from harmful ones so less damage is done (i.e. the most successful survive) while maintaining a high rate of mutation.
- With asexual reproduction it takes so long for beneficial mutations to accumulate in the population that if sexual selection had not evolved, life would probably not have evolved past the bacterial stage.
Sharing of beneficial mutations theory?
Even bacteria that reproduce by binary fission, will also exchange genetic material (via plasmids and pili - conjugation).
Beneficial mutations can be shared.
Evolution generally favours any mutation that increases the drive to find sexual partners.
This leads to the vast range of behaviors.
Define a male and a female?
Male: produces small, motile gametes called sperm. Males produce large numbers of sperms with small investment in each
Female: produces small, motile gametes called eggs. Females produce small numbers of eggs with large investment in each.
Hermaphroditism?
When an animal has both male and female organs/gametes
They tend to swap sperm in order to fertilise each other
Many (especially marine) invertebrates.
Why two sexes?
- When sex does evolve, two sexes are favoured because that is the easiest way to prevent competition between the organelles of the parents.
- An organism’s organelles (i.e mitochondria and epigenetic material) are all acquired from its mother.
- If some were to be inherited from each parent, the two sets of genetically identical organelles would compete to be passed on to the offspring’s offspring.
What does natural selection favour?
Favours production of the rarer sex, so sex ratio is usually balanced at 1:1
Polygynandry?
Species varies mating strategy.
Natural selection?
Process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Sexual selection?
Promotes traits that will increase an organism’s mating success.
Forms of sexual selection?
Intersexual: member of one sex chooses mate based on particular characteristics (mate choice).
Intrasexual: members of one sex compete over partners with the winner performing most of the mating.
Monogamy?
May range from a breeding season to a life time: - Genetic Monogamy (only reproduces with one partner ever). Social Monogamy (pair bonding)
Animal Examples: Black Vulture, White Cheeked Gibbons, Kirk’s Dikdik & Laysan Albatross (in courtship dance to strengthen pair bonds).
Resource defense polygyny?
The male defends a territory that centres on a resource needed for breeding success.
The quality of the territory determines the size of his harem.
Polygyny threshold model?
Female decision about whether to be a secondary female in a good territory or sole female in a poorer territory.
Polyandry?
One female mate with multiple males
Classical Polyandry - sexes-roles reversal
Cooperative Polyandry – 2 or more males are associated with one female
Why may classic polyandry have come about?
Female bigger and defend males Females carry out infanticide Males may become ‘pregnant’ Unusual situations e.g. energy constraints and clutch losses.
