IMPORTANT COMPONENTS OF ANIMAL BEHAVIOR

Stimulus characteristics

Motivation of the animals

Causality of different orders

Ultimate reasons inclusive fitness and survival; evolutionary adaptive functions

Why do birds sit on their eggs? BEHAVIOR

This is what animal do

It is the way in which an organism adjust to and interact with its environment

Everything animals do have functions and should promote inclusive fitness and survival

Behavior covers a wide range of activities including self-oriented and other oriented activities

Branches of animal behavior Ethology- study of behavior under natural environment with emphasis on

evolution and phylogenetic relationship Comparative pyschology- this focuses more on the principles of associative

learning with basic underlying interest on the internal control (via learning) in humans

Neurobiology- the interest is based on the underlying immediate and proximate mechanism of the NS rather than the whole functional and units of behavior, or the ultimate with evolutionary considerations

Physiological psychology- concerns more with the proximate causes of behavior with interest on human behavior

Proximate, or how, questions about behaviour

- focus on the environmental stimuli that trigger a behavior. -Focus on the genetic, physiological, and anatomical mechanisms

underlying a behavioral act. - Those that focus on the immediate stimulus and mechanism for

the behavior.

LEVEL OF ANALYSIS IN THE STUDY OF ANIMAL BEHAVIOR

PROXIMATE Genetic developmental mechanism Effect of heredity Development of sensory-motor system via gene-

environment interaction Sensory motor

Nervous system for detection of stimuli Hormone system Skeletal system

Ulimate, or why, questions about behaviour - focus on the evolutionary changes (i.e., both the evolutionary

history and changes which may be initiated by the present behavior) - Those that explore how the behavior contributes to survival and

reproduction.

LOGIC OF NATURAL SELECTION

Variations exists members of species differ in their characteristics (of a phenotypic trait among individuals in the same population)

Heredities..parents pass on some of their distinct characters to their offspring ("like begets like"--or, phenotypic differences are produced in part by genetic differences)

Differential reproduction because of distinctive characters, some individuals within a population have more surviving offspring than others (different phenotypic variants have differing probabilities of survival and reproduction)

Darwinian Evolution - differential reproductive success modifies genotypic frequencies in a

manner that in principle may be predicted given knowledge of circumstances

LOGIC Populations tend to have high reproductive potentials () Populations tend to be stable in size () Environments tend to possess limited resources ()

Differential reproductive success leads to a decline in frequency of genotypes that underlie phenotypes that are less fit to the environment

Differential reproductive success also results in a corresponding increase in frequency of genotypes that underlie phenotypes that are more fit to the environment

More specifically, differential reproductive success based on phenotypic differences is Natural Selection

NATURAL SELECTION

An evolutionary process of elimination of spread of beneficial ones as the natural consequences of hereditary variation

Evolutionary change always promote successful reproduction by the individuals

Trait unfavorable to reproduction are eliminated occurs through an interaction between the environment and the

variability inherent among individual organisms making up a population

The product of natural selection is the adaptation of populations of organisms to their environment

Natural selection removes variation from populations; it is not a source of variation (mutation is the ultimate source of genetic variation within populations)

differential reproduction of genotypes. Darwin's Theory (evolutionary theory)

Darwin's theory of evolution has four main parts: Organisms have changed over time, and the ones living today are

different from those that lived in the past. Furthermore, many organisms that once lived are now extinct. The world is not constant, but changing. The fossil record provided ample evidence for this view.

All organisms are derived from common ancestors by a process of branching. Over time, populations split into different species, which are related because they are descended from a common ancestor. Thus, if one goes far enough back in time, any pair of organisms has a common ancestor. This explained the similarities of organisms that were classified together -- they were similar because of shared traits inherited from their common ancestor. It also explained why similar species tended to occur in the same geographic region.

Change is gradual and slow, taking place over a long time. This was supported by the fossil record, and was consistent with the fact that no naturalist had observed the sudden appearance of a new species. [This is now contested by a view of episodes of rapid change and long periods of stasis, known as punctuated equilibrium].

The mechanism of evolutionary change was natural selection. This was the most important and revolutionary part of Darwin's theory

The Process of Natural Selection

Parents possessing certain traits that enable them to survive and

reproduce will contribute disproportionately to the offspring that make up the next generation

Why Genetics Matters for the study of Behavioral Biology

1. Evolutionary issues -Viewing behavior as a phenotypic feature that evolves by natural selection presupposes a genetic basis for behavioral traits

2. Mechanistic issues on Genes, because of their role in the development of the neural machinery underlying behavior, need to be examined as one of the causal bases of behavior

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Genetic thinking Animals do things because they have the necessary genetic information How We Study the Role of Genes in Producing Behavioral Differences Among Individuals

Isolation experiment -If behavior develops normally in the absence of environmental factors that might have shaped it, then we can conclude that genes provided adequate instructions

Comparing relatives -Behavioral example: height and IQ in humans -Regression of offspring trait values on parental trait values gives measure of "heritability" -Monozygotic (MZ) (identical) twins: Twins that share the same sperm and egg. -Dizygotic (DZ) (fraternal) twins: Twins that have different sperm and egg.

Genetically they are no more alike than any other two siblings.

Hybridization studies -Cross individuals expressing different phenotypes -Single-locus case (e.g., Mendel's peas): two distinct phenotypes continue to be seen in individuals descending from hybrids -Multilocus case (far more common for behavioral traits) -Trait results from action of many genes of small effect -Hybrids are typically intermediate in phenotype between the parents

Artificial selection A response to selection is evidence of heritable variation

Molecular approaches: deletion or mutation of single genes -Mutation produced by radiation, chemical agents, or P-element insertion Screen mutated populations to find phenotype that differs distinctly from the norm -Use genetic and molecular methods to isolate gene involved, and study how it exerts its effect -Examples: learning speed in fruit flies and mice, song rhythms and circadian rhythms in flies, etc. Pitfalls in inferring role of single genes in behaviour

How many genetic differences are needed to produce a difference in behavior?

Single gene effects the single nucleotide translates into a single amino acid difference in the long chain of amino acids that constitute the protein encoded by the gene

Single gene experiments are facilitated by gene knockout Gene knockout-genetic technique in which one of an organisms

genes are made inoperatives (knocked out of organism) Genomic Imprinting- epigenetic phenomenon by which certain

genes can be expressed in a parent-of-origin-specific manner Instinct

a conventional vehicle for the non-rational elements of behavior

as irrational and compelling sources of conduct that oriented the organism towards its goal

fixed-action patterns (FAP), which are characteristics of species and largely genetically determined

FAP is motivated by action-specific energy

The relationships IRM and sign stimulus

the recognition of sign stimulus and the resulting response to it are inborn and characteristics of species

IRM has the role of releasing response to the sign stimulus

the response released by IRM is stereotyped Three important components: innate IRM is the releaser of response to sign stimuli the response released by IRM is stereotyped and part of FAP

FAP versus Reflexes FAP Reflex -released by a variety of stimuli - released by specific stimuli -with motivation -no motivation -without external stimuli -with

Imprinting any kind of phase-sensitive learning (associated with the critical

period) that is rapid and independent of the consequences of behavior.

It was first used to describe situations in which an animal or person learns the characteristics of some stimulus, which is therefore said to be "imprinted" onto the subject.

Irreversible process, innate but the object of imprinting is not innate filial imprinting

-in which a young animal learns the characteristics of its parent ( e.g., incubator-hatched geese egg by Konrad Lorenz) -begins in the womb ( parents voice)

Sexual imprinting is the process by which a young animal learns the characteristics of a desirable mate

The famous psychologist John Money called it the lovemap. Westermarck effect

Reverse sexual imprinting when two people live in close domestic proximity during the first few years in the life of either one, both are desensitized to later close sexual attraction

Kin recognition -animals' abilities to distinguish between close genetic kin and non-kin. In evolutionary biology and in psychology, such capabilities are presumed to have evolved to serve the adaptive functions of kin altruism and inbreeding avoidance Habituation

It is an example of non-associative learning in which there is a progressive diminution of behavioral response probability with repetition of a stimulus.

. An animal first responds to a stimulus, but if it is neither rewarding nor harmful, the animal reduces subsequent responses.

Sensitization non-associative learning in which the progressive amplification of a

response follows repeated administrations of a stimulus (Bell et al., 1995).

An everyday example of this mechanism is the repeated tonic stimulation of peripheral nerves that will occur if a person rubs his arm continuously. After a while, this stimulation will create a warm sensation that will eventually turn painful. The pain is the result of the progressively amplified synaptic response of the peripheral nerves warning the person that the stimulation is harmful.

Associative learning the process by which an element is learned through association

with a separate, pre-occurring element. Operant conditioning/instrumental learning

the use of consequences to modify the occurrence and form of behavior Operant conditioning is distinguished from Pavlovian conditioning in

that operant conditioning deals with the modification of voluntary behavior.

Classical conditioning (Ivan Pavlov) Classical conditioning involves repeatedly pairing an unconditioned

stimulus (which unfailingly evokes a particular response) with another previously neutral stimulus (which does not normally evoke the response).

Following conditioning, the response occurs both to the unconditioned stimulus (US) and to the other, unrelated stimulus

Unconditioned Stimulus (US): a stimulus that has the ability to produce a specified response before conditioning begins. (FOOD)

Unconditioned Response (UR): the response produced by the US. (Salivation by food)

Conditioned Stimulus (CS): an initially neutral stimulus that comes to produce a new response because it is associated with the US. (BELL)

Conditioned Response (CR): the response produced by the CS (Salivation by bell)

Spontaneous Recovery Following extinction, the CR reappears at reduced strength if the CS is presented again after a rest period.

Presentation of UCS.- greater strength of CS-withholding the UCS- gradual disappearance of CR (extinction of behavior)

If CS is paired again with the reinforcement (UCS)- CR reappear more rapidly than did the original conditioning (spontaneous recovery)

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Repeated application of stimulus often results in decreased responsiveness (habituation)

Positive conditioning -employing beneficial of positive reinforcer (e.g., food). The presentation of the UCS (food) following the bell (CS) reinforces the conditioned reflexes Negative conditioning -UCS alone elicits response: eg., tone of music (CS)- provide air puff (UCS)- blink- removal of the air puff and tone of music alone would elicit blinking LAW OF EFFECTS A RESPONSE FOLLOWED BY A REWARDING OR SATISFYING STATE OF AFFAIRS WOULD INCREASE IN PROBABILITY OF OCCURRENCE, WHILE A RESPONSE FOLLOWED BY AVERSIVE OR ANNOYING CONSEQUENCES WOULD DECREASE THE PROBABILITY OF OCCURRENCE. -thorndike 1913 Instrumental Conditioning

Instrumental (Operant) Conditioning a form of learning in which a reinforcer (e.g., food) is given only if the animal performs the instrumental response (e.g., pressing a lever). In effect, what as to be learned is the relationship between the response and the outcome.

Operant (R) according to Skinner, in instrumental response; a behavior that is emitted to receive the reinforce Discriminative Stimulus (SD) a stimulus (e.g., a tone, light, a behavior) that sets the occasion for the operant response to be performed in order to receive the reinforcer.

The SD signals a particular relationship between the instrumental response and the re-inforcer

A discriminative stimulus can also be a signal that the instrumental response will not currently deliver the reinforcer (S)

Contingent a relation between two events in which one is dependent upon another (the animal must press the lever for food to be delivered) Reinforcement (SR) the procedure by which

the instrumental response is made contingent upon some sought-after outcome Three-Term Contingency the relationship between the SD , the R and the SR; the SR can then serve as the SD for a different three term contingency Types of Learning Positive Reinforcement any stimulus the presentation of which strengthens the behavior upon which it is made contingent. (e.g., lever pressing for food) Negative Reinforcement any (aversive) stimulus the withdrawal of which strengthens the behavior. (e.g., lever pressing to terminate or escape shock) Positive Punishment any (aversive) stimulus the presentation of which weakens a behavior. (e.g., spanking a child for misbehaving) Negative Punishment any stimulus the withdrawal of which weakens a behavior. (e.g., taking candy from a child for misbehaving) Insight learning - "highest form" of learning observed.

-It is the ability to problem solve or to perform a correct or appropriate behavior the first time the animal is exposed to a situation.

MEMORY - the mental capacity or faculty of retaining and reviving facts, events, impressions, etc., or of recalling or recognizing previous experiences. three storage systems:

Sensory Memory: -retains an exact copy of what is seen or heard (visual and auditory). -lasts for a few seconds, while some theorize it last only 300 milliseconds -has unlimited capacity.

Short-Term Memory (STM) -Selective attention determines what information moves from sensory memory to short-term memory - most often stored as sounds, especially in recalling words, but may be stored as images.

Long-Term Memory -This is relatively permanent storage -Information is stored on the basis of meaning and importance

HORMONES AND BEHAVIOR GLANDS

Exocrine Release chemicals into ducts which carry them to their targets.

Sweat glands, for example. Endocrine Ductless. Release hormones directly into the circulatory

system.

Only organs whose primary function is hormone release are referred to as endocrine glands

Hormones Amino acid derivatives

Epinephrine, for example (adrenal medulla) Peptides and proteins

Short and long chains of amino acids Steroids

Synthesized from cholesterol (fat) Fat-soluble able to enter cells and bind to receptors in cytoplasm or nucleus

Master gland or Pituitary Gland Posterior pituitary hormones synthesized in the hypothalamus Anterior pituitary tropic hormones

Tropic hormones- influence the release of hormones by other glands Sex Steroids released by Gonads

Androgens - e.g., testosterone (more in adult testes) Estrogens - e.g., estradiol (more in adult ovaries) Progestins progesterone prepares uterus and breasts for

pregnancy (also present in both sexes) Adrenal cortex also releases sex steroids What determine sex? dimorphic exist in 2 forms

Initially there is a primordial gonad

Cortex potential to be ovary

Medulla potential to be a testis If XY, Y triggers the synthesis of H-Y antigen and promotes

development of the medulla Testis-determining factor (TDF), also known as sex-determining

region Y (SRY) protein, is a DNA-binding protein encoded by the SRY gene that is responsible for the initiation of male sex determination in humans

Sexual Development

6-weeks post-conception: Gonads develop

H-Y antigen > testes

No H-Y antigen > ovaries Both sexes begin with 2 sets of reproductive ducts

Wolffian system male seminal vesicles, vas deferens

Mullerian system female uterus, vagina, fallopian tubes Differentiation occurs in the 3rd prenatal month

3rd prenatal month: differentiation of ducts

Testes produce testosterone and Mullerian-inhibiting substance

Wolffian system develops, Mullerian degenerates, testes descend

No testes no testicular hormones

Mullerian system develops, Wolffian degenerates

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External reproductive structures genitalia develop from one

bipotential precursor -Differentiation occurs in 2nd month -Testosterone > male -No testosterone > female

Estradiol- masculinizes the brain

Puberty

Fertility achieved, secondary sex characteristics develop

Features that distinguish sexually mature men and women

Development determined by relative levels of androgen and estrogen

Increase in release of anterior pituitary hormones

Growth hormone acts on bone and muscle

Gonadoptrophic hormone

Adrenocorticotrophic hormone Androstenedione androgen necessary for the growth of axillary

and pubic hair in both sexes

Puberty defines a period of sexual maturation resulting from activation of the hypothalamic-pituitary-gonadal axis

Characterised by pulsatile secretion of gonadotropin-releasing hormone (GnRH)

Most obvious features are: - development of secondary sexual characteristics

- and attainment of acceleration of growth When acceleration of growth occurs, boys greater than girls:

- average 9.0cm/year (boys) - average 7.1cm/year (girls)

Hypothalamus: GnRH synthesised Pituitary: GnRH relsed to Pituitary gland to

signal synthesis and secretion of pituitary gonadotropins LH and FSH

Blood-borne LH and FSH act on target cells in testes and ovaries - direct production of sperm and eggs - secrete steroid hormones

Gonadal steroids vital for gonadal function and reproductive behaviour

In gonads: steroid hormones participate in spermatogenesis and follicle maturation

In brain: steroids influence GnRH secretion and facilitate sexual behaviour

FSH stimulates spermatogenesis in males and ovulation in females. LH stimulates Testosterone secretion in males and estrogen

secretion in females. It is Testosterone and estrogen that underpin the physical changes

that occur during puberty. Puberty usually begins at 11 13 years in females and 12 14 years

in males. Fertility in males occurs before completion of puberty, not case in

females

Hormone-Behavior Relations in the Regulation of Parental Behavior

Parental behavior evolved to supplement physiological mechanisms of reproduction--increasing the likelihood that the offspring will survive.

Different patterns of parental behavior In females, hormones of pregnancy synchronize several events:

reproductive tract: stimulate uterine contractions (parturition or childbirth)

mammary gland: stimulate production and secretion of milk (lactation)

central nervous system: stimulate parental behavior

Link: oxytocin--maternal behavior--social bonds In males, hormonal changes are not strongly linked to parental

responses Two main patterns of parental behavior based on developmental status of young: Leading-Following Pattern:

species with precocial newborn: young that are quite mature at birth--young have vision, hearing, locomotive ability, and the ability to achieve thermoregulation

parental care is limited--young depend on mother for food (may include nursing) and protection, but soon after birth young can feed themselves

in many instances, the mother leads the young who follow her Avian species: chickens and ducks (10% avian species) Mammalian species: ungulates (sheep, cows), guinea pigs, whales

Clinging-Carrying Pattern: species with semialtricial/semiprecocial newborn: young are

considered intermediate in development compared to altricial and precocial species; typically, young can hear and see, but require assistance in locomotion

parental care involves transportation (young will cling to mother or be carried by her), feeding (nursing), thermoregulation and protection

Avian species: gulls and terns (10% avian species)

nestbuilding is minimal, young are fairly mobile and parents feed young special food which is often regurgitated

Mammalian species: most primate species (including humans)

female rat as a model Broad overview (hormone in parental behavior):

events that occur with mating, fertilization and the start of pregnancy

events that occur during pregnancy (22 gestation period in the rat) events that occur at the end of pregnancy:

parturition

lactation

maternal behavior

aggressive behavior

postpartum estrus Ovulation:

as follicles develop in ovary

increasing levels of estrogen are released

in female rats, increases in estrogen lead to a GnRH surge (positive feedback)

GnRH surge leads to LH surge

LH surge leads to ovulation

Formation of the Corpus Luteum Not Spontaneously Functional:

corpus luteum will not form unless female engages in copulation

Ex: rats critical stimulus--vaginocervical stimulation (e.g., intromissions) insertion of penis into vagina by male during mating will stimulate a

neuroendocrine reflex in the female leading to release of PRL which then acts to form the corpus luteum

corpus luteum will secrete progesterone mating, fertilization and the start of pregnancy:

a female rat has gone through a spontaneous estrous cycle

increased estrogen lead to a GnRH surge, LH surge and ovulation

increased estrogen followed by a preovulatory rise in progesterone stimulated proceptive and receptive behaviors--female mated with a male rat (multiple eggs are released and fertilized by sperm leading to development of several embryos)

intromissions associated with mating activated a neuroendocrine reflex leading to formation of the corpus luteum

prolactin maintains the corpus luteum

LH stimulates production of progesterone from corpus luteum (smaller amounts of estrogen)

estrogen: important for preparing uterus for implantation

progesterone: important for implantation of embryo into uterine wall and maintenance of pregnancy

placenta is a high vascularized organ that allows nutritive substances and gases in mothers blood to diffuse to embryo and a mechanism for metabolic wastes to leave developing embryo; placenta can also produce hormones

Events that occur during pregnancy: pregnancy lasts approximately 22 days in the rat (gestational

period) progesterone: levels rise shortly after mating and are elevated

throughout pregnancy until near parturition (end of pregnancy) estrogen: levels are relatively low during first half of pregnancy, but

rise significantly during the second half of pregnancy

midway through pregnancy (days 12-13), regulation of ovarian hormone secretion switches from Moms anterior pituitary to the placenta

LH (released from Moms pituitary) is replaced by chorionic gonadotropin

PRL (released from Moms pituitary) is replaced by placental lactogen

species differences in terms of when, and if, this switch takes place

mammary glands must develop to provide milk for nursing (lactation)

full development of the mammary glands requires hormones and stimulation of the nipples and genital region

hormonal control:

progesterone stimulates proliferation of secretory cells located in the alveoli of mammary gland

estrogen stimulates duct development (carry milk from secretory cells to nipple)

prolactin (placental lactogen) stimulates synthesis of milk by secretory cells

at parturition, with nursing of young, oxytocin (from Moms posterior pituitary) will stimulate release of milk (milk-letdown)

at parturition, with nursing of young, prolactin (from Moms anterior pituitary) will rise and stimulate milk synthesis

somatosensory control:

during pregnancy, the female rat will lick her ventral body region (nipples and genital region)

this sensory input is critical for normal development of mammary glands

Exp. #1: if you block the ability of a female to lick her ventral region by fitting her with a collar so that she cant lick her body, mammary development will be significantly impaired (50% of normal development on day 21)

Exp. #2: if you take another group of collared females (that cannot lick themselves), and stimulate them with a brush along the nipples and genital region, you can stimulate full mammary development

Events that occur at the end of pregnancy: levels of progesterone drop levels of estrogen remain elevated levels of prolactin rise These hormonal events (and others) signal the end of pregnancy,

initiate labor (parturition), and initiate maternal behavior and maternal aggression.

In addition, the process of giving birth--uterine-cervical-vaginal stimulation--stimulates postpartum estrus:

8-11 hours after parturition, females will be sexually receptive and will mate

18 hours after parturition, ovulation occurs and the female can become pregnant (although implantation is delayed while female engages in nursing)

2 phases to maternal behavior: hormonal phase:

decrease in progesterone, increase in prolactin with elevated levels of estrogen

hormonal changes are important for the initiation of maternal behavior

however, once maternal behavior has been initiated, removal of the ovaries, adrenal gland, pituitary and placenta will not affect behavior (i.e., removal of gonadal steroids and peptide/protein hormones present within bloodstream)

nonhormonal phase:

a transition occurs in which maintenance of maternal behavior depends on stimuli received from young (pups): suckling by pups at nipple, visual stimuli, auditory stimuli (crying)

neurocircuits within the brain that process somatosensory, visual, auditory information can feed into, and stimulate, neurons within MPOA to stimulate maternal behavior

transition period last approximately one week following parturition

COURTSHIP Basic differences between males and females in terms of gamete production

operational sex ratio--this is number of sexually receptive males to recpeptive females (this is biased to males hence induces competition)

Parental investments--expenditures of time, energy, and risks by parents on offspring that reduce a chance of parents to produce more (parental trade-off)

-Sex role reversal once the pattern of parental investment is reversedthe operational sex ratio becomes biased to females -The concept of male pregnancy, sexual reversal Do not reproduce sexually every generation

these include aphids, parasitic wasps, mites, certain crustaceans, the majority of vascular plants, and many others.

Never reproduce sexually These include several whiptail lizards Cnemidophorus sp., many

geckos, the stream fish Pocelliopsis sp., many snails, a great many fungi and protozoa.

One entire animal phylum never reproduces sexually the bellidoid rotifers (small freshwater invertebrates) never

reproduce sexually. Pseudocopulation- in at least 6 of 15 unisexual whiptail lizards Sex is expensive

Sexual displays and rituals can be enormously expensive in terms of energy, time, and resources.

Example: male bower birds in Australia spend weeks constructing enormous bowers, which they decorate with found objects, solely for the purpose of attracting mates.

Female water striders are ridden by the males after copulation, sometimes for many hours. This process interferes with the foraging of females and places them at increased risk of some forms of predation.

Sex is dangerous Seeking mates is dangerous for many species:

Example; tree frogs in Central America call to attract mates. Females are strongly attracted to the calls, it is much easier to get a mate if a frog invests a lot of time calling.

Carnivorous bats are also attracted to the calls. They come in on the calling male and pluck them right off of the tree.

Calling crickets suffer a similar situation. Calling males are much more attractive, but parasitic flies home in on the sound and deposit their eggs into singing males.

Sexual selection is natural selection imposed on individuals based on their ability to obtain mates.

It is a pervasive and important mechanism of evolution in all sexual species.

The idea was first proposed by Charles Darwin, in The Descent of Man

He saw it as antagonistic to natural selection, though nowadays, it is usually viewed as one more aspect of selection.

Two Basic Mechanism Male competition is the process by which males compete with each

other for access to females. (stag beetles) Female choice is selection imposed by females when choosing

males as mates. Sexual Dimorphism, a difference in appearance or behavior between the two sexes, is frequently due to sexual selection.

It can also be due to differing selective pressures between the two sexes-I.e., males increase their fitness by obtaining more mates and females increase their fitness by laying more eggs.

Intra-Sexual Selection This arises when the member of one sex compete for mates

Inter-Sexual Selection Females choosing males (usually); female as the choosier sex determine which member of the other sex will have chance to mate

Mate Choice Genetic, intelligence, wealth, health

Good parent theorysome females prefer males capable of more intense or more varied courtship stimulation, also tactile stimulation

Healthy mate theory male courtship and displays inform females about the health conditions of the potential mate

Good genes theorythe displays and courtship provide information on character related with viability-promoting genes

Runaway selection theory this proposes that females can acquire sperms with genes whose primary effects is to influence their daughter to prefer attractive males, and endow their sons with attributes attractive to females

Alternative mating strategies

Satellite mating Sneak copulation Male mimics female Develop friendship with either males or females The use of pre-ejaculated sperms for insemination (eg., among

iguanas) Mating systems

Monogamythis exists where each breeding adult is mated to anyone member of the opposite sex

Polygamythis is the state in which an individual has two or more mates; there 2 forms: polyandry and polygyny

Polyandrythis occurs when a female mates with several males Polygyny where males mates with several females

e.g. California elephant seals defend territories on the beach. They mate with all the females in their territories.

Lek system this exists where males assemble in a concentration to which females come to mate. In this case, breeding males occupy a central position and are surrounded by a number of satellite males

Note that in polygynous species, the male does not generally

provide anything toward parental care.

Even in resource-based systems, he is basically monopolizing a resource she needs, and protecting it from males, he does not create or provide it.

Thus, males can potentially mate with many females. Male fitness is proportional to the number of mates.

The basic inequality between the sexes is increased, since the female provides all the parental care. Females do not

benefit from more mates because their fitness is limited by time and resources.

In these systems, there is strong sexual selection on males to obtain more mates.

MONOGAMY AMONG MAMMALS--among menstrual cyclic versus estrous cyclic

Mate assistance monogmy this is practiced by carnivores than herbivores

Female-enforced monogamyprevalent among carnivorous than herbvivores